September 13, 2013

AMSTERDAM — Systematic screening of more than 25,000 individuals aged 75 to 76 years identified untreated atrial fibrillation (AF) in 5%, putting them at increased stroke risk, preliminary findings of the STROKESTOP study show.

The Swedish study is investigating whether the identification of patients with AF through such screening will lead to a reduction in future stroke events.

Presenting the preliminary data at last week's European Society of Cardiology (ESC) Congress 2013 in Amsterdam, the Netherlands, Emma Svennberg, MD, Danderyd University Hospital, Sweden, noted that AF is estimated to affect about 1.5% to 2% of the general population, and its prevalence is expected to double in the next 50 years as the population ages.

"Ticking Bomb"

Chair of the STROKESTOP steering committee, Professor Mårten Rosenqvist, also at Danderyd University Hospital, Karolinska Institute, described AF as a "ticking bomb." Patients with AF have a 5-fold increased risk for ischemic stroke, he noted, but this can be reduced by anticoagulant treatment.

Dr. Svennberg stressed the importance of identifying patients with the condition. "Around 30% of patients with AF do not have symptoms, and more than 50% do not receive any treatment, so we are looking at an epidemic of AF-related strokes if nothing is done to improve treatment levels," she said.

In the STROKESTOP trial, all 25,000 people aged 75 to 76 years in Stockholm County and Region Halland in Sweden were randomly assigned to screening for AF or to a control group. Screening was done at home by the individuals themselves with a handheld electrocardiography (ECG) device and took 1 minute per day for 2 weeks.

When AF is diagnosed, patients are offered oral anticoagulant treatment. Both groups will be followed prospectively for 5 years for thromboembolic events, bleeding, and mortality.

The current data show that at 1 year into the trial, 6496 (50%) of the 13,000 inhabitants in the screening group agreed to screening for AF. A lower proportion of patients agreed to screening in Stockholm (49%) than in rural areas (65%), Dr. Svennberg said. The investigators are looking into factors related to participation, in an effort to increase uptake.

Results showed that more than 11% of the screening group had AF. Previously undiagnosed AF was found in 3% of patients, whereas in 2% of patients AF had been diagnosed but the patients were not receiving oral anticoagulation.

More than 90% of the patients with undiagnosed AF began receiving oral anticoagulation. "This should reduce their risk of a stroke by up to 70%," Dr. Svennberg said.

She added that the researchers were still collecting data on patients with known AF but not on anticoagulation. Final results from the trial should be available by 2018.

Every Tool Meaningful

Commenting on the study for Medscape Medical News, Professor Robert Hatala, National Heart Institute, Bratislava, Slovak Republic, called screening the elderly population "a very good idea. It is a simple measure that could identify a lot of AF patients."

He explained that guidelines recommend screening for pulse irregularities at every physician visit in patients older than 65 years, and patients found to have an irregular pulse should have ECG. However, this is not always done. "Just getting GPs [general practitioners] to feel the pulse of all eldery patients who visit them would be great help."

He pointed out that using a hand-held ECG device for 1 minute every day for 2 weeks is a better screening tool than single ECG, which takes just a couple of seconds. "While it will not be absolutely reliable — that would need longer monitoring — it is a good compromise."

He added: "There are certainly a significant number of elderly people in real life with undiagnosed AF who are at a very high risk of stroke. Every tool we can use to identify these people is very meaningful. This will contribute to a reduction in stroke."

Professor Hatala pointed out that in the last 20 years, heart attacks have been constantly highlighted as a major killer, but data from the OXVASC study in the United Kingdom show that even when ST-segment elevation myocardial infarction (MI) and sudden deaths are combined, these make up only half as many events as strokes. "Stroke is now much more prevalent than MI in the western world. Cardiologists need to collaborate with neurologists to address this problem."

It is rare in medicine that there is 1 risk factor that has a hazard ratio of 5 or more for a particular event, but this is the case for AF and stroke. It is an extremely powerful risk factor. Dr. Robert Hatala

He emphasized the strong link between AF and stroke. "It is rare in medicine that there is 1 risk factor that has a hazard ratio of 5 or more for a particular event, but this is the case for AF and stroke. It is an extremely powerful risk factor. We must focus our efforts on it."

Professor Hatala said he would expect the STROKESTOP trial to show that screening for AF results in a reduction in stroke and would lead to this being introduced throughout the world.

European Society of Cardiology (ESC) Congress 2013. Abstract 4382. Presented September 3, 2013.


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