Outcome of mildly symptomatic or asymptomatic obstructive hypertrophic cardiomyopathy: a long-term follow-up study

The purpose of this study was to characterize the prognosis of minimally symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM).

Recent data have suggested that obstruction may be present in the majority of HCM patients, irrespective of cardiac symptoms. The prognosis of minimally symptomatic obstructive HCM remains poorly defined.

We examined 544 consecutive adult patients (age 59 +/- 16 years; 55% men) with obstructive HCM documented by Doppler echocardiography who were free of severe cardiac symptoms, and we performed clinical follow-up (median 9.3 years).

There was only a slight excess mortality of the cohort in comparison to the expected survival of a similar U.S. general population (10-year observed vs. expected survival, 69.3% vs. 71.9%; p = 0.04) and 46% of the deaths were attributable to noncardiac causes. However, there was a clear relation between increasing severity of the left ventricular outflow tract (LVOT) gradient and outcome. For patients with high resting gradients (Doppler peak velocity >4 m/s), survival was significantly impaired (53% at 10 years; p = 0.001 vs. expected), and death or severe symptoms occurred in 68% of these patients within 10 years after the initial evaluation. Conversely, there was no impairment of long-term survival for patients with less-severe resting obstruction. Independent predictors of mortality in the entire cohort were age, prior stroke, and LVOT gradient severity.

Patients with obstructive HCM and mild or no symptoms have only slight excess mortality. However, patients with markedly elevated resting LVOT gradients are at a high risk of heart failure and death. These findings may have important implications for therapy, including the timing of septal reduction therapy.