Validation of a novel smartphone-based photoplethysmographic method for ambulatory heart rhythm diagnostics: the SMARTBEATS study.

AIMS: In the current guidelines, smartphone photoplethysmography (PPG) is not recommended for diagnosis of atrial fibrillation (AF), without a confirmatory electrocardiogram (ECG) recording. Previous validation studies have been performed under supervision in healthcare settings, with limited generalizability of the results. We aim to investigate the diagnostic performance of a smartphone-PPG method in a real-world setting, with ambulatory unsupervised smartphone-PPG recordings, compared with simultaneous ECG recordings and including patients with atrial flutter (AFL). METHODS AND RESULTS: Unselected patients undergoing direct current cardioversion for treatment of AF or AFL were asked to perform 1-min heart rhythm recordings post-treatment, at least twice daily for 30 days at home, using an iPhone 7 smartphone running the CORAI Heart Monitor PPG application simultaneously with a single-lead ECG recording (KardiaMobile). Photoplethysmography and ECG recordings were read independently by two experienced readers. In total, 280 patients recorded 18 005 simultaneous PPG and ECG recordings. Sufficient quality for diagnosis was seen in 96.9% (PPG) vs. 95.1% (ECG) of the recordings (P < 0.001). Manual reading of the PPG recordings, compared with manually interpreted ECG recordings, had a sensitivity, specificity, and overall accuracy of 97.7%, 99.4%, and 98.9% with AFL recordings included and 99.0%, 99.7%, and 99.5%, respectively, with AFL recordings excluded. CONCLUSION: A novel smartphone-PPG method can be used by patients unsupervised at home to achieve accurate heart rhythm diagnostics of AF and AFL with very high sensitivity and specificity. This smartphone-PPG device can be used as an independent heart rhythm diagnostic device following cardioversion, without the requirement of confirmation with ECG.

Adherence to a handheld device-based atrial fibrillation screening protocol is associated with clinical outcomes.

OBJECTIVE: To evaluate adherence and adherence consistency to the handheld ECG device-based screening protocol and their association with adverse cerebral and cardiovascular outcomes in two systematic atrial fibrillation (AF) screening programmes. METHODS: In 2012 (Systematic ECG Screening for Atrial Fibrillation Among 75-Year Old Subjects in the Region of Stockholm and Halland, Sweden (STROKESTOP) study) and 2016 (Stepwise mass screening for atrial fibrillation using N-terminal pro b-type natriuretic peptide (STROKESTOP II) study), half of all 75- and 76-year-old inhabitants of up to two Swedish regions were invited to participate in a systematic AF screening programme. Participants were instructed to perform 30-second measurements twice daily in STROKESTOP and four times daily in STROKESTOP II for 2 weeks. Adherence was defined as the number of measurements performed divided by the number of measurements asked, whereas adherence consistency was defined as the number of days with complete registrations. RESULTS: In total, 6436 participants (55.7% female) from STROKESTOP and 3712 (59.8% female) from STROKESTOP II were included. Median adherence and adherence consistency were 100 (92-100)% and 12 (11-13) days in STROKESTOP and 90 (75-98)% and 8 (3-11) days in STROKESTOP II. Female sex and lower education were factors associated with both optimal adherence and adherence consistency in both studies. In STROKESTOP, low adherence and adherence consistency were associated with higher risk of adverse cerebral and cardiovascular outcomes (HR for composite primary endpoint 1.30 (1.11 to 1.51), p=0.001), including stroke (HR 1.68 (1.22 to 2.32), p=0.001) and dementia (1.67 (1.27 to 2.19), p<0.001). CONCLUSIONS: Adherence to twice daily handheld ECG measurements in STROKESTOP was higher than to four times daily measurements in STROKESTOP II. Female sex and lower educational attainment were associated with ≥100% adherence and adherence consistency. Low adherence and adherence consistency were associated with a higher risk of adverse outcomes.

Examining the continuum of resistance model in two population-based screening studies in Sweden.

In studies recruited on a voluntary basis, lack of representativity may impair the ability to generalize findings to the target population. Previous studies, primarily based on surveys, have suggested that generalizability may be improved by exploiting data on individuals who agreed to participate only after receiving one or several reminders, as such individuals may be more similar to non-participants than what early participants are. Assessing this idea in the context of screenings, we compared sociodemographic characteristics and health across early, late, and non-participants in two large population-based screening studies in Sweden: STROKESTOP II (screening for atrial fibrillation; 6,867 participants) and SCREESCO (screening for colorectal cancer; 39,363 participants). We also explored the opportunities to reproduce the distributions of characteristics in the full invited populations, either by assuming that the non-participants were similar to the late participants, or by applying a linear extrapolation model based on both early and late participants. Findings showed that early and late participants exhibited similar characteristics along most dimensions, including civil status, education, income, and health examination results. Both these types of participants in turn differed from the non-participants, with fewer married, lower educational attainments, and lower incomes. Compared to early participants, late participants were more likely to be born outside of Sweden and to have comorbidities, with non-participants similar or even more so. The two empirical models improved representativity in some cases, but not always. Overall, we found mixed support that data on late participation may be useful for improving representativeness of screening studies.

An artificial intelligence-based model for prediction of atrial fibrillation from single-lead sinus rhythm electrocardiograms facilitating screening.

AIMS: Screening for atrial fibrillation (AF) is recommended in the European Society of Cardiology guidelines. Yields of detection can be low due to the paroxysmal nature of the disease. Prolonged heart rhythm monitoring might be needed to increase yield but can be cumbersome and expensive. The aim of this study was to observe the accuracy of an artificial intelligence (AI)-based network to predict paroxysmal AF from a normal sinus rhythm single-lead ECG. METHODS AND RESULTS: A convolutional neural network model was trained and evaluated using data from three AF screening studies. A total of 478 963 single-lead ECGs from 14 831 patients aged ≥65 years were included in the analysis. The training set included ECGs from 80% of participants in SAFER and STROKESTOP II. The remaining ECGs from 20% of participants in SAFER and STROKESTOP II together with all participants in STROKESTOP I were included in the test set. The accuracy was estimated using the area under the receiver operating characteristic curve (AUC). From a single timepoint ECG, the artificial intelligence-based algorithm predicted paroxysmal AF in the SAFER study with an AUC of 0.80 [confidence interval (CI) 0.78-0.83], which had a wide age range of 65-90+ years. Performance was lower in the age-homogenous groups in STROKESTOP I and STROKESTOP II (age range: 75-76 years), with AUCs of 0.62 (CI 0.61-0.64) and 0.62 (CI 0.58-0.65), respectively. CONCLUSION: An artificial intelligence-enabled network has the ability to predict AF from a sinus rhythm single-lead ECG. Performance improves with a wider age distribution.

Clinical and echocardiographic characteristics of individuals aged 75/76 years old with screening-detected elevated NT-proBNP levels.

Background: High plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) indicate increased probability of congestive heart failure (CHF) and atrial fibrillation (AF) and are associated with poor prognosis. Objective: We aimed to describe the clinical and echocardiographic characteristics of a population of individuals aged 75/76 years old with NT-proBNP ≥900 ng/L without previously known CHF or AF. Methods: All individuals aged 75/76 years in the Stockholm region were randomised to a screening study for AF. Half of them were invited to screening. Of those invited, 49.5% agreed to participate. Individuals with NT-proBNP ≥900 ng/L without known CHF were invited for further clinical evaluation. Results: Among 6315 participants without AF who had NT-proBNP sampled, 102 without previously known CHF had ≥900 ng/L. Of these, 93 completed further clinical investigations. In the population that was clinically investigated, 53% were female, and the median NT-proBNP was 1200 ng/L. New AF was found in 28 (30%). The NT-proBNP value in this group was not significantly different from those where AF was not detected (median 1285 vs 1178 ng/L). Patients with newly detected AF had larger left atrial volume and higher pulmonary artery pressure than those without AF. Preserved left ventricular ejection fraction (≥50%) was found in 86% of the participants, mid-range ejection fraction (40%-49%) in 3.2% and reduced ejection fraction (<40%) in 10.8%. Thirteen patients (14%) had other serious cardiac disorders that required medical attention. Conclusion: Elderly individuals with NT-proBNP levels ≥900 ng/L constitute a population at high cardiovascular risk even in the absence of diagnosed CHF or AF, and therefore merit further investigation.

Intermittent vs continuous electrocardiogram event recording for detection of atrial fibrillation-Compliance and ease of use in an ambulatory elderly population.

BACKGROUND: There are many atrial fibrillation (AF) screening devices available. Validation studies have mainly been performed in optimal settings in the young population. HYPOTHESIS: We aim to compare the yield of AF detection, compliance, and patient-based experience in an ambulatory elderly population by using intermittent electrocardiogram (ECG) recordings and continuous event recording simultaneously. METHODS: The study participants were part of the STROKESTOP II study, a Swedish screening study for AF. All participants were 75/76 years of age, were clinically free of AF, and had N-terminal pro b-type natriuretic peptides levels ≥125 ng/L. AF screening was performed in parallel during a 2-week period, using a continuous event recording device (R-test 4; Novacor) and 30-second intermittent recordings using a handheld ECG device (Zenicor II) four times daily. Participants were asked to fill out a questionnaire with regard to compliance and ease of use of the devices. RESULTS: During continuous event recording, 6% (n = 15/269) were diagnosed with AF and intermittent ECG detected AF in 2% (n = 5/269) of the participants (P = .002). No new cases of AF were detected using intermittent ECG monitoring only, but some episodes were detected in parallel for patients. On a graded ordinal scale of 1 to 5, with 1 reflecting "very easy to use", continuous monitoring was graded 2 (interquartile range [IQR]: 1-3) compared to intermittent 1 (IQR: 1-1) (P < .001). CONCLUSION: Continuous event recording detected three times more AF compared to intermittent ECG in an elderly ambulatory population. Compliance and user-friendliness were rated higher for the intermittent ECG device.

Stepwise mass screening for atrial fibrillation using N-terminal B-type natriuretic peptide: the STROKESTOP II study.

AIMS: To study the prevalence of unknown atrial fibrillation (AF) in a high-risk, 75/76-year-old, population using N-terminal B-type natriuretic peptide (NT-proBNP) and handheld electrocardiogram (ECG) recordings in a stepwise screening procedure. METHODS AND RESULTS: The STROKESTOP II study is a population-based cohort study in which all 75/76-year-old in the Stockholm region (n = 28 712) were randomized 1:1 to be invited to an AF screening programme or to serve as the control group. Participants without known AF had NT-proBNP analysed and were stratified into low-risk (NT-proBNP <125 ng/L) and high-risk (NT-proBNP ≥125 ng/L) groups. The high-risk group was offered extended ECG-screening, whereas the low-risk group performed only one single-lead ECG recording. In total, 6868 individuals accepted the screening invitation of which 6315 (91.9%) did not have previously known AF. New AF was detected in 2.6% [95% confidence interval (CI) 2.2-3.0] of all participants without previous AF. In the high-risk group (n = 3766/6315, 59.6%), AF was diagnosed in 4.4% (95% CI 3.7-5.1) of the participants. Out of these, 18% had AF on their index-ECG. In the low-risk group, one participant was diagnosed with AF on index-ECG. The screening procedure resulted in an increase in known prevalence from 8.1% to 10.5% among participants. Oral anticoagulant treatment was initiated in 94.5% of the participants with newly diagnosed AF. CONCLUSION: N-terminal B-type natriuretic peptide-stratified systematic screening for AF identified 4.4% of the high-risk participants with new AF. Oral anticoagulant treatment initiation was well accepted in the group diagnosed with new AF.

[Early or delayed cardioversion in atrial fibrillation?] / Tidig eller sen konvertering vid förmaksflimmer? - En stor andel av patienterna spontankonverterar till sinusrytm.

Atrial fibrillation is one of the most common arrhythmias. As the symptoms can be abrupt in onset it is associated with a substantial burden on the medical emergency system. By routine practice patients with symptomatic atrial fibrillation of a duration less than 48 hours are commonly offered cardioversion therapy. Data from a recent study shows that more than two thirds of patients convert to sinus rhythm spontaneously within 48 hours. A watch-and-wait approach in rhythm control management may be suggested for clinical praxis, considering the high chance of spontaneous cardioversion. Long-term results for a group with early and delayed cardioversion were similar with regards to maintenance of sinus rhythm at 4 weeks.

Stepwise mass screening for atrial fibrillation using N-terminal pro b-type natriuretic peptide: the STROKESTOP II study design.

AIM: Atrial fibrillation (AF) is the most prevalent clinical arrhythmia and a major risk factor for ischaemic stroke. Treatment with oral anticoagulants (OACs) reduces the risk of stroke by two thirds in AF patients with risk factors. Due to its often paroxysmal and asymptomatic presentation, AF is sometimes challenging to diagnose. So far, AF screening studies have applied opportunistic or systematic screening, most often using a single 12-lead electrocardiogram (ECG) recording or ambulatory ECG. We hypothesise that the biomarker N-terminal pro b-type natriuretic peptide (NT-proBNP) is a valuable adjunct in population based AF screening. METHODS: We are conducting a randomized population-based study on AF screening using ambulatory ECG recording where the decision to use prolonged intermittent ECG recording is directed by NT-proBNP levels, the STROKESTOP II trial. The entire population of inhabitants 75 or 76 years of age (n = 28 712) in the capital region of Sweden will be randomized 1:1 to intervention or control group. In the intervention group NT-proBNP will be analysed in all without previously known AF. Those with NT-proBNP ≤ 125 pg/L will make a single one lead ECG recording, participants with NTproBNP ≥ 125 np/L will be instructed to record ECG for 30 s at least twice daily for 2 weeks with a handheld ambulatory ECG recorder. Participants with newly diagnosed or undertreated AF will be referred to a cardiologist and offered OAC treatment. Primary endpoint is incidence of stroke or systemic embolus, during a 5 year follow-up period in the control group vs the group invited to screening.