A 60-year-old man presented to the emergency department after a brief syncopal episode without a prodrome. The patient was alert and oriented after the episode, and witnesses reported no seizure activity. He had no history of syncope, but did have a history of hypertension and left nephrectomy (he was an elective donor). His only medication was amlodipine 5 mg/d orally. He had no allergies and was a half-packper-day smoker. He did not use marijuana, alcohol or illicit drugs.
His heart rate was 35-40 beats/min and blood pressure was 190/80 mm Hg. His temperature, oxygen saturation and respiratory rate were normal, as was the remainder of the physical examination. An electrocardiogram (ECG) showed 2:1 atrioventricular (AV) block with left bundle branch block (Figure 1). No previous ECGs were available. Chest radiograph was normal. The patient had a normal complete blood count, electrolytes, renal function, liver enzymes and thyroid-stimulating hormone level, which ruled out electrolyte abnormalities and thyroid disease as a cause of heart block. High-sensitivity troponin-T levels were mildly elevated (23, 60, 84 [reference range 0-14] ng/L). We admitted him for further investigations including C-reactive protein levels, immunoglobulins, vasculitis panel, blood cultures and Lyme serology, and all were negative. Thus, we considered it unlikely that his heart block was caused by infectious or autoimmune diseases (Box 1).
Transthoracic echocardiography (TTE) showed moderately reduced left ventricular systolic function (LVEF 40%) with wall motion abnormalities in a noncoronary distribution and mild left ventricular hypertrophy. Coronary angiography showed normal coronary arteries, which ruled out coronary artery disease. After admission, the patient had multiple episodes of lightheadedness and near syncope with his heart rate dropping into the 20s on telemetry. We inserted an urgent temporary venous pacer.
Unfortunately, the patient continued to have symptoms and episodes of pacer noncapture, so we implanted a magnetic resonance imaging (MRI)-conditional dual-chamber pacemaker on postadmission day 2 before our workup for secondary causes of heart block was complete.
A computed tomography (CT) scan of the patient's chest showed multiple mediastinal and paratracheal lymph nodes larger than 1 cm, scattered pulmonary nodules but no hilar adenopathy, which we felt was suspicious for sarcoidosis. Cardiac MRI showed late gadolinium enhancement in the apical inferior wall and sub epicardial enhancement in the basal anterior wall and midseptum, suggesting a nonischemic cardiomyopathy (Figure 2). We did not perform a right ventricular endomyocardial biopsy as the patient's cardiac MRI results showed no late gadolinium enhancement in the region usually targeted for biopsy. Instead, we arranged a transbronchial lung biopsy, which found noncaseating granulomatous inflammation consistent with sarcoidosis.
We started treatment with prednisone 40 mg/d orally, with a planned taper of 5 mg per week. We also started guideline-directed medical therapy for heart failure with reduced EF (angiotensin-converting enzyme inhibitor, [beta]-blocker and mineralocorticoid receptor antagonist), given the patient's reduced LV function. (1,2)
A fluorodeoxyglucose positron emission tomography (PET) scan was ordered but unfortunately not completed until 10 months after admission. It showed intense uptake in the entire anterolateral wall, and moderate uptake throughout the inferior...