Accelerated hypertension following mavacamten introduction in severe obstructive hypertrophic cardiomyopathy with hypertension: a case report.

Background: Mavacamten in Phase 2 and 3 clinical trials was well tolerated, reduced left ventricular outflow tract obstruction (LVOTO), and improved exercise capacity and symptoms. However, due to its recent introduction in the market, there is limited evidence from real-world patients with severe/multiple comorbidities and/or who are exposed to potential treatment interactions. Hypertension is common in patients with hypertrophic cardiomyopathy (HCM), but its impact on the treatment of LVOTO is undefined. Case summary: A 55-year-old man with severely obstructive symptomatic HCM and Grade I arterial hypertension underwent treatment with mavacamten 5 mg. He presented an accelerated hypertension from Day 10 of treatment. On admission, he reported improvement of his dyspnoea [New York Heart Association (NYHA) Class II] and NT-pro BNP decreased to 1646 ng/L. Echocardiography showed a left ventricular ejection fraction of 60% with reduced systolic anterior motion and LVOTO (max 21 mmHg). Causes of secondary hypertension were excluded, and blood pressure (BP) was controlled by eplerenone and amlodipine introduction. Accelerated hypertension was concluded as a final diagnosis, and a potential causal link with the introduction of mavacamten was made. Evolution up to Day 135 proved a stabilization of the BP profile and of the LVOT gradient (max 36 mmHg) as well as improvement in functional capacity (NYHA Class I). Discussion: We hypothesize that rapid relief of excess afterload may induce alterations potentially leading to high BP in patients with impaired peripheral vascular resistances. Patients with severe obstructive HCM and hypertension should be given special attention during mavacamten titration and should self-monitor the BP during this phase.