Dynamic left main coronary artery compression by a dilated pulmonary artery in a patient with pulmonary hypertension-a case report demonstrating the significance of multimodular imaging.

Background: Although rare, dilation of the pulmonary artery, which can be present in patients with pulmonary arterial hypertension (PAH), can cause compression of the left main coronary artery (LMCA), leading to progressive dyspnoea, fatigue, syncope, and angina. Over time, this rare complication might lead to acute coronary syndrome. Case summary: A 63-year-old White female with a background of systemic hypertension and mild obstructive sleep apnoea was admitted to the emergency unit because of gradually worsening shortness of breath and generalized weakness, without associated anginal symptoms. Blood gas evaluation demonstrated impaired oxygenation, with a partial pressure of oxygen of 6.8 kPa and an oxygen saturation of 87.9%. Transthoracic echocardiography demonstrated marked right ventricular strain along with features consistent with pulmonary arterial hypertension. A CT pulmonary angiographic study showed pronounced enlargement of the pulmonary trunk, measuring 62 mm in diameter. Subsequent coronary angiography combined with intravascular ultrasound identified greater than 50% narrowing of the left main coronary artery due to extrinsic compression, which was corroborated by dynamic CT imaging. The patient underwent IVUS-guided percutaneous revascularization of the left main coronary artery with placement of a drug-eluting stent. One week post-discharge, prior to additional diagnostic evaluation and management of pulmonary arterial hypertension, the patient reported significant symptomatic relief, with functional status improving from New York Heart Association (NYHA) class III to class II. Discussion: This case underscores that extrinsic compression of the LMCA due to pulmonary artery dilatation warrants consideration as a potential aetiology of symptoms, even in the absence of angina.