Pacinginduced

Pacing-induced cardiomyopathy (PICM) refers to the development or worsening of left ventricular systolic dysfunction attributable to long-term right ventricular pacing from a cardiac rhythm device, such as a pacemaker or implantable cardioverter-defibrillator. It is typically diagnosed when a patient without another plausible cause for heart failure shows reduced ejection fraction and heart failure symptoms after sustained pacing, and when improvement occurs after reducing pacing burden or resynchronization therapy.

The underlying mechanism involves electrical dyssynchrony caused by chronic RV pacing, which imitates a left bundle branch block pattern. This dyssynchrony can lead to unfavorable LV remodeling, impaired contractility, and progressive heart failure. Reversing dyssynchrony, either by lowering the percentage of paced beats or by upgrading to biventricular pacing (cardiac resynchronization therapy, CRT), can improve LV function and clinical status in many patients. Alternative pacing approaches that preserve physiologic conduction, such as His-bundle or left bundle branch area pacing, are increasingly considered to reduce PICM risk.

Epidemiology estimates vary, but PICM is considered a relatively uncommon complication among all pacemaker recipients, with higher risk in patients who receive a large burden of RV pacing, have longer pacing duration, or have preexisting LV dysfunction. Other risk factors may include advanced age and atrial fibrillation with rapid ventricular response.

Diagnosis relies on documentation of a high pacing burden, new or worsened LV dysfunction, and exclusion of other causes of cardiomyopathy. Improvement after pacing optimization or CRT supports the diagnosis.

Management focuses on reducing RV pacing burden whenever feasible, using pacing strategies that minimize dyssynchrony, and upgrading to CRT in eligible patients with persistent dysfunction and heart failure symptoms. Optimal medical therapy for heart failure remains essential.