157. Case Report: A Case of Complete Heart Block In A Young Adult – Stanford University

CardioNerds (Amit Goyal and Daniel Ambinder), join CardioNerds FIT Ambassador, Dr. Pablo Sanchez, and his co-fellows, Dr. Jimmy Tooley and Dr. Maggie Ning from Stanford University for an important case discussion about an An otherwise healthy young adult presented with fatigue and was found to be in complete heart block due to sarcoidosis. Dr. Ronald Witteles, (Stanford University Program Director for the Stanford Internal Medicine residency program and advanced heart failure specialist who’s particular expertise focuses in the treatment of amyloidosis, sarcoidosis, and cardio-oncology) provides the E-CPR for this episode. 

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Disclosures: Dr. Witteles reports that he has served as an advisor for Pfizer, Alnylam, Eidos, Regerenon Pharmaceuticals, Janssen, and Ionis
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Patient Summary – NotesComplete Heart Block due to Sarcoidosis

An otherwise healthy young adult presented with fatigue and was found to be in complete heart block. Imaging studies were suspicious for cardiac and pulmonary sarcoidosis. Sarcoidosis was confirmed on biopsy. Given the high risk of future cardiac events our patient underwent a dual chamber ICD implantation. He was started on prednisone and methotrexate for immunosuppression.

Episode Teaching – NotesComplete Heart Block due to Sarcoidosis

Pearls – Complete NotesComplete Heart Block due to Sarcoidosis

  1. Cardiac sarcoidosis is a disease characterized by noncaseating granulomas involving the heart that can exist alone or together with other organ system involvement
  2. Depending on the sites of cardiac involvement it can present as conduction system disease, ventricular arrhythmia, or heart failure
  3. Cardiac sarcoidosis should be considered in patients with history of sarcoidosis involving other organ systems who develop left ventricular dysfunction, wall motion abnormalities, or arrhythmias
  4. Cardiac sarcoidosis should be considered in patients who present with otherwise unexplained heart block or ventricular tachycardia (VT)
  5.  It is generally recommended that patients with cardiac sarcoidosis with an indication for pacemaker receive an ICD at time of implantation regardless of history of VT

NotesComplete Heart Block due to Sarcoidosis

1. What is Sarcoidosis?

Sarcoidosis is a rare disorder of inflammation characterized by the formation of noncaseating granulomas in affected tissues. It most commonly involves the pulmonary system, but other organ systems can be involved including the heart. Sarcoidosis typically affects young adults, and its etiology is still uncertain.

2. What is Cardiac Sarcoidosis and how is it diagnosed?

Cardiac sarcoidosis (CS) can occur alone or with systemic disease and depending on the cardiac sites of involvement, can present as conduction system disease, ventricular arrhythmia, heart failure, or sudden cardiac death.

3. How is Cardiac Sarcoidosis diagnosed?

Diagnosis of CS is challenging as the gold standard is endomyocardial biopsy (EMB), though sensitivity of EMB is low given the often-patchy tissue involvement. Societal guidelines on the diagnosis of CS require either a positive EMB or biopsy-confirmed extracardiac sarcoidosis with evidence of secondary criteria to suggest cardiac involvement – unexplained VT, high grade AV block, third degree AV block, LVEF <40%, or characteristic imaging finding on cardiac MRI and cardiac PET.

The diagnosis of CS must be considered in all patients with a diagnosis of extra cardiac sarcoidosis who develop symptoms to suggest cardiac involvement. Additionally,

screening for CS should be done in all patients <60 years of age presenting with unexplained Mobitz type II block, 3rd degree AV block, or VT.

Our patient was a previously healthy very active gentleman in his 30s with fairly sudden onset of fatigue found to have 100% burden of high-grade AV block and third-degree AV block on ambulatory rhythm monitor. Given his young age and no other explanation for his conduction system disease, he underwent a workup for CS.  Cardiac MRI revealed mesocardial scarring in the mid inferior and anteroseptal walls with prominent mediastinal and hilar lymphadenopathy suggestive of sarcoidosis with pulmonary and cardiac involvement. FDG-PET was also highly suggestive of CS given FDG uptake of the basal septum and lymph nodes. Diagnosis was ultimately confirmed based on FNA of a supraclavicular lymph node, though EMB would have been the appropriate next step if there were no extracardiac sites available for biopsy.

4. What are important considerations of conduction disease associated with cardiac sarcoidosis?

Third degree AV block typically occurs with increased frequency at advanced age and most commonly is due to idiopathic myocardial fibrosis of the conduction system. However, in younger patients, CS is an important cause of AV block that must be considered. In a single-center study, CS was diagnosed in greater than ⅓ of patients <60 years of age with unexplained high grade AV block.

The diagnosis of AV block associated with CS is important to distinguish from idiopathic AV block as it is associated with higher rates of adverse cardiac events. Patients with CS that present with high grade AV block have similar rates of fatal cardiac events – cardiac death, VF, and sustained VT – compared to those who present with VT or HF. In a single center study, >50% of CS patients who presented with AV block experienced a fatal cardiac event at 34 months follow up.

Societal recommendations reflect this increased cardiac risk in CS patients and give a Class IIa recommendation for ICD implantation in CS patients with indication for permanent pacing, unexplained syncope, or inducible VT/VF.


  1. Barra, Sérgio Nuno Craveiro, Rui Providência, Luís Paiva, José Nascimento, and António Leitão Marques. “A Review on Advanced Atrioventricular Block in Young or Middle-Aged Adults: ATRIOVENTRICULAR BLOCK IN YOUNG ADULTS.” Pacing and Clinical Electrophysiology 35, no. 11 (November 2012): 1395–1405. https://doi.org/10.1111/j.1540-8159.2012.03489.x.
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  5. Takaya, Yoichi, Kengo Fukushima Kusano, Kazufumi Nakamura, and Hiroshi Ito. “Outcomes in Patients With High-Degree Atrioventricular Block as the Initial Manifestation of Cardiac Sarcoidosis.” The American Journal of Cardiology 115, no. 4 (February 2015): 505–9. https://doi.org/10.1016/j.amjcard.2014.11.028.
  6. Terasaki, Fumio, Arata Azuma, Toshihisa Anzai, Nobukazu Ishizaka, Yoshio Ishida, Mitsuaki Isobe, Takayuki Inomata, et al. “JCS 2016 Guideline on Diagnosis and Treatment of Cardiac Sarcoidosis ― Digest Version ―.” Circulation Journal 83, no. 11 (October 25, 2019): 2329–88. https://doi.org/10.1253/circj.CJ-19-0508.
  7. Uemura, A., S. Morimoto, S. Hiramitsu, Y. Kato, T. Ito, and H. Hishida. “Histologic Diagnostic Rate of Cardiac Sarcoidosis: Evaluation of Endomyocardial Biopsies.” American Heart Journal 138, no. 2 Pt 1 (August 1999): 299–302. https://doi.org/10.1016/s0002-8703(99)70115-8.

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