Cost-effectiveness of population screening for atrial fibrillation: the STROKESTOP study.

AIMS: Previous studies on the cost-effectiveness of screening for atrial fibrillation (AF) are based on assumptions of long-term clinical effects. The STROKESTOP study, which randomised 27 975 persons aged 75/76 years into a screening invitation group and a control group, has a median follow-up time of 6.9 years. The aim of this study was to estimate the cost-effectiveness of population-based screening for AF using clinical outcomes. METHODS AND RESULTS: The analysis is based on a Markov cohort model. The prevalence of AF, the use of oral anticoagulation, clinical event data, and all-cause mortality were taken from the STROKESTOP study. The cost for clinical events, age-specific utilities, utility decrement due to stroke, and stroke death was taken from the literature. Uncertainty in the model was considered in a probabilistic sensitivity analysis. Per 1000 individuals invited to the screening, there were 77 gained life years and 65 gained quality-adjusted life years. The incremental cost was €1.77 million lower in the screening invitation group. Gained quality-adjusted life years to a lower cost means that the screening strategy was dominant. The result from 10 000 Monte Carlo simulations showed that the AF screening strategy was cost-effective in 99.2% and cost-saving in 92.7% of the simulations. In the base-case scenario, screening of 1000 individuals resulted in 10.6 [95% confidence interval (CI): -22.5 to 1.4] fewer strokes (8.4 ischaemic and 2.2 haemorrhagic strokes), 1.0 (95% CI: -1.9 to 4.1) more cases of systemic embolism, and 2.9 (95% CI: -18.2 to 13.1) fewer bleedings associated with hospitalization. CONCLUSION: Based on the STROKESTOP study, this analysis shows that a broad AF screening strategy in an elderly population is cost-effective. Efforts should be made to increase screening participation.

Prognostic implication of premature ventricular contractions in patients without structural heart disease.

AIMS: Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with an unfavourable prognosis in patients with structural heart disease. However, the prognostic significance in absence of heart disease is debated. With this study, we aim to investigate whether subjects with PVC, without structural heart disease, have a worse prognosis than the general population. METHODS AND RESULTS: Patients evaluated for PVC at a secondary care centre in Stockholm County from January 2010 to December 2016 were identified. We included patients without history of previous heart disease who had undergone echocardiography and exercise test with normal findings. Based on sex and age, we matched the PVC cohort to a four times bigger control group from the general population and compared the outcome in terms of mortality and cardiovascular morbidity during a median follow-up time of 5.2 years. We included 820 patients and 3,264 controls. Based on a non-inferiority analysis, the PVC group did not have a higher mortality than the control group (0.44, CI 0.27-0.72). Sensitivity analysis with propensity score matching confirmed this result. CONCLUSIONS: PVC patients, who after thorough evaluation showed no signs of structural heart disease, did not have a worse prognosis when compared to an age- and sex- control group based on the general population.

Prognostic impact of morphology and duration of premature ventricular contractions in a population without structural heart disease.

BACKGROUND: Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with an unfavorable prognosis in patients with structural heart disease. It is unclear whether PVCs site of origin and QRS-width has a prognostic significance in patients without structural heart disease. The aim of this study was to assess the prognostic importance of PVCs morphology and duration in this patient group. METHODS: We included 511 consecutive patients without a history of previous heart disease. They were examined with echocardiography and exercise test with normal findings. We categorized the PVCs from a 12 lead ECG according to morphology and width of the QRS-complex and analyzed the outcome in terms of a composite endpoint of total mortality and cardiovascular morbidity. RESULTS: During a median follow-up time of 5.3 years, 19 patients (3.5%) died and 61 (11.3%) met the composite outcome. Patients with PVCs originating from the outflow tracts had a significantly lower risk for the composite outcome compared to patients with non-OT-PVCs. Similarly, patients with PVC originating from the right ventricle had a better outcome than patients with left ventricular PCVs. No difference in outcome depending on QRS-width during PVCs was noticed. CONCLUSION: In our cohort of consecutively included PVC patients without structural heart disease PVCs from the outflow tracts were associated with a better prognostic outcome than non-OT PVCs; the same was true for right ventricular PVCs when compared to left ventricular ones. The classification of the origin of the PVCs was based on 12-lead ECG morphology. QRS-width during PVC did not seem to have prognostic significance.

Clinical outcomes in systematic screening for atrial fibrillation (STROKESTOP): a multicentre, parallel group, unmasked, randomised controlled trial.

BACKGROUND: Atrial fibrillation is a leading cause of ischaemic stroke. Early detection of atrial fibrillation can enable anticoagulant therapy to reduce ischaemic stroke and mortality. In this randomised study in an older population, we aimed to assess whether systematic screening for atrial fibrillation could reduce mortality and morbidity compared with no screening. METHODS: STROKESTOP was a multicentre, parallel group, unmasked, randomised controlled trial done in Halland and Stockholm in Sweden. All 75-76-year-olds residing in these two regions were randomly assigned (1:1) to be invited to screening for atrial fibrillation or to a control group. Participants attended local screening centres and those without a history of atrial fibrillation were asked to register intermittent electrocardiograms (ECGs) for 14 days. Treatment with oral anticoagulants was offered if atrial fibrillation was detected or untreated. All randomly assigned individuals were followed up in the intention-to-treat analysis for a minimum of 5 years for the primary combined endpoint of ischaemic or haemorrhagic stroke, systemic embolism, bleeding leading to hospitalisation, and all-cause death. This trial is registered with ClinicalTrials.gov, NCT01593553. FINDINGS: From March 1, 2012, to May 28, 2014, 28 768 individuals were assessed for eligibility and randomly assigned to be invited to screening (n=14 387) or the control group (n=14 381). 408 individuals were excluded from the intervention group and 385 were excluded from the control group due to death or migration before invitation. There was no loss to follow-up. Of those invited to screening, 7165 (51·3%) of 13 979 participated. After a median follow-up of 6·9 years (IQR 6·5-7·2), significantly fewer primary endpoint events occurred in the intervention group (4456 [31·9%] of 13 979; 5·45 events per 100 years [95% CI 5·52-5·61]) than in the control group (4616 [33·0%] of 13 996; 5·68 events per 100 years [5·52-5·85]; hazard ratio 0·96 [95% CI 0·92-1·00]; p=0·045). INTERPRETATION: Screening for atrial fibrillation showed a small net benefit compared with standard of care, indicating that screening is safe and beneficial in older populations. FUNDING: Stockholm County Council, the Swedish Heart & Lung Foundation, King Gustav V and Queen Victoria's Freemasons' Foundation, the Klebergska Foundation, the Tornspiran Foundation, the Scientific Council of Halland Region, the Southern Regional Healthcare Committee, the Swedish Stroke Fund, Carl Bennet AB, Boehringer Ingelheim, Bayer, and Bristol Myers Squibb-Pfizer.

Factors predicting participation and potential yield of screening-detected disease among non-participants in a Swedish population-based atrial fibrillation screening study.

BACKGROUND: The success of any screening program is dependent on participation. The characteristics of participants vs. non-participants have been studied and non-participants usually have a higher risk of disease. The potential yield of screening-detected disease in non-participants could be of interest to several screening programs. AIMS: This is a sub-study to STROKESTOP II, a Swedish atrial fibrillation screening study. The aim was to study factors predicting participation and to estimate the potential yield of screening-detected disease in non-participants. METHODS: Individual, anonymized data for participants and non-participants with respect to socioeconomic factors, medical history and drugs dispensed were obtained from Swedish registries. A random forest model was trained to predict propensity scores for participation. The propensity scores were used to estimate potential screening-detected disease among non-participants. RESULTS: Non-participants (n = 7086) had lower income, were more likely to have been hospitalized and had higher CHA2DS2-VASc scores compared to participants (n = 6868). The strongest factor predicting non-attendance was low income. The weighted estimates suggested that the yield of new atrial fibrillation was 2.4% in non-participants compared to 2.3% in the participants, which was not significant. CONCLUSIONS: Non-participants had higher CHA2DS2-VASc scores, indicating a higher stroke-risk and presumable benefit from attending screening, although estimated new atrial fibrillation detected was not significantly more common when compared to participants. Low income was the strongest factor for predicting non-attendance and should be a focus area when planning future screening scenarios.

Progression and clinical manifestations in screening-detected atrial fibrillation: A follow-up of the STROKESTOP study.

BACKGROUND: There is a lack of data on atrial fibrillation (AF) progression after AF screening. HYPOTHESIS: We studied the hypothesis that progression of AF subtype after AF screening was similar to the progression noted in clinical AF cases. We also studied predictors for AF progression and AF symptoms during 5-year follow-up. METHODS: All participants from the STROKESTOP study with screening-detected AF were included in this prospective cohort study (n = 218). Deceased patients, patients with dementia and/or patients receiving institutional care were excluded (n = 31). Patients were interviewed at their visit regarding symptoms, treatment with oral anticoagulation and clinical events during follow-up and instructed to record ECG using a handheld ECG recording twice daily for two weeks. RESULTS: A total of 187 patients were invited for follow-up and 120 (64%) participated. The mean age was 81.0 ± 0.6 years and 56 (47%) of the participants were women. The mean follow-up time was 5.3 ± 0.4 years. Among the participants with 5-year follow-up data available, 18% (22/120) were diagnosed with permanent AF at study entry, compared to 49/120 (41%) after five years (p < 0.001). Among patients with paroxysmal AF at study entry, 33/98 (34%) had progressed to permanent AF after five years. Among participants approximately half remained asymptomatic, whereas 48% reported predominantly mild symptoms. None of the components of CHA2DS2-VASc were significantly predictive of AF progression. CONCLUSIONS: The progression for screening-detected AF is like that of clinically detected AF. Half of the patients with screening-detected AF report symptoms over time, and symptoms were generally mild.

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.

Brief episodes of rapid irregular atrial activity (micro-AF) are a risk marker for atrial fibrillation: a prospective cohort study.

BACKGROUND: Short supraventricular tachycardias with atrial fibrillation (AF) characteristics are associated with an increased risk of developing AF over time. The aim of this study is to determine if presence of very short-lasting episodes of AF-like activity (micro-AF) can also be used as a marker of undiagnosed silent atrial fibrillation. METHODS: In the STROKESTOP II study, a Swedish mass screening study for AF among 75- and 76-year-olds, participants with NT-proBNP ≥125 ng/L performed intermittent ECG recordings 30 s, four times daily for 2 weeks. Participants with micro-AF (sudden onset of irregular tachycardia with episodes of ≥5 consecutive supraventricular beats and total absence of p-waves, lasting less than 30 s) were invited to undergo extended AF screening using continuous event recording for 2 weeks. A control group of individuals without micro-AF was examined using the same ECG modalities. RESULTS: Out of 3763 participants in STROKESTOP II who had elevated NT-proBNP levels and were free of AF, n = 221 (6%) had micro-AF. The majority of participants with micro-AF (n = 196) accepted further investigation with continuous ECG monitoring which showed presence of AF in 26 of them. In the control group (n = 250), continuous monitoring detected 7 new AF cases. Thus, AF was significantly more common in the micro AF group (13%) compared to the control group (3%), p < 0.001. CONCLUSIONS: Presence of short-lasting episodes of AF-like activity (micro-AF) indicates increased likelihood for undetected AF. Continuous screening therefore seems recommendable if a finding of AF would change clinical management. TRAIL REGISTRATION: ClinicalTrials.gov, identifier: NCT02743416, registered April 19, 2016.

Physicians' knowledge of implantable defibrillator treatment: are we good enough?

AIMS: When admitted to hospitals, patients with an implantable cardioverter defibrillator (ICD) are treated in a variety of departments. Physicians need to have basic ICD knowledge in order to provide the best possible care from implantation to the end of life. The aim of this study was to assess the levels of knowledge concerning ICD treatment among physicians active in Cardiology, Internal Medicine, and Geriatrics. METHODS AND RESULTS: This cross-sectional comparative study, after stratified sampling, distributed 432 surveys in 18 hospitals with a response rate of 99.5%. As many as 349 (83%) physicians had experience with ICD patients; 288 (68%) rated their ICD knowledge to be low. According to predefined criteria, 175 (41%) physicians' scores reflected sufficient knowledge. There was a significant difference in the level of knowledge between specialities. Sufficient knowledge was reached by 56 (30%) of the physicians in Internal Medicine and 20 (19%) of them in Geriatrics, whereas in Cardiology 99 (71%) reached sufficient knowledge. CONCLUSION: There is lack of basic knowledge in ICD treatment and clinical management among physicians. The majority of the respondents had prior experience in treating ICD patients. Over two-thirds of the physicians rated their knowledge to be low, while test scores revealed sufficient knowledge in only 41% of the physicians surveyed. The lack of ICD knowledge is most prominent in Internal Medicine and Geriatrics, but it also extends to physicians in Cardiology departments. With an increasing number of ICD patients, it is of great importance to fill this knowledge gap as soon as possible.

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.

Safe automatic one-lead electrocardiogram analysis in screening for atrial fibrillation.

AIMS: Screening for atrial fibrillation (AF) using intermittent electrocardiogram (ECG) recordings can identify individuals at risk of AF-related morbidity in particular stroke. We aimed to validate the performance of an AF screening algorithm compared with manual ECG analysis by specially trained nurses and physicians (gold standard) in 30 s intermittent one-lead ECG recordings. METHODS AND RESULTS: The STROKESTOP study is a mass-screening study for AF using intermittent ECG recordings. All individuals in the study without known AF registered a 30-s ECG recording in Lead I two times daily for 2 weeks, and all ECGs were manually interpreted. A computerized algorithm was used to analyse 80 149 ECG recordings in 3209 individuals. The computerized algorithm annotated 87.1% (n = 69 789) of the recordings as sinus rhythm/minor rhythm disturbances. The manual interpretation (gold standard) was that 69 758 ECGs were normal, making the negative predictive value of the algorithm 99.9%. The number of ECGs requiring manual interpretation in order to find one pathological ECG was reduced from 288 to 35. Atrial fibrillation was diagnosed in 84 patients by manual interpretation, in all of whom the algorithm indicated pathology. On an ECG level, 278 ECGs were manually interpreted as AF, and of these the algorithm annotated 272 ECGs as pathological (sensitivity 97.8%). CONCLUSION: Automatic ECG screening using a computerized algorithm safely identifies normal ECGs in Lead I and reduces the need for manual evaluation of individual ECGs with >85% with 100% sensitivity on an individual basis.

Designing an optimal screening program for unknown atrial fibrillation: a cost-effectiveness analysis.

AIMS: The primary objective of this study was to use computer simulations to suggest an optimal age for initiation of screening for unknown atrial fibrillation and to evaluate if repeated screening will add value. METHODS AND RESULTS: In the absence of relevant clinical studies, this analysis was based on a simulation model. More than two billion different designs of screening programs for unknown atrial fibrillation were simulated and analysed. Data from the published scientific literature and registries were used to construct the model and estimate lifelong effects and costs. Costs and effects generated by 2 147 483 648 different screening designs were calculated and compared. Program designs that implied worse clinical outcome and were less cost-effective compared to other programs were excluded from the analysis. Seven program designs were identified, and considered to be cost effective depending on what the health-care decision makers are ready to pay for gaining a quality-adjusted life-year (QALY). Screening at the age of 75 implied the lowest cost per gained QALY (€4 800/QALY). CONCLUSION: In conclusion, examining the results of more than two billion simulated screening program designs for unknown atrial fibrillation, seven designs were deemed cost-effective depending on how much we are prepared to pay for gaining QALYs. Our results showed that repeated screening for atrial fibrillation implied additional health benefits to a reasonable cost compared to one-off screening.

Clinical risk profile score predicts all cause mortality but not implantable cardioverter defibrillator intervention rate in a large unselected cohort of patients with congestive heart failure.

BACKGROUND: Primary prophylactic implantable cardioverter defibrillator (ICD) therapy is indicated for patients with reduced left ventricular ejection fraction (LVEF). We aimed to determine if preoperative clinical risk profiling can predict long-term benefit, and if clinical risk scores can be applied and improved in a patient cohort outside the clinical trial setting. METHODS: Using registry data, 789 patients with reduced LVEF who received ICDs for primary prevention during 2006-2011 were identified (age 64 ± 11 years, 82% men, 63% ischemic etiology, 52% cardiac resynchronization therapy with defibrillator). The patients were divided into three risk groups, based on the presence of baseline clinical risk factors (age >70, QRS duration >120 ms, New York Heart Association class III-IV, atrial fibrillation history, or creatinine >106 µmol/L). Endpoints were all-cause mortality and survival free of adequate ICD therapy. RESULTS: Mean follow-up was 39 ± 18 months. Annual mortality was 7.6%, and increased with risk group (p < .001). Rates of appropriate antitachycardia pacing and shock therapy were not statistically different between the groups, and ranged from 11%-16% and 6%-14%, respectively. By combining the previous risk score with data on diabetes, a better independent prediction of mortality was achieved; mortality rates then ranged from 11% (low-risk) to 46% (high-risk) (p < .0001). CONCLUSIONS: Implantable cardioverter defibrillator therapies occur across the spectrum of comorbidities in a population with systolic heart failure. However, all-cause mortality is considerably higher in the group of patients with accumulated risk factors, and using the proposed scoring system can be helpful for the evaluation and risk stratification of the patient prior to making a decision for a primary prophylactic ICD implantation.

Mass Screening for Untreated Atrial Fibrillation: The STROKESTOP Study.

BACKGROUND: The aims of the present study were to define the prevalence of untreated atrial fibrillation (AF) in a systematic screening program using intermittent ECG recordings among 75- to 76-year-old individuals and to study the feasibility of initiating protective oral anticoagulant (OAC) treatment. METHODS AND RESULTS: Half of the 75- to 76-year-old population in 2 Swedish regions were invited to a screening program for AF. Participants without a previous diagnosis of AF underwent intermittent ECG recordings over 2 weeks. If AF was detected, participants were offered OAC. During the 28-month inclusion period, 13 331 inhabitants were invited. Of these, 7173 (53.8%) participated. Of the participants, 218 (3.0%; 95% confidence interval [CI], 2.7-3.5) were found to have previously unknown AF, and of these, AF was found in 37 (0.5% of the screened population) on their first ECG. The use of intermittent ECGs increased new AF detection 4-fold. A previous diagnosis of AF was known in 9.3% (n=666; 95% CI, 8.6-10.0). Total AF prevalence in the screened population was 12.3%. Of participants with known AF, 149 (2.1%; 95% CI, 1.8-2.4) had no OAC treatment. In total, 5.1% (95% CI, 4.6-5.7) of the screened population had untreated AF; screening resulted in initiation of OAC treatment in 3.7% (95% CI, 3.3-4.2) of the screened population. More than 90% of the participants with previously undiagnosed AF accepted initiation of OAC treatment. CONCLUSIONS: Mass screening for AF in a 75- to 76-year-old population identifies a significant proportion of participants with untreated AF. Initiation of stroke prophylactic treatment was highly successful in individuals with newly diagnosed AF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01593553.

Implantable cardioverter-defibrillator therapy before death: high risk for painful shocks at end of life.

BACKGROUND: Several trials have demonstrated improved survival with implantable cardioverter-defibrillator (ICD) therapy. The cause and nature of death in the ICD population have been insufficiently investigated. The objective of this study was to analyze ICDs from deceased patients to assess the incidence of ventricular tachyarrhythmias, the occurrence of shocks, and possible device malfunction. METHODS AND RESULTS: We prospectively analyzed intracardiac electrograms in 125 explanted ICDs. The incidence of ventricular tachyarrhythmia, including ventricular fibrillation, and shock treatment was assessed. Ventricular tachyarrhythmia occurred in 35% of the patients in the last hour of their lives; 24% had an arrhythmic storm, and 31% received shock treatment during the last 24 hours. Arrhythmic death was the primary cause of death in 13% of the patients, and the most common cause of death was congestive heart failure (37%). More than half of the patients (52%) had a do-not-resuscitate order, and 65% of them still had the ICD shock therapies activated 24 hours before death. Possible malfunctions of the ICD were found in 3% of all patients. CONCLUSIONS: More than one third of the patients had a ventricular tachyarrhythmia within the last hour of life. Cardiac death was the primary cause and heart failure the specific cause of death in the majority of the cases. Devices remained active in more than half of the patients with a do-not-resuscitate order; almost one fourth of these patients received at least 1 shock in the last 24 hours of life.

Population screening of 75- and 76-year-old men and women for silent atrial fibrillation (STROKESTOP).

Atrial fibrillation (AF) is important because it is common and is a major cause of stroke unless treated with oral anticoagulant. The prevalence of AF increases with age as does the risk of stroke. At 75 years the risk from age alone is so high that current guidelines recommend anticoagulation even in the absence of other risk factors. Atrial fibrillation is often asymptomatic and only discovered by chance or when a stroke already has occurred. We have launched a major screening study for silent AF in which 25,000 Swedes aged 75 and 76 years are randomized to either participate in a screening programme using ambulant intermittent electrocardiogram (ECG) recording to detect silent AF, or act as a control group. Patients in whom AF is detected are offered cardiological examination and anticoagulant treatment according to current guidelines. The cohort and the controls will be followed prospectively for 5 years after the inclusion of the first participant. An interim analysis will be made after 3 years. Our hypothesis is that screening for AF will reduce stroke incidence in the screened population, and that this screening will prove to be cost effective. Secondary endpoints are: any thromboembolic event, intracranial bleeding, other major bleeding, first ever diagnosis of dementia, death from any cause, and a composite of these endpoints.

Short-Term Ambient Air Pollution Exposure and Risk of Out-of-Hospital Cardiac Arrest in Sweden: A Nationwide Case-Crossover Study.

Background Air pollution is one of the main risk factors for cardiovascular disease globally, but its association with out-of-hospital cardiac arrest at low air pollution levels is unclear. This nationwide study in Sweden aims to investigate if air pollution is associated with a higher risk of out-of-hospital cardiac arrest in an area with relatively low air pollution levels. Methods and Results This study was a nationwide time-stratified case-crossover study investigating the association between short-term air pollution exposures and out-of-hospital cardiac arrest using data from the SRCR (Swedish Registry for Cardiopulmonary Resuscitation) between 2009 and 2019. Daily air pollution levels were estimated in 1×1-km grids for all of Sweden using a satellite-based machine learning model. The association between daily air pollutant levels and out-of-hospital cardiac arrest was quantified using conditional logistic regression adjusted for daily air temperature. Particulate matter <2.5 µm exposure was associated with a higher risk of out-of-hospital cardiac arrest among a total of 29 604 cases. In a multipollutant model, the association was most pronounced for intermediate daily lags, with an increased relative risk of 6.2% (95% CI, 1.0-11.8) per 10 µg/m3 increase of particulate matter <2.5 µm 4 days before the event. A similar pattern of association was observed for particulate matter <10 µm. No clear association was observed for O3 and NO2. Conclusions Short-term exposure to air pollution was associated with higher risk of out-of-hospital cardiac arrest. The findings add to the evidence of an adverse effect of particulate matter on out-of-hospital cardiac arrest, even at very low levels below current regulatory standards.

Primary prevention of defibrillator implantation after myocardial infarction: clinical practice and compliance to guidelines.

AIMS: The purpose of this study is to investigate compliance to established guidelines regarding primary prevention with implantable cardioverter-defibrillator (ICD) in patients with left ventricular dysfunction after acute myocardial infarction (AMI) in a clinical setting. METHODS AND RESULTS: A retrospective study of medical records from patients admitted to two hospitals in Stockholm during 2008-2009 with a diagnosis of AMI and who at discharge had a left ventricular ejection fraction ≤35%. An evaluation of follow-up and echocardiographic recordings was performed 1-3 months after AMI. A total of 2023 patients <80 years, with AMI discharged from hospital, were screened for left ventricular dysfunction defined as ejection fraction (EF) ≤35%. Altogether 187 patients were identified and an ICD was implanted in 25 (13%) patients. In 52 (28%) patients, there were contraindications for ICD therapy. An improved EF at follow-up, making ICD treatment redundant, was observed in 48 (41%) patients who underwent an ECHO at follow-up or later. Seventeen (9%) patients without an ICD died during follow-up and out of these five patients died from sudden cardiac death (SCD), they had no contraindication to ICD therapy. An inadequate follow-up according to guidelines was found in 59 (32%) patients. CONCLUSION: The follow-up of post-myocardial infarction patients with left ventricular dysfunction according to guidelines was insufficient in this population and may have increased the risk for SCD. A significant proportion of patients experienced improved left ventricular function during short-term follow-up making preventive ICD treatment redundant.

Paroxysmal atrial fibrillation with silent episodes: intermittent versus continuous monitoring.

OBJECTIVES: Asymptomatic atrial fibrillation (AF) presents the same risk for cardioembolic events as symptomatic AF. Intermittent ECG recordings may be helpful in detecting asymptomatic paroxysmal arrhythmias. The objective of this study was to compare short intermittent heart rhythm recordings with or without symptoms with continuous ECG recordings. DESIGN: Twenty-two patients with diagnosed symptomatic paroxysmal AF participated. Patients used a handheld transtelephonic ECG device for a 30-day period performing two registrations of 10 seconds per day. Additionally patients were asked to make registrations if arrhythmia symptoms occurred. Patients also performed a 24-hour ambulatory continuous ECG recording during a single twenty-four hours period of the 30 day period. AF was defined as an irregular ventricular rhythm without visible p-waves for at least 10 seconds. RESULTS: 1425 intermittent ECG recordings were performed. AF episodes were diagnosed in 18 (82%) patients compared with 7 (32%) patients using continuous ECG, (p = 0.001). All patients with AF detected by continuous monitoring were also detected by intermittent recordings. Of the episodes, 16% were judged as symptomatic. CONCLUSION: Short-term ECG registrations over extended time periods seem to be a more sensitive tool, compared with short continuous ECG recordings, for detection of AF episodes.

Anticoagulation control in Sweden: reports of time in therapeutic range, major bleeding, and thrombo-embolic complications from the national quality registry AuriculA.

AIMS: In anticoagulation treatment with warfarin, the risk of thrombo-embolic events must be weighed against the risk of bleeding. Time in therapeutic range (TTR) is an important tool to assess the quality of anticoagulation treatment, and has been shown to correlate with less bleeding and thrombo-embolic complications. AuriculA, the Swedish national quality registry for atrial fibrillation and anticoagulation, is used for follow-up and dosage control of warfarin. This is the first report of TTR in AuriculA and, in a subgroup of two centres, bleeding and thrombo-embolic complications during 2008. METHODS AND RESULTS: Prothrombin complex (International normalized ratio) values from 18 391 patients in 67 different centres were analysed. The mean (SD) age was 70 (12) years. The main indications for warfarin treatment were: atrial fibrillation (64%), venous thromboembolism (19%), and heart valve dysfunction (13%). Time in therapeutic range for all patients was 76.2%. The mean weekly dose of warfarin decreased with age and TTR increased with age. In 4273 patients from two centres in AuriculA, the frequency of major bleedings and venous/arterial thrombo-embolism were 2.6 and 1.7% and for atrial fibrillation, 2.6 and 1.4%, per treatment year, respectively. A correlation between age and the risk of major bleeding (P< 0.001), but not thrombo-embolic complications (P= 0.147), was seen. CONCLUSION: Compared with prospective randomized trials of warfarin treatment, TTR in the AuriculA population was higher. Complications were low, probably due to the organization of anticoagulation treatment in Sweden. Use of the AuriculA dosing programme could have contributed to the results by keeping dosing regimens consistent over all centres.