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New data from a predefined secondary analysis of the STROKE-AF trial provides insight into the 3-year incidence of atrial fibrillation among patients with a history of ischemic stroke caused by atherosclerosis.
Data from the 3-year follow-up of the STROKE-AF trial presented at American Stroke Association’s International Stroke Conference (ISC) 2023 is underlining the importance of long-term monitoring and use of insertable cardiac monitors (ICMs) for arrhythmias in patients with a history of ischemic stroke.
Results of the secondary analysis, which compared detection of arrhythmia with ICM against standard of care, suggest more than 20% of patients with ischemic stroke attributed to small or large vessel disease had atrial fibrillation (AF), with the detection rate 10 times greater using ICM than with standard of care.1
“We found that the rate of atrial fibrillation continued to increase over the course of the three years, therefore, it’s not just a short-lived event and self-resolving related to the initial stroke,” said Lee Schwamm, MD, a professor of neurology at Harvard Medical School in Boston.2 “Fibrillation is common in these patients. Relying on routine monitoring strategies is not sufficient and neither is placing a 30-day continuous monitor on the patient. Even if fibrillation is ruled out in the first 30 days, most of the cases are missed — because, as we found, more than 80% of the episodes are first detected more than 30 days after the stroke.”
A prospective, randomized, controlled, multicenter trial STROKE-AF randomized 492 patients in a 1:1 ration to ICM insertion within 10 days of the index stroke or standard of care, which was defined as site-specific usual care consisting of external cardiac monitoring.3 As part of the study protocol, patients included in the trial were 60 years of age or older or 50-59 years with an additional stroke risk factors and no contraindication to long-term oral anticoagulation.
The 12-month results of the STROKE-AF trial indicated use of ICM was associated with a significantly increased rate of AF detection compared with standard of care (hazard ratio [HR], 7.4 [95% CI, 2.6-21.3]; P <.001).3 A predefined secondary analysis of the trial, the current study, which was funded by Medtronic, was designed as an analysis of AF incidence up to 3 years following index event.1
Upon analysis, the 3-year incidence rates of AF were 21.7% in the ICM arm and 2.4% in the standard of care (hazard ratio [HR], 10.0 [95% CI, 4.0-25.2]; P <.001), with investigators reporting no significant differences between stroke subtypes. Among those in the ICM arm who experienced AF, the median duration of their longest episode was 10.0 (interquartile range [IQR], 4.0-192.0) minutes, with investigators pointed out 37.2% of patients experiencing an episode lasting at least an hour. In further subgroup analyses, results indicated the median maximum daily AF burden in those AF burden was 0.3 hours, with 25% having AF longer than 5.3 hours. Investigators pointed out there was no significant differences in rates of recurrent stroke between the ICM (17.0%) and the standard of care (14.1%) at 3 years (HR, 1.10 [95% CI, 0.67-1.78]; P=.71).1
“There is still a lot that we don’t yet understand about why people who have had a previous stroke have another one; however, this study contributes important information to one potential cause— namely, unsuspected atrial fibrillation—for some of those 25% of patients with recurrent strokes,” Schwamm added.2 “These patients are at increased risk of recurrent strokes due to their known cardiovascular risk factors, such as hypertension and elevated cholesterol and blood pressure. What we need to sort out is what additional risk does atrial fibrillation add, and can the use of anticoagulation reduce that risk, especially for the type of major and disabling strokes that are often associated with atrial fibrillation.”