Paradoxical Pulmonary Congestion After Mavacamten in Obstructive HCM: A Case Illustrating Hemodynamic Transition.

BACKGROUND

Mavacamten effectively reduces left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM).

CASE SUMMARY: A 51-year-old man with obstructive HCM developed paradoxical pulmonary congestion after successful LVOT relief with mavacamten. Despite a dramatic reduction in LVOT gradient and preserved ejection fraction, he experienced dyspnea and pleural effusion in week 6. Notably, an increase in tricuspid regurgitation pressure gradient and E/A ratio preceded clinical congestion. Initiation of an SGLT2 inhibitor led to clinical stabilization and hemodynamic re-equilibration by week 8.

DISCUSSION: This case illustrates a "functional dam" mechanism, where rapid LVOT obstruction relief may increase forward flow, potentially overwhelming a noncompliant left ventricle.

TAKE-HOME MESSAGES: Relief of LVOT obstruction can be associated with paradoxical pulmonary congestion despite apparent left-sided unloading. This observation highlights the importance of comprehensive noninvasive hemodynamic assessment during the early treatment phases of obstructive HCM.