The deleterious effects of RV pacing: applicable to all patients?
- Correspondence to Dr Jeanne E Poole, Division of Cardiology, Department of Medicine, University of Washington School of Medicine, 1959 NE Pacific Street, Box 356422, Seattle, WA 98195-6422, USA;
In their paper Gierula et al,1 present results from a small prospective series of 66 consecutive patients who, at the time of pulse generator replacement, underwent programming changes to minimise unnecessary pacing of the RV. While substantial data exists from randomised trials to suggest RV pacing is detrimental in patients with heart failure, whether long-term RV pacing is safe in patients with normal or mildly impaired cardiac function remains an unanswered question. In a twist on the theme, this study examines the question, not at the time of initial implantation but, on average, 10 years later, at the time of generator replacement.
Unfortunately, an important remaining question cannot be answered by this study. That is, what percentage of patients with normal left ventricular function at the time of initial dual chamber pacemaker implantation develop symptomatic heart failure over the long term (∼10 years) due solely to RV pacing-induced systolic heart failure? That question will almost always be confounded by the fact that patients with a bradycardia need for pacing most often have underlying cardiac disease and, therefore, have an alternative reason to ultimately develop heart failure.
The patients for this study were followed prospectively at Leeds General Infirmary, UK. Patients who had already demonstrated a low LVEF by the time of pacemaker generator replacement were not included in this study, but were instead, considered for cardiac resynchronisation therapy (CRT) upgrade. As a consequence, the patients in this study had normal or only mildly impaired cardiac function. The question asked was whether programming changes instituted to reduce unneeded RV pacing at the time of generator change would favourably impact the outcome measures of LVEF, quality of life (QOL), NT-pro-BNP levels, and cardiopulmonary exercise testing at 6 months of follow-up.
Programming changes made in those patients considered to have avoidable RV pacing included, …