Abstract 3597: Late Benefits of Dual-Chamber Pacing in Obstructive Hypertrophic Cardiomyopathy. A 10-year Follow-Up.
Introduction: Dual-chamber pacing reduces left ventricular outtlow tract (LVOT) gradient in obstructive hypertrophic cardiomyopathy (HC), but there is controversy about real benefit. Short-term studies have suggested that elderly patients benefit most from this therapy. We assessed our 10-year single, non-referral center experience with pacing in HC, in order to establish the global impact of such therapy.
Methods: We prospectively studied 50 patients (62±11y) withHC, all in NYHA III or IV, refractory to medical therapy, with a rest LVOT gradient > 50mmHg. A dual-chamber pacemaker was implanted and patients were followed-up 5.0±2.9y (range 0.6–10.1).
Results: During the first year of follow-up, LVOT rest gradients were reduced (baseline 86±29mmHg; 3-months 55±37; 1-year 41±26; p=.0001). Inducible gradients declined in similar manner (baseline 114±53; 3-m 67±30; 1-y 68±46), mitral insufficiency was reduced (p=.0001), NYHA class improved (p<.0001), as well as exercise tolerance (6-min corridor test distance: baseline 281±112m; 3-m 334±106; 1-y 348±78, p<.0001). Physical SF-36 improved (baseline 32.5±6.8; 3-m 36.1±8.2; 1-y 37.3±9.2; p=.0001), as well as mental SF-36 (baseline 33.1±9.1; 3-m 36.3±10.3; 1-y 40.9±9.5; p<.0002). Left ventricular septal and posterior wall thickness remained unchanged, while ejection fraction decreased (baseline 76±10%; 3-m 74±8%; 1-y 66±13%; p=.03). During the long-term follow-up, an additional reduction in LVOT gradient was found (final rest gradient 28±24mmHg, p<.02 in relation to 1-year). All patients that did not achieve NYHA class I or II and remained with persistent LVOT gradient were submitted to other types of therapy (6 patients to alcohol septal ablation, and 3 to surgical myectomy). Six patients died (5 of CV causes, none related to procedures).
Conclusions: In this subset of relatively elderly patients with obstructive HC, pacing results in a significant reduction in LVOT obstruction, improvement in symptoms, exercise capacity, and quality of life. The decrease in pressure gradient is progressive and may be achieved along an extended period of time. In our series, only 18% of cases needed a more aggresive therapy to relieve residual obstruction and obtain a satisfactory symptomatic status.