Very late effects of dual chamber pacing therapy for obstructive hypertrophic cardiomyopathy. [Effets à très long terme du traitement électrique dans la cardiomyopathie hypertrophique obstructive.]
Résumé
Background The very long-term effects of dual chamber pacing as a primary treatment for hypertrophic obstructive cardiomyopathy (HOCM) are poorly known and controversial. Aims To examine the intermediate- and long-term clinical and haemodynamic effects of permanent dual chamber pacing in patients presenting with HOCM. Methods Between 1991 and 2007, 51 patients (mean age 59 ± 14 years) presenting with HOCM and New York Heart Association (NYHA) functional class ≥ II despite optimal medical therapy underwent implantation of DDD pacemakers with or without a defibrillator and were followed for 11.5 years (range 0.4-21.8 years). Results During follow-up, no patient underwent myectomy or septal alcohol ablation. NYHA functional class and other disease manifestations decreased significantly over 1-2 years of follow-up and remained stable thereafter. The left intraventricular (LV) gradient decreased by a mean of 78% over 1-2 years, reaching 89% at end of follow-up, along with disappearance of systolic anterior motion of the mitral valve. Mean LV ejection fraction decreased from a mean of 64 ± 8% before pacing to 56 ± 9% at end of follow-up (P = 0.05), while LV end-diastolic diameter did not change significantly. The 5- and 10-year actuarial survival rates were 90% and 65%, respectively. Among 22 deaths, 10 were due to cardiovascular and 12 to non-cardiovascular causes; two patients underwent cardiac transplantation after 8 and 13 years of DDD pacing, respectively. Conclusions In this sample of patients with HOCM, DDD pacing alleviated symptoms and improved haemodynamic function over the very long term. The merits of this treatment should be revisited in a controlled trial.