Atrial fibrillation boosted VTE risk

Atrial fibrillation is at least as strong a risk factor for venous thromboembolism as for ischemic stroke.

This novel finding from Swedish national registry study suggests it’s time for thoughtful consideration of revision of risk scores in patients with atrial fibrillation (AF).

VTE risk is not included as an outcome in the CHA2DS2-VASc score, so we underestimate the total thromboembolic risk in AF patients.

A Swedish registry study of 1.36 million patients, including 470,738 patients with new-onset AF and no previous diagnosis of VTE of ischemic stroke and twice as many controls without AF who were matched to the AF patients by age, gender, and country.

The VTE risk was highest during the first 30 days after diagnosis of AF. Women with new-onset AF had and 8.3-fold increased risk of VTE compared with controls during this early period, by a margin of 55.8 versus 6.4 cases per 1000 person-years. Men with newly diagnosed AF had a 7.2-fold increased risk of VTE in the first 30 days, reflecting a rate of 40.1 percent per 1000 person-years compared to a 5.6 per 1000 in controls.

The VTE risk dropped off precipitously in men after the first month. The rate was cut in half by 2 months after AF diagnosis and was no different from that of controls by nine months.

In women, too, early elevated VTE risk was halved by 2 months out, but thereafter the rate of decline in VTE risk slowed. Even after 10 years after AF diagnosis, women had a 21 percent greater VTE risk than did matched colors.

Of note, the risk of VTE during this first 12 months after diagnosis of AF was nearly twice as great in both men and women under age 65 than in those older than 75.

This data raise the question of whether standard therapy in AF patients needs to be modified, especially during what now appears to be the critical time frame of the first 3 to 6 months after diagnosis of the rhythmic.