104. Nuclear and Multimodality Imaging: Anomalous Coronary Arteries & Myocardial Bridges

CardioNerd Amit Goyal is joined by Dr. Erika Hutt (Cleveland Clinic general cardiology fellow), Dr. Aldo Schenone (Brigham and Women’s advanced cardiovascular imaging fellow), and Dr. Wael Jaber (Cleveland Clinic cardiovascular imaging staff and co-founder of Cardiac Imaging Agora) to discuss nuclear and complimentary multimodality cardiovascular imaging for the evaluation of abnormal coronary anatomy including anomalous coronary arteries and myocardial bridges. Show notes were created by Dr. Hussain Khalid (University of Florida general cardiology fellow and CardioNerds Academy fellow in House Thomas). To learn more about multimodality cardiovascular imaging, check out Cardiac Imaging Agora!

Collect free CME/MOC credit just for enjoying this episode! 


Show Notes & Take Home Pearls

Five Take Home Pearls

  1. Anomalous coronaries are present in 1-6% of the general population and predominantly involve origins of the right coronary artery (RCA). Anomalous origination of the left coronary artery from the right sinus, although less common, is consistently associated with sudden cardiac death, especially if there is an intramural course. Sudden cardiac death can occur due to several proposed mechanisms: (1) intramural segments pass between the aorta and pulmonary artery making them susceptible to compression as the great vessels dilate during strenuous exercise; (2) an acute angle takeoff of the anomalous coronary can create a “slit-like” ostium making it vulnerable to closure. Anomalous left circumflex arteries are virtually always benign because the path taken behind the great vessels to reach the lateral wall prevents vessel compression.
  2. Myocardial bridging (MB) is a congenital anomaly in which a segment of the coronary artery (most commonly, the mid-left anterior descending artery [LAD]) takes an intramuscular course and is “tunneled” under a “bridge” of overlying myocardium. In the vast majority of cases, these are benign. However, a MB >2 mm in depth, >20 mm in length, and a vessel that is totally encased under the myocardium are more likely to be of clinical significance, especially if there is myocardial oxygen supply-demand mismatch such as with tachycardia (reduced diastolic filling time), decreased transmural perfusion gradient (e.g. in myocardial hypertrophy and/or diastolic dysfunction), and endothelial dysfunction resulting in vasospasm.
  3. PET offers many benefits over SPECT in functional assessment of MB including the ability to acquire images at peak stress when using dobutamine stress-PET, enhanced spatial resolution, and quantification of absolute myocardial blood flow. For pharmacologic stress in evaluation of MB, we should preferentially use dobutamine over vasodilator stress. Its inotropic and chronotropic effects enhance systolic compression of the vessel, better targeting the pathological mechanisms in pearl 2 above that predispose a MB to being clinically significant.
  4. CCTA can help better define the anatomy of MB as well as anomalous origination of the coronary artery from the opposite sinus (ACAOS), help with risk stratification, and assist with surgical planning.
  5. Instantaneous wave-free ratio (iFR) measures intracoronary pressure of MB during the diastolic “wave-free” period – the period in the cardiac cycle when microvascular resistance is stable and minimized allowing the highest blood flow. This allows a more accurate assessment of a functionally significant dynamic stenosis than fractional flow reserve (FFR) – which can be falsely normal due to systolic overshooting.
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Detailed Show Notes

  1. What are some examples of abnormal coronary anatomies and how often do they lead to clinical events?
    • Abnormal coronary anatomy can relate to the origin (e.g. anomalous origination of coronary artery from the opposite sinus [ACAOS]), course (e.g. myocardial bridging [MB]), intrinsic properties (e.g. aneurysm or hypoplasia), or termination (e.g. fistula) of the coronary artery. In this episode and in these notes, we examine MB and ACAOS in more detail. For an excellent case discussion of anomalous left coronary artery from the pulmonary artery (ALCAPA) by the team from Massachusetts General Hospital, listen to CardioNerds Podcast Episode 81!
    • MB –Myocardial Bridging
      • MB is a congenital anomaly in which a segment of the coronary artery (most commonly, the mid-left anterior descending artery [LAD]) takes an intramuscular course and is “tunneled” under a “bridge” of overlying myocardium.
      • MB was originally identified at autopsy by Reyman in his dissertation, “Disertatio de vasis cordis propriis “ in 1737. In the largest subsequent autopsy study by Risse et al. involving 1056 patients, MB was demonstrated in 26% of patients.
      • Because it is so prevalent, it is difficult to determine its clinical significance. In most patients, MB is an incidental finding with an excellent survival rate (97% at 5 years); however, there are associations with myocardial ischemia, infarction, stress cardiomyopathy, arrhythmia, and sudden cardiac death (SCD).
      • MB can generally be classified into two subtypes: a “superficial” variant which represents 75% of cases and a “deep” variant in which the LAD deviates towards the right ventricle (RV) and dives into the intraventricular septum. The overlying muscle bundle in the deep variant is typically at an oblique or transverse angle resulting in twisting of the tunneled segment and more commonly compromised coronary flow.
      • One of the longest MB usually occurs in association with ACAOS! In this case, the left coronary artery comes off the right coronary cusp. The Left Main (LM) is around 3-4x longer in this instance and dives into the interventricular septum and takes a trans-septal course behind the pulmonary artery before emerging on the other side.
      • There is increased prevalence in certain patient populations: hypertrophic cardiomyopathy (HCM), patients with spontaneous coronary artery dissection (SCAD) +/- fibromuscular dysplasia (FMD), and heart transplant recipients
    • ACAOS – anomalous origination of coronary artery from the opposite sinus
      • Anomalous coronaries are present in 1-6% of the general population and predominantly involve the origin of the right coronary artery (RCA)
      • Anomalous origination of the left coronary artery from the right sinus, although less common, is consistently related to SCD. Separate studies have shown the incidence of SCD may be as high as 23% or 59% of cases in athletes under the age of 20 years.
      • In a large Armed Forces Institute of Pathology (AFIP) study of 6.3 million military recruits, the autopsies of recruits who suffered nontraumatic deaths over a 25-year period were reviewed and ACAOS was found to be the most common cause. It accounted for 33% (64 of 126) of nontraumatic deaths and all cases involved a left coronary artery with an interarterial course.
  1. What features predispose MB or ACAOS to become clinically significant? What is the pathophysiology behind development of ischemia in those with clinically significant MB or ACAOS?
    • MB – myocardial bridging
      • Given the majority of MB is benign, correlating MB  as causative in myocardial ischemia and its consequences has been a diagnostic challenge.
      • In systole, the portion of the artery that is tunneled under the MB (bridge segment) is compressed. This can manifest clinically as angina, acute coronary syndrome, left ventricular (LV) dysfunction, arrhythmias, and SCD. However, the majority of myocardial perfusion occurs in diastole which is why MB is usually benign. Nonetheless, certain conditions in patients with MB can set up an oxygen supply-demand mismatch severe enough to lead to myocardial ischemia:
        • Exercise-related stress  leads to tachycardia which can decrease diastolic filling time for the coronary arteries and lead to more of the cardiac cycle to be spent in systole
        • Myocardial hypertrophy and diastolic dysfunction can affect the transmural perfusion gradient increasing supply-demand mismatch. Furthermore, LV hypertrophy can compress the microvasculature and reduce the microvascular reserve.
        • Endothelial dysfunction (driven by metabolic changes secondary to hypoxia) can contribute to coronary compression and lead to the development of accelerated atherosclerosis and/or coronary vasospasm (leading to compression of the epicardial coronary artery throughout the cardiac cycle, not just during systole)
        • There has been a recognized multiplier-effect described by Klues et al. in which the greater the degree of systolic narrowing of the MB, the greater the reduction in diastolic vessel diameter. This is also associated with increased retrograde flow in the coronary artery (which not only reduces perfusion but can introduce shear wall stress and predispose to plaque formation) and reduced flow reserve.
        • Myocardial ischemia can also occur due to “branch steal.” The LAD may have septal perforators that arise from the tunneled segment. When there is compression of the vessel under the MB, there can be “steal” from these septal branches due to the Venturi effect. The septal branches are essentially depressurized because as the vessel narrows, velocity increases but the fluid (coronary blood flow) exerts less pressure. Thus, mild to moderate MB severity typically demonstrates septal ischemia (due to branch steal) rather than distal ischemia downstream from the compression.
        • The vessel segment proximal to the bridge appears to develop atherosclerosis at increased rates approaching 90% — likely as the sequela of shear stress. In contrast, the tunneled segment of the artery is usually spared of atherosclerosis because:
          1. The intima is significantly thinner with a higher prevalence of contractile cells (thought to be negatively associated with development of atherosclerotic lesions)
          1. There is a lack of foam cells (lipid-laden macrophages that are important components of atherosclerosis)
          1. There is reduced expression of known vasoactive agents such as nitric oxide synthase, endothelin-1, and angiotensin-converting enzyme
    • ACAOS – anomalous origination of coronary artery from the opposite sinus
      • The mechanism of ischemia for ACAOS with an interarterial course (between the pulmonary artery and the aorta) and specifically an intramural course has not fully been determined. An intramural course refers to the proximal part of the epicardial coronary artery being contained within the aortic wall and sharing the aortic wall media without a separating adventitia. There are several proposed mechanisms for why this anatomic setup can lead to myocardial ischemia.
        • Compression of the vessel between the aorta and the pulmonary artery during intense exercise as the great vessels dilate
          1. The pulmonary artery likely needs to be enlarged secondary to concomitant pulmonary hypertension for this to occur
          1. An anomalous left circumflex is almost never clinically significant because the path it takes behind the great vessels to reach the lateral wall means the vessel is not exposed to compression!
        • Anacute angle takeoff of the coronary artery, which shares a common wall with the aorta, can result in a significantly narrowed coronary artery ostium (e.g., “slit-like”). This is even further narrowed during exercise when the great vessels expand.
        • Marked narrowing of the intramural segment due to hypoplasia of the intramural segment
  1. What is the role of nuclear imaging in the evaluation of MB or ACAOS?
  • MB – myocardial bridging
    • In general, nuclear imaging evaluation of MB has had mixed results, and available studies generally have smaller sample sizes and most are retrospective. Prior studies — predominantly involving exercise SPECT — have shown that reversible ischemia may be present in patients with MB and systolic compression of the vessel >50% or >75%. However, other studies in similar populations have shown that reversible ischemia was not inducible in patients with MB with similar degrees of systolic compression of the vessel. There are very few studies available assessing the utility of PET stress testing in patients with MB. One prior study demonstrated that PET stress testing revealed decreased myocardial perfusion reserve in patients with MB, although this was with adenosine rather than dobutamine stress (more on this below).
    • In patients who are symptomatic and have full encasement of the epicardial artery or a deep course seen on coronary CTA, it is reasonable to pursue functional testing, either noninvasive or invasive. Otherwise, we shouldn’t pursue functional testing as the overwhelming majority of MB are benign.
    • Rest/Stress myocardial perfusion imaging with PET has certain advantages over SPECT:
      • Improved spatial resolution
      • Ability to acquire stress images at peak stress if using dobutamine (versus lag time with SPECT)
      • Absolute myocardial blood flow quantification with PET (not available with SPECT where perfusion is relative)
      • With PET we can use either Rubidium-82 (half-life = 76 sec) or N-13 Ammonia (half-life = 10 min) as tracers to assess myocardial perfusion. If using dobutamine as the stress agent, either tracer can be injected at peak stress for the stress imaging. However, if we are using exercise as the stress agent, the patient must be transferred from the treadmill to the camera for stress image acquisition. Because of the time it takes to transfer, Rb-82 cannot be used for exercise PET; it’s half-life is so short (76 sec), it will be gone by the time images are acquired! Therefore, if using exercise PET, you must use N-13 Ammonia PET.
    • When picking a stress agent, remember the goal is to look for significant mechanical compression that leads to coronary ischemia. Therefore, a vasodilator (e.g., adenosine or regadenoson) would be inappropriate. Rather we need to increase chronotropy and inotropy to simulate mechanical compression and can use either dobutamine or exercise.
      • NOTE – If the patient has a resting significant mid ventricular or left ventricular outflow gradient (as occasionally seen in HCM) and/or is pacer-dependent, dobutamine and exercise may increase the LVOT gradient and compromise hemodynamics. Rather, consider rapid atrial pacing or other pharmacologic stress in these patients.
    • Dobutamine or exercise echocardiography are alternatives to nuclear imaging.
      • Since MB is often studied in younger patients and since younger patients generally have rapid heart rate recovery, if using exercise as a stressor, consider supine bicycle rather than treadmill so that stress TTE images may be acquired prior to HR recovery for increased sensitivity.
  • ACAOS – anomalous origination of coronary artery from the opposite sinus
    • The 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease state that in patients w/ ACAOS with either left coronary artery arising from the right sinus or right coronary artery arising from the left sinus, ischemic symptoms or ischemia during functional testing is a Class I indication for surgery.
    • After identification of ACAOS, it is reasonable to consider functional testing with nuclear imaging, however the sensitivity of this approach is not yet known. Also, the intense physical exertion that usually results in SCD in these patients is usually not achieve with standard stress tests, so the sensitivity of these tests are difficult to judge. The risks/benefits of functional nuclear imaging should be addressed with patients  in shared decision making with the patient.
    • A number of case reports have described inducible ischemia on myocardial perfusion imaging in patients with ACAOS. This may provide additional justification for surgical intervention.
      • Dr. Wael Jaber (our excellent podcast expert guest on this episode!) as part of the group with Cremer et al. demonstrated in a retrospective study of 27 patients with anomalous take-off of the RCA from the left coronary sinus (AAORCA) that patients with typical angina and exertional dyspnea had a significantly higher rate of demonstrable ischemia on an exercise N13-ammonia positron emission tomography (PET) protocol compared to patients without symptoms. The large majority (11/12) of the patients who underwent surgery had demonstrable ischemia on the above protocol. There were no deaths at 245 days in either the conservative management group or those who underwent surgery. Evidence of ischemia on exercise N13-ammonia positron emission tomography (PET) protocol in patients with may identify patients with AAORCA who would benefit from surgical vs. conservative management.
  1. What is the role of coronary CTA (CCTA) in the evaluation of MB or ACAOS?
  • Cross-sectional imaging with CCTA is crucial in the assessment of MB and ACAOS for both identifying the abnormality and risk stratification.
  • MB – myocardial bridging
    • CCTA has increased the detection of MB from ~5% on invasive coronary angiography to ~21% – much closer to what has been identified on autopsy studies.
    • CCTA can help risk stratify by:
      • Quantifying the depth (>2mm considered clinically significant)
      • Quantifying the length (>20 mm considered clinically significant)
      • Observing the degree of encasement (more fully encased considered clinically significant)
      • Detect concurrent atherosclerosis (particularly proximal to the MB)
      • If there are high risk features and corrective surgery is planned, the anatomical information provided by the CCTA is useful for surgical planning.  NOTE – If depth >5 mm and/or length >25 mm, CABG is preferred over myotomy as risks of myotomy is considerable in these circumstances!
  • ACAOS – anomalous origination of coronary artery from the opposite sinus
    • CCTA is endorsed by the European Society of Cardiology (ESC) as the first-line diagnostic imaging in known or suspected coronary artery anomalies. The American Heart Association (AHA) Committee on Cardiovascular Imaging provides a IIa recommendation for CCTA or MRI in the evaluation of anomalous coronary arteries.
    • CCTA can help risk stratify patients by identifying anatomic features that confer a higher risk of SCD:
      • Slit-like orifice of the coronary ostium
      • Acute angle of origin
      • Intramural segment: identification of an intramural segment is physiologically important (as discussed above), but also guides treatment. These patients can be potentially treated by coronary unroofing, unlikepatients with intraarterial course and no intramural segment
    • Some general considerations for CCTA evaluation:
      • Low heart rate is needed to optimize image quality. We commonly accomplish this by giving beta blocker and/or ivabridine.
      • Consider strategies to minimize radiation exposure as able (e.g., in ACAOS we can use prospective gating in which we choose only to image in a certain prespecified phase of the cardiac cycle rather than the whole cardiac cycle as done in retrospective gating)
    • To avoid radiation exposure and iodinated contrast administration with CCTA, cardiac MRI can be considered
      • Additionally, you can obtain concomitant assessment of ventricular size, function, shunt, perfusion, and viability
      • This comes at the expense of decreased spatial resolution, long examination time necessitating significant patient cooperation, and artifact and incompatibility (sometimes prohibitive) from pacemaker or other metallic implants
  1. What is the role of left heart catheterization in the evaluation of MB and ACAOS?
  • MB – myocardial bridging
    • Coronary angiography is useful for identifying MB, but is less sensitive than CCTA. Altogether, MB identified by coronary angiography may be more severe than those identified by CCTA, as the mechanical compression must be severe enough to be noticed angiographically. However, a majority of even these bridges have a benign natural history. Therefore, additional risk stratification may be obtained invasively to understand the functional significance of a MB. This can be obtained by combining invasive coronary angiography with tools such as instantaneous wave-free ratio (iFR) and intravascular ultrasound (IVUS).      
    • Fractional flow reserve (FFR) is the gold-standard for invasive assessment of intermediate fixed coronary stenoses and correlates with outcomes. iFR has been shown to be non-inferior to FFR.
    • However, FFR has not been validated in the assessment of dynamic compression, as with myocardial bridging. In dynamic compression, iFR offers some notable advantages over FFR:
      • In FFR we are checking the average of the blood pressure and flow over the whole cardiac cycle — systole and diastole. Because of systolic compression in MB, there is a spurious increase in the intracoronary systolic pressure that may yield a falsely normal FFR value — this is known as systolic pressure overshooting
      • In iFR, on the other hand, we are measuring intracoronary pressure during the diastolic “wave free” period — the period in the cardiac cycle when microvascular resistance is stable and minimized allowing the highest blood flow. This gives a more accurate assessment of functionally significant dynamic stenosis
      • iFR is considered positive if it is < 0.89. The grey zone in iFR studies is >0.86 and <0.93, so ideally, we want < 0.86 for a more definitive true positive.
      • Pre- and post-invasive intervention with dobutamine stress iFR testing in addition to relief of symptoms can help guide when to recommend to patients to return to exercise after an invasive intervention on the MB. IVUS imaging shows a highly specific “Half Moon” sign associated with MB—it is unclear why this happens. We can utilize assistance of provocative testing (dobutamine, acetylcholine, rapid A-pacing) to further assess the change in the vessel structure under stress
    • The Myocardial Bridge Study, led by Dr. Joanna Ghobrial, is an ongoing prospective study looking to correlate functional testing of MB (invasive and non-invasive) and long-term clinical outcomes.
  • ACAOS – anomalous origination of coronary artery from the opposite sinus
    • Similar to in MB, iFR and IVUS are emerging tools utilized to help risk stratify patients with ACAOS
    • IVUS with concurrent dobutamine stress testing can allow for dynamic assessment of anomalous coronary arteries both at rest and under stress. The effects of physiologicor pharmacological stress on the morphology of the intramural segment of an interarterial coronary can provide additionaldata to guide which patients may warrant surgery – particularly patients with anomalous take-off of the right coronary artery from the left coronary sinus (in which surgical intervention is more controversial).

Detailed Show Notes

Guest Profiles

Wael Jaber, MD, is a staff cardiologist in the Section of Cardiovascular Imaging, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, at the Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute at Cleveland Clinic. Dr. Jaber specializes in cardiac imaging (both nuclear cardiology and echocardiography) and valvular heart disease. Dr. Jaber attended college at the American University in Beirut, graduating with a Bachelor of Science in biology. He then went on at the American University to receive his medical degree while making the Dean’s honor list. He completed his residency in internal medicine at the St. Luke’s-Roosevelt Hospital Center at Columbia University College of Physicians and Surgeons, where he also completed fellowships in cardiovascular medicine and nuclear cardiology. Dr. Jaber is currently is the Medical Director of the Nuclear Lab and of the Cardiovascular Imaging Core Laboratory in C5Research. He is fluent in English, French and Arabic. He is the author of Nuclear Cardiology review: A Self-Assessment Tool and cofounder of Cardiac Imaging Agora.

Dr. Aldo L Schenone is one of the current Chief Non-Invasive Cardiovascular Imaging Fellows at the Brigham and Women’s Hospital. He completed medical school at the University of Carabobo in Valencia, Venezuela, and then completed both his Internal Medicine residency and Cardiology fellowship at the Cleveland Clinic where he also served as a Chief Internal Medicine Resident.

Dr. Erika Hutt @erikahuttce is a cardiology fellow at the Cleveland Clinic. Erika was born and raised in Costa Rica, where she received her MD degree at Universidad de Costa Rica. She then decided to pursue further medical training in the United States, with the goal of becoming a cardiologist. She completed her residency training at Cleveland Clinic and went on to fellowship at the same institution. Her passions include infiltrative heart disease, atrial fibrillation, valvular heart disease and echocardiography among many. She is looking forward to a career in advanced cardiovascular imaging.


References and Links

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2.         Angelini P, Villason S, Chan AV, et al. Normal and anomalous coronary arteries in humans.In: Angelini P, ed. Coronary Artery Anomalies: A Comprehensive Approach. Philadelphia: Lippincott Williams & Wilkins; 1999:27–150.

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4.         Admin CL. Return to Play and Sports Cardiology. In: Clinic C, ed. Tall Rounds2020: http://consultqdlive.mediaspace.kaltura.com/media/t/0_ivale2zp/75663251..         

5.         Cremer PC, Mentias A, Koneru S, et al. Risk stratification with exercise N(13)-ammonia PET in adults with anomalous right coronary arteries. Open Heart. 2016 2016;3(2):e000490.

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7.         Erbel R, Rupprecht H-J, Ge J, Gerber T, Görge G, Meyer J. Coronary artery shape and flow changes induced by myocardial bridging: assessment by intravascular ultrasound. Echocardiography 1993;10:71–7.

8.         Escaned J, Cortés J, Flores A, et al. Importance of diastolic fractional flow reserve and dobutamine challenge in physiologic assessment of myocardial bridging. J Am Coll Cardiol 2003;42:226–33.

9.         Gawor R, Kuśmierek J, Płachcińska A, et al. Myocardial perfusion GSPECT imaging in patients with myocardial bridging. J Nucl Cardiol. Dec 2011;18(6):1059-1065.

10.       Götberg M, Christiansen EH, Gudmundsdottir IJ, Sandhall L, Danielewicz M, Jakobsen L, Olsson SE, Öhagen P, Olsson H, Omerovic E, Calais F, Lindroos P, Maeng M, Tödt T, Venetsanos D, James SK, Kåregren A, Nilsson M, Carlsson J, Hauer D, Jensen J, Karlsson AC, Panayi G, Erlinge D, Fröbert O; iFR-SWEDEHEART Investigators. Instantaneous wave-free ratio versus fractional flow reserve to guide PCI.N Engl J Med. 2017; 376:1813–1823

11.       Hakeem A, Cilingiroglu M, Leesar MA. Hemodynamic and intravascular ultrasound assessment of myocardial bridging: fractional flow reserve paradox with dobutamine versus adenosine. Catheter Cardiovasc Interv 2010;75:229–36.

12.       IGe J, Erbel R, Rupprecht HJ, et al. Comparison of intravascular ultrasound and angiography in the assessment of myocardial bridging. Circulation 1994;89:1725–32.

13.       Kanwal A, Sha AB. Myocardial Bridging in Adults. 2020. https://www.acc.org/latest-in-cardiology/articles/2020/08/04/08/48/myocardial-bridging-in-adults.

14.       McCray LC, Fogwe DT, Aggarwal K, Karuparthi PR. Novel Assessment of Ischemia in Patients With Anomalous Right Coronary Artery. JACC: Case Reports. 2019;1(5):819-822.

15.       Lee MS, Chen C-H. Myocardial bridging: an up-to-date review. J Invasive Cardiol                   2015;27:521–8.

16.       Lim JC, Beale A, Ramcharitar S, Medscape. Anomalous origination of a coronary artery from the opposite sinus. Nat Rev Cardiol. Oct 2011;8(12):706-719.

17.       Lin S, Tremmel JA, Yamada R, et al. A novel stress echocardiography pattern for myocardial bridge with invasive structural and hemodynamic correlation. J Am Heart Assoc. Apr 2013;2(2):e000097.

18.       Monroy-Gonzalez AG, Alexanderson-Rosas E, Prakken NHJ, et al. Myocardial bridging of the left anterior descending coronary artery is associated with reduced myocardial perfusion reserve: a. Int J Cardiovasc Imaging. Feb 2019;35(2):375-382.

19.       Sen S, Asrress KN, Nijjer S, Petraco R, Malik IS, Foale RA, Mikhail GW, Foin N, Broyd C, Hadjiloizou N, Sethi A, Al-Bustami M, Hackett D, Khan MA, Khawaja MZ, Baker CS, Bellamy M, Parker KH, Hughes AD, Francis DP, Mayet J, Di Mario C, Escaned J, Redwood S, Davies JE. Diagnostic classification of the instantaneous wave-free ratio is equivalent to fractional flow reserve and is not improved with adenosine administration. Results of CLARIFY (Classification Accuracy of Pressure-Only Ratios Against Indices Using Flow Study).J Am Coll Cardiol. 2013; 61:1409–1420

20.       Stout KK, Daniels CJ, Aboulhosn JA, et al.2018 ACC/AHA Guideline for the managementof adults with congenital heart disease: AReport of the American College of Cardiology/American Heart Association Task Force onClinical Practice Guidelines. Circulation 2019;139:e698–800

21.       Tarantini G, Barioli A, Nai Fovino L, et al. Unmasking Myocardial Bridge-Related Ischemia by Intracoronary Functional Evaluation. Circ Cardiovasc Interv. 06 2018;11(6):e006247.

22.       Tarantini G, Migliore F, Cademartiri F, Fraccaro C, Iliceto S. Left Anterior Descending Artery Myocardial Bridging: A Clinical Approach. J Am Coll Cardiol. Dec 2016;68(25):2887-2899.

23.       Uusitalo V, Saraste A, Knuuti J. Multimodality Imaging in the Assessment of the Physiological Significance of Myocardial Bridging. Curr Cardiol Rep. Jan 2016;18(1):2.

87. Case Report: Giant Coronary Aneurysm Presenting with Heart Failure – University of Hawaii

Aloha! CardioNerds (Amit Goyal & Karan Desai)  join University of Hawaii cardiology fellows (Isaac Mizrahi, Nath Limpruttidham, Nishant Trivedi, and Shana Greif) for some shaved iced on the Big Island’s north shore! They discuss a fascinating case of a patient presenting with decompensated heart failure found to have a giant coronary aneurysm. Program director Dr. Dipanjan Banerjee provides the E-CPR as well as a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Tommy Das with mentorship from University of Maryland cardiology fellow Karan Desai.  

Jump to: Patient summaryCase mediaCase teachingReferences

Aloha! CardioNerds (Amit Goyal & Karan Desai)  join University of Hawaii cardiology fellows (Isaac Mizrahi, Nath Limpruttidham, Nishant Trivedi, and Shana Greif) for some shaved iced on the Big Island's north shore! They discuss a fascinating case of a patient presenting with decompensated heart failure found to have a giant coronary aneurysm. Program director Dr. Dipanjan Banerjee provides the E-CPR as well as a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Tommy Das with mentorship from University of Maryland cardiology fellow Karan Desai.
Episode graphic by Dr. Carine Hamo

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Patient Summary

A man in his early 60s with history of hypertension, peripheral arterial disease, atrial fibrillation, and AAA s/p repair presented with subacute fatigue, palpitations, shortness of breath, and lower extremity edema. On exam he was warm and well perfused, though hypotensive, tachycardic with an irregular rhythm, and had an elevated JVP. ECG showed AF with RVR without evidence of acute MI, and troponin was negative. TTE revealed a reduced LVEF and WMA in the inferolateral walls with akinesis of the basal mid septum; additionally, two large extracardiac structures were noted, one with heterogenous echotexture in the AV groove, and a second with an echolucent interior adjacent to the RA.  

The patient underwent coronary angiography, showing a dilated and calcified proximal LAD with high grade stenosis adjacent to the first septal perforator, a ectatic LCX that supplied left to right collaterals, and a giant RCA aneurysm with TIMI 0 flow distally. CCTA confirmed these findings, showing thrombosed aneurysms of the LAD, LCX, and RCA. Interventional cardiology and cardiac surgery both evaluated the patient’s case, and determined that he was not a candidate for intervention. He was ultimately diuresed to euvolemia with significant improvement in symptoms, and plans to follow-up as an outpatient for heart transplant evaluation.  


Case Media

A. CXR
B. ECG: atrial fibrillation with RVR, left axis deviation, poor r wave progression
C. Wide complex tachycardia
D. CT chest demonstrating giant aneurysm

TTE
Coronary Angiography

Episode Schematics & Teaching

Coming soon!


The CardioNerds 5! – 5 major takeaways from the #CNCR case

1) This case featured a patient with a giant coronary aneurysm – how are coronary artery aneurysms defined and classified?  

  • Coronary artery aneurysms (CAA) are defined as a focal dilation of a coronary segment at least 1.5x the adjacent normal segment. Contrast this with coronary artery ectasia, which refers to a diffuse, as opposed to focal, coronary dilation.  
  • CAA morphology can be classified as either saccular (transverse > longitudinal diameter) or fusiform (transverse < longitudinal diameter). 
  • Giant CAA’s are >20mm in diameter. 
  • Aortocoronary saphenous vein graft aneurysms have distinct characteristics and natural history compared to native coronary aneurysms. These aneurysms tend to present late (e.g., > 10 years following CABG) and tend to be larger than native CAA. 
  • IVUS can help differentiate between a true aneurysm with preserved integrity of all 3 vessel layers (intima, media, and adventitia) and a pseudoaneurysm with loss of wall integrity and damage to the adventitia. 

2) Now that we have the language to define and classify coronary artery aneurysms, what are some causes these lesions?  

  • Atherosclerosis: lipid deposition, focal calcification, and fibrosis can weaken the vessel wall and predispose to subsequent coronary artery dilation. Up to 50% of CAAs are linked to arteriosclerosis.  
  • Autoimmune/inflammatory processes: Lupus and systemic vasculitis, such as Kawasaki’s disease and Takayasu arteritis, can all lead to CAAs. Vasculitic CAAs usually affect more than one artery.  
  • Connective Tissue Disease: Marfan’s syndrome and Ehlers-Danlos disease, for instance, are characterized by deficiencies in vessel wall integrity, leading to CAAs. 
  • Dynamic Wall StressEpisodic hypertension and vasoconstriction, such as that seen in frequent cocaine use, can lead to wall stress, endothelial damage, and coronary artery aneurysms.  
  • Direct Vessel Wall Injury: Intracoronary interventions, such as angioplasty, stent delivery, and brachytherapy, can cause shear wall stress that leads to CAAs.  
  • Infectious Causes: Direct vessel wall invasion or immune complex deposition can be seen in bacterial, mycobacterial, fungal, and syphilitic infections. Septic emboli from infectious endocarditis can also lead to mycotic coronary aneurysms.  
  • Genetic susceptibility: Certain HLA class II genotypes are susceptible to CAAs. This may be the underlying pathology in certain idiopathic and congenital CAAs.  

3) How do coronary artery aneurysms clinically present? 

  • Most CAAs are asymptomatic, and are found incidentally on coronary angiography or CCTA.  
  • Concomitant obstructive arteriosclerosis can cause angina or plaque rupture, and thrombosis in the aneurysm lumen can lead to distal embolization and myocardial infarction.  
  • Massive enlargement of CAAs and saphenous vein graft aneurysms can compress adjacent structures. 
  • CAA rupture is rare, though can cause cardiac tamponade.  
  • Stress-induced myocardial ischemia can also occur due to microvascular dysfunction  

4) How do we diagnosis and assess CAAs? 

  • Most CAAs are evaluated via coronary angiography, though a complete angiographic evaluation can be complicated by delayed antegrade contrast filling, segmental back flow, and contrast stasis. In giant aneurysms, a forceful and prolonged contrast injection is needed to avoid misinterpreting slow aneurysmal filling as thrombosis.  
  • IVUS can help differentiate between true aneurysms, pseudoaneurysms, and coronary segments with aneurysmal appearance due to plaque rupture or stenosis. Furthermore, IVUS can assist in sizing aneurysm and planning for potential PCI.  
  • Coronary CTA noninvasively allows for a more accurate assessment of aneurysm size and degree of thrombus than angiography. CCTA is particularly useful in patients with giant CAA as it can provide an understanding of mechanical complications of these aneurysms.  

5) How are coronary artery aneurysms managed?  

  • Notably, there is a lack of randomized and large-scale trial data to guide the treatment of CAAs; most recommendations are made on the basis of small case series and expert opinion.  
  • Medical Management: Given the association between CAA and arteriosclerosis, risk factor modification should be emphasized. The role of antiplatelet and anticoagulant agents is an area of ongoing debate, though there may be benefit in patients with multivessel ectasia. Furthermore, the context in which the patient presents (e.g., incidental finding vs. acute coronary syndrome) will guide the antiplatelet and/or anticoagulant strategy.  
  • Invasive (Percutaneous) Management: PCI of an aneurysmal vessel in the setting of acute MI is associated with lower rates of procedural success, and higher rates of distal embolization and no-reflow phenomenon. Additionally, these patients have higher rates of stent thrombosis and mortality. Given the higher thrombus burden in aneurysmal arteries, thrombectomy may be helpful in aiding PCI. Some case studies have additionally utilized intracoronary thrombolytics. Another strategy is a stent-assisted coil embolization technique in cases where covered stent placement is not possible due to tortuosity, calcification, or risk of side branch compromise. To date, there haven’t been covered stents specifically designed for CAAs, but stents have been used off-label. 
  • Surgical Management: The most common operative strategy is to open the aneurysm, suture the afferent and efferent vessels, and finish with bypass grafting if possible. Other operative strategies include aneurysm ligation, resection, or marsupialization with interposition graft.

References

  1. Thibodeau, J. T., & Drazner, M. H. (2018). The Role of the Clinical Examination in Patients With Heart Failure. JACC. Heart failure, 6(7), 543–551.  
  2. Abou Sherif, S., Ozden Tok, O., Taşköylü, Ö., et al. (2017). Coronary Artery Aneurysms: A Review of the Epidemiology, Pathophysiology, Diagnosis, and Treatment. Frontiers in cardiovascular medicine, 4, 24. 
  3. Kawsara, A., Núñez Gil, I. J., Alqahtani, F., et al. (2018). Management of Coronary Artery Aneurysms. JACC. Cardiovascular interventions, 11(13), 1211–1223.  
  4. Newburger, J. W., Takahashi, M., & Burns, J. C. (2016). Kawasaki Disease. Journal of the American College of Cardiology, 67(14), 1738–1749.  
  5. McCrindle, B. W., Rowley, A. H., Newburger, J. W., et al. (2017). Diagnosis, Treatment, and Long-Term Management of Kawasaki Disease: A Scientific Statement for Health Professionals From the American Heart Association. Circulation, 135(17), e927–e999.  

The CardioNerds Cardiology Case Reports series shines light on the hidden curriculum of medical storytelling. We learn together while discussing fascinating cases in this fun, engaging, and educational format. Each episode ends with an “Expert CardioNerd Perspectives & Review” (E-CPR) for a nuanced teaching from a content expert. We truly believe that hearing about a patient is the singular theme that unifies everyone at every level, from the student to the professor emeritus.

We are teaming up with the ACC FIT Section to use the #CNCR episodes to showcase CV education across the country in the era of virtual recruitment. As part of the recruitment series, each episode features fellows from a given program discussing and teaching about an interesting case as well as sharing what makes their hearts flutter about their fellowship training. The case discussion is followed by both an E-CPR segment and a message from the program director.

Cardionerds Cardiology Podcast Presents CardioNerds Case Report Series

CardioNerds Case Reports: Recruitment Edition Series Production Team

75. Case Report: Coronary Vasospasm Presenting as STEMI – UCSF

CardioNerds (Amit Goyal & Daniel Ambinder) join UCSF cardiology fellows (Emily Cedarbaum, Matt Durstenfeld, and Ben Kelemen) for some fun in San Francisco! They discuss a informative case of ST-segment elevation (STEMI) due to coronary vasospasm. Dr. Binh An Phan provides the E-CPR and program director Dr. Atif Qasim provides a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Evelyn Song with mentorship from University of Maryland cardiology fellow Karan Desai.

Jump to: Patient summaryCase mediaCase teachingReferences

CardioNerds (Amit Goyal & Daniel Ambinder) join UCSF cardiology fellows (Emily Cedarbaum, Matt Durstenfeld, and Ben Kelemen) for some fun in San Francisco! They discuss a fascinating case of ST-segment elevation (STEMI) due to coronary vasospasm. Dr. Binh An Phan provides the E-CPR and program director Dr. Atif Qasim provides a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Evelyn Song with mentorship from University of Maryland cardiology fellow Karan Desai.
Episode graphic by Dr. Carine Hamo

The CardioNerds Cardiology Case Reports series shines light on the hidden curriculum of medical storytelling. We learn together while discussing fascinating cases in this fun, engaging, and educational format. Each episode ends with an “Expert CardioNerd Perspectives & Review” (E-CPR) for a nuanced teaching from a content expert. We truly believe that hearing about a patient is the singular theme that unifies everyone at every level, from the student to the professor emeritus.

We are teaming up with the ACC FIT Section to use the #CNCR episodes to showcase CV education across the country in the era of virtual recruitment. As part of the recruitment series, each episode features fellows from a given program discussing and teaching about an interesting case as well as sharing what makes their hearts flutter about their fellowship training. The case discussion is followed by both an E-CPR segment and a message from the program director.

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Patient Summary

A man in his mid-50s with alcohol use disorder, cirrhosis, atrial fibrillation, and alpha thalassemia complicated by iron overload presented with hematemesis. He was tachycardic and hypotensive. Labs were notable for Hgb 8.1 (baseline of 10.2), INR 1.3, lactate 4.2, and ferritin 4660. He was started on IV PPI and octreotide. Course was complicated initially by Afib with RVR with hypotension. Subsequently, the patient developed unstable VT requiring CPR. Post-code EKG showed inferolateral ST elevations. Troponin-I rose from 19 to 225 and his pressor requirement continued to increase despite resolution of his GIB. TTE showed LVEF 42% with new inferolateral wall motion abnormalities, normal RV systolic function, severe mitral regurgitation, and small pericardial effusion. After treatment of his GIB by IR and GI, he underwent an urgent LHC which showed 30% stenosis in proximal LAD, 70% in LADD2, and 95% in distal RCA. Coronary spasm was noted in all vessels. Intracoronary nitroglycerin and nicardipine were administered with significant improvement in spasm and resolution of STE on EKG. Vasopressors were quickly weaned off after. He was eventually stabilized, extubated, and started on an oral nitrate and calcium channel blocker. Repeat TTE showed normalized systolic function without any wall motion abnormalities.  


Case Media

A. Baseline ECG – atrial fibrillation
B. ECG with inferior STEMI

CORS – left system
CORS- RCA pre-vasodilator
CORS- RCA post-vasodilator

Episode Schematics & Teaching


The CardioNerds 5! – 5 major takeaways from the #CNCR case

  1. What are the cardiac manifestations of hemochromatosis? 
    • Cardiac hemochromatosis encompasses cardiac dysfunction from either primary or secondary hemochromatosis. Initially, hemochromatosis leads to diastolic dysfunction and arrhythmias. In later stages, it can lead to dilated cardiomyopathy.  
    • Diagnosis of iron overload is established by elevated transferrin saturation (>55%) and elevated serum ferritin (>300 ng/mL). Genetic testing for mutations in the HFE gene should be pursued. 
    • Cardiac MRI with measurement of T2* relaxation times is the diagnostic test of choice as it can both detect and quantify myocardial iron overload. The iron content in the myocardial tissue is inversely proportional to the time constant of decay for relaxation time. Thus the higher the iron content, the shorter T2* relaxation time.  
  2. What are the causes of ST-segment elevation on EKG besides acute plaque rupture or vasospasm? 
    • Pericarditis: in acute pericarditis, ST elevation can be seen diffusely in all leads, with PR segment depression (except lead aVR +/- V1). The diffuse ST elevations are due to involvement of subepicardial layer of the ventricular wall. The PR depressions are due to involvement of the subepicardial layer of the atrial wall.  
    • Stress CM: The ECG findings of stress cardiomyopathy may be indistinguishable from STEMI secondary to acute plaque rupture. 
    • Brugada syndrome: >2 mm ST-segment elevation in the right precordial leads followed be a negative T wave can be seen in patients with Type 1 Brugada. Type 2 and Type 3 Brugada will have STE as well but with different morphologic criteria.  
    • Electrolyte abnormalities: hyperkalemia can sometimes cause ST elevation. Other EKG findings of hyperkalemia include widened QRS, tall and peaked T waves, low-amplitude or lack of P waves, high grade AV Block, sine wave, and/or ventricular fibrillation or PEA. 
    • Pulmonary embolism: the classic EKG features of PE are S1Q3T3 with signs of RV strain (RBBB, RAD) though these are neither sensitive or specific. Sometimes, ST elevation in aVR and right-sided precordial are seen in massive PE due to RV overload, dilation, and/or ischemia (see the Cedars-Sinai episode for more details!).  
    • Cardioversion: striking ST-segment elevation, often >10mm, can be seen after cardioversion but only lasts 1-2 minutes.  
    • Raised ICP: can mimic acute myocardial infarction with widespread T-wave inversions +/- STE (or depression). Other non-cardiac causes, albeit rare causes, include significant gastrointestinal visceral distension, pneumonia, and pancreatitis.  
  3. What are the two types of ischemic mitral regurgitation (IMR)? 
    • IMR is often a complication of ischemic heart disease and is associated with a worse prognosis across a variety of settings. Ischemic MR can occur due to a primary cause (e.g., abnormality of the valve apparatus and specifically papillary muscle rupture) or secondary cause (e.g., acutely from ischemia and chronically from a complex pathophysiologic changes).  
    • In chronic IMR, regional and/or global LV systolic dysfunction and ventricular remodeling can cause restricted leaflet motion. There can be outward papillary muscle displacement and when this happens, mitral leaflet coaptation moves apically away from the mitral annulus. Further, scarring of the papillary muscles may produce further mitral leaflet tethering and LV dilation can lead to mitral annular dilation. The posterior mitral annulus may contract less as well (which contributes to as much as 25% of the closure of the mitral orifice during systole). The ultimate results is poor leaflet coaptation and mitral regurgitation.  
    • MR secondary to papillary muscle rupture after an acute MI will almost certainly require surgery; while secondary MR from acute ischemia will often respond to revascularization. The treatment of chronic ischemic MR is a topic for another Cardionerds Episode so stay tuned!  
  4. What’s the pathogenesis of coronary vasospasm? 
    • In coronary vasospasm, the coronary arteries – and specifically the vascular smooth muscle layer – constricts due to various causes including emotional distress, changes in sympathetic tone, cocaine, or cigarette smoking, leading to myocardial ischemia.  
    • The causes and mechanisms of coronary vasospasms are still poorly understood but there are a few potential mechanisms proposed. 
      • Autonomic nervous system: increase in sympathetic tone can induce coronary vasospasms. Vasospasms more commonly occur at night during rapid eye movement sleep, when a reduction in vagal activity is associated with an increase in adrenergic activity.  
      • Inflammation: chronic inflammation and cigarette smoking are shown to be associated with vasospasm. Patients with vasospasm are found to have elevated hs-CRP, IL-6, and peripheral WBC.  
      • Other mechanisms have also been proposed including smooth muscle cell hypercontractility, oxidative stress, and genetics 
  5. What’s the treatment for coronary vasospasm? 
    1. Any factor that may precipitate coronary vasospasm, especially smoking, should be avoided. There are additionally certain medications that should be avoided including non-selective beta blockers like propranolol and triptans.  
    2. For medical treatment, long-acting calcium channel blockers can be used, especially taken at nighttime when attacks of coronary vasospasm are frequent 
    3. Long-acting nitrates can also be added to prevent recurrent attacks if calcium channel blockers alone are inadequate 

References

  1. Gulati, V., Harikrishnan, P., Palaniswamy, C., Aronow, W. S., Jain, D., & Frishman, W. H. (2014). Cardiac involvement in hemochromatosis. Cardiology in review22(2), 56–68. 
  2. Wang, K., Asinger, R. W., & Marriott, H. J. (2003). ST-segment elevation in conditions other than acute myocardial infarction. The New England journal of medicine349(22), 2128–2135.  
  3. Báez-Ferrer, N., Izquierdo-Gómez, M. M., Marí-López, B., Montoto-López, J., Duque-Gómez, A., García-Niebla, J., Miranda-Bacallado, J., de la Rosa Hernández, A., Laynez-Cerdeña, I., & Lacalzada-Almeida, J. (2018). Clinical manifestations, diagnosis, and treatment of ischemic mitral regurgitation: a review. Journal of thoracic disease10(12), 6969–6986.  
  4. Hung, M. J., Hu, P., & Hung, M. Y. (2014). Coronary artery spasm: review and update. International journal of medical sciences11(11), 1161–1171.  
  5. Slavich, M., & Patel, R. S. (2016). Coronary artery spasm: Current knowledge and residual uncertainties. International journal of cardiology. Heart & vasculature10, 47–53.  

CardioNerds Case Reports: Recruitment Edition Series Production Team