Stroke and bleeding risk in atrial fibrillation

Abstract

Non-valvular atrial fibrillation (AF) is the most common cardiac arrhythmia in the clinical setting. AF increases both the risk and severity of strokes, and is associated with substantial morbidity and mortality. Despite the clear net clinical benefit of oral anticoagulants (OACs) in patients with AF at risk for stroke, major bleeding events, especially intracranial bleeds, may be devastating. In the last decade, four new OACs have been approved for stroke prevention in patients with AF and are at least as effective as warfarin with better bleeding profiles. These new agents have changed and simplified our approach to stroke prevention because the threshold for initiation of OACs is lowered. An important clinical practice shift is the initial identification of "low-risk" patients who do not need antithrombotic therapy, with low-risk comprising CHA2DS2-VASc {Congestive heart failure, Hypertension, Age ≥75 years (double), Diabetes mellitus, previous Stroke/transient ischemic attack/thromboembolism (double), Vascular disease, Age 65-74 years, and female gender (score of 0 for males and 1 for female)}. Subsequent to this step, effective stroke prevention consisting of OACs can be offered to patients with one or more stroke risk factors. Apart from stroke risk, another consideration is bleeding risk assessment, with a focus on the use of the validated HAS-BLED {Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile international normalized ratio (INR), Elderly (age >65 years), drugs or alcohol concomitantly} score. A high HAS-BLED score can flag patients potentially at risk for bleeding, and alert clinicians to the need for careful review and follow up, and the need to consider potentially correctable bleeding risk factors that include uncontrolled hypertension, labile INRs, concomitant aspirin use, and alcohol excess.

Keywords: Atrial fibrillation; Hemorrhage; Risk assessment; Stroke.

Fig. 1

Flow diagram for stroke prevention based on the 2012 ESC guideline on atrial fibrillation. Antiplatelet therapy with aspirin plus clopidogrel or-, less effectively, aspirin only, should be considered in patients who refuse any OAC, or cannot tolerate anticoagulants for reasons unrelated to bleeding. If there are contraindications to OAC or antiplatelet therapy, left atrial appendage occlusion, closure or excision may be considered. Line: solid: best option, dashed: alternative option. ^*Includes rheumatic valvular disease and prosthetic valves. AF: atrial fibrillation, CHA₂DS₂-VASc: congestive heart failure, Hypertension, Age ≥75 years (double), Diabetes mellitus, previous stroke/transient ischemic attack/thromboembolism (double), Vascular disease, age 65-74 years, and female gender, HAS-BLED: hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile international normalized ratio (INR), Elderly (age >65 years), drugs or alcohol concomitantly, NOAC: novel oral anticoagulant, VKA: vitamin K antagonist.

Fig. 2

One year risk of major bleeding with increasing HAS-BLED score. Event rates progressively increased from 1.13% to 12.5% in patients with different HAS-BLED scores. Hypertension: uncontrolled systolic blood pressure >160 mm Hg, Abnormal renal function: chronic dialysis, renal transplant, or serum creatinine ≥200 µmol/L, Abnormal liver function: chronic hepatic disease (e.g., cirrhosis) or bilirubin >2x, and serum transaminases >3x, upper limit of normal, Bleeding: previous bleeding requiring hospitalization or causing a decrease in hemoglobin >2 g/L and/or requiring blood transfusion, or predisposition to bleeding such as bleeding diathesis or anemia, Labile INR: time spent within target therapeutic range <60%, Drugs or alcohol: concomitant use of aspirin, non-steroidal anti-inflammatory drugs or alcohol >20 U/week. INR: international normalized ratio.