The Effect of Atrial Fibrillation on the Long-Term Mortality of Patients with Acute Coronary Syndrome: The TACOS Study

Introduction: Atrial fibrillation (AF) is a frequent finding in acute coronary syndrome (ACS), but there is conflicting scientific evidence regarding its long-term impact on patient outcome. The aim of this study was to survey and compare the ≥10-year mortality of ACS patients with sinus rhythm (SR) and AF. Methods: Patients were divided into 2 groups based on rhythm in their 12-lead ECGs: (1) SR (n = 788) at hospital admission and discharge (including sinus bradycardia, physiological sinus arrhythmia, and sinus tachycardia) and (2) AF/atrial flutter (n = 245) at both hospital admission and discharge, or SR and AF combination. Patients who failed to match the inclusion criteria were excluded from the final analysis. The main outcome surveyed was long-term all-cause mortality between AF and SR groups during the whole follow-up time. Results: Consecutive ACS patients (n = 1,188, median age 73 years, male/female 58/42%) were included and followed up for ≥10 years. AF patients were older (median age 77 vs. 71 years, p < 0.001) and more often female than SR patients. AF patients more often presented with non-ST-elevation myocardial infarction (69.8 vs. 50.4%, p < 0.001), had a higher rate of diabetes (31.0 vs. 22.8%, p = 0.009), and were more often using warfarin (32.2 vs. 5.1%, p < 0.001) or diuretic medication (55.1 vs. 25.8%, p < 0.001) on admission than patients with SR. The use of warfarin at discharge was also more frequent in the AF group (55.5 vs. 14.8%, p < 0.001). The rates of all-cause and cardiovascular mortality were higher in the AF group (80.9 vs. 50.3%, p < 0.001, and 73.8 vs. 69.6%, p = 0.285, respectively). In multivariable analysis, AF was independently associated with higher mortality when compared to SR (adjusted HR 1.662; 95% CI: 1.387-1.992, p < 0.001). Conclusion: AF/atrial flutter at admission and/or discharge independently predicted poorer long-term outcome in ACS patients, with 66% higher mortality within the ≥10-year follow-up time when compared to patients with SR.