A screening program using intermittent electrocardiogram (ECG) recordings detected previously unknown atrial fibrillation in 3 percent of the 75- and 76-year-old participants, most of whom then initiated treatments.

The findings were published online April 27 in Circulation. It is the first report from STROKESTOP, an ongoing study in Sweden that will evaluate the long-term benefit of mass screening for untreated atrial fibrillation, the initiation of treatment with oral anticoagulants to reduce the risk of stroke and the cost-effectiveness of the intervention at five years.

Emma Svennberg, MD, of Danderyd’s University Hospital in Stockholm, and the other STROKESTOP researchers identified all residents in two regions who were either 75 or 76 years old in 2011 and randomized half of them for screening. After receiving invitations, 7,173 participants in the screening arm with no prior history of atrial fibrillation agreed to take intermittent ECG recordings over two weeks using a handheld ECG recorder. The screening detected atrial fibrillation in 3 percent of those participants.

In the other group, 9.3 percent had a previous diagnosis of atrial fibrillation, and 2.1 percent of them were not taking oral anticoagulants. Based on those two groups, Svennberg et al reported a prevalence rate for untreated atrial fibrillation of 5.1 percent.

A total of 93 percent of participants with newly detected atrial fibrillation agreed to start oral anticoagulant treatment. In addition, 47 percent of those with known but untreated atrial fibrillation initiated treatment.

The STROKESTOP team pointed out that atrial fibrillation was rarely detected in the first ECG reading (0.5 percent). “Intermittent ECG screening increased the prevalence of [atrial fibrillation] in the screened population by 33%,” they wrote. That gave physicians the opportunity to diagnose and treat some cases of paroxysmal atrial fibrillation, before it possibly developed into permanent atrial fibrillation.

They may have underestimated the prevalence of atrial fibrillation because of the two-week duration of screening. Also, the study population is predominantly of European descent and the findings may not apply to other patient populations.