Low-Risk Afib Often Doesn’t Stay That Way

Patients with initially low-risk atrial fibrillation (AF) may require periodic reassessment of stroke risk to determine whether oral anticoagulants have become warranted, a study showed.

Among patients whose CHA₂DS₂-VASc score didn’t qualify them for anticoagulation at diagnosis, 16.2% of women and 16.1% of men moved into the higher risk category requiring treatment by 1 year, reported Shih-Ann Chen, MD, of Taipei Veterans General Hospital in Taiwan, and colleagues in Annals of Internal Medicine.

The proportion of women who went from below to above the 1-point CHA₂DS₂-VASc score threshold for prophylaxis was 24.9% at 2 years and 49.9% at 7 years after atrial fibrillation onset.

For men, the overall incidence of an increase in CHA₂DS₂-VASc score from 0 at baseline to above that threshold for prophylaxis was 24.5% at 2-year follow-up and 49.1% at 7-year follow-up.

Previous research has also shown that for patients with AF stroke risk is not static, and the vast majority of these patients acquire another risk factor before ischemic stroke, the researchers noted.

“We propose that CHA₂DS₂-VASc scores should be reassessed at least annually in patients with AF so that OACs [oral anticoagulants] can be prescribed in a timely manner for stroke prevention,” the study authors concluded.

Jonathan Hsu, MD, of the University of California in San Diego, who was not involved in the study, agreed.

“Even though practitioners know that the score will never decrease, but can only increase, there have been few studies that have evaluated the rate of change of this score. This study adds value to previous literature that helps to quantify the amount of increase of the CHA₂DS₂-VASc score in patients with atrial fibrillation,” Hsu told MedPage Today.

“This study supports the assertion that stroke risk in patients with atrial fibrillation may change over time, and when using the CHA₂DS₂-VASc score to assess stroke risk, the possibility for an increase in score needs to be considered by the practitioner and patient.”

Using the Taiwan National Health Insurance Research Database, Chen’s group studied 14,606 patients (mean age 47.8 years) that had recently been diagnosed with AF and had not been prescribed OACs or antiplatelets. At baseline, 5,861 women had a CHA₂DS₂-VASc score of one and 8,745 men had a score of zero.

There were 5,301 patients who developed at least one additional risk factor at the median 3.24 years follow-up.

The CHA₂DS₂-VASc stroke risk assessment tool assigns one point for female sex, diabetes mellitus, hypertension, congestive heart failure, and age from 65 to 74 years. The model gives the patient two points for age ≥75 years and a prior transient ischemic event or stroke.

last updated 01.04.2019