Relationship Between CHADS2 Score and Ischemic Stroke During Rhythm Control Therapy for Paroxysmal Atrial Fibrillation

The CHADS2 score has been proposed for stratifying patients with nonvalvular atrial fibrillation (NVAF) according to the risk of thromboembolism in the AHA/ACC/ESC guidelines. However, there is little information about its usefulness for predicting the long-term risk of ischemic stroke in Japanese patients with paroxysmal AF. We retrospectively evaluated the incidence of ischemic stroke and the efficacy of anticoagulant therapy in paroxysmal AF patients on rhythm control therapy who were stratified by their CHADS2 score. The subjects were 334 NVAF atients (229 men and 105 women, mean age, 68 +/- 12 years, mean follow-up period, 60 +/- 35 months) who were categorized into low risk (score 0), moderate risk (1 or 2), and high risk (3 or more) groups for thromboembolism. The low, moderate, and high risk groups accounted for 34%, 50%, and 16% of the patients, respectively. Among 257 patients without warfarin therapy, the annual rate of symptomatic ischemic stroke was 0.6% in the score 0 group, 0.5% in the score 1 group, 3.1% in the score 2 group, and 9.6% in the score 3 or more group. Among 77 patients treated with warfarin (target PT-INR: 1.6-3.0), the stroke rate was 0% in the score 0 group, 0% in the score 1 group, 1.4% in the score 2 group, and 6.6% in the score 3 or more group. The annual rate of ischemic stroke was 0.88% in patients treated with warfarin versus 2.67% in those without warfarin, or a decrease in risk of 68% with warfarin (P < 0.01). In Japanese patients with paroxysmal AF, the CHADS2 score is useful for predicting the risk of ischemic stroke. Anticoagulant therapy is needed to prevent ischemic stroke in patients with paroxysmal AF, especially those who have a CHADS2 score of 2 or more.