Wearable cardiac monitors for screening atrial fibrillation increase diagnosis but do not prevent stroke

Screening for atrial fibrillation (AF) for two weeks using a wearable heart monitor can identify older people with potentially dangerous abnormal heart rhythms, but it does not prevent subsequent strokes, according to new research presented during a Hotline session at this year's ESC Congress 2024 (August 30 – September 2) in London, UK.

However, the authors note that because the trial was terminated early due to the COVID-19 pandemic, its results cannot provide a definitive answer about the ultimate benefit of AF screening for reducing stroke hospitalization rates.

Our study showed a 52% increase in the number of diagnosed cases of atrial fibrillation over a follow-up period of up to 2.5 years, an increase in oral anticoagulant initiation without an increase in the rate of hospitalization for bleeding, and a non-significant reduction in the rate of hospitalization for all strokes compared with usual care. Despite being the largest study using 14-day patch-based continuous ECG monitoring as a screening strategy, our results cannot be considered conclusive due to the early termination of the study and the lower than expected number of clinical events.”

Renato Lopez Lead author, Professor Duke University Medical Center (USA)

He added: “Further studies with longer follow-up and including participants at high risk of stroke are needed to establish the true potential of AF screening in reducing stroke incidence.”

As cardiovascular diseases (CVD), primarily heart attacks and strokes, remain the leading cause of death in Europe and worldwide, the European Society of Cardiology is calling for CVD and diabetes screening to be part of national and European Union health plans in order to prevent CVD and raise awareness about CV health at population level.

AF is the most common heart rhythm disorder, affecting more than 40 million people worldwide. It is estimated that one in three Europeans will develop the disease in their lifetime. Symptoms include palpitations, shortness of breath, fatigue and sleep disorders. However, many people never experience any symptoms and AF often goes undiagnosed. Moreover, AF can be intermittent, making it even more difficult to identify patients.

Because AF patients have a five times higher risk of stroke, they are often prescribed blood-thinning medications (anticoagulants) to prevent blood clotting.

Recent trials have shown that a single brief screening for AF did not significantly increase AF diagnoses, whereas other trials looking at longer-term screening have found an increase in AF diagnoses, primarily for paroxysmal AF (an intermittent heart rhythm disorder). However, AF screening has not yet been proven to reduce stroke rates.

The GUARD-AF trial, which began in December 2019, randomized 11,905 patients from 149 primary care sites across the United States to test whether AF screening with a continuous ECG patch monitor (Zio XT, which records heart rhythm for 14 days) can identify older adults with undiagnosed AF and reduce the incidence of stroke compared to usual care.

A total of 5,952 people were randomly assigned to screening and 5,953 to usual care (median age 75 years, 57% women). Of those randomly assigned to screening, 5,684 (96%) returned ECG monitors with analyzable results. Researchers examined Medicare claims and Kaiser Permanente data to determine clinical outcomes.

During a mean (median) follow-up period of 15 months, the number of patients in the screening group who had a stroke was numerically higher than in the usual care group (37 vs. 34), and the number of patients who experienced a bleeding event was numerically lower in the screening group than in the usual care group (52 vs. 60).

In the screening group, both the diagnosis of AF and treatment with oral anticoagulation were more likely (5% vs. 10% in the usual care group). [284 patients] 3.3% vs. [196] 4.2% [239] 2.8% [167]respectively).

Professor Lopez said: “Our findings add to the growing body of evidence on AF screening and highlight the challenges in determining the impact of AF screening on clinical outcomes. Until we have clear information about who should be screened, how, for how long, and the real-world impact in preventing stroke, AF screening should not be routinely recommended.”