Screening patients in a primary care setting over one year after occurrence of a stroke using seven-day Holter monitoring uncovered atrial fibrillation (AF) in 4.6% of patients without known AF, a study of the diagnostic benefit of continuous electrocardiogram (cECG) monitoring in post-stroke patients, published in Heart, has found.
According to the study’s authors, Louise Feldborg Lyckhage (Department of Neurology, Zealand University Hospital, Roskilde, Denmark) et al, the results suggest that cECG methods should be considered for post-stroke AF screening even long after the initial incidence. The results also further question the lack of guidelines for AF screening during post-stroke primary care, Lyckhage and colleagues suggest.
AF is one of the most important risk factors for the identification and treatment of ischaemic stroke, the study team notes in its introduction to the paper, although effective AF detection after stroke is challenging as AF is often paroxysmal and asymptomatic. Randomised critical trials and meta-analyses have shown that increasing the time of ECG monitoring in the early phase after ischaemic stroke uncovers progressively more AF, they add, which have lead to current recommendations for the inclusion of cECG early after ischaemic stroke. However, they note, there are currently no guidelines specific to primary care post-stroke AF screening.
Consequently, the study sought to investigate the role of external cECG as an AF screening tool in a primary care setting beyond the first year after ischaemic stroke to determine the proportion of newly diagnosed AF by use of seven-day Holter monitoring. Secondary aims included assessment of the sensitivity of pulse palpation and 12-lead ECG, using 7-day Holter monitoring as a reference standard, and assessment of the association of high versus low levels of N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) with the risk of AF.
The prospective cohort study was a collaboration between the Neurovascular Center, Zealand University Hospital (NVC) and two GP clinics in the Region of Zealand, Denmark (Borup and Havdrup). Patient recruitment began in November 2016 at Borup GP clinic and in November 2017 at Havdrup GP clinic, and enrolment was completed in April 2019. Participants included were AF-naive, had ischaemic stroke over one year before enrollment and were older than 49 at stroke onset. Participants with a systemic infection or taking antiarrhythmic drugs who had cECG within one year before inclusion, and who had an implanted loop recorder, cardioverter defibrillator or pacemaker were not eligible. Participants with an acute infection or surgery were included at least one month after remission. Participants taking OAC for other indications than AF were included.
Study evaluation for AF or atrial flutter included pulse palpation for irregular pulse, 12-lead ECG and 7-day cECG monitoring. All three evaluations were performed on all participants and 12-lead ECG was performed minutes before or after application of Holter equipment. Radial artery pulse palpation for pulse irregularity was done for a minimum of 20 seconds or as long as needed. Two-channel seven-day Holter monitoring was conducted using the Lifecard CF (Spacelabs Healthcare) and Pathfinder SL software was used for subsequent automatic AF screening.
Of 1,424 participants eligible for inclusion, 418 (29.4 %) accepted study participation and of these, the first 400 were enrolled and after excluding 34 participants, the study population consisted of 366 participants. The mean age was 70 years and 65.6% of the participants were men. The median time from last stroke was 3.9 years and the median CHA₂DS₂-VASc score (Congestive heart failure, Hypertension, Age, Diabetes, previous Stroke/transient ischemic attack, Vascular disease, Sex category) was 4.
Pulse palpation, 12-lead ECG and seven-day Holter monitoring were conducted on all patients and the median duration of interpretable Holter data was 6.9 days. Pulse palpation revealed irregular pulse in 122 of 366 patients (33%) Lyckhage et al note, adding that 12-lead ECG showed AF in 3 of 366 patients (0.82%). After seven-day Holter monitoring, AF was detected in 17 of 366 patients (4.6%). The number needed to screen with 7-day Holter monitoring was 22.
Discussing the findings, Lyckhage and colleagues note that screening patients in a primary care setting over one year post-stroke using seven-day Holter monitoring uncovered AF in 4.6% of participants without known AF. “Compared with seven-day Holter monitoring, more than half of AF diagnoses were undetectable with pulse palpation and more than 82.3% were missed by 12-lead ECG,” they add. “High versus low levels of NT-proBNP were not significantly associated with AF. Without the use of cECG, in addition to opportunistic pulse palpation and routine 12-lead ECG, a considerable number of patients with AF may be underdiagnosed during routine post-stroke AF screening in the primary sector.”
In conclusion the study team adds: “cECG seems relevant not only for AF detection in the acute phase after ischaemic stroke, but also as an additional tool for AF screening in GP clinics long after stroke. Further studies investigating primary sector AF screening long after stroke would be needed to clarify the prognostic impact, the benefit and feasibility of different cECG devices, and to identify which markers of AF could be used as a selection tool for extended screening.”