Mass ECG screening for atrial fibrillation in older adults does not seem to prevent stroke
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Key takeaways:
- Two studies found that mass screening for atrial fibrillation in older adults does not reduce stroke.
- In one study, levels of a biomarker may indicate who does not need to be screened.
Mass ECG screening for atrial fibrillation in older adults did not reduce the incidence of stroke or stroke hospitalization, according to the results of two trials presented at the European Society of Cardiology Congress.
In the GUARD-AF study, screening U.S. adults from primary care practices aged 70 years or older for AF did not reduce risk for stroke compared with the usual care.
In the STROKESTOP II study, screening Swedish adults aged 75 or 76 years for AF did not reduce risk for stroke or systemic embolism compared with no screening, but individuals with a low N-terminal pro-B natriuretic peptide level were at low risk for stroke and may represent a population that does not need ECG screening for AF.
GUARD-AF
For GUARD-AF, simultaneously published in the Journal of the American College of Cardiology, Renato D. Lopes, MD, PhD, professor of medicine at Duke University School of Medicine and a member of the Duke Clinical Research Institute, and colleagues randomly assigned 11,905 participants aged 70 years or older (median age, 75 years; 56.6% women) from 149 U.S. primary care practices to receive screening for AF via wearing a single-lead continuous ECG monitor (Zio XT, iRhythm Technologies) for 14 days or to receive the usual care. Participants were followed for a median of 15.3 months.
“Recent trials of brief one-time screening for AFib have not consistently shown an increase in the diagnosis of AFib,” Lopes said during a press conference at the ESC Congress. “Conversely, trials that use longer-term screening strategies have shown an increase in the diagnosis of AFib. But today, no trials have established that AFib screening can actually reduce stroke. Therefore, the main goal of the GUARD-AF trial was to determine whether AFib screening reduces the risk of stroke and provides a net clinical benefit compared with the usual care.”
The trial was scheduled to enroll more than 50,000 participants but was terminated early after the sponsor pulled funding due to the COVID-19 pandemic, Lopes said at the press conference.
The primary efficacy outcome of hospitalization for stroke did not differ between the screening (0.7%) and usual care groups (0.6%; HR = 1.1; 95% CI, 0.69-1.75), he said.
The primary safety outcome of hospitalization for bleeding also did not differ between the groups (screening, 1%; usual care, 1.1%; HR = 0.87; 95% CI, 0.6-1.26), according to the researchers.
Clinical diagnosis of AF or atrial flutter was 52% greater in the screening group compared with the usual care group (4 per 100 person-years vs. 2.63 per 100 person-years), and the screening group was more likely to have a prescription for oral anticoagulation filled during the study period than the usual care group (4.2% vs. 2.8%), Lopes and colleagues found.
Most AF episodes detected were short, and most patients diagnosed with AF had paroxysmal AF, Lopes said.
“Screening ... increased the detection of AFib by 52% and increased initiation of oral anticoagulation, but did not reduce hospitalization for stroke,” he said. “No differences were seen in the rates of hospitalization for bleeding or all-cause mortality between the study groups. The premature termination of enrollment and low statistical power unfortunately do not allow for a definitive conclusion about the effect of AFib screening on stroke prevention.”
Factors beyond age will be needed to identify a population at high-enough risk to benefit from AF screening, he said.
STROKESTOP II
For STROKESTOP II, simultaneously published in Circulation, Katrin Kemp Gudmundsdottir, MD, PhD, from the division of cardiology in the department of clinical sciences at Danderyd University Hospital, Stockholm, Sweden, and colleagues randomly assigned all adults aged 75 and 76 years in the Stockholm region to be invited to screening or serve as a control group.
“The ESC AF guidelines recommend AF screening in adults aged 75 years or older or those at high risk of stroke,” Kemp Gudmundsdottir said during a press conference at the Congress. “Our questions were, can atrial fibrillation screening using NT-pro BNP combined with ECG reduce stroke or systemic embolism, and what is the prognostic value of NT-pro BNP in AF screening.”
After exclusion of individuals who died or emigrated, the study population (mean age, 76.5 years; 53% women) consisted of 13,905 adults in the screening group and 13,884 adults in the control group. The latter “received no information on the study and no intervention,” she said. Results were registry-based.
The response rate of the screening group was 49.2%, translating to 6,843 people, Kemp Gudmundsdottir said at the press conference. Of the screening group, 6,288 had available NT-pro BNP levels, and of those, 40% were classified as low risk (less than 125 ng/L) and 60% were classified as high risk (125 ng/L or more), she said, noting the low-risk group had a one-time ECG screening at the initial visit and the high-risk group had a prolonged screening — 30 seconds of ECG four times daily for 2 weeks.
Among the screening group, 2.4% had newly detected AF (an additional 0.8% had known but untreated AF), and at 5 years, there was no difference between the screening and control groups in prevalence of AF or treatment with oral anticoagulation, according to the researchers.
However, those in the screening group classified as high risk based on NT-pro BNP had greater risk for new AF compared with those classified as low risk (HR = 2.42; 95% CI, 2.02-2.9; P < .001), they reported.
At a median follow-up of 5.1 years, there was no difference between the screening and control groups in the primary outcome of stroke or systemic embolism (HR = 0.96; 95% CI, 0.86-1.06; P = .412), Kemp Gudmundsdottir said at the press conference.
But compared with controls, the low-risk individuals in the screening group had reduced risk for stroke or systemic embolism (HR = 0.59; 95% CI, 0.46-0.74; P = .001), she said.
In addition, the high-risk individuals in the screening group had elevated risk for stroke or systemic embolism compared with the low-risk individuals (HR = 1.57; 95% CI, 1.22-2.02; P = .001), according to the researchers.
“NT-pro BNP can safely be used to determine who not to screen for AF,” Kemp Gudmundsdottir said.
References:
- Kemp Gudmundsdottir K, et al. Hot line 9. Presented at: European Society of Cardiology Congress; Aug. 30-Sept. 2, 2024; London (hybrid meeting).
- Kemp Gudmundsdottir K, et al. Circulation. 2024;doi:10.1161/CIRCULATIONAHA.124.071176.
- Lopes RD, et al. J Am Coll Cardiol. 2024;doi:10.1016/j.jacc.2024.08.019.
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Lopes RD, et al. Hot line 9. Presented at: European Society of Cardiology Congress; Aug. 30-Sept. 2, 2024; London (hybrid meeting).
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