Maheshwari, Ankit2020-08-252020-08-252018-02https://hdl.handle.net/11299/215011University of Minnesota M.S. thesis. February 2018. Major: Epidemiology. Advisor: Lin Chen. 1 computer file (PDF); viii, 34 pages.Introduction: In people with atrial fibrillation (AF), periods of sinus rhythm present an opportunity to detect pro-thrombotic atrial remodeling through measurement of P-wave indices (PWIs)—prolonged P-wave duration, abnormal P-wave axis, advanced inter-atrial block, and abnormal P-wave terminal force in lead V1. We hypothesized that addition of PWIs to the CHA2DS2-VASc score would improve its ability to predict AF-related ischemic stroke. Methods: We included 2229 Atherosclerosis Risk in Communities (ARIC) study and 700 Multi-Ethnic Study of Atherosclerosis (MESA) participants with incident AF and without anticoagulant use within 1 year of AF diagnosis. PWIs were obtained from study visit ECGs before development of AF. AF was ascertained using study visit ECGs and hospital records. Ischemic stroke cases were based on physician adjudication of hospital records. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) of PWIs for ischemic stroke. Improvement in 1-year stroke prediction was assessed by C-statistic, categorical net reclassification improvement (NRI), and relative integrated discrimination improvement (IDI). Results: Abnormal P-wave axis was the only PWI associated with increased ischemic stroke risk (HR, 1.84; 95% CI, 1.33-2.55) independent of CHA2DS2-VASc variables and that resulted in meaningful improvement in stroke prediction. The beta estimate was approximately twice that of the CHA2DS2-VASc variables, thus abnormal P-wave axis was assigned 2 points to create the P2-CHA2DS2-VASc score. This improved the C-statistic (95% CI) from 0.60 (0.51-0.69) to 0.67 (0.60-0.75) in ARIC and 0.68 (0.52-0.84) to 0.75 (0.60-0.91) in MESA (validation cohort). In ARIC and MESA, the categorical NRI (95% CI) were 0.25 (0.13-0.39) and 0.51 (0.18-0.86), respectively, and the relative IDI (95% CI) were 1.19 (0.96-1.44) and 0.82 (0.36-1.39), respectively. Conclusions: Abnormal P-wave axis—an ECG correlate of left atrial abnormality— improves ischemic stroke prediction in AF. Compared with CHA2DS2-VASc, the P2-CHA2DS2-VASc is a better prediction tool for AF-related ischemic stroke.enatrial fibrillationp wavestrokeThesis or Dissertation