Clinical progress after randomized on/off pacemaker treatment for hypertrophic obstructive cardiomyopathy. Pacing in Cardiomyopathy (PIC) Study Group.
BACKGROUND
The therapeutic options for hypertrophic obstructive cardiomyopathy (HOCM) classically include medical treatment with beta-blockers and calcium antagonists or myectomy-myotomy as a surgical possibility for refractory cases. The observation that pacemaker activation of the heart in HOCM reduces the subaortic gradient is well known but less well investigated.


METHODS
Eighty-three patients (33 female and 50 male) mean age 53 (18-82) years, with symptoms refractory to drug treatment and a resting gradient above 30 mmHg, who responded favourably to temporary pacing, were included in this prospective study and had a pacemaker (DDD) implanted. After an initial double-blind crossover phase of 6 months, patients were reinvestigated at 12 months and followed for a mean of 36 months.


RESULTS
As observed during a screening investigation, the obstruction was significantly reduced from 72 +/- 35 mmHg to 29 +/- 24 mmHg (P < 0.01) when the pacemaker was on, while no major effect was seen during the sham phase. The effect was persistent at 1 year with a remaining resting gradient of 28 +/- 24 mmHg. In parallel, we documented an improvement in functional capacity, according to the NYHA classification and by quality of life analysis, and a significant improvement in dyspnoea and angina. Exercise on treadmill improved only in patients with reduced initial tolerance (< 8 min). During the mean follow-up of 36 months, 65 patients remained on pacing alone, with eight patients having additional AV-node ablation and five patients finally having surgery.


CONCLUSIONS
This controlled multicentre study shows that pacemaker treatment is an option for HOCM patients; it is inoffensive and does not exclude alternative methods, but satisfies 79% of patients beyond 3 years.
PIC Coordination Centre, Division of Cardiology, Centre Hospitalier Universitaire Vaudois (CHUV), CH-1011 Lausanne, Switzerland.
L J
LJ
Kappenberger
C
C
Linde
X
X
Jeanrenaud
C
C
Daubert
W
W
McKenna
E
E
Meisel
N
N
Sadoul
L
L
Chojnowska
L
L
Guize
D
D
Gras
N
N
Aebischer
F
F
Gadler
L
L
Rydén
D000293:Adolescent; D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000628:therapy*; D004311:Double-Blind Method; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011788:Quality of Life; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000503:physiopathology