Primary Care Screening for Atrial Fibrillation in Older Adults Feasible But Inefficient
Key findings
- The VITAL-AF trial randomized eight primary care clinics to provide screening for atrial fibrillation (AF), using handheld single-lead ECG during vital sign assessment of adults ≥65 years of age, and eight primary care clinics to provide usual care
- During the study period, 15,393 patients in the screening arm had at least one eligible visit, of whom 14,047 (91%) agreed to be screened. A total of 29,952 screening single-lead ECGs were done
- The primary endpoint of newly diagnosed AF was observed in 1.72% of individuals in the screening arm versus 1.59% in the usual care arm (P=0.38)
- However, among patients ≥85 years old, the difference was nearly two percentage points (5.56% vs. 3.76%; risk difference, 1.80%; 95% CI, 0.18–3.30), a statistically significant difference
- Single-lead ECG rhythm assessment is feasible but inefficient when applied to all older adults, but may be effective for our oldest patients, those ≥85 years old. Studies are needed to better identify other patients at elevated risk of AF
Single-lead electrocardiography (ECG), now available on smartphones, enables rapid mass screening for atrial fibrillation (AF). This idea is appealing since AF can be asymptomatic and not diagnosed until the time of stroke. Currently, practice guidelines offer conflicting recommendations about AF screening.
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Steven A. Lubitz, MD, MPH, a cardiac electrophysiologist in the Telemachus & Irene Demoulas Family Foundation Center for Cardiac Arrhythmias at Massachusetts General Hospital, Daniel E. Singer, MD, and Steven J. Atlas MD, MPH, in the Division of General Internal Medicine, and colleagues conducted VITAL-AF, the first U.S.-based randomized, controlled trial of point-of-care AF screening. Based on results they report in Circulation, they do not encourage routine screening for all older adults.
Methods
VITAL-AF was a cluster trial in which the clinic was the unit of randomization. Eight primary care clinics at Mass General were randomized to screening, and eight served as controls, offering usual care.
Over 12 months, all patients ages ≥65 at the intervention clinics were offered AF screening before they saw a primary care clinician. To collect vital signs, medical assistants asked consenting patients to place their fingers on a single-lead KardiaMobile ECG device (AliveCor Inc, Mountain View, CA) affixed to an iPad using the KardiaAI version 1 algorithm. Screening results were "Possible AF," "Normal," "Unclassified," "No Analysis (Unreadable)," and "Patient Declined Screening."
Medical assistants documented the screening result in the electronic medical record and verbally notified the primary care clinician if a patient had a "Possible AF" reading. All subsequent management was determined by the primary care clinician, including follow-up 12-lead ECGs and possible treatment with anticoagulant medicines. Independent cardiologists reviewed all tracings within seven days and notified primary care if a prespecified actionable rhythm was identified.
Feasibility of Screening
Between July 31, 2018, and October 8, 2019, among patients without pre-existing AF:
- 15,393 individuals in the screening arm had at least one eligible visit, and 14,047 (91%) agreed to be screened. A total of 29,952 screening single-lead ECGs were done during the study
- 15,322 in the control arm had at least one eligible visit
Primary Analysis
The primary endpoint was newly diagnosed AF at one year:
- 264 (1.72%) patients in the screening arm vs. 243 (1.59%) in the control arm were diagnosed with AF (risk difference, 0.13%; 95% CI, −0.16 to 0.42; P=0.38)
- Among patients ≥85 years old, 65 patients (5.56%) in the screening arm vs. 47 (3.76%) in the control arm were diagnosed with AF (risk difference, 1.80%; 95% CI, 0.18–3.30)
- In other prespecified age groups, there was little effect of screening
Takeaway Messages
- Single-lead ECG rhythm assessment is feasible in contemporary U.S. routine primary care practice
- However, it is not an efficient approach for detecting undiagnosed AF when applied to all older adults
- Screening may be effective for identifying AF among individuals ≥85 years old, but prospective validation of this secondary result is needed
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