Stroke mechanism in patients with non-valvular atrial fibrillation according to the CHADS ₂ and CHA ₂DS ₂-VASc scores

Background and purpose: The CHADS ₂ and CHA ₂DS ₂-VASc scores are useful to stratify embolic risks in patients with non-valvular atrial fibrillation (NVAF) and to identify patients eligible for anticoagulation. Although the risk of stoke increases in patients with higher CHADS ₂ or CHA ₂DS ₂-VASc scores, it is uncertain why the stroke rate increases in them. Concomitant potential cardiac sources of embolism (PCSE) may be more frequent in patients with higher CHADS ₂ or CHA ₂DS ₂-VASc scores because stroke risks increase when concomitant PCSE is present in Atrial fibrillation (AF). On the other hand, atherothrombosis may be the cause when considering that most components of the CHADS ₂ and CHA ₂DS ₂-VASc scores are risk factors for atherosclerosis. Methods: Amongst 5493 stroke patients who were prospectively registered with the stroke registry for 11years, 860 consecutive patients with NVAF were included for this study. We investigated the mechanisms of stroke according to the CHADS ₂/CHA ₂DS ₂-VASc score in stroke patients with NVAF. Results: Amongst 860 patients, concomitant PCSE were found in 334 patients (38.8%). The number of PCSE increased as the CHADS ₂/CHA ₂DS ₂-VASc score increased (P<0.001). Of individual PCSE, akinetic left ventricular segment, hypokinetic left ventricular segment and myocardial infarction <4weeks were associated with the CHADS ₂/CHA ₂DS ₂-VASc score. The presence of possible atherothrombotic mechanism, in addition to AF, was suggested in 27.3%. The proportion of patients with concomitant presence of possible atherothrombosis was increased as the CHADS ₂/CHA ₂DS ₂-VASc score increased (P<0.001). Conclusions: Increased frequency of concomitant PCSE and that of the atherothrombotic mechanism may explain the high risk of stroke in patients with higher CHADS ₂/CHA ₂DS ₂-VASc score.