Significance of Atrial Fibrillation Complicating ST-Segment Elevation Myocardial Infarction.

The aim of the present study is to assess the clinical impact of atrial fibrillation (AF) in patients with ST-segment elevation myocardial infarction (STEMI) complicated by new-onset AF depending on STEMI location and timing of arrhythmia. We analyzed 4,363 consecutive STEMI patients treated invasively. Finally, 4,099 subjects were included into further analysis, as 264 patients were excluded because of previous AF history. In total, 1,800 (43.9%) subjects with anterior infarction were included into Group 1, whereas Group 2 encompassed 2,299 (56.1%) patients with nonanterior infarction. Subsequently, both groups were divided into patients with new-onset AF (AF Group 1 and 2, respectively) and without AF (Control Group 1 and 2). New-onset AF was recognized in 225 patients (5.5%): 96 (5.3%) with an anterior wall infarction (AF Group 1) and 129 (5.6%) with a nonanterior wall infarction (AF Group 2). The incidence of early-onset arrhythmia (within 24 hours after admission) was significantly higher in AF Group 2 than in AF Group 1: 71.3% versus 35.4% (p <0.001). In Group 1, both early- and late-onset AFs were associated with significantly increased in-hospital mortality compared with AF-free population (17.7% and 27.4%, respectively vs 6.3%; p <0.05), whereas in Group 2, in-hospital mortality was increased only in subjects with late-onset AF compared with AF-free population (13.5% vs 4.2%, p <0.05). New-onset AF was the independent predictor of death only in Group 1 (hazard ratio 2.16) and this effect was stronger for late-onset AF (hazard ratio 2.86). In conclusion, 1 in 20 patients with STEMI treated invasively was affected by new-onset AF. The predictive value of new-onset AF was strongly related with STEMI location and timing of arrhythmia.