(HealthDay News) – Beta blockers (BBs) are effective as an early prophylactic pharmacologic treatment for patients with mild hypertrophic cardiomyopathy (HC) who have exercise-induced left ventricular outflow tract (LVOT) obstruction, according to a study published in the Sept 1 issue of The American Journal of Cardiology.

Stefano Nistri, MD, PhD, of CMSR-Veneto Medica in Vicenza, Italy, and associates examined the benefits of BBs in a prospective study involving 27 patients with HC with mild or no symptoms of heart failure, without obstruction at rest, but with exercise-induced LVOT gradients of ≥30mmHg.

The researchers found that the mean post-exercise LVOT gradient was 87±29mmHg. After an average of 12 months of BB treatment with nadolol or bisoprolol, the post-exercise LVOT gradient decreased significantly and was almost abolished in 52% of patients (0–<30 mm Hg), considerably reduced in 33% (≥20mmHg reduction), and unchanged in 15%. Severe post-exercise obstruction persisted in 22% of treated patients, compared with 93% of untreated patients. Body mass index was increased among non-responders (hazard ratio, 2.03 per 1kg/m²).

“In patients with HC with mild or no symptoms, treatment with BBs can prevent the development of LVOT obstruction triggered by physiologic exercise,” the authors write. “These findings provide a rationale for the novel strategy of early prophylactic pharmacologic treatment with standard, well-tolerated doses of BBs in physically active patients with provocable gradients, aimed at effective prevention of the hemodynamic burden associated with dynamic obstruction.”

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