Age is the most important risk factor for stroke in patients with atrial fibrillation, and not all stroke risk factors in the CHA2DS2-VASc score carry equal risk, a retrospective, population-based study showed.
Analysis of data from 186,570 Taiwanese patients with atrial fibrillation (AF) found that the risk of ischemic stroke ranged from 1.96% per year for men with vascular diseases to 3.5% per year for those aged 65-74 years. In women, the risk increased from 1.91% per year for women with hypertension to 3.34% per year for those aged 65-74 years, wrote Dr. Tze-Fan Chao of Taipei (Taiwan) Veterans General Hospital and coauthors (J. Am. Coll. Cardiol. 2015;65:635-42 [doi: 10.1016/j.jacc.2014.11.046]).
The study results showed that male AF patients with a CHA2DS2-VASc score of 1 had an annual stroke rate of 2.75%; women with a CHA2DS2-VASc score of 2 had a greater than two-fold increase in stroke risk, compared with women with a score of 1.
“Our study is the first population-based investigation analyzing the risk of ischemic stroke in nonanticoagulated AF male patients with a CHA2DS2-VASc score of 1 and female patients with a CHA2DS2-VASc score of 2, according to the specific covariates composing the CHA2DS2-VASc score,” Dr. Chao wrote.
The investigators cited several limitations. One is that they were unable to determine whether the cause of ischemic stroke was tied to AF-related thromboembolism or atherosclerosis and thrombosis of the cerebral artery. This limitation, however, was common among previous randomized trials, they noted.
The study was partly supported by grants from the National Science Council and Taipei (Taiwan) Veterans General Hospital. One author declared consultancies and speakers fees from private industry. No other conflicts of interest were declared.