ABSTRACT
Background: Acute coronary syndrome (ACS) includes ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI), each with distinct clinical profiles and outcomes. While STEMI is typically associated with more extensive infarcts, emerging data suggest NSTEMI may carry a greater burden of comorbidities and anatomical complexity. Objective: To compare the incidence of ventricular arrhythmias and hemodynamic instability in patients with STEMI vs. NSTEMI and to analyze the distribution of culprit coronary lesions. Methods: This retrospective single-center study included 172 patients who underwent coronary revascularization between April and July 2021. Clinical outcomes, arrhythmias, and hemodynamic instability were compared between groups with STEMI (n = 108) and NSTEMI (n = 64). Culprit lesions were evaluated by angiography and categorized by vessel. Results: Hemodynamic instability was significantly more common in patients with NSTEMI (10.93%) compared to STEMI (0.18%) (p = 0.005). Ventricular arrhythmias occurred in 12.03% of patients with STEMI and 7.81% of patients with NSTEMI, with no significant difference. Left main coronary artery lesions were notably more frequent in NSTEMI (47.4% vs. 2.04%; p < 0.0001), whereas right coronary artery involvement was higher in STEMI (40.81% vs. 7.4%; p < 0.0001). Ventricular arrhythmias were significantly associated with circumflex artery lesions in patients with NSTEMI (p = 0.0001). Conclusions: Despite often being perceived as lower risk, patients with NSTEMI exhibited a higher rate of hemodynamic instability and more complex coronary involvement, particularly left main disease. These findings highlight the need for vigilant monitoring and individualized treatment strategies in populations with NSTEMI.