CASE
A 70-year-old man presents to his primary oncologist to consider new chemotherapy to treat relapsed chronic lymphocytic leukemia. During the assessment, a routine ECG reveals new-onset bradycardia. The patient is sent to our cardiology clinic for further evaluation. In our clinic, he describes a 1-day history of increasing exertional dyspnea, fatigue, bilateral flank pain, and dark tea-colored urine. He denies nausea, vomiting, chest pain, fever, or syncope. His medical history includes diabetes, hypertension, chronic renal insufficiency, heart failure, and the leukemia. Medications include enalapril, half a 5-mg tablet daily; spironolactone, half a 25-mg tablet daily; furosemide, 40 mg twice a day; isosorbide mononitrate, 30 mg daily; simvastatin, 40 mg daily; metformin, 500 mg twice a day; and metoprolol succinate, 100 mg daily.
Physical examination The patient appears somewhat somnolent, but he is responsive. His BP is 100/56 mm Hg; pulse, 48 beats per minute. The jugular venous pressure is elevated at 11 cm above the right atrium. Faint bibasilar crackles are heard on lung auscultation. Cardiac evaluation reveals a bradycardic rate but a regular rhythm; S1 and S2 sounds are normal, without an S3. A grade II/VI holosystolic murmur is noted at the apex. The abdomen is nondistended with active bowel sounds and tenderness at the bilateral flanks. There is no significant evidence of edema in the lower extremities. The ECG shows bradycardia (44 beats per minute) and a widened QRS complex (see Figure 1).
WHAT IS YOUR WORKING DIAGNOSIS?
• Myocardial infarction
• Hyperkalemia
• Myocarditis
• Tachy-brady syndrome