OBJECTIVE The purpose of this study was to determine the prognostic significance of cardiac magnetic resonance imaging (MRI) findings in patients with apical hypertrophic cardiomyopathy (HCM). METHODS Cardiac MRI studies of 93 consecutive patients with apical HCM were retrospectively evaluated. Quantification of late gadolinium enhancement (LGE) was determined and expressed as a percentage of total left ventricular (LV) myocardial mass (%LGE). Morphologic features including presence of apical aneurysm, right ventricular hypertrophy, and LV thrombus were also assessed. Clinical data were collected during follow-up to assess for occurrence of major adverse events, defined as: heart failure, stroke, appropriate automatic implantable cardioverter defibrillator discharge, sustained ventricular tachycardia, aborted sudden cardiac death, and/or all-cause death. RESULTS The mean age of the patients was 54.9±13.8 years, and 72.0% (n=67) were male. LGE, right ventricular hypertrophy, apical aneurysm, and LV thrombus were identified in 69.4%, 25.8%, 18.3%, and 4.3%, respectively. Mean %LGE was 10.8%±11.1%. Over 2.4±1.7 years of follow-up, 14 subjects (15.1%) experienced a major adverse event (event rate, 6.3%/y): heart failure (6.5%), stroke (6.5%), appropriate automatic implantable cardioverter defibrillator discharge (2.2%), sustained ventricular tachycardia (2.2%), aborted sudden cardiac death (1.1%), and all-cause death (0.0%). Presence of apical aneurysm and extent of LGE were significant predictors of major adverse events [odds ratio (OR) 4.6, P=0.015; and OR 1.4/5% LGE, P=0.030, respectively]. Patients with both apical aneurysm and >5% LGE were at highest risk for major adverse events (OR 6.7, P=0.004) and had shortest event-free survival (P=0.001). CONCLUSIONS Within our population of apical HCM patients, the extent of LGE and the presence of an apical aneurysm identified by cardiac MRI were both significant predictors of major adverse clinical events.