Extracranial Systemic Embolic Events in Patients With Nonvalvular Atrial Fibrillation: Incidence, Risk Factors, and Outcomes

Abstract

Background: Nonvalvular atrial fibrillation is a major cause of thromboembolic events. In comparison with atrial fibrillation-related stroke, extracranial systemic embolic events (SEEs) remain poorly defined.

Methods and results: All suspected SEEs reported among 37 973 participants of 4 large contemporary randomized clinical trials of anticoagulation in atrial fibrillation were independently readjudicated for clinical and objective evidence of sudden loss of perfusion of a limb or organ. Over 91 746 patient-years of follow-up, 221 SEEs occurred in 219 subjects. The SEE incidence was 0.24 of 100 and stroke incidence was 1.92 of 100 patient-years. In comparison with patients with stroke, those with SEE were more often female (56% versus 47%; P=0.01) and had comparable mean age (73.1±8.5 versus 73.5±8.8 years; P=0.57) and mean CHADS2 scores (2.4±1.3 versus 2.5±1.2; P=0.33). SEEs more frequently involved the lower extremity (58%) than visceral-mesenteric (31%) or upper extremity (10%). SEE-related care involved clinic assessment alone in 5%, 30% were hospitalized without procedures, 60% underwent endovascular or surgical intervention, and 5% underwent amputation. Within 30 days, 54% of patients recovered fully, 20% survived with deficits, and 25% died. Thirty-day mortality was greater after visceral-mesenteric than lower- or upper-extremity SEE (55%, 17%, and 9%, respectively, P≤0.0001). The relative risk of death throughout follow-up was 4.33 (95% confidence interval, 3.29-5.70) after SEE versus 6.79 (95% confidence interval, 6.22-7.41) after stroke in comparison with patients without either event.

Conclusions: SEE constituted 11.5% of clinically recognized thromboembolic events in patients with atrial fibrillation and was associated with high morbidity and mortality. SEE mortality was comparable to that of ischemic stroke and varied by anatomic site.

Keywords: arrhythmias, cardiac; atrial fibrillation; embolism; peripheral artery disease; risk factors.