Tailored Anticoagulation for Thromboembolic Risk Reduction in Paroxysmal Atrial Fibrillation

Abstract

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting up to six million people in the United States and more than 35 million individuals worldwide. Thromboembolism, including stroke, represents the most common AF-related morbidity and mortality and data indicate that anticoagulation can mitigate this risk by 65%. Our understanding of thromboembolism in AF, however, remains incomplete, and the mechanisms by which AF increases thromboembolic risk are areas of ongoing investigation and debate. Current guidelines do not differentiate between the frequency and duration of AF episodes (AF burden) when selecting which patients with AF should be treated with anticoagulation for thromboembolic risk reduction. Recent data, primarily using cardiac implantable electronic devices (CIEDs) such as pacemakers, implantable cardioverter-defibrillators, and implantable loop recorders, however, have challenged this longstanding notion that AF burden does not influence thromboembolic risk. Continuous and automated cardiac rhythm monitoring via CIEDs with accurate and rapid acquisition and transmission of rhythm data also affords the opportunity to study the relationship between AF burden and thromboembolism and novel ways to reduce thromboembolic risk while minimizing the risk associated with chronic anticoagulation use. This manuscript will review the associations between subclinical, CIED-detected atrial arrhythmias and thromboembolic events. It will also discuss the emergence of "tailored anticoagulation," an anticoagulation strategy wherein CIEDs and remote AF monitoring are employed to allow dynamic administration of oral anticoagulation only around episodes of AF, and the holding of anticoagulation during prolonged periods of sinus rhythm when the thromboembolic risk associated with AF is presumably very low.

Keywords: Anticoagulation; atrial fibrillation; stroke; thromboembolism.

Figure 1:

Remote transmission of arrhythmia data. Reproduced with permission from Zimetbaum et al.

Figure 2:

Thromboembolic risk stratified by AF duration and CHADS₂ score. An assessment of AF burden and thromboembolic risk factors as assessed by the CHADS₂ score separated patients into two groups with significantly different thromboembolic risks (0.8% versus 5.0%). The columns correspond with CHADS₂ scores (0, 1, 2, and ≥ 3, respectively) and the rows correspond with AF duration over the course of 24 hours (none, more than five minutes, and 24 hours continuous, respectively). Pts: patients. Reproduced with permission from Botto et al.