Mitral valve posteromedial papillary muscle head rupture presenting after liposomal doxorubicin chemotherapy for metastatic lung liposarcoma: a case report

Doxorubicin-induced cardiotoxicity classically manifests as dose-dependent left ventricular systolic dysfunction. Herein, we describe an unusual case of acute mitral papillary muscle rupture following cumulative anthracycline therapy, presenting despite a preserved ejection fraction.

A 78-year-old woman with metastatic liposarcoma and multiple cardiovascular risk factors developed acute dyspnoea 1 week after completing liposomal doxorubicin (cumulative absolute dose 534 mg). She previously received 5-fraction stereotactic body radiation therapy to the lower lung lobes in September 2024 (9 months prior), targeting fields in close geographic proximity to the diaphragmatic and inferior heart walls. Surveillance echocardiograms from 2022 to 2025 showed a preserved left ventricular ejection fraction (65%–75%). At presentation, cardiac biomarkers showed a normal brain natriuretic peptide and flat, minimally elevated troponins. Transoesophageal echocardiography confirmed an acute rupture of the posteromedial papillary muscle head and associated chordae causing severe (4+) mitral regurgitation. Open surgical intervention was deferred due to advanced malignancy and goals of care. Her acute heart failure was optimized medically with intravenous loop diuretics, low-dose lisinopril for afterload reduction, and metoprolol succinate, while home amlodipine and hydrochlorothiazide were discontinued. She stabilized and is undergoing evaluation for transcatheter edge-to-edge repair.

While a direct causal link is unproven, this case highlights a rare structural complication. We present this ‘two-hit’ model as a hypothesis-generating observation, suggesting that chemotherapy-induced structural changes might compound underlying ischaemic or radiation-induced vulnerabilities. As such, advanced imaging modalities may offer value in future efforts to implement risk-adapted surveillance.