Prognostic impact of atrial fibrillation occurrence in patients with non-ST-elevation acute coronary syndromes: is dysrhythmia duration a parameter to focus on?

Several studies have evaluated the prognostic impact of atrial fibrillation (AF) in ST-elevation myocardial infarction (STEMI) patients, but scarce data are available on the role of AF in non-ST-elevation acute coronary syndromes (NSTE-ACS). The aim of this study was to investigate long-term outcome of NSTE-ACS patients experiencing an episode of AF during in-hospital course. Of 1,147 NSTE-ACS patients, 54.4% for non-STEMI (NSTEMI) and 45.6% for unstable angina, 65 (5.7%) had an episode of AF. Long-term survival was compared with that of 1,082 NSTE-ACS patients who did not develop AF. Patients who developed AF, with respect to those who did not, were older and more frequently with NSTEMI at admission (69.2 vs. 53.5%, p = 0.013), diabetes, dyslipidemia and history of heart failure. Moreover, patients who developed AF had a significantly higher New York Heart Association class and lower values of glomerular filtration rate. During a median follow-up of 40.7 months, we observed a significantly higher mortality in NSTE-ACS patients who developed AF versus those who did not (42.2 vs. 19.8%, p < 0.001). AF occurrence in NSTE-ACS was a significant predictor of mortality at Cox regression (adjusted HR: 1.85; p = 0.03). After propensity score analysis, only patients with AF duration >6 h showed a significantly higher mortality at Cox regression (p = 0.021). Our results suggest that NSTE-ACS patients who develop AF are characterized by a higher clinical complexity. The occurrence of AF, when longer than 6 h, represents an important negative prognostic factor for long-term survival.