Prognostic Significance of Non-Dilated Left Ventricular Size and Mitral Regurgitation in Patients With Dilated Phase of Hypertrophic Cardiomyopathy.

Although a subtype of hypertrophic cardiomyopathy (HCM), dilated phase of HCM (D-HCM) characterized by left ventricular (LV) systolic dysfunction, has been reported to have a poor prognosis, some patients with D-HCM survive for a relatively long period. The degree of LV dilatation and functional mitral regurgitation (MR) are generally thought to be important predictors of poor prognosis in patients with LV systolic dysfunction. However, there is little information available on the relations among LV size, presence of significant MR, and prognosis in D-HCM patients.We retrospectively studied 31 patients with D-HCM to determine whether echocardiographic assessment of LV size and MR provides incremental prognostic information.During a follow-up period of 5.6 ± 4.2 years, there were 13 cardiovascular deaths. When the patients were divided into two groups by LV size at diagnosis of D-HCM, a non-dilated LV group (LV end-diastolic diameter (LVEDD) < 50 mm, n = 9) and a dilated LV group (LVEDD ≥ 50 mm, n = 22), the clinical course in the non-dilated LV group was significantly worse. As for the clinical impact of MR, no patient in the non-dilated LV group showed significant MR and 7 of the patients with dilated LV size showed significant MR during follow-up. Once significant MR was reached, cardiovascular deaths were significantly more frequent in patients with MR.Patients with D-HCM, particularly those with less LV dilatation at diagnosis of dilated phase and with significant MR during follow-up, have a poor prognosis.