Left main coronary artery compression due to pulmonary artery dilatation complicated by acute biventricular dysfunction: a case report.

Background: Left main coronary artery (LMCA) compression by a dilated pulmonary artery (PA) is one of the lesser known but severe complications in the setting of severe pulmonary hypertension (PH). This phenomenon can lead to critical myocardial ischaemia and poses unique diagnostic and therapeutic challenges. Case Summary: A 36-year-old female with PH due to peripheral pulmonary arterial stenoses presented with significant dyspnoea and exercise intolerance. Echocardiography revealed mild biventricular systolic dysfunction. Right heart catheterization confirmed severe pre-capillary PH, while coronary computed tomography angiography demonstrated a dilated PA compressing the proximal LMCA. Invasive coronary angiography confirmed a subocclusive LMCA stenosis, but during the procedure the patient developed refractory cardiogenic shock with biventricular failure. LMCA percutaneous coronary intervention (PCI) with a single drug-eluting stent was performed with the assistance of mechanical circulatory support (MCS). After the procedure, the ventricular function gradually improved, the patient was weaned from MCS by day 2 and discharged after 10 days. Discussion: LMCA compression in PH is often underdiagnosed due to its non-specific symptoms. However, early recognition is crucial as it significantly impacts outcomes by preventing the progression to biventricular dysfunction and reducing the risk of sudden death. Management typically requires a multi-disciplinary approach, with PCI often being the treatment of choice due to the high surgical risk in PH patients and the peculiar aetiology of the stenosis secondary to extrinsic compression instead of luminal atherosclerosis. In this case, the use of MCS was essential in stabilizing the patient and enabling successful PCI.