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  • Although the CHADS score is useful for evaluating the risk

    2019-04-22

    Although the CHADS2 score is useful for evaluating the risk of stroke in NVAF patients, about half of all NVAF patients have a score of 0 or 1 [7]. There are no clear guidelines on whether warfarin should be administered or not, to these patients because the risk of annual incidence of stroke is so low for such patients that the benefits of anticoagulation therapy do not clearly exceed the increased risk of major bleeding. The CHA2DS2-VASc score has been proposed as a complement for the CHADS2 score, since it uses additional risk factors to predict stroke risk in NVAF patients [8]. The scoring system of the CHA2DS2-VASc score ranges from 0 to 9; 1 point each is assigned for congestive kinesin spindle protein failure, hypertension, an age of 65–74 years, diabetes mellitus, vascular disease, and female gender, and 2 points are assigned for an age of at least 75 years and a previous incidence of stroke or TIA. A nationwide cohort study conducted in Denmark demonstrated that at 1-year follow-up, the rate of thromboembolism per 100 people per year was 1.67 (95% confidence interval, 1.47–1.89) in patients with a CHADS2 score of 0 and 0.78 (0.58–1.04) in patients with a CHA2DS2-VASc score of 0 [7]. This rate was found to rise to 4.75 (4.45–5.07) and 2.01 (1.70–2.36) in patients with a CHADS2 and CHA2DS2-VASc scores of 1, respectively, and to 7.34 (6.88–7.82) and 3.71 (3.36–4.09) in patients with a CHADS2 and CHA2DS2-VASc scores of 2, respectively. Patients were categorized as low- (score of 0), intermediate- (score of 1), or high-risk (score of 2 or more), and the C statistics at the 10-year follow-up was 0.812 (0.796–0.827) when patients were categorized according to the CHADS2 score and 0.888 (0.875–0.900) when categorized according to the CHA2DS2-VASc score. Thus, the CHA2DS2-VASc score performed better than the CHADS2 score in predicting thromboembolism. Furthermore, these results indicate that patients categorized as low-risk by CHA2DS2-VASc are truly at a low risk for thromboembolism and that anticoagulation should be recommended for NVAF patients with a CHA2DS2-VASc score of 2 or more and considered for NVAF patients with a CHA2DS2-VASc score of 1. Although the CHA2DS2-VASc score was found to be superior to the CHADS2 score in predicting patients at risk for thromboembolism, it is more complicated than CHADS2. Therefore, we typically perform CHADS2 scoring for all NVAF patients, and recommend dabigatran, rivaroxaban, or warfarin treatment for patients with a score of 2 or more and dabigatran treatment for patients with a score of 1. For patients who have a CHADS2 score of 0 or have a CHADS2 score of 1 but develop renal dysfunction or other adverse effects after dabigatran treatment, CHA2DS2-VASc scoring is performed for more precise stratification. Dabigatran, rivaroxaban, or warfarin are recommended for patients with a CHA2DS2-VASc score of 2 or more and considered for patients with a CHA2DS2-VASc score of 1. Patients with a CHA2DS2-VASc score of 0 have a low risk for thromboembolism and may not benefit from anticoagulants; however, dabigatran or rivaroxaban may be considered as these anticoagulants have a low risk of inducing intracranial bleeding. This strategy is depicted in Fig. 4.
    Prevention of intracranial and major bleeding History of stroke or TIA is as a major risk factor for intracranial hemorrhage and recurrent stroke [9–11]. Therefore, it is necessary to pay attention to preventing intracranial bleeding and recurrent stroke in NVAF patients with a history of stroke or TIA. Compared to warfarin, the aforementioned novel anticoagulants show the same efficiency in suppressing stroke and systemic embolism and are associated with a much lesser incidence of intracranial bleeding [1–4]; therefore, the novel anticoagulants should be the first choice for preventing stroke recurrence in NAVF patients with a history of stroke or TIA. To avoid brain hemorrhage, it is essential to manage risk factors such as blood pressure, blood glucose, smoking, and excess alcohol consumption. Of these, management of blood pressure is the most important, and the lower the blood pressure the better for reducing the risk of brain hemorrhage or brain infarction [12]. High blood pressure is associated with intracranial bleeding, and the optimal cut-off value for preventing intracranial bleeding is 130/81mmHg, as determined by receiver–operating characteristic curve analysis [13]. In patients treated with antithrombotic agents, blood pressure can be controlled to values below 130/80mmHg in a manner similar to the one used for patients with kidney disease, past history of myocardial infarction, and diabetes mellitus [14].