The Spatial Ventricular Gradient Is Associated with Pacing-Induced Cardiomyopathy.

Background: Pacing-induced cardiomyopathy (PICM) is a frequent complication of right ventricular pacing that often requires re-operation for biventricular or conduction system pacing. Better methods for predicting PICM may inform initial pacing strategy and follow-up monitoring.

Objective: To determine if the spatial ventricular gradient (SVG), a vectorcardiographic marker of ventricular electrical and mechanical heterogeneity, is associated with subsequent development of PICM.

Methods: Retrospective study of patients with pacemakers implanted between 2003 and 2012 at the Hospital of the University of Pennsylvania. Baseline demographic, echocardiographic and electrocardiographic parameters, including SVG magnitude, elevation, and azimuth, were measured from standard 12-lead electrocardiograms. Adjusted Cox proportional hazards modeling was used to assess the associations between SVG and the risk of PICM over follow-up.

Results: Among 203 patients with a median age of 74 years, 54% male, and a median baseline LVEF of 65%, 44 patients (22%) developed PICM during follow-up. In unadjusted Cox regression, male sex, native QRS duration among patients without bundle branch block, and both native and paced mean adjusted SVG azimuth predicted future PICM. After multivariable adjustment, higher tertile (tertile 3 vs tertiles 1-2) of mean adjusted SVG azimuth before (HR = 1.95, P = 0.047) and immediately after (HR 2.55, P=0.003) pacemaker implantation remained significant predictors of PICM.

Conclusion: Assessment of the SVG both before and immediately after pacemaker implantation can help identify patients at elevated risk for PICM, and may identify a cohort of patients who would be better served with initial biventricular or conduction system pacing.