Key Points:
- A 14-day heart rhythm monitoring with a wearable patch in primary care increased the diagnostic yield for atrial fibrillation by 52% compared to usual care.
- Despite treatment with oral anticoagulants, rates of stroke and hospitalizations were similar between screened patients and those receiving usual care.
Atrial fibrillation (AF) is a common abnormal heart rhythm that increases the risk of debilitating strokes by about fivefold. Guidelines recommend anticoagulation treatment to reduce this stroke risk. The burden of AF and its associated risks—including stroke, hospitalizations, heart failure, and death—is expected to rise significantly in the coming decades. Consequently, interest in AF screening has surged due to the remarkable progress in AF treatment and advances in cardiac rhythm monitoring. Recent trials of AF screening have demonstrated that screening increases the diagnosis of AF. However, it remains uncertain whether patients with screen-detected AF are at a high enough stroke risk to warrant treatment, and whether treatment with oral anticoagulation effectively reduces the risk of stroke in these patients.
In a Hot Line session on September 1, 2024, at the ESC Congress 2024 in London, UK, Professor Renato Lopes from Duke University Medical Center in the USA presented the results of the GUARD-AF study. The objective of this study was to examine whether AF screening using a continuous ECG patch monitor (Zio XT, which records heart rhythm for 14 days) could identify older adults with undiagnosed AF and result in a reduced rate of any stroke compared with usual care.
A total of 11,905 patients (average age 75 years, about half were women) across multiple centers in the US were randomized 1:1 to 14-day AF screening with the Zio XT patch versus usual care. Almost all participants (96%) returned their ECG monitors. Study outcomes were determined via Medicare claims and Kaiser Permanente data. The trial was terminated early due to the COVID-19 pandemic. Over a median follow-up of 15 months, AF detection was higher in the screened group compared to usual care (5% vs. 3.3%). Similarly, oral anticoagulant use was higher in the screening group (4.2% vs. 2.8%). However, the rate of hospitalizations for all strokes was similar between the two groups.
According to Professor Lopes: “Despite being the largest study using a 14-day, patch-based continuous ECG monitor as the screening strategy, our results should not be considered conclusive due to the early termination of the study and a lower-than-expected number of clinical events.” He also added: “Our results add to the body of evidence around AF screening and highlight the challenges in determining the impact of AF screening on clinical outcomes. Until we have clear information on who should be screened, how, for how long, and its real impact on stroke prevention, AF screening should not be routinely recommended.”