['Atrial fibrillation (AF) is a major cause of ischemic stroke. Cardiac troponin (cTnI) is a marker of myocardial damage and may predict arrhythmia. We sought to determine if increased cTnI levels were a predictor of new-onset AF in ischemic stroke or patients with transient ischemic attack (TIA).', 'Consecutive patients who presented to Charles-Lemoyne Hospital between October 2006 and November 2010 with a diagnosis of acute ischemic stroke or TIA, without a history of AF, with a baseline measurement of cTnI were included in the study. The primary outcome was new-onset AF on 24-hour Holter measurement within 1 week of admission in patients without AF on the baseline electrocardiogram (ECG). Secondary outcomes included AF on Holter measurement, death, myocardial infarction (MI), and stroke within 3 months.', 'A total of 408 patients were included. Forty-six patients (11.3%) had elevated cTnI levels. These patients were older and had a higher prevalence of coronary artery disease and diabetes. AF on baseline ECG or 24-hour Holter measurement was present in 51 patients (12.5%) and was more frequent among patients with increased cTnI levels compared to patients with normal cTnI levels (34.7% vs 9.7%; P = .004 multivariate analysis). Elevated cTnI levels also predicted the composite outcome of stroke, MI, and death at 3 months (50.0% vs 16.1%; P = .0001).'] Does troponin elevation predict atrial fibrillation in patients with stroke or transient ischemic attack?