Timing of stroke risk reassessment in atrial fibrillation patients with CHA2DS2-VA score of 0 or 1: the Norwegian AFNOR study

Reassessment of stroke risk is important in patients with atrial fibrillation (AF), but the optimal time interval for reassessment remains unclear. The CHA2DS2-VA score is used to predict stroke risk, which is dynamic and increases over time. This study aimed to investigate temporal changes in the CHA2DS2-VA score in patients with AF with low (score 0) or intermediate (score 1) stroke risk. Additionally, we sought to explore appropriate time intervals for reassessment in different subgroups of AF patients.

We identified 40,782 individuals with incident non-valvular AF aged ≥18 years, with a CHA2DS2-VA score of 0 or 1, using data from Norwegian national registries from 2011 to 2018. Stroke risk factors were assessed with a minimum three-year look-back period. Patients were followed from the date of first AF diagnosis until the occurrence of a new CHA2DS2-VA risk factor. We assessed the proportion of patients with an increased CHA2DS2-VA score at selected time intervals after AF diagnosis for different age groups, and calculated the number needed to reassess to detect one new CHA2DS2-VA risk factor as the inverse of the absolute risk at different time intervals after AF diagnosis.

The CHA2DS2-VA score increased in 50% (95% CI 49.5-50.5) of patients with low or intermediate stroke risk after a median follow-up of 1.7 years. The proportion of patients with an increased CHA2DS2-VA score was 19% at 6 months, 25% at 1 year, and 40% at 3 years after AF diagnosis. At 1 year after AF diagnosis, the proportion of patients with a new risk factor was lower in those aged 18-44 years (8%) and 45-54 years (14%) compared to those aged >55 years (30%), with the number needed to reassess at 1 year of 12, 7 and 3, respectively. Age 65-74 and age ≥75 years were the most commonly acquired CHA2DS2-VA risk factor, although hypertension was more frequent during the first two years after AF diagnosis.

In this nationwide study, half of AF patients with low or intermediate stroke risk developed a new risk factor during a median follow-up of 1.7 years, with one-fourth of the patients having CHA2DS2-VA score increment within the first year after AF diagnosis. Age-specific differences in stroke risk progression underscore the need for tailored reassessment intervals, suggesting a shorter interval of 6 months for older AF patients (≥55 years) and 1 year for younger patients (<55 years). Routine reassessment around ages 65 and 75 years could be beneficial.