RESUMEN
BACKGROUND: The long-term risk of stroke after acute myocardial infarction (AMI) complicated with new-onset atrial fibrillation (AF) remains unclear. The aim of this study was to determine the long-term risk of AF and stroke in patients with AMI complicated with new-onset AF. METHODS: Patients with AMI complicated with new-onset AF (n = 260) and those without new-onset AF (n = 292) were followed for a mean of 7 years. All patients had sinus rhythm at hospital discharge. RESULTS: During the follow-up, AMI patients with new-onset AF had more frequent AF than those without new-onset AF (10.4% vs 2.7%, respectively; P < 0.0001). New-onset AF during AMI was a significant predictor of subsequent AF occurrence (the time elapsing between 2 consecutive R waves [RR] = 3.15, P = 0.004); but AF recurrence in follow-up (RR = 5.08, P = 0.001) and non-anticoagulation at discharge (RR = 0.29, P = 0.008) were independent predictors of stroke (Cox regression analysis). A period of 3.5 hours of AF within the first 48 hours of AMI was the high sensitivity cut-off level for the prediction of low long-term risk of stroke obtained by receiver operating characteristic analysis. Among patients who did not receive anticoagulants at discharge, the patients with short AF did not experience stroke and AF recurrence during follow-up, while those in the other group developed it (10.8%, P = 0.038 and 13.5%, P = 0.019, respectively). CONCLUSION: New-onset AF during AMI identifies the patients at long-term risk for stroke who may potentially benefit from anticoagulant therapy. Atrial fibrillation recurrence in follow-up was independently related to the development of stroke. However, for low-risk patients with AF (those with short AF occurring early in AMI) long-term anticoagulants might not be required.