Can Right Ventricular Lead Position Influence Paced QRS Duration in Patients with Abnormal and Normal Left Ventricular Function?

Abstract

Right ventricular apical pacing (RVAP) in pacemaker or implantable cardioverter‐defibrillator (ICD) therapy has been associated with the development and exacerbation of heart failure (HF). Studies have suggested that RVAP resulting in dyssynchronous left ventricular (LV) activation and prolonged QRS duration leads to progressive mechanical dysfunction, decreased systolic function and increased mortality. These data suggest that the effect may be most pronounced in patients with pre‐existing LV systolic dysfunction. Pacing at the RV septum however has demonstrated narrower paced QRS durations and is being considered as an alternative pacing site to the RVA. In this study, the effect of RV lead placement on the QRS duration in patients with LV systolic dysfunction who demonstrate a left ventricular ejection fraction (LVEF) < 35% and normal LVEF was compared. Patients of a minimum age of 18 years with LVEF ≥ 50% (normal cohort) and LVEF ≤ 30% (HF cohort) were recruited. Four 3 minute high resolution recordings were obtained from an orthogonal lead position for subsequent offline signal averaging. Recordings of native rhythm and pacing at three RV sites: right ventricular outflow tract (RVOT), mid‐septum and RV apex (RVA) were obtained. A 12‐lead electrocardiogram (ECG) recording at each pacing site was stored for later confirmation of pacing location and comparison with paced averaged QRS duration. The QRS duration at different RV sites in the two populations was then compared. As studies to date are limited, this study provided valuable insight on RV lead placement on QRS duration in device therapy for HF treatment.