Non-Vitamin K Antagonist Anticoagulants and Atrial Fibrillation
Non-Vitamin K Antagonist Anticoagulants and Atrial Fibrillation
The three main goals in the treatment of AF are rate control, rhythm control, and managing stroke risk. Following confirmation of AF and determination of stroke risk, patients who require anticoagulation should be evaluated to balance the risk of stroke with the risk of bleeding resulting from antithrombotic therapy. Current American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines recommend risk stratification using the CHA2DS2-VASc (Congestive heart failure, Hypertension, Age ≥75 years [doubled], Diabetes mellitus, prior Stroke or transient ischemic attack [TIA] or thromboembolism [doubled], Vascular disease, Age 65–74 years, Sex category) scoring system (Fig. 1). CHA2DS2-VASc outperforms CHADS2 (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, prior Stroke or TIA or thromboembolism [doubled]) ( Table 1 ) and the ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation) score in determining patients for whom there is a truly low thrombotic risk.
(Enlarge Image)
Figure 1.
Flowchart of oral anticoagulant use for stroke prevention based on risk factors [4]. Reduced doses should be considered; safety and efficacy not established. Recommended for patients with trouble controlling INR. CHA 2 DS 2 -VASc congestive heart failure, hypertension, age ≥75 years (doubled), diabetes mellitus, prior stroke or TIA or thromboembolism (doubled), vascular disease, age 65–74 years, sex category. INR international normalized ratio, OAC oral anticoagulation, TIA transient ischemic attack
Based on this risk stratification, anticoagulation may be omitted for patients who have NVAF and a CHA2DS2-VASc score of 0. Oral anticoagulants, aspirin, or no treatment may be considered for patients with an intermediate risk of stroke (CHA2DS2-VASc score of 1). Patients with NVAF and a CHA2DS2-VASc score ≥2 or who have had a prior stroke or TIA should receive oral anticoagulation, based on current guideline recommendations. Some debate exists regarding the net benefit of anticoagulant treatment in patients with a CHA2DS2-VASc score of 1. Differing rates of stroke risk in patients with AF and one additional stroke risk have been reported, suggesting that further determination of critical risk factors in various populations should be assessed.
Assessment of the 1-year risk of major bleeding in patients with AF by HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly [>65 years], Drugs/alcohol concomitantly) is recommended by European Heart Rhythm Association (EHRA), and European Society of Cardiology guidelines, but not AHA/ACC/HRS. To calculate this score, each named clinical characteristic present is assigned 1 point and summed ( Table 1 ). A HAS-BLED score ≥3 indicates a patient who is potentially at high risk for bleeding events. HAS-BLED demonstrates good predictive accuracy overall, with a better predictive accuracy for patients receiving either no antithrombotic therapy or antiplatelet therapy. In initial validation studies, a score of 1 was associated with a 0.83 % yearly incidence of major bleeding events, whereas a score >5 was associated with an incidence of 16.6 % per year. In patients for whom the risk for thromboembolism and bleeding are both high, a comprehensive management approach would include assessment and modification of extrinsic factors that impact risk. These include adequate control of hypertension (both for thromboembolism and bleeding risk), examination of alcohol intake, and the current use of drugs that could increase risk. Furthermore, it should be noted that in patients with AF who develop gastrointestinal (GI) bleeding while receiving warfarin, restarting warfarin is associated with an overall decreased risk of thromboembolism and mortality without a significantly increased risk of recurrent GI bleeding.
Risk Stratification
The three main goals in the treatment of AF are rate control, rhythm control, and managing stroke risk. Following confirmation of AF and determination of stroke risk, patients who require anticoagulation should be evaluated to balance the risk of stroke with the risk of bleeding resulting from antithrombotic therapy. Current American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines recommend risk stratification using the CHA2DS2-VASc (Congestive heart failure, Hypertension, Age ≥75 years [doubled], Diabetes mellitus, prior Stroke or transient ischemic attack [TIA] or thromboembolism [doubled], Vascular disease, Age 65–74 years, Sex category) scoring system (Fig. 1). CHA2DS2-VASc outperforms CHADS2 (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, prior Stroke or TIA or thromboembolism [doubled]) ( Table 1 ) and the ATRIA (AnTicoagulation and Risk factors In Atrial fibrillation) score in determining patients for whom there is a truly low thrombotic risk.
(Enlarge Image)
Figure 1.
Flowchart of oral anticoagulant use for stroke prevention based on risk factors [4]. Reduced doses should be considered; safety and efficacy not established. Recommended for patients with trouble controlling INR. CHA 2 DS 2 -VASc congestive heart failure, hypertension, age ≥75 years (doubled), diabetes mellitus, prior stroke or TIA or thromboembolism (doubled), vascular disease, age 65–74 years, sex category. INR international normalized ratio, OAC oral anticoagulation, TIA transient ischemic attack
Based on this risk stratification, anticoagulation may be omitted for patients who have NVAF and a CHA2DS2-VASc score of 0. Oral anticoagulants, aspirin, or no treatment may be considered for patients with an intermediate risk of stroke (CHA2DS2-VASc score of 1). Patients with NVAF and a CHA2DS2-VASc score ≥2 or who have had a prior stroke or TIA should receive oral anticoagulation, based on current guideline recommendations. Some debate exists regarding the net benefit of anticoagulant treatment in patients with a CHA2DS2-VASc score of 1. Differing rates of stroke risk in patients with AF and one additional stroke risk have been reported, suggesting that further determination of critical risk factors in various populations should be assessed.
Assessment of the 1-year risk of major bleeding in patients with AF by HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly [>65 years], Drugs/alcohol concomitantly) is recommended by European Heart Rhythm Association (EHRA), and European Society of Cardiology guidelines, but not AHA/ACC/HRS. To calculate this score, each named clinical characteristic present is assigned 1 point and summed ( Table 1 ). A HAS-BLED score ≥3 indicates a patient who is potentially at high risk for bleeding events. HAS-BLED demonstrates good predictive accuracy overall, with a better predictive accuracy for patients receiving either no antithrombotic therapy or antiplatelet therapy. In initial validation studies, a score of 1 was associated with a 0.83 % yearly incidence of major bleeding events, whereas a score >5 was associated with an incidence of 16.6 % per year. In patients for whom the risk for thromboembolism and bleeding are both high, a comprehensive management approach would include assessment and modification of extrinsic factors that impact risk. These include adequate control of hypertension (both for thromboembolism and bleeding risk), examination of alcohol intake, and the current use of drugs that could increase risk. Furthermore, it should be noted that in patients with AF who develop gastrointestinal (GI) bleeding while receiving warfarin, restarting warfarin is associated with an overall decreased risk of thromboembolism and mortality without a significantly increased risk of recurrent GI bleeding.