Magnetic resonance imaging evaluation of the effects of myosin inhibitors (mavacamten and aficamten) in hypertrophic cardiomyopathy: a systematic review and case report

Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disorder, affecting approximately 1 in 250 individuals. It is defined by unexplained left ventricular (LV) hypertrophy in the absence of other identifiable cardiac or systemic causes. The clinical presentation is highly variable, ranging from asymptomatic individuals to those with complications such as sudden cardiac death, heart failure, and atrial fibrillation. Multimodal and longitudinal imaging is essential in HCM management. Among these, cardiac magnetic resonance (CMR) provides superior tissue characterization and accurate assessment of myocardial hypertrophy and fibrosis. CMR allows quantification of fibrosis through late gadolinium enhancement and T1 mapping, both critical for risk stratification and prognostic evaluation. Recently, cardiac myosin inhibitors (CMIs)—mavacamten and aficamten—have shown unprecedented potential in altering disease progression by reducing myocardial hypertrophy, hypercontractility, and LV outflow tract obstruction. This systematic review, prompted by a clinical case comparing baseline and 13-month follow-up CMR findings after mavacamten therapy in a female patient with HCM, aims to evaluate the impact of CMIs on CMR-derived parameters. Following a comprehensive PRISMA-guided search, three randomized controlled trials were included. Results demonstrated consistent reductions in LV mass, maximum LV wall thickness, and left atrial volume index. Two studies also reported significant reductions in absolute myocyte mass index, and one found a decrease in native T1 with aficamten. These findings highlight the value of CMR in unveiling the real effects of CMIs and reinforce the need for large-scale studies to confirm their long-term benefits in HCM management.