Long-term results of dual-chamber (DDD) pacing in obstructive hypertrophic cardiomyopathy. Evidence for progressive symptomatic and hemodynamic improvement and reduction of left ventricular hypertrophy.

BACKGROUNDWe previously reported that 6 to 12 weeks of dual-chamber (DDD) pacing results in clinical and hemodynamic improvement in obstructive hypertrophic cardiomyopathy (HCM). This study examines the long-term results of DDD pacing in obstructive HCM.METHODS AND RESULTSDDD devices were implanted in 84 patients (mean age, 49 +/- 16 years) with obstructive HCM and severe drug-refractory symptoms. At a mean follow-up of 2.3 +/- 0.8 years (maximum, 3.5 years), the New York Heart Association (NYHA) functional class had improved significantly (1.6 +/- 0.6 versus 3.2 +/- 0.5, P < .00001). Symptoms were eliminated in 28 patients (33%), improved in 47 patients (56%), but remained unchanged in 7 patients (8%). Two patients died suddenly (97% cumulative 3-year survival rate). In 74 patients with significant left ventricular outflow tract (LVOT) obstruction at rest, the LVOT gradients were significantly reduced at follow-up (27 +/- 31 versus 96 +/- 41 mm Hg, P < .00001). Symptoms and provokable LVOT gradients were...