Influence Of Pacing Mode On Exercise Parameters In Chronic Heart Failure Patients With Implanted Cardioverter Defibrillators

Abstract

PURPOSE Patients with chronic heart failure and implanted cardioverter-defibrillators (ICD) may have a higher incidence of new onset or worsening heart failure requiring hospitalization with dual-chamber compared with single-chamber ICD. The purpose of this study was to show the impact of permanent right ventricular pacing on exercise capacity and related cardiorespiratory parameters in patients with chronic heart failure and ICD. METHODS Seventeen patients with chronic heart failure and a dual-chamber ICD, an intrinsic atrioventricular conduction delay between 150 and 250msec, performed cardiopulmonary exercise testing (CPX) on three different days. After CPX 1, patients were randomized either to back-up pacing (NONPACE) or permanent right ventricular pacing (PERMPACE). After 3 months, CPX 2 was performed and patients changed groups (crossover design); CPX 3 was performed after 3 additional months. RESULTS Maximal values for workload (108±46W vs. 117±48W, p < 0.01), oxygen consumption (21.0±5.3ml·min. kg−1 vs. 22.5±6.4ml·min·kg−1, p < 0.05), oxygen pulse (13±3.7ml vs. 14±4.0ml, p < 0.05) and metabolic equivalent (6.0±1.5 vs. 6.4±1.8, p < 0.05) were significantly lower for PERMPACE compared with NONPACE. Workload, oxygen consumption and oxygen pulse were significantly reduced at the ventilatory anaerobic threshold, while workload and oxygen consumption were significantly lower at the respiratory compensation point. No differences were found for maximal heart rate, minute ventilation, carbon dioxide production, respiratory exchange ratio and the oxygen uptake efficiency slope (OUES). The ventilatory efficiency expressed by the VE/VCO2-slope was significantly lower with PERMPACE compared to NONPACE. CONCLUSIONS Permanent right ventricular pacing significantly reduced submaximal and maximal cardio-respiratory parameters of exercise. For patients with chronic heart failure and sufficient atrioventricular conduction, every effort should be made to minimize permanent right ventricular pacing.