From the Guidelines
Pacemaker-induced cardiomyopathy is a form of heart dysfunction that develops as a result of chronic right ventricular pacing, leading to reduced cardiac efficiency and eventual heart failure, as supported by the American Heart Association's scientific statement 1.
Definition and Mechanism
Pacemaker-induced cardiomyopathy occurs when the artificial electrical stimulation from a pacemaker causes dyssynchronous ventricular contraction. This condition typically develops after prolonged periods of high percentage right ventricular pacing, usually exceeding 40% of heartbeats. The proposed mechanisms include myocardial energy depletion and decreased energy utilization, myocardial ischemia, and abnormal calcium handling 1.
Clinical Presentation and Diagnosis
The condition is characterized by biventricular dilatation, decreased contractility, and elevated filling pressures. Patients may present with symptoms of heart failure, such as shortness of breath, fatigue, and swelling. Diagnosis is typically made using echocardiography to detect early signs of ventricular dysfunction.
Management and Treatment
Management involves minimizing right ventricular pacing when possible by programming the pacemaker to allow intrinsic conduction, using alternative pacing sites such as the His bundle or left ventricular lead placement (cardiac resynchronization therapy), or upgrading to a biventricular pacing system 1. Standard heart failure medications are also important, including ACE inhibitors or ARBs, beta-blockers, and aldosterone antagonists when appropriate. Regular echocardiographic monitoring is essential for patients with high pacing burdens to detect early signs of ventricular dysfunction.
Key Considerations
- The condition is potentially reversible if identified early and appropriate interventions are implemented to restore more physiologic ventricular activation patterns.
- Cardiac resynchronization therapy (CRT) may be considered for suspected cardiomyopathy caused by left bundle branch block (LBBB) 1.
- Radiofrequency ablation and antiarrhythmic drugs, including β-blockers, may be effective in reducing premature ventricular contraction (PVC) burden and improving ventricular function in patients with PVC-induced cardiomyopathy 1.
From the Research
Definition of Pacemaker-Induced Cardiomyopathy
- Pacemaker-induced cardiomyopathy (PICM) is defined as a drop in left ventricular ejection fraction (LVEF) in the setting of chronic, high-burden right ventricular pacing 2.
- It is characterized by a decrease of ≥10% in LVEF, resulting in LVEF <50% among patients with ≥20% right ventricular pacing burden without an alternative cause for cardiomyopathy 3, 4.
Prevalence and Risk Factors
- The pooled prevalence of PICM was 12% (95% confidence interval 11%-14%) 5.
- Risk factors for PICM include male sex, history of myocardial infarction, chronic kidney disease, atrial fibrillation, baseline left ventricular ejection fraction, native QRS duration, right ventricular pacing percentage, and paced QRS duration 5.
Management and Treatment
- Cardiac resynchronization therapy (CRT) may reverse PICM, with 72% of severe PICM patients achieving LVEF >35% 4.
- CRT upgrade has been shown to improve LVEF significantly, from 28.7% preupgrade to 44.3% post-CRT upgrade (P < .01) 3.
- His-bundle pacing is also a potential treatment strategy for PICM 5.
Comparison of Leadless and Traditional Pacemakers
- The incidence of PICM was high in both leadless pacemaker (LP) and transvenous pacemaker (TVP) groups, with no significant difference in CRT upgrade between LP and TVP 6.
- RV time, a surrogate for how long the RV was paced, was significantly different between LP and TVP, but did not affect the incidence of PICM or CRT upgrade 6.