Rapid reversal of right ventricular pacing–induced cardiomyopathy by His bundle pacing

Case report A 78-year-old woman with hypertension, paroxysmal atrial fibrillation treated with pulmonary vein isolation 4 years prior, and normal biventricular systolic function presented with symptomatic high-grade heart block with junctional escape rhythm and QRS duration of 84 ms (Figure 1A). She underwent dual-chamber pacemaker implantation with apical RV lead placement and resolution of her presenting symptoms. After 6 months of 99% RV pacing with paced QRS duration of 166 ms (Figure 1B), she developed increasing exertional dyspnea and volume overload necessitating hospital admission. Transthoracic echocardiogram during this admission showed decline in left ventricular ejection fraction (LVEF) from 60% prior to pacemaker implantation to 35% (Video 1, available online) with 3þ mitral and tricuspid regurgitation. Following intravenous diuresis, she was discharged with beta blocker, angiotensinconverting enzyme inhibitor, and oral diuretic therapy. Attempts to minimize RV pacing by reprogramming her device were unsuccessful owing to underlying symptomatic slow junctional escape (30–40 beats per minute [bpm]). Two weeks after her initial heart failure hospitalization, she was readmitted with acute systolic heart failure and volume overload. Due to suspected RV pacing–related