Echocardiographic characteristics predicting efficacy of drug therapy in patients with hypertrophic obstructive cardiomyopathy

Background The efficacy of long-term drug therapy for patients with hypertrophic obstructive cardiomyopathy (HOCM) remains unclear. This study was performed to characterize the echocardiographic findings of patients responsive to drug therapy. Methods Left ventricular outflow tract (LVOT) gradient and morphologic characteristics of the septum, posterior wall, and mitral valve were measured echocardiographically in 35 Japanese patients. The mean follow-up time was 41±22 months. Results Long-term drug therapy was effective in 14 patients and ineffective in 21 patients. Five of the refractory patients required mitral valve replacement to become free of symptoms. Only 5 of 21 patients whose LVOT gradient was 100 mm Hg were responsive to drug therapy, whereas 9 of 14 patients whose LVOT gradient was <100 mm Hg were responsive to drug therapy. Seven of eight patients with an asymmetric septal hypertrophy (ASH) ratio greater-than over equal to1.3 and LVOT gradient <100 mm Hg were responsive to drug therapy. Only 3 of 16 patients with an ASH ratio <1.3 were responsive to drug therapy. There was no correlation between the efficacy of drug therapy and the morphology of the mitral valve or the width of the LVOT. Conclusion Our results demonstrate that drug therapy effectively reduces the LVOT gradient in patients with asymmetric septal hypertrophy and a less severe LVOT gradient.