Background: Cardiac magnetic resonance (CMR) is used in the diagnosis and risk stratification of hypertrophic cardiomyopathy (HCM) and can detect myocardial replacement fibrosis (anindependent predictor of adverse cardiac outcomes) using late gadolinium enhancement (LGE).
Methods: We retrospectively analysed CMR studies carried out over a 2 year period identifying those which were diagnostic of HCM. 117 cases were analysed. Mean age of subjects was 53 years and 78 (67%) were male. Mean ejection fraction (EF) was 68.3% with a mean left ventricular (LV) mass index of 89.4 g/m². Hypertrophy was predominantly asymmetric in 94 (80%).
Results: All subjects received gadolinium and 80 (68%) had evidence of LGE. LVEF was lower (67 vs. 71%; p = 0.015) and LV mass index higher (94 vs. 81 g/m²; p = 0.007) in the LGE group. The proportion of patients with at least 1 clinical risk factor for sudden cardiac death (SCD) was similar in groups with and without LGE (48% vs. 32%; p = 0.160). In this study, a significant proportion (62%) of patients without clinical risk factors for SCD were found to have LGE on CMR. These patients would not currently be considered for therapy with an implantable cardiac defibrillator.
Conclusions: 1. Patients with HCM are at increased risk of SCD, but identifying patients who may benefit from implantable defibrillators is difficult. 2. LGE is associated with adverse cardiovascular outcomes in HCM, but is present in a large proportion of patients. 3. Many patients without clinical risk factors for SCD have LGE and would not currently be considered for an implantable cardiac device.