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Clinical progress after randomized on/off pacemaker treatment for hypertrophic obstructive cardiomyopathy. Pacing in
L J Kappenberger1, C Linde, X Jeanrenaud
1PIC Coordination Centre, Division of Cardiology, Centre Hospitalier Universitaire Vaudois (CHUV), CH-1011 Lausanne, Switzerland.
Insights
Pacemaker implantation effectively reduces the subaortic gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM) refractory to drug treatment. This safe and effective therapy improves symptoms and quality of life for most patients long-term.
Area of Science:
- Cardiology
- Medical Devices
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) treatment options include medication or surgery.
- Pacemaker activation is known to reduce the subaortic gradient in HOCM but requires further investigation.
Purpose of the Study:
- To evaluate the efficacy and safety of pacemaker implantation in HOCM patients with drug-refractory symptoms and a significant subaortic gradient.
Main Methods:
- Prospective study of 83 HOCM patients with refractory symptoms and resting gradient >30 mmHg.
- Patients received DDD pacemaker implantation after favorable response to temporary pacing.
- Double-blind crossover phase (6 months) followed by 12-month reinvestigation and mean 36-month follow-up.
Main Results:
- Pacemaker significantly reduced the mean subaortic gradient from 72 mmHg to 29 mmHg (P < 0.01), an effect sustained at 1 year.
- Significant improvements observed in functional capacity (NYHA classification), quality of life, dyspnea, and angina.
- 83% of patients remained on pacing alone after a mean follow-up of 36 months, with 79% satisfied.
Conclusions:
- Pacemaker treatment is a safe and effective option for HOCM patients with refractory symptoms.
- It does not preclude alternative treatments and satisfies a majority of patients long-term.
- This study supports pacemaker implantation as a valuable therapeutic strategy for selected HOCM patients.
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.
Conclusion:
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.