Background: Although apical hypertrophic cardiomyopathy (ApHCM) has been generally considered a benign disease, recent studies have reported that it is less benign than previously known. However, those studies were performed with relatively small number of patients. We investigated long-term clinical outcomes of ApHCM patients referred to a tertiary center and sought to find predictors of prognosis. Methods: A total of four hundred and fifty four patients (316 males, age: 61짹11 years, 51% hypertension, 15% diabetes mellitus [DM]) entered this retrospective study. Cardiovascular (CV) events were defined as unplanned hospitalization for worsening heart failure, ischemic stroke, or cardiovascular death. Clinical data and comprehensive echocardiographic data at the time of initial presentation were analyzed to determine poor prognostic factor. Results: During follow-up period (mean 43 months [range 0-84]), CV mortality rate was 5% (22 patients) and 110 patients (24%) had other CV events (88 hospitalizations due to heart failure and 26 strokes). In multivariate Cox regression analysis, increased LAVI was found to be an independent predictor of CV events (for each 1 mL/m2 increase, hazard ratio [HR]=1.01; 95% confidence interval [CI], 1.00-1.03; P=0.047) along with S��� (for each 1 cm/s increase, HR=0.83; 95% CI, 0.72-0.96; P=0.014), age (for each 1 year increase, HR=1.02; 95% CI, 1.00-1.04; P=0.028) and the presence of DM (HR=1.83; 95% CI, 1.16-2.88; P=0.009) and hypertension (HR=2.25; 95% CI, 1.44-3.51; P<0.0001) In addition, patients with larger left atrium (LA) (LAVI���29 ml/m2) showed significantly increased CV mortality (P=0.002) and poorer event free survival (P=0.005) than those who had smaller LA (LAVI<29 ml/m2) (Figure). Conclusion: Patients with ApHCM showed less benign prognosis than previously thought. LA enlargement at the time of presentation along with other co-morbidities was an independent predictor of poor clinical outcome in patients with ApHCM.