PROJECT SUMMARY Atrial fibrillation (AF) is an important ischemic stroke risk factor, increasing the risk 5-fold and accounting for 1 in every 4 ischemic strokes. Extended rhythm monitoring for AF following ischemic stroke is recommended because 10-20% experience recurrent stroke due to undetected AF and up to 30% of patients with ischemic stroke are diagnosed with new AF after hospital discharge. Since 25-50% of AF cases are due to paroxysmal AF, opportunistic screening with bedside electrocardiogram will miss a substantial portion of AF cases. Implantable loop recorders (ILRs) are guideline-endorsed, long-term rhythm monitors that detect paroxysmal AF. But universal ILR placement is suboptimal because ILRs are resource-intensive and only 30% of patients who receive ILR after stroke are diagnosed with AF. An alternative, yet untested, strategy is to calculate patient risk of AF in order to identify patients who are most likely to have undetected AF and will derive the most clinical benefit from ILR monitoring. Using individual AF risk estimates can improve the appropriateness of overall ILR use in a resource-effective manner. To test our hypothesis, the specific objectives of the current application are to identify healthcare settings in which a risk-guided approach will be most impactful, develop a post-stroke AF risk estimation tool, and pilot test the tool to assess acceptability, adoption, and validity of our intervention prior to its testing in a randomized trial. Through the Mentored Career Development Award, the candidate will undergo training in research with large healthcare databases, advanced prediction modeling, and clinical trial methodology to facilitate transition to an independent investigator with expertise in prevention and treatment of AF and its complication. The information produced from the proposed project will address important knowledge gaps in healthcare utilization for prevention of AF-related stroke and inform future effectiveness trials designed to directly inform selection of appropriate AF monitoring strategy following ischemic stroke.

PROJECT NARRATIVE Atrial fibrillation (AF) is an important risk factor for recurrent stroke that can be effectively mitigated with anticoagulation if detected. Implantable loop recorders (ILRs) are the most sensitive method to detect paroxysmal AF, but universal ILR placement is suboptimal because ILRs are resource-intensive and only 30% of patients who receive ILR after stroke are diagnosed with AF. To test the hypothesis that using individual AF risk estimation can improve the appropriateness of overall ILR use in a resource-effective manner, the proposed research seeks to identify healthcare settings in which a risk-guided approach will be most impactful, develop a post-stroke AF risk estimation tool, and pilot test the tool to assess acceptability, adoption, and validity prior to testing it in a randomized trial.