Abstract

Chronic right ventricular (RV) pacing has been associated with decreased exercise capacity and left ventricular (LV) function in adults with congenital complete atrioventricular block (CCAVB), but not in children.The purpose of this study was to evaluate the exercise capacity and LV function in pediatric patients with CCAVB receiving chronic RV pacing.We prospectively evaluated pediatric patients with isolated CCAVB receiving atrial synchronous RV pacing for at least 5 years. Supine bicycle ergometry was performed, and LV ejection fraction (EF) was evaluated by echocardiography.Ten CCAVB subjects and 31 controls were matched for age, gender, and body surface area. CCAVB subjects had normal resting EF (63.1% ± 4.0%) and had been paced for 7.9 ± 1.4 years. Exercise testing demonstrated reduced functional capacity in CCAVB patients compared to controls with a lower VO2peak (26.0 ± 6.6 mL/kg/min vs 39.9 ± 7.0 mL/kg/min, P <.001), anaerobic threshold (15.6 ± 3.9 mL/kg/min vs 18.8 ± 2.7 mL/kg/min, P = .007), and oxygen uptake efficiency slope (1210 ± 406 vs 1841 ± 452, P <.001). Maximum heart rate (165 ± 8 bpm vs 185 ± 9 bpm, P <.001) and systolic blood pressure (159 ± 17 mm Hg vs 185 ± 12 mm Hg, P <.019) also were reduced in CCAVB patients despite maximal effort (respiratory exchange ratio 1.2 ± 0.1). EF was augmented with exercise in controls but not in CCAVB patients (13.2% ± 9.3% vs 0.2% ± 4.8% increase, P <.001).Clinically asymptomatic children with chronic RV pacing due to CCAVB have significant reductions in functional capacity accompanied by chronotropic incompetence and inability to augment EF with exercise.

View details for DOI 10.1016/j.hrthm.2014.11.036

View details for PubMedID 25433143