Background: Frequent right ventricular (RV) pacing can lead to a decline in left ventricular ejection fraction (LVEF).
Objective: This study aimed to identify incidence and predictors of RV pacing-induced cardiomyopathy (PICM).
Methods: We retrospectively studied 1750 consecutive patients undergoing pacemaker implantation between 2003 and 2012. Patients were included if baseline LVEF was normal, single-chamber ventricular or dual-chamber pacemaker (but not implantable cardioverter-defibrillator or biventricular pacemaker) was implanted, frequent (≥20%) RV pacing was present, and repeat echocardiogram was available ≥1 year after implantation. PICM was defined as ≥10% decrease in LVEF, resulting in LVEF <50%. Patients with alternative causes of cardiomyopathy were excluded. Predictors of the development of PICM were identified using multivariate Cox proportional hazards modeling.
Results: Of 257 patients meeting study criteria, 50 (19.5%) developed PICM, with a decrease in mean LVEF from 62.1% to 36.2% over a mean follow-up period of 3.3 years. Those who developed PICM were more likely to be men, with lower baseline LVEF and wider native QRS duration (bundle branch blocks excluded; P = .005, P = .03, and P = .001, respectively). In multivariate analysis, male gender (hazard ratio 2.15; 95% confidence interval 1.17-3.94; P = .01) and wider native QRS duration (hazard ratio 1.03 per 1 ms increase; 95% confidence interval 1.01-1.05; P < .001) were independently associated with the development of PICM. Native QRS duration >115 ms was 90% specific for the development of PICM.
Conclusion: PICM may be more common than previously reported, and risk for its occurrence begins below the commonly accepted threshold of 40% pacing burden. Men with wider native QRS duration (particularly >115 ms) are at increased risk. These patients warrant closer follow-up with a lower threshold for biventricular pacing.
Keywords: Heart failure; Pacing; Pacing-induced cardiomyopathy; Right ventricular pacing.
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