Kamel H, Hunter M, Moon YP, Yaghi S, Cheung K, Di Tullio MR, et al. Electrocardiographic Left Atrial Abnormality and Risk of Stroke: Northern Manhattan Study. Stroke. 2015
In the current study, Dr. Kamel et al evaluate the relationship between left atrial disease, as measured by P-wave terminal force in lead V1, and the risk of stroke while adjusting for atrial fibrillation and other stroke risk factors. P-wave terminal force is an established electrocardiographic marker of left atrial cardiomyopathy without necessarily having atrial fibrillation and can be easily calculated on a standard EKG. In order to test the hypothesis that atrial disease may lead to thromboemoblism without atrial fibrillation, atrial disease should be specifically associated with cardioembolic or cryptogenic stroke subtypes as opposed to non-cardioembolic stroke subtypes.
The authors measured the P-wave terminal force in 241 patients with ischemic stroke and a randomly selected cohort of 798 patients without ischemic stroke. P-wave terminal force in lead V1was indeed associated with the composite of cryptogenic and cardioemoblic stroke, but not non-cardioembolic stroke subtypes. In addition, in a sensitivity analysis that excluded any patient with atrial fibrillation, the results were unchanged or stronger. However, adjustment for left atrial size on echocardiography attenuated the results.
Limitations include the small sample size, the fact that two people manually calculated the P-wave terminal force and the inter-rater reliability was only moderately reliable, and the lack of more definitive methods to rule out atrial fibrillation.
Overall, the manuscript questions the long believed understanding that atrial fibrillation causes stroke. Instead, atrial fibrillation may merely represent part of the spectrum of atrial cardiomyopathy, which in itself may lead to thromboembolism. Furthermore, if proven true, the ease and cost-effectiveness of simply checking an EKG may prove to be an efficient way to assess for thromboembolic risk as compared to years of heart-rhythm monitoring.Sanna T, Diener HC, Passman RS, Di Lazzaro V, Bernstein RA, Morillo CA, et al. Cryptogenic stroke and underlying atrial fibrillation. N Engl J Med. 2014;370:2478-2486. Tweet: Atrial cardiomyopathy may be an independent risk factor for stroke