Chronic Total Occlusions in Non-Infarct-Related Coronary Arteries and Long-Term Cardiovascular Mortality in Patients Receiving Percutaneous Coronary Intervention in Acute Coronary Syndromes

<b>Background and aim</b>: Patients with non-infarct-related artery chronic total occlusion (non-IRA CTO) found during percutaneous coronary intervention (PCI) in acute coronary syndromes (ACSs) are not rare and have worse clinical outcomes. We aimed to analyze their long-term clinical outcomes in regard to clinical characteristics, revascularization strategies, and adherence to medical therapy. <b>Patients and methods</b>: The dual-center ACS registry of patients treated from Jan 2017 to May 2023 was used to identify 1950 patients with timely PCI in ACS who survived to discharge with documented adequate demographic, clinical, and angiographic characteristics, treatment strategies, and medical therapy adherence during a median follow-up time of 49 months. <b>Results</b>: There were 171 (9%) patients with non-IRA CTO. In comparison to patients without non-IRA CTO, they were older, with more diabetes mellitus (DM), higher Syntax scores (median 27.5 vs. 11.5), and lower left ventricular ejection fraction (LVEF) at discharge (median LVEF 50% vs. 55%). There was also a lower proportion of patients with high adherence to medical therapy (32% vs. 46%). Patients with non-IRA CTO had significantly higher cardiovascular mortality during follow-up (18% vs. 8%, RR 1.87, 95% CI 1.27-2.75). After adjusting for relevant clinical and treatment characteristics in a multivariate Cox regression analysis, only lower LVEF, worse renal function, the presence of DM, and lower adherence to medical therapy were independently associated with higher cardiovascular mortality during follow-up, with low adherence to medical therapy as the strongest predictor (RR 3.18, 95% CI 1.76-5.75). Time to cardiovascular death was significantly lower in patients who did not receive non-IRA CTO revascularization, although CTO revascularization did not show independent association with survival in the multivariate analysis. <b>Conclusions</b>: Patients with non-IRA CTO found during ACS treatment have more unfavorable clinical characteristics, worse adherence to medical therapy, and higher cardiovascular mortality. They need a more scrutinized approach during follow-up to increase adherence to optimal medical therapy and to receive revascularization of the non-IRA CTO whenever it is clinically indicated and reasonably achievable without excess risks.