Ventricular pacing with premature excitation for treatment of hypertensive-cardiac hypertrophy with cavity-obliteration

Background-Hypertensive left ventricular hypertrophy with supranormal systo lic ejection and distal cavity obliteration (HHCO) can result in debilitati ng exertional fatigue and dyspnea. Dual-chamber pacing with ventricular pre activation generates discoordinate contraction, which can limit cavity obli teration and thereby increase potential ejection reserve. Accordingly, we h ypothesized that pacing may improve exercise tolerance long-term in this sy ndrome. Methods and Results-Dual-chamber pacemakers were implanted in 9 patients wi th exertional dyspnea caused by HHCO. Intrinsic atrial rate was sensed, and ventricular preactivation was achieved by shortening the atrial-ventricula r delay. Pacing was on or off for successive 3-month periods (randomized, d ouble-blind, crossover design), followed by 6 additional pacing-on months. Metabolic exercise testing, quality-of-life assessment, and rest and dobuta mine-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 greater than or equal to 30%), an d 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 basel ine during the pacing-off period. Improved exercise capacity persisted at I -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 li ttle changed during the pacing-off period. Despite similar basal values, st roke 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 b aseline. Conclusions-Long-term dual-chamber pacing can improve exercise capacity, ca rdiac reserve, clinical symptoms, and activities of daily living in patient s with HHCO. This therapy may provide a novel alternative for patients in w hom traditional pharmacological treatment proves inadequate.