Atherosclerotic cardiovascular disease remains one of the leading causes of morbidity and mortality worldwide, accounting for approximately 3.9 million deaths annually due to its complications. This single-center, retrospective cohort study included 109 patients who underwent coronary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) between April and July 2022 at the Cardiology Clinic of the County Emergency Clinical Hospital in Targu Mureș, Romania. Women diagnosed with STEMI were found to be older at the time of presentation compared to men, with this difference reaching statistical significance (P = 0.0148). The incidence of atrial fibrillation was higher in women, with a statistically significant difference (P = 0.0258). Stratification of patients based on the location of culprit lesions did not reveal a statistically significant difference in the occurrence of atrial fibrillation. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were significantly higher in women than in men (P = 0.0200). The multivariate analysis revealed that the occurrence of atrial fibrillation was dependent on age (P = 0.0025), smoking (P < 0.0001), and cholesterol levels (P = 0.0182), but independent of sex (P = 0.2094), ejection fraction (P = 0.2293), the presence of hypertension (P = 0.1142), chronic kidney disease (P = 0.6935), diabetes mellitus (P = 0.9375), triglyceride levels (P = 0.7614), high-sensitivity cardiac troponin I (hs-cTnI, P = 0.4422), and creatine kinase (CK, P = 0.7420). In summary, women with STEMI presented at an older age, had higher NT-proBNP levels, experienced more frequent atrial fibrillation, and had a greater likelihood of circumflex artery involvement. Smoking and age were the only factors significantly associated with atrial fibrillation in the multivariable analysis.