Abstract Body (Do not enter title and authors here): Background: Revascularisation for a significant left main (LM) stenosis is considered the gold standard. However, significant risk factors may preclude any type of intervention in these patients. Data on the outcomes of this cohort when managed medically are limited.

Methods: Consecutive medically managed patients with surgical coronary anatomy who were discussed at a cardiac case conference of a tertiary Australian institution were included between 2012 and 2021. Surgical CAD was defined as stenosis >70% (or fractional flow reserve <0.8) in a triple vessel distribution or double vessel distribution with a dominant circumflex and/or significant left main stenosis. Severe LM coronary artery stenosis was defined as a stenosis of >50%. Thirty day and 12-month rates of hospital readmission and cardiac complications were recorded. Comparison was made between those with and without severe LM stenosis. Long term mortality data were collected until 31st December 2023.

Results: In total, 121 patients with surgical anatomy were managed medically following multidisciplinary discussion. Of these, 27 patients (22.3%) had a severe stenosis of their LM coronary artery. Median follow-up was 3.6 years (IQR 1.9-6.4) post discussion. Both groups were similar with regards to age (76.3 years (68.9-82.1) vs 72.7 (64.5-80.4), p=0.13), male gender (18 (66.7%) vs 67 (71.3%), p=0.64) and prevalence of diabetes (16 (59.3%) vs 52 (55.3%), p=0.72). Rates of cardiac death were similar in patients with and without LM disease, both at 12 months (4 (14.8%) vs 9 (9.6%), p=0.44) and at maximal follow up (7 (25.9%) vs 24 (25.5%), p=0.97). Similarly, no difference was seen in rates of 12-month hospital readmission (20 (74.1%) vs 60 (63.8%), p=0.32) or number of anti-anginal agents required to control symptoms (1 (IQR 1-2) vs 1 (1-2), p=0.18).

Conclusions: In our real-world cohort, among patients with surgical coronary anatomy who were managed medically due to prohibitive surgical risk following multidisciplinary discussion, the presence of a severe LM stenosis did not portend a worse prognosis. These data suggest that opting for medical management is a reasonable option in these patients when surgical revascularisation is inappropriate.