Arterial thromboembolism in patients with atrial fibrillation and CHA2DS2-VASc score 1: a nationwide study

Abstract Background Knowledge is sparse on whether rate of stroke differs in patients with atrial fibrillation (AF) and a CHA2DS2-VASc of 1 according to how this point is obtained. Objectives To examine the associated rate of thromboembolism according to subgroups with a CHA2DS2-VASc of 1. Methods From nationwide registries, patients with incident AF from 2000–2021 and without oral anticoagulants were categorized according to the CHA2DS2-VASc score (CHA2DS2-VASc 0, CHA2DS2-VASc 1: heart failure [HF], hypertension [HT], diabetes mellitus [DM], vascular disease, age 65-74, or CHA2DS2-VASc 2, due to age ≥75 years). Female sex was not considered a risk factor. Outcome was one-year rate of thromboembolism (ischemic stroke, embolism of extremity, or transient cerebral ischemia). Main safety outcome was hospitalization with bleeding. The cumulative incidence of thromboembolism and bleeding were computed for CHA2DS2-VASc 0, the five subgroups of CHA2DS2-VASc 1, and CHA2DS2-VASc 2 (due to age ≥75 years) accounting for death as competing risk. For comparison between study groups crude Cox proportional hazard analysis was used. Results We included 29,369 patients with CHA2DS2-VASc 0; 27,845 patients with CHA2DS2-VASc 1: 1,890 (6.8%) patients with HF, 9,649 (34.7%) with HT, 968 (3.5%) with DM, 906 (3.3%) with vascular disease, 14,432 (51.8%) with age 65-74 years; 19,387 patients with CHA2DS2-VASc 2 (age ≥75 years). At one year of follow-up, the cumulative incidence of thromboembolism was 1.1% for CHA2DS2-VASc 1, 2.7% for CHA2DS2-VASc 1 (overall), and 4.9% for CHA2DS2-VASc 2 (age ≥75 years). Within subgroups of CHA2DS2-VASc 1, the cumulative incidence of thromboembolism was 1.7% for HF, 2.6% for HT, 2.2% for DM, 2.7% for vascular disease, and 2.9% for age 65-74 years (Figure 1). Within subgroups of CHA2DS2-VASc 1, age (65-74 years) was associated with the highest rate of thromboembolism, while HF was associated with the lowest rate (Figure 2). The one-year cumulative incidence of hospital admission with bleeding was 0.4%, 1.2%, 1.1%, 1.4%, 1.8%, 1.2%, and 2.2% for CHA2DS2 -VASc 0, CHA2DS2-VASc 1: HF, HT, DM, vascular disease, age 65-74, and CHA2DS2 -VASc 2 (age ≥75), respectively. Conclusion Within the spectrum of CHA2DS2-VASc 1, age seemed to be the risk factor with most impact on the rate of thromboembolism, while HF seemed to have the least impact. All subgroups of CHA2DS2-VASc 1 were associated with lower rate of arterial thromboembolism as compared with CHA2DS2-VASc 2 and a higher rate as compared with CHA2DS2-VASc 0. These findings lay the ground for a better understanding of when to initiate oral anticoagulation in patients with CHA2DS2-VASc 1.