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


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.
Kass
D A
DA
Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA. dkass@bme.jhu.edu
Chen
C H
CH
Talbot
M W
MW
Rochitte
C E
CE
Lima
J A
JA
Berger
R D
RD
Calkins
H
H
D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015150:Echocardiography, Doppler; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000150:complications*; D017379:Hypertrophy, Left Ventricular / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D013318:Stroke Volume; D016277:Ventricular Function, Left