Seeking to answer if screening asymptomatic individuals for atrial fibrillation (AF) could offer meaningful protection against strokes and other clinical outcomes, Steven Steinhubl, MD, from the Scripps Research Translational Institute in La Jolla, CA, and other collaborators analyzed data from the mHealth Screening to Prevent Strokes (mSToPS) trial.
They found that individuals actively screened for AF had a lower rate of clinical events over three years after electrocardiogram (ECG)-patch screening relative to routine care, though the impact of earlier AF detection via screening was not clear.
The study report, published in PLoS One, argued that the observations made “support the need for randomized trials to determine whether screening for AF will yield a meaningful protection from strokes and other clinical events.”
Participants in the mSToPS study were randomized to immediate or delayed screening groups with an ECG patch to detect possible undiagnosed instances of AF. Clinical outcomes were compared at three years in the study’s cohort of 1,718 individuals who underwent active AF monitoring and 3,371 matched controls. The primary endpoint was the time to first event of the combined outcomes of death, stroke, systemic embolism, or myocardial infarction among individuals with a new AF diagnosis.
AF was newly diagnosed in 11.4% (n = 196) of participants in the screening group versus 7.7% (n = 261) of the observational controls (P <0.01). For all individuals diagnosed clinically, a clinical event was common in the four weeks surrounding that diagnosis: 6.6% experienced a stroke, 10.2% were newly diagnosed with heart failure, 9.2% had a myocardial infarction, and 1.5% had a systemic embolus.
On the other hand, in the one-third of incident AF cases diagnosed through active ECG monitoring, no patients experienced stroke, myocardial infarction, or systemic emboli in the period surrounding their diagnosis, and only one had a new diagnosis of heart failure. The incidence of the primary endpoints was 3.6 per 100 person-years among the actively screened group and 4.5 per 100 person-years in the controls.
The investigators did note their study was limited by the strong possibility of unmeasured confounders. Additionally, endpoints were based on claims and membership data which limited follow-up data if participants changed plans (less than three years in some participants). The authors also noted that approximately one-third of study participants never wore their ECG patch monitor, indicating a need for different real-world implementation.
Despite the unclear effect of earlier diagnoses of AF via active screening on the clinical events and outcomes seen in the study, the researchers argued that their observations—particularly the heightened rate of events surrounding a clinical AF diagnosis—supported the “need for randomized trials to determine whether screening for AF will yield a meaningful protection from strokes and other clinical events.”