The existence of a coronary artery aneurysm (CAA) can pose significant risk for death. It can cause thrombosis, dissection, rupture or myocardial infarction. An exceedingly rare involvement of the left main coronary artery (LMCA), particularly giant-sized is even more catastrophic, a finding seen in only 0.1% of patients. Furthermore, co-existence with significant stenotic coronary artery disease (CAD) portends grim survival. Owing to the rarity of this combination, no data is available locally and only limited case reports are documented internationally. Hence, no consensus guidelines have been published yet. This paper aims to contribute to the sparse medical knowledge on the treatment approach and management of LMCA aneurysm with concomitant CAD.

A 62-year-old male, Filipino, hypertensive and hyperlipidemic sought consult due to one-year exertional chest pain. Coronary angiogram revealed the LMCA to be a diffusely aneurysmal, large-sized vessel measuring 9.7 mm x 7.9 mm with a significant two-vessel CAD affecting the proximal left anterior descending (LAD) and right coronary artery (RCA). As per multidisciplinary decision, the patient underwent surgical revascularization via cardiopulmonary bypass graft (CABG) addressing the CAD and LMCA aneurysm managed conservatively through guideline-directed medical therapy. The patient’s course of treatment was uneventful. He returned for follow-ups for three months post-surgery and remained symptom-free.

Giant coronary artery aneurysms (GCAA) are vessel dilatations that exceed 4x the diameter of a normal adjacent artery. The patient had a unique case of GCAA involving the LMCA combined with two-vessel CAD. Few studies have documented a medical or surgical approach and long-term outcomes are unknown. Without sufficient evidence-based guidelines, the multidisciplinary decision was to perform CABG and manage the LMCA aneurysm conservatively.

Due to extremely limited information available on the giant LMCA aneurysm natural history, definitive management remains controversial. A multidisciplinary team approach is highly recommended for patient-specific needs to achieve favorable outcome and ensure survival.