Reference: JAMA. 2018 Jul 10;320(2):146-155 (level 2 [mid-level] evidence)
Atrial fibrillation (AF) increases the risk of stroke 5-fold and accounts for almost one-third of all strokes (JAMA. 2018 Jul 10). A systematic review of 50 studies evaluating rates of newly diagnosed AF in 11,658 patients after stroke or TIA found that AF was detected in approximately 24% of patients (Lancet Neurol. 2015 Apr). The United States Preventative Services Task Force found inadequate data for the screening of asymptomatic adults with ECG (JAMA. 2018 Jun 12). However, newer technologies have become available since this recommendation. The mHealth Screening to Prevent Strokes (mSToPS) trial was conducted to determine if a home-based, self-applied, wearable electrocardiogram (ECG) patch could improve the diagnosis of AF relative to routine care, and if earlier detection of AF leads to faster diagnosis and better clinical outcomes (JAMA. 2018 Jul 10).
The mSToPS trial included both a randomized trial and a prospective, observational cohort study of patients considered at increased risk of having undiagnosed AF. Study inclusion criteria consisted of > 1 specified comorbidities plus one of the following 1) ≥ 75 years of age 2) Males > 55 years or 3) Females > 65 years old. Exclusion criteria included current or prior diagnosis of AF, atrial flutter or atrial tachycardia, prescription for anticoagulation therapy, or an implantable pacemaker, defibrillator, or both.
In the randomized trial portion of the study, 2,659 adults were randomly assigned to immediate (≤ 2 weeks after enrollment) vs. delayed (4 months after enrollment) active home-based monitoring and were followed for 4 months for the detection of newly diagnosed AF. Adults in the immediate home-based monitoring group were instructed to wear two different patches. The first patch was worn for 2 weeks and then mailed back to the patch developer. After 3 months, a second patch was worn for an additional 2 weeks. Adherence to wearing the patches was low, with only 65.5% of adults completing active monitoring.
In the 1-year observational cohort study, each actively monitored participant from the trial who completed the study (n = 1,734) was then age-, sex-, and CHA2DS2-VASc score-matched with two controls (n=5214) from the original eligible population, who were not invited to enroll.
In an intention-to-treat analysis at 4 months, there was an increased incidence of newly diagnosed AF in the continuous monitoring group (3.9%) compared to 4-month delayed monitoring group (0.9%) (p < 0.0001, NNS 34). In the per-protocol analysis, similar results were noted with new AF diagnosed by patch in 2.7% in the immediate continuous monitoring group compared to 0.9% in the delayed monitoring group (no p value reported). The difference in diagnosis rate in the per-protocol analysis compared to the intention to treat analysis is explained by (n=44) being diagnosed with AF either prior to monitoring (n=12) or after monitoring was completed (n=32) without any findings during monitoring.
In the 1-year cohort study, active monitoring was associated with a higher rate of initiation of anticoagulant therapy overall (5.7 per 100 person-years) compared to control (3.7 per 100 person-years) (absolute difference, 2.0 [95% CI for difference 1.9-2.2]).
Active monitoring was also associated with an increase in initiation of antiarrhythmic medication, ablation or cardioversion procedures, placement of pacemaker or defibrillator, and outpatient cardiology or primary care visits. There was no significant difference between groups in AF-related emergency department visits and hospitalizations (JAMA. 2018 Jul 10).
A limitation to the validity of the results was the poor adherence rate of the patients (about 1/3 of the enrolled participants did not wear a patch). The number of participants diagnosed with AF may have been even higher with increased compliance (JAMA. 2018 Jul 10). While monitoring for AF may result in higher rates of diagnosis as compared to routine care, it is unclear whether this results in improved outcomes. While it is possible that earlier initiation of therapies may prevent negative outcomes, current therapies are not without significant risks and harms. Future studies will need to assess the harms of identifying asymptomatic patients using this technology. As with all population screening, evidence needs to demonstrate clear benefits that translate into improved clinical outcomes.
For more information, see the topic Atrial Fibrillation Screening in DynaMed.
This Resident Focus was written by Rob Harbolovic, originally from Georgetown, Texas. He received his undergraduate degree in Accounting from Texas A&M Corpus Christi. Dr. Harbolovic went on to obtain his medical degree from Universidad Autonoma de Guadalajara in Guadalajara, Mexico. He is fluent in Spanish and plans to return to South Texas following residency to practice medicine helping the underserved. His interests include integrative medicine and the full scope of Family practice. Dr. Harbolovic is currently a PGY-2 at Memorial Health University Medical Center in Savannah, Georgia. When he’s not seeing patients, Dr. Harbolovic enjoys spending time with his wife and two small children and exploring all the history that Savannah has to offer.