Ventricular Pacing With Premature Excitation for Treatment of Hypertensive-Cardiac Hypertrophy With Cavity-Obliteration

Abstract

Background —Hypertensive left ventricular hypertrophy with supranormal systolic ejection and distal cavity obliteration (HHCO) can result in debilitating exertional fatigue and dyspnea. Dual-chamber pacing with ventricular preactivation generates discoordinate contraction, which can limit cavity obliteration and thereby increase potential ejection reserve. Accordingly, we hypothesized that pacing may improve exercise tolerance long-term in this syndrome. Methods and Results —Dual-chamber pacemakers were implanted in 9 patients with exertional dyspnea caused by HHCO. Intrinsic atrial rate was sensed, and ventricular preactivation was achieved by shortening the atrial-ventricular delay. Pacing was on or off for successive 3-month periods (randomized, double-blind, crossover design), followed by 6 additional pacing-on months. Metabolic exercise testing, quality-of-life assessment, and rest and dobutamine-stress echocardiographic/Doppler data were obtained. After 3 months of pacing-on, exercise duration rose from 324±133 to 588±238 s (mean±SD; P =0.001, with 7 of 9 patients improving ≥30%), and maximal oxygen consumption increased from 13.6±2.9 to 16.7±3.3 mL of O 2 · min −1 · kg −1 ( P <0.02). Both parameters were little changed from baseline during the pacing-off period. Improved exercise capacity persisted at 1-year follow-up. Clinical symptoms and activities of daily living improved during the pacing-on period and stayed improved at 1 year, but they were little changed during the pacing-off period. Despite similar basal values, stroke volume ( P <0.001) and cardiac output ( P <0.02) increased with dobutamine stimulation 2 to 3 times more after 1 year of follow-up as compared with baseline. Conclusions —Long-term dual-chamber pacing can improve exercise capacity, cardiac reserve, clinical symptoms, and activities of daily living in patients with HHCO. This therapy may provide a novel alternative for patients in whom traditional pharmacological treatment proves inadequate.