CardioNerds (Amit Goyal & Daniel Ambinder) join University of California San Diego (UCSD) cardiology fellows (Harpreet Bhatia, Dan Mangels, and Quan Bui) for a relaxing beach bonfire in the beautiful city of San Diego! They discuss a challenging case of post-transplant cardiac allograft vasculopathy. Dr. Hao (Howie) Tran provides the E-CPR and program director Dr. Daniel Blanchard provides a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Richard Ferraro with mentorship from University of Maryland cardiology fellow Karan Desai.
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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A man in his late 20s with a past medical history of orthotopic heart transplant, presents with one-week of progressive lower extremity edema and dyspnea with NYHA class IV symptoms. 5 years prior, he underwent orthotopic heart transplant for arrhythmogenic right ventricular cardiomyopathy. Subsequently, he has had multiple episodes of rejection or recurrent graft dysfunction. On presentation, he was normotensive and borderline tachycardic. Exam revealed elevated JVP, decreased breath sounds, and pitting edema. Labs demonstrated leukocytosis, acute kidney injury, and elevated pro-BNP. TTE demonstrated LVEF 35%, apical akinesis, and grade III diastolic dysfunction (all similar to prior). He was initially diuresed and RHC/EMB was performed to evaluate for rejection. Early in his course, the patient unfortunately suffered a PEA arrest with ROSC was quickly achieved after 1 minute of CPR. He was intubated and cannulated for VA ECMO. EMB demonstrated ISHLT Grade 1R cellular rejection and he was ultimately listed for re-transplant. Shortly thereafter, the patient received an OHT. His pathology demonstrated intimal thickening of all his coronaries, consistent with coronary artery vasculopathy, felt to be the major contributor to his presentation.
Episode Schematics & Teaching
The CardioNerds 5! – 5 major takeaways from the #CNCR case
1. What is CAV?
- CAV stands for cardiac allograft vasculopathy. Within the transplanted heart, CAV is the proliferation of vascular smooth muscle and intimal thickening in the epicardial coronary arteries and microvasculature leading to diffuse narrowing. CAV is common, present in greater than 30% of patients at 5 years post-transplant. It is a significant contributor to post-transplant mortality after the first year.
- CAV, in contrast to typical atherosclerotic lesions, is diffuse and concentric while atherosclerosis tends to be focal with eccentric luminal narrowing and heterogenous plaque composition. Patients s/p OHT can still develop typical coronary artery disease, likely developed from pre-existing disease in the donor heart. CAV should be high on the differential for the cause of graft dysfunction, especially after the first year post-transplant.
2. How and Why Does CAV Occur?
- CAV has multiple contributing factors. There are immunologic and non-immunologic factors, but it appears the immunologic components play the larger role given that the pan-vasculopathy develops in the donor heart and not in the recipient’s vasculature. In CAV, there is chronic immune-mediated injury creating a persistent inflammatory state in the donor coronary endothelium leading to a neointimal proliferative process in the coronaries. Amongst immunologic factors, it appears the number of episodes of cellular rejection correlates with the development of CAV.
- CAV occurs when foreign antigens are recognized by the host immune system as “non-self,” a process termed allorecognition. T-cells are subsequently activated, and release a number of inflammatory cytokines that leads to additional T-cell stimulation, inflammatory cell proliferation, and endothelial cell propagation. Ultimately this inflammatory cascade leads to smooth muscle cell advancement and intimal growth into the arterial lumen.
- Other immunologic factors include HLA mismatch and antibody-mediated rejection. There are numerous non-immunologic factors, including older donor age, CMV infection, hyperlipidemia, insulin resistance, donor brain death secondary to intracranial hemorrhage, and prolonged ischemic time.
3. How Do Patients with CAV Present?
- Donor hearts are denervated at explantation, and so post-transplant patients typically will not develop classic anginal symptoms as seen with typical atherosclerotic coronary disease. Thus, routine surveillance is necessary (see below).
- If not diagnosed early, the clinical presentation may include LV dysfunction (with or without symptoms), acute myocardial infarction, heart block, arrhythmias, syncope, or sudden cardiac death.
4. How Do We Diagnose CAV?
- Routine surveillance is necessary because patients are generally asymptomatic and there is a high incidence of CAV posttransplant.
- The most common method for screening includes coronary angiography, but its sensitivity is reduced compared to traditional atherosclerotic disease as CAV is diffuse. Intravascular ultrasound (IVUS) significantly improves sensitivity and the early the detection of disease.
- The timing and method of screening will be center-specific. As the patient is farther removed from their transplant date, dobutamine stress echo may be a reasonable method to screen for CAV. Myocardial perfusion imaging, specifically with PET Rest/Stress with absolute myocardial blood flow quantification, and coronary CTA may also be effective methods to diagnose CAV.
- The ISHLT grading of CAV by angiography is as follows:
- CAV0 (Nonsignificant): No detectable angiographic lesion
- CAV1 (mild): Angiographic LM lesion <50%; or primary vessel with maximum lesion of <70%; or any branch vessel stenosis <70% without allograft dysfunction
- CAV2 (moderate): Angiographic LM <50%; or a single primary vessel ≥70% stenosis; or isolated branch stenosis in 2 systems ≥ 70% without allograft dysfunction
- CAV3 (Severe): Angiographic LM ≥50%; or ≥2 primary vessel ≥70% stenosis; or isolated branch stenosis in all 3 systems ≥70%; CAV1 or CAV2 with allograft dysfunction or evidence of significant restrictive physiology
5. How Do we Treat CAV?
- Primary prevention remains key. Statins have been shown prospectively to reduce cardiac allograft vasculopathy and improve survival. Chronic immunosuppression is the foundation of post-transplant care. The mTOR inhibitors, everolimus and sirolimus, harbor antiproliferative properties that may prevent allograft vasculopathy. However, these are generally not first-line immunosuppressive medications in the United States, given the potential for multiple side effects including impaired wound healing in new transplant patients. In patients with documented or progressive CAV, escalation of immunosuppression to sirolimus may be considered. Revascularization for patients may be considered, given the morbidity associated with CAV, though no survival advantage has been shown. In patients with severe CAV, re-transplantation should be considered.
- Mehra, M. R., Crespo-Leiro, M. G., Dipchand, A., et. al (2010). International Society for Heart and Lung Transplantation working formulation of a standardized nomenclature for cardiac allograft vasculopathy—2010.
- Chih, S., Chong, A. Y., Mielniczuk, L. M. et. al. (2016). Allograft vasculopathy: the Achilles’ heel of heart transplantation. Journal of the American College of Cardiology, 68(1), 80-91.
- Schmauss, D., & Weis, M. (2008). Cardiac allograft vasculopathy: recent developments. Circulation, 117(16), 2131-2141.