Incidence and predictors of right ventricular pacing-induced cardiomyopathy

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.