Early Mild Hypertrophic Cardiomyopathy May Still Carry Significant Cardiovascular Risk

Approximately 21% of patients with phenotypically mild hypertrophic cardiomyopathy (HCM) experienced major adverse cardiovascular events (MACE) during a mean follow-up of seven years, highlighting that even apparently mild disease requires careful long-term monitoring. In this prospective analysis of 2,500 patients from the Sarcomeric Human Cardiomyopathy Registry, 21% developed MACE, including atrial fibrillation (289 patients), malignant ventricular arrhythmias (69 patients), and heart failure (193 patients). Nearly one-quarter (23%) progressed from no symptoms (NYHA class I) to symptomatic disease, and this symptom progression was associated with a 2.79-fold higher risk of MACE. Older age, higher body mass index, larger left atrial diameter, greater left ventricular (LV) wall thickness, higher LV outflow tract gradient, and the presence of late gadolinium enhancement on cardiac MRI were all associated with increased cardiovascular risk. Importantly, disease progression over time was also highly predictive: each 0.5 mm/year faster enlargement of the left atrium was associated with approximately doubled risks of atrial fibrillation and heart failure, while each 0.5 mm/year faster increases in LV wall thickness nearly doubled the risk of malignant ventricular arrhythmias. Patients with persistently higher or more rapidly increasing left atrial size, LV hypertrophy, or LV outflow tract gradient had the highest event rates. These findings suggest that serial assessment of cardiac remodeling and symptom development can improve risk stratification and may help identify patients with early-stage HCM who could benefit from future disease-modifying therapies. Source: https://www.jacc.org/