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Dual-chamber pacing in hypertrophic obstructive cardiomyopathy: a comparison of acute and chronic effects
Y Sakai1, Y Kawakami, Y Hirota
1Third Division, Department of Internal Medicine, Osaka Medical College, Takatsuki, Japan.
Insights
Dual-chamber (DDD) pacing effectively treats drug-refractory hypertrophic obstructive cardiomyopathy (HOCM). Chronic DDD pacing significantly reduces outflow tract pressure gradients and hypertrophic cardiomyopathy symptoms, unlike acute pacing assessments.
Area of Science:
- Cardiology
- Medical Devices
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) presents challenges for drug-refractory patients.
- Dual-chamber (DDD) pacing is explored as a therapeutic option.
Purpose of the Study:
- To evaluate the acute and chronic effects of DDD pacing in patients with drug-refractory HOCM.
Main Methods:
- 14 patients with HOCM underwent temporary DDD pacing.
- 11 patients received permanent DDD pacemaker implantation.
- Evaluated left ventricular outflow tract pressure gradients, symptoms, and echocardiographic parameters.
Main Results:
- Temporary pacing showed limited reduction in pressure gradients.
- Permanent DDD pacing led to significant reduction in outflow tract pressure gradients (p<0.002).
- Symptoms like syncope and dyspnea resolved within 1 month.
- Echocardiography revealed regression of septal hypertrophy and disappearance of systolic anterior motion of the mitral valve.
Conclusions:
- DDD pacemaker implantation is an effective and safe treatment for drug-refractory HOCM.
- Chronic pacing benefits, including gradient reduction and symptom improvement, are not predictable by acute pacing assessments.
Abstract:
This study describes the acute and chronic effects of dual-chamber (DDD) pacing in 14 consecutive patients with hypertrophic obstructive cardiomyopathy (HOCM), whose symptoms were refractory to drug therapy. Although left ventricular (LV) outflow tract pressure gradients diminished from 106+/-47 to 62+/-33 mm Hg (p<0.001) by temporary pacing, the residual pressure gradients were >30 mm Hg in the majority of those with concomitant reductions in cardiac output. The DDD pacing was judged as insufficient by the acute study in the majority of patients. A dual-chamber pacemaker was, however, implanted in 11 patients, and the chronic pacing effects were evaluated. All symptoms (syncope, fainting, palpitation and dyspnea) subsided within 1 month. Left ventricular outflow tract pressure gradients diminished from 99+/-56 to 21+/-13 mm Hg (p<0.004) at 1 week after, and to 17+/-12 mm Hg (p<0.002) at 1 year after the implantation, as measured by Doppler echocardiography. Echocardiogram showed disappearance of the systolic anterior motion of the mitral valve, and significant regression of the septal hypertrophy (from 18.5+/-4.3 to 15.7+/-4.1 mm, p<0.04). There was no significant correlation between the acute and chronic pacing effects in the reduction of the pressure gradients or symptomatic improvement. These results suggest that DDD pacemaker implantation is an effective treatment without any serious risks for patients with drug-refractory HOCM. The chronic-pacing effect in the reduction of the pressure gradient, the regression of hypertrophy and symptomatic improvement cannot be predicted by the assessment of temporary DDD pacing.