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Refining AF-Related Stroke Prediction Using the P2-CHA2DS2-VASc Score
Study Questions:
Does the addition of P-wave indices improve the predictive ability of the CHA2DS2-VASc score for the prediction of atrial fibrillation (AF)-related stroke risk?
Methods:
The authors studied 2,229 patients from the ARIC (Atherosclerosis Risk in Communities) study and 700 patients from the MESA (Multi-Ethnic Study of Atherosclerosis) study with incident AF who were not on anticoagulation within 1 year of AF diagnosis. P-wave indices, including abnormal P-wave axis and other P-wave measures, were measured on baseline electrocardiogram (ECG), when sinus rhythm was present before developing AF. Association with ischemic stroke risk was assessed using Cox proportional hazards models. The authors compared the standard CHA2DS2-VASc and P2-CHA2DS2-VASc scores using C-statistics and net reclassification improvement. The ARIC study served as the derivation cohort and the MESA study as the validation cohort.
Results:
Abnormal P-wave axis was associated with an increased risk of ischemic stroke (hazard ratio [HR], 1.84; 95% confidence interval [CI], 1.33-2.55) independent of other CHA2DS2-VASc risk elements. The C-statistic (95% CI) improved 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 from the CHA2DS2-VASc to P2-CHA2DS2-VASc score. Categorical net reclassification improvement was 0.25 (95% CI, 0.13-0.39) in ARIC and 0.51 (95% CI, 0.18-0.86) in MESA.
Conclusions:
The authors concluded that adding abnormal P-wave axis improves the predictive ability of the CHA2DS2-VASc score for predicting AF-related stroke risk.
Perspective:
The authors derive and validate the P2-CHA2DS2-VASc score, adding two points for an abnormal p-wave axis (any value outside 0-75°) to the traditional CHA2DS2-VASc risk elements. In doing so, prothrombotic atrial remodeling is incorporated into stroke risk estimation. While the P-wave axis is conveniently calculated on most ECGs, it can only be measured during periods of sinus rhythm. Therefore, patients with persistent or permanent AF may not benefit from this revised stroke risk score if they do not have older ECGs demonstrating sinus rhythm. Additionally, it is unknown how the timing between measuring an abnormal P-wave axis and the development of AF may impact stroke risk prediction. Finally, further validation of this risk score is needed before widespread use.
Keywords: Anticoagulants, Arrhythmias, Cardiac, Atherosclerosis, Atrial Fibrillation, Atrial Remodeling, Brain Ischemia, Electrocardiography, Risk, Stroke, Thrombolytic Therapy, Vascular Diseases
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