Additive effect of the metabolic syndrome score to the conventional CHADS₂ score for the thromboembolic risk stratification of patients with atrial fibrillation

Background The CHA₂DS₂-VASC scoring scheme may not be better than the CHADS₂ scoring scheme in predicting thromboembolic risk for patients with atrial fibrillation (AF) in Asians. Metabolic syndrome is associated with an increased risk of thrombosis. Objective To evaluate whether metabolic syndrome offers incremental information over the CHADS₂ scheme in predicting thromboembolic risk for patients with AF in the Taiwanese population. Methods The study population consisted of 721 consecutive patients with AF who had been followed up for a median of 10.8 years. Thromboembolic end points were defined as ischemic stroke/transient ischemic accident and peripheral embolisms. Clinical factors associated with thromboembolic end points were identified by Cox regression analysis. Different scoring systems were compared by receiver operating characteristic (ROC) analysis. Results We found that components in the CHADS₂ scheme were associated with an increased risk of thromboembolism. The CHA₂DS₂-VASC scheme did not provide information additional to that provided by the CHADS ₂ scheme on thromboembolism risk (ROC area: 0.670 vs 0.665; P >.05). Metabolic syndrome components were also associated with increased risk of thromboembolism. The incident thromboembolic rate increased incrementally when metabolic syndrome score increased. Additional metabolic syndrome components provide additional information to the CHADS₂ scheme on thromboembolism risk (ROC area: 0.670 vs 0.729; P =.034). We therefore proposed a new scoring scheme called CHADS₂-MS scoring scheme. In patients with low to intermediate CHADS₂ scores (0-1), the use of the CHADS₂-MS score may additionally identify patients with high-risk AF for future thromboembolism. Conclusions We, for the first time, demonstrated that metabolic syndrome components were associated with thromboembolic risk in Taiwanese patients with AF. In addition to the conventional CHADS₂ scheme, the calculation of the CHADS₂-MS score provides additional information on stroke risk assessment.