Mass screening for atrial fibrillation (AF) using electrocardiography (ECG) together with a heart failure biomarker does not prevent ischaemic stroke or systemic in older adults—aged 75–76 years—over five years of follow-up. However, the biomarker in question may improve the prediction of which individuals have a low risk for ischaemic stroke and systemic embolism beyond single-lead ECG in older adults undergoing mass screening for AF.
That is according to late-breaking research presented at the recent European Society of Cardiology (ESC) congress (30 August–2 September, London, UK).
“Our findings do not support this way of systematic screening for AF in older adults, but they indicate that it may be safe not to concentrate screening efforts at those individuals with low levels of NT-proBNP [N-terminal pro-B-type natriuretic peptide]—although this needs confirmation in further studies,” said Katrin Kemp Gudmundsdottir (Karolinska Institute, Stockholm, Sweden), lead author for the STROKESTOP II study. “Individuals with a low biomarker level ran a lower risk of both developing AF during the five-year follow-up as well as stroke or systemic embolism compared to both the control group and individuals with higher biomarker levels.”
Internationally, most AF guidelines currently recommend ‘opportunistic screening’ for AF in people aged 65 years and older, and oral anticoagulant treatment for those at high stroke risk. The ESC also recommends systematic ECG screening to detect AF in patients aged 75 years or older, or those at high stroke risk. It is also believed that adding biomarkers could enhance screening accuracy, and research suggests NT-proBNP—a marker of cardiovascular health—to be a strong predictor of incident AF and stroke.
In 2020, the baseline screening results of the STROKESTOP II trial showed that NTproBNP can be useful as a stratifying tool for screening of AF, and that those with elevated NTproBNP might benefit from more intensive screening.
STROKESTOP II—a mass screening programme of all 75–76-year-olds in the Stockholm region of Sweden—enrolled 28,712 people born between 1940 and 1941 to examine whether being invited for screening would reduce the risk of thromboembolic events compared to a control group of patients not invited for screening. Analyses of those invited for screening included adults who came for screening as well as those who did not attend.
Participants were randomised in a 1:1 ratio to either be invited for AF screening (13,905 patients) or to the control group (13,884)—after excluding those who died or emigrated. Of those invited to screening, 6,843 (49%) accepted the invitation. Some 53% of these patients were found to be women.
Participants without previously known AF had blood samples taken and NTproBNP levels analysed, and were then stratified into high-risk (≥125 ng/L NTproBNP) and low-risk (<125ng/L) groups. They were then screened, based on NT-proBNP level, to either one-time (low-risk group) or more intense (high-risk group) screening. In the high-risk group (3,743 patients; 60%), screening was done at home with a handheld, single-lead ECG device four times per day for two weeks, while, in low-risk participants (2,545 patients; 40%), a single episode of screening was performed with a single-lead ECG but without the two weeks of intensive screening.
Ultimately, new AF was detected in 2.4% (165 out of 6,843) of all participants, who were offered oral anticoagulant treatment—as per outcome data collected from national Swedish registries. In addition, after a median follow-up of five years, no difference was noted in the risk of any stroke or clotting event between the intervention group (including invited participants that both did and did not attend screening) and the control group.
Further subanalyses found that the risk of stroke or blood clots was 41% lower among participants with low levels of the heart failure marker NTproBNP compared to the control group (0.61 vs 1.03 events per 100 years at risk). In the high-risk group consisting of those with elevated levels of NTproBNP, individuals had more than double the risk of developing new AF in the five years, and the risk of ischaemic stroke or systemic embolism was 57% higher than in the low-risk group (0.95 vs 0.61 events per 100 years).
“Participation in the screening study was lower than expected and this could have hampered the results,” Kemp Gudmundsdottir concluded. “Further studies are needed, and it seems reasonable to concentrate screening efforts on those at highest risk and potentially lower the incident of preventable strokes.”
