One-Year Prognosis for Patients Diagnosed with Acute Coronary Syndrome Compared to Those with Chronic Coronary Syndrome Following Complex Coronary Procedures

<b>Background:</b> Acute coronary syndrome (ACS) remains the primary cause of mortality worldwide. Performing complex coronary intervention in patients with ACS is considered a significant factor for worsening prognosis. This study aimed to evaluate the prognosis of patients with ACS treated with complex procedures compared to patients with chronic coronary syndrome (CCS). <b>Methods:</b> Among 980 patients from the Polish Complex Registry, we enrolled 829 consecutive patients who underwent complex percutaneous coronary intervention (PCI) for acute or chronic coronary syndrome with a completed one-year follow-up. The primary endpoint is defined as the major adverse cardiac event (MACE) at 12 months, a composite endpoint including all-cause death, target lesion revascularization, target vessel revascularization, and non-fatal myocardial infarction. <b>Results:</b> The incidence of the composite endpoint of MACE at one-year follow-up was comparable between the patients with acute and chronic coronary syndrome who underwent complex PCI (12.4% vs. 7.6%, LogRank <i>p</i> = 0.035). Cox multivariate analysis indicated that ACS is an independent risk factor for death at one-year follow-up. Additionally, age and comorbidities, such as heart failure and chronic kidney disease, along with procedural factors, including lesion length and pre-procedural diameter stenosis, are independent predictors of death in patients with complex lesions. Independent risk factors for MACE at one-year follow-up include age, heart failure, previous PCI, in-stent restenosis, and pre-procedural diameter stenosis. <b>Conclusions:</b> The prognosis of patients with acute and chronic coronary syndrome in the annual follow-up is comparable in the context of cardiovascular events. The clinical presentation of ACS is an independent risk factor for all-cause death.