Abstract 14979: Progressive Heart Failure is Uncommon in Patients With Nonobstructive Hypertrophic Cardiomyopathy
Background: Historically, left ventricular outflow tract obstruction has been the most visible pathophysiologic component of HCM, with substantial attention directed toward its management strategies. However, nearly one-third of HCM patients do not generate outflow gradients, and the natural history of this large subgroup is nevertheless incompletely defined. Therefore, we sought to determine the demographics, clinical profile, and outcome of patients with the nonobstructive form of HCM.
Methods: We prospectively studied 416 consecutive HCM patients in 3 centers (44 ± 17 years; 63% male). LV outflow obstruction (≥ 30 mmHg) at rest or following exercise was present in 270 (65%). The remaining 146 (35%) patients did not develop a gradient (<30mmHg) at rest nor with exercise (nonobstructive).
Results: Over the follow-up period of 6.3 ± 2.1 years, of the 416 patients 129 (31%) developed progressive limiting NYHA class III/IV symptoms, occurring much less commonly in nonobstructive patients than in those with outflow obstruction (26/146 [18%] vs. 103/270 [38%] vs. p<0.001). However, those nonobstructive patients who did develop NYHA class III/IV symptoms more frequently required heart transplant (4.1% vs 0.7% for patients with obstruction; p=0.02), including: 2 with end-stage with systolic dysfunction and 4 with preserved systolic function. Furthermore, nonobstructive HCM patients showed increased risk for developing the end-stage with systolic dysfunction (ejection fraction, <50%; 8% vs 4% for patients with obstruction; p=0.05). Neither overall mortality nor the HCM-related event rate was significantly different in nonobstructive versus obstructive HCM patients (0.5% vs 1.0% per year; p=0.15 and 1.8% vs 1.1% per year; p=0.07, respectively).
Conclusions: Morbidity from advanced heart failure symptoms is relatively uncommon among nonobstructive HCM patients. Although infrequent, nonobstructive patients who develop advanced heart failure symptoms are more likely than obstructive HCM patients to require heart transplantation as definitive treatment.
- © 2013 by American Heart Association, Inc.