Incidence and outcomes of transient new-onset atrial fibrillation complicating acute coronary syndromes: results from a systematic review and meta-analysis

Background: The overall risk of long-term adverse events of a transient episode of new-onset atrial fibrillation (AF) in patients with acute coronary syndrome (ACS) remains uncertain. This meta-analysis aimed to assess the prognostic impact of transient new-onset AF complicating ACS. Methods and results: Cohort studies examining the risk of adverse events in patients with transient new-onset AF compared to those in sinus rhythm after ACS were identified through a comprehensive search of MEDLINE, Scopus, Cochrane, and Google Scholar Library. Studies reporting the incidence of ischaemic stroke events, recurrent AF, or all-cause mortality at the longest follow-up were included. Adjusted hazard ratios (aHRs) with 95% confidence intervals (CI) were synthesized using inverse variance-weighted random-effects meta-analysis. In the seven observational studies included, comprising 151 735 patients, 6 597 (4.3%) experienced transient new-onset AF, which was associated with an increased risk of ischaemic stroke, recurrent AF, or all-cause mortality (HR: 2.24, 95% CI: 1.75-2.85; P < 0.0001; I2 = 30.76%; seven studies). The results remained consistent across each individual endpoint, including ischaemic stroke (HR 2.38, 95% CI: 1.64-3.44; P < 0.01; I2 = 50.2%; five studies), recurrent AF (HR 4.68, 95% CI: 2.07-10.59; P = 0.0002; I2 = 50.2%; four studies), and all-cause mortality (HR 1.36, 95% CI: 1.08-1.71; P = 0.0089; I2 = 53.25%; four studies). Meta-regression analyses revealed a significant increase in these adverse events associated with ST-elevation myocardial infarction (P = 0.001), while there was a tendency for their decrease associated with oral anticoagulant prescription at discharge (P = 0.07). Conclusions: The occurrence of transient new-onset AF is associated with an elevated long-term risk of stroke, recurrent AF, and all-cause mortality in patients with ACS. Consequently, these data urge randomized clinical trials to assess the best antithrombotic regimen while potentially helping the current treatment decision-making process for these patients.