Objective: Prolonged monitoring times (72h) are recommended to detect paroxysmal atrial fibrillation (pAF) after ischemic stroke, but not yet clinical practice; therefore, an individual patient selection for prolonged ECG monitoring might increase the diagnostic yield of pAF in a resource-saving manner. Methods: We used individual patient data from three prospective studies (ntotal=1556) performing prolonged Holter ECG monitoring (at least 72h) and centralized data evaluation after TIA or stroke in patients with sinus rhythm. Based on the TRIPOD guideline, a clinical score was developed on one cohort, internally validated by bootstrapping and externally validated on two other studies. Results: pAF was detected in 77 (4.9%) of 1556 patients during 72h-Holter monitoring. After logistic regression analysis with variable selection, age and the qualifying stroke event (categorised as stroke severity with NIH-SS≤5 (OR 2.4 vs. TIA; 95%CI0.8-6.9,p=0.112) or stroke with NIH-SS>5 (OR 7.2 vs. TIA; 95%CI 2.4-21.8,p<0.001)) were found to be predictive for the detection of pAF within 72h-Holter monitoring and included in the final score (Age: 0.76 points/year, Stroke Severity NIH-SS≤5 = 9 points, NIH-SS>5 = 21 points; to Find AF, AS5F). The high risk group defined by AS5F is characterized by a predicted risk between 5.2% and 40.8% for detection of pAF with a number needed to screen of 3 for the highest observed AS5F points within the study population. Regarding the low number of outcomes before generalization of AS5F the results need replication. Conclusion: The AS5F score can select patients for prolonged ECG monitoring after ischemic stroke to detect pAF.