A man in his 60s with a history of end-stage renal disease status post–renal transplant, atrial fibrillation, and sick sinus syndrome status after dual-chamber pacemaker placement presented to the emergency department complaining of progressively worsening dyspnea and diarrhea of 1 week’s duration. He denied any chest pain, palpitations, or syncope. Vital signs on admission were significant for hypoxia with an oxygen requirement of 4 L/min, blood pressure of 130/79 mm Hg, and heart rate of 90 bpm. Physical examination was remarkable for an elevated jugular venous pressure, bilateral pulmonary basilar crackles, and lower extremity pitting edema. Initial laboratory evaluation revealed an elevated potassium level of 9.0 mmol/L and a creatinine level of 2.8 mg/dL. Severe bilateral pulmonary congestion was noted on chest radiography. A 12-lead electrocardiogram (ECG) was obtained at the time of admission (Figure 1). Echocardiography demonstrated a reduced left ventricular ejection fraction of 35% and normal regional wall motion.