['The etiology of cerebral ischemia is undetermined in one-third of patients upon discharge. Occult paroxysmal atrial fibrillation (PAF) is considered a potential etiology. A high rate of PAF detection with 21-day mobile cardiac outpatient telemetry (MCOT) has been reported in two small studies. Optimal monitoring duration and factors predicting PAF have not been adequately defined.', 'We performed a retrospective analysis on patients evaluated by MCOT monitoring within 6 months of a cryptogenic stroke or TIA. Multivariate analysis with survival regression methods was performed using baseline characteristics to determine predictive risk factors for detection of PAF. Kaplan-Meier estimates were computed for 21-day PAF rates.', 'We analyzed 156 records; PAF occurred in 27 of 156 (17.3%) patients during MCOT monitoring of up to 30 days. The rate of PAF detection significantly increased from 3.9% in the initial 48 h, to 9.2% at 7 days, 15.1% at 14 days, and 19.5% by 21 days (p<0.05). Female gender, premature atrial complex on ECG, increased left atrial diameter, reduced left ventricular ejection fraction and greater stroke severity were independent predictors of PAF detection on multivariate analysis with strongest correlation seen for premature atrial complex on ECG (HR 13.7, p=0.001).'] Does outpatient cardiac telemetry detect a high rate of atrial fibrillation in cryptogenic stroke?