Ischemic stroke risk in East Asian patients with CHA₂DS₂-VASc score of 1: systematic review and meta-analysis

Background: The use of anticoagulation for stroke prevention in patients with atrial fibrillation (AF) and CHA₂DS₂-VASc score of 1 has been debated, partially due to limited data on ischemic stroke risk and specific clinical trials in these patients. East Asian patients have a different stroke risk profile compared to non-East Asians. We performed a systematic review and meta-analysis of ischemic stroke risk in AF patients with a CHA₂DS₂-VASc score of 1 in East Asian countries.

Methods: A comprehensive literature search for studies evaluating ischemic stroke risk related with AF with CHA₂DS₂-VASc score of 1 was conducted by two reviewers. We used a fixed-effect model first, then a random-effect model if heterogeneity was assessed with I².

Results: After pooling 6 studies, the annual rate of ischemic stroke in East Asian patients with AF and a CHA₂DS₂-VASc score of 1 was 1.66% (95% CI: 0.71%-2.61%, I2 = 98.4%). There was a wide range in reported pooled rates between countries, from 0.59% to 3.13%. Significant difference existed not only in the community-based studies (Chinese: 2.10% vs. Japanese: 0.60%), but also from the hospital-based studies (Chinese: 3.55% vs. Japanese: 0.42%). Confining the analysis to those on no antithrombotic treatment had limited effect on the summary estimate (eg. Chinese: 4.28% vs. Japanese: 0.6%). In Chinese studies, ischemic stroke rate was lower in females than males (female: 1.40% vs. male: 1.79%). However, the low event rate in Japanese studies may reflect unrecorded anticoagulation status at follow-up.

Conclusions: Some regional differences between East Asian countries were observed for ischemic stroke risk in patients with a CHA₂DS₂-VASc score of 1. This may reflect methodological differences in studies and unrecorded anticoagulation use at followup, but further prospective studies are required to ascertain ischemic stroke risks, as well as the differences and reasons for this between East Asians and non-East Asians.