Usefulness of continuous electrocardiographic monitoring for atrial fibrillation

New-Onset Atrial Fibrillation in the Critically Ill

OBJECTIVE

To determine the association of new-onset atrial fibrillation with outcomes, including ICU length of stay and survival.

DESIGN

Retrospective cohort of ICU admissions. We found atrial fibrillation using automated detection (≥ 90 s in 30 min) and classed as new-onset if there was no prior diagnosis of atrial fibrillation. We identified determinants of new-onset atrial fibrillation and, using propensity matching, characterized its impact on outcomes.

SETTING

Tertiary care academic center.

PATIENTS

A total of 8,356 consecutive adult admissions to either the medical or surgical/trauma/burn ICU with available continuous electrocardiogram data.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

From 74 patient-years of every 15-minute observations, we detected atrial fibrillation in 1,610 admissions (19%), with median burden less than 2%. Most atrial fibrillation was paroxysmal; less than 2% of admissions were always in atrial fibrillation. New-onset atrial fibrillation was subclinical or went undocumented in 626, or 8% of all ICU admissions. Advanced age, acute respiratory failure, and sepsis were the strongest predictors of new-onset atrial fibrillation. In propensity-adjusted regression analyses, clinical new-onset atrial fibrillation was associated with increased hospital mortality (odds ratio, 1.63; 95% CI, 1.01-2.63) and longer length of stay (2.25 d; CI, 0.58-3.92). New-onset atrial fibrillation was not associated with survival after hospital discharge (hazard ratio, 0.99; 95% CI, 0.76-1.28 and hazard ratio, 1.11; 95% CI, 0.67-1.83, respectively, for subclinical and clinical new-onset atrial fibrillation).

CONCLUSIONS

Automated analysis of continuous electrocardiogram heart rate dynamics detects new-onset atrial fibrillation in many ICU patients. Though often transient and frequently unrecognized, new-onset atrial fibrillation is associated with poor hospital outcomes.

Cryptogenic ischemic stroke and prevalence of asymptomatic atrial fibrillation: a prospective study

BACKGROUND

Atrial fibrillation is responsible for up to one-third of ischemic strokes, and is also associated with silent cerebral infarctions and transient ischemic attacks (TIAs). The self-terminating and often asymptomatic nature of paroxysmal atrial fibrillation (PAF) may lead to its underdiagnosis. A continuous and long-term heart rhythm monitoring can be useful in unmasking PAF episodes.

OBJECTIVE

Prevalence of asymptomatic PAF in patients suffering a cryptogenic stroke, at risk for atrial fibrillation but without any history of arrhythmia or palpitations, using a continuous electrocardiographic monitoring.

METHODS

One hundred and forty-two consecutive patients were admitted to the Stroke Unit of 'Città della Salute e della Scienza' Hospital of Turin between June 2010 and March 2013 and discharged with the diagnosis of ischemic cryptogenic stroke. Sixty fulfilled predefined inclusion criteria. Follow-up was carried on and completed for the 54 patients who consented to implantable loop recorder (ILR) implantation. After ILR implantation, trans-telephonic data were collected monthly.

RESULTS

Atrial fibrillation episodes lasting more than 5 min were recorded in 25 patients (46%), median detection time was 5.4 months (range 1-18) and median duration of atrial fibrillation episodes was 20 h (range 7 min-8 days) with 19 patients (76%) remaining asymptomatic and the others experiencing weakness and dyspnoea but not palpitations.

CONCLUSION

Long-term heart rhythm monitoring is successful in unmasking silent atrial fibrillation in 46% of patients suffering a cryptogenic stroke with concomitant atrial fibrillation risk factors, but without history of arrhythmia or palpitations.

N-terminal pro B-type natriuretic peptide in systematic screening for atrial fibrillation

OBJECTIVE

Screening for atrial fibrillation (AF) in individuals aged 65 and above is recommended by the European Society of Cardiology. Increased levels of the biomarker N-terminal pro B-type natriuretic peptide (NT-proBNP) has in cohort studies been associated with incident AF.The aim of this study was to assess whether NT-proBNP could be useful for AF detection in systematic screening.

METHODS

The Strokestop study entailed 7173 Swedish residents aged 75/76 that were screened for AF using twice daily intermittent ECG recordings during 2 weeks. In a substudy of 886 participants, the last 815 consecutive participants and 71 individuals with newly detected AF, levels of NT-proBNP were determined.

RESULTS

Participants with newly detected AF (n=96) had a median NT-proBNP of 330 ng/L (IQR 121;634). In individuals without AF (n=742), median NT-proBNP was 171 ng/L (IQR 95;283), p<0.001. The CHA₂DS₂-VASc parameters did not differ significantly between individuals with newly detected AF and without AF nor between newly detected AF in the NT-proBNP cohort compared with the cohort where NT-proBNP was not assessed. Using an NT-proBNP cut-off of ≥125 ng/L in a non-acute setting yielded a negative predictive value of 92%, meaning that 35% fewer participants would need to be screened when applied to systematic AF screening. Adding weight to NT-proBNP further reduced participants needed to be screened with a preserved sensitivity.

CONCLUSIONS

NT-proBNP was increased in individuals with newly detected AF. Prospective studies could clarify if NT-proBNP can be used to correctly select individuals that benefit most from AF screening.

CLINICAL TRIALS

ClinicalTrials.gov. Identifier: NCT01593553.

Factors Predicting Arrhythmia-Related Symptoms and Health-Related Quality of Life in Patients Referred for Radiofrequency Ablation of Atrial Fibrillation: An Observational Study (the SMURF Study)

OBJECTIVES

The purpose of this study was to correlate the arrhythmia-related symptoms and health-related quality of life (HRQoL) in patients with atrial fibrillation (AF) who are eligible for radiofrequency ablation (RFA) with a number of objective indicators.

BACKGROUND

Although the clinical consequences of AF have been studied extensively, the variation in the symptoms of patients with AF and HRQoL remains under-researched.

METHODS

We studied 192 patients eligible for RFA of AF referred to the University Hospital, Linköping, Sweden, between January 2012 and April 2014. The ASTA (Arrhythmia-Specific questionnaire in Tachycardia and Arrhythmia) symptom scale was used to assess arrhythmia-related symptoms in the patients. The ASTA HRQoL scale and the short-form 36 (SF-36) physical and mental components summaries (PCS and MCS) were used to express disease-specific and overall HRQoL of the patients, respectively.

RESULTS

Anxiety, low-grade inflammation, and left atrial dilatation significantly predicted arrhythmia-related symptoms (R² = 0.313; p < 0.001). Depression was the most important predictor of arrhythmia-specific HRQoL (standardized beta: 0 .406), and the produced model explained a significant proportion of the variation in arrhythmia-specific HRQoL (R² = 0.513; p < 0.001). The most important predictor of PCS was obesity (body mass index >30 kg/m²) (standardized beta: -0.301), whereas the most important predictor of MCS was anxiety (standardized beta: -0.437).

CONCLUSIONS

Anxiety, depression, and low-grade inflammation were the factors that predicted both arrhythmia-related symptoms and HRQoL in patients with AF. Obesity was the most significant predictor of patient general physical status. These factors need to be addressed in patients with AF to improve management of their disease. Intensive risk factor modification can be of great importance. (Reasons for Variations in Health Related Quality of Life and Symptom Burden in Patients With Atrial Fibrillation [SMURF]; NCT01553045).

CHA2DS2-VASc Score: A Predictor of Thromboembolic Events and Mortality in Patients With an Implantable Monitoring Device Without Atrial Fibrillation

OBJECTIVE

To determine if the CHA₂DS₂-VASc score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke or transient ischemic attack, vascular disease, age 65-74 years, sex category) predicts thromboembolism and death in patients without atrial fibrillation in a population with implantable cardiac monitoring devices.

PATIENTS AND METHODS

A retrospective review utilizing the Rochester Epidemiology Project research infrastructure was conducted to evaluate the CHA₂DS₂-VASc tool as a predictor of mortality and ischemic stroke, transient ischemic attack, or systemic embolism in patients without atrial fibrillation. An implantable device was required in the inclusion criteria to discern the absence of atrial fibrillation. The study period was January 1, 2004, through March 7, 2016.

RESULTS

The study population (N=1606) had a mean (SD) age of 69.8 (12.6) years and median follow-up of 4.8 years (range, 0-12 years; quartile 1, 2.6 years and quartile 3, 8.1 years). The number of thromboembolic and mortality events stratified by CHA₂DS₂-VASc score groupings of 0 to 2 (399 patients), 3 to 5 (756 patients), and 6 to 9 (451 patients) were 12 (3.0%), 109 (14.4%), and 123 (27.3%) and 22 (5.5%), 205 (27.1%), and 214 (47.4%), respectively. The CHA₂DS₂-VASc score predicted thromboembolism and death. The hazard ratios (HRs) for thromboembolic events for CHA₂DS₂-VASc scores 3 to 5 and 6 to 9 were 4.84 (95% CI, 2.66-8.80) and 10.53 (95% CI, 5.77-19.21) (reference group, scores 0-2). The HRs for death for the corresponding score categories were 4.45 (95% CI, 2.86-6.91) and 8.18 (95% CI, 5.23-12.78). The CHA₂DS₂-VASc score also predicted development of atrial fibrillation, for which the HRs for scores 3 to 5 and 6 to 9 were 1.51 (95% CI, 1.13-2.00) and 2.17 (95% CI, 1.60-2.95).

CONCLUSION

The CHA₂DS₂-VASc tool predicts thromboembolic events and overall mortality in patients without atrial fibrillation who have implantable devices.

Prognostic Impact of Atrial Fibrillation and New Risk Score of Its Onset in Patients at High Risk of Heart Failure - A Report From the CHART-2 Study

BACKGROUND

The prognostic impact of atrial fibrillation (AF) among patients at high risk for heart failure (HF) remains unclear. In addition, there is no risk estimation model for AF development in these patients.Methods and Results:The present study included 5,382 consecutive patients at high risk of HF enrolled in the CHART-2 Study (n=10,219). At enrollment, 1,217 (22.6%) had AF, and were characterized, as compared with non-AF patients, by higher age, lower estimated glomerular filtration rate, higher B-type natriuretic peptide (BNP) level and lower left ventricular ejection fraction. A total of 116 non-AF patients (2.8%) newly developed AF (new AF) during the median 3.1-year follow-up. AF at enrollment was associated with worse prognosis for both all-cause death and HF hospitalization (adjusted hazard ratio (aHR) 1.31, P=0.027 and aHR 1.74, P=0.001, for all-cause death and HF hospitalization, respectively) and new AF was associated with HF hospitalization (aHR 4.54, P<0.001). We developed a risk score with higher age, smoking, pulse pressure, lower eGFR, higher BNP, aortic valvular regurgitation, LV hypertrophy, and left atrial and ventricular dilatation on echocardiography, which effectively stratified the risk of AF development with excellent accuracy (AUC 0.76).

CONCLUSIONS

These results indicated that AF is associated with worse prognosis in patients at high risk of HF, and our new risk score may be useful to identify patients at high risk for AF onset.

Long-term Arrhythmia Monitoring in Cryptogenic Stroke: Who, How, and for How Long?

Cryptogenic stroke and transient ischemic attack (TIA) account for approximately one-third of stroke patients [1]. Paroxys-mal atrial fibrillation (PAF) has been suggested as a major etiology of these cryptogenic strokes [2, 3]. PAF can be difficult to diagnose because it is intermittent, often brief, and asymptomatic. PAF might be more prevalent than persistent atrial fibrillation in stroke and TIA patients, especially in younger populations [4, 5]. In patients with atrial fibrillation, anticoagulation provides significant risk reduction [6]. A new generation of oral anticoagulants has been approved for non-valvular atrial fibrillation, providing a variety of therapeutic options for patients with atrial fibrillation and risk of stroke [7]. Prior practice included an admission electrocardiogram (ECG) and continuous telemetry monitoring while in hospital [8]. However, this approach can lead to under-detection of brief asymptomatic events, which can occur at variable intervals, often outside of the hospital setting. Technological advancements have led to devices that can monitor cardiac rhythms outside of the hospital for longer durations resulting in higher yield of detection of atrial fibrillation events. Moreover, recent studies show that the normal monitoring time for arrhythmias may be shorter than ideal in order to detect atrial fibrillation, and increasing this interval could significantly improve detection of atrial fibrillation in these patients [9, 10]. The aim of this study is to review the literature in order to define what subgroup of patients, with what methodologies, and for how long monitoring for atrial fibrillation should occur in patients presenting with cryptogenic stroke.

Cost-effectiveness of an insertable cardiac monitor to detect atrial fibrillation in patients with cryptogenic stroke

Background and aims

Documentation of atrial fibrillation is required to initiate oral anticoagulation therapy for recurrent stroke prevention. Atrial fibrillation often goes undetected with traditional electrocardiogram monitoring techniques. We evaluated whether atrial fibrillation detection using continuous long-term monitoring with an insertable cardiac monitor is cost-effective for preventing recurrent stroke in patients with cryptogenic stroke, in comparison to the standard of care.

Methods

A lifetime Markov model was developed to estimate the cost-effectiveness of insertable cardiac monitors from a UK National Health Service perspective using data from the randomized CRYSTAL-AF trial and other published literature. We also conducted scenario analyses (CHADS2 score) and probabilistic sensitivity analyses. All costs and benefits were discounted at 3.5%.

Results

Monitoring cryptogenic stroke patients with an insertable cardiac monitor was associated with fewer recurrent strokes and increased quality-adjusted life years compared to the standard of care (7.37 vs 7.22). Stroke-related costs were reduced in insertable cardiac monitor patients, but overall costs remained higher than the standard of care (£19,631 vs £17,045). The incremental cost-effectiveness ratio was £17,175 per quality-adjusted life years gained, compared to standard of care in the base-case scenario, which is below established quality-adjusted life years willingness-to-pay thresholds. When warfarin replaced non-vitamin-K oral anticoagulants as the main anticoagulation therapy, the incremental cost-effectiveness ratio was £13,296 per quality-adjusted life years gained.

Conclusion

Insertable cardiac monitors are a cost-effective diagnostic tool for the prevention of recurrent stroke in patients with cryptogenic stroke. The cost-effectiveness results have relevance for the UK and across value-based healthcare systems that assess costs relative to outcomes.

Are implantable cardiac monitors the 'gold standard' for atrial fibrillation detection? A prospective randomized trial comparing atrial fibrillation monitoring using implantable cardiac monitors and DDDRP permanent pacemakers in post atrial fibrillation ablation patients

AIMS

Implantable devices are widely accepted, but not proven, to be the most reliable monitoring method to assess atrial fibrillation (AF) therapies. We compared REVEAL(®)XT implantable cardiac monitors (ICMs) and permanent pacemakers (PPMs).

METHODS AND RESULTS

Fifty patients with paroxysmal AF were randomized to ICM or PPM implant 6 weeks prior to pulmonary vein isolation. Permanent pacemakers were programmed to monitoring only (ODO). Device downloads were performed at 0, 3, 6, 9, and 12 months. All patients underwent 7-day external loop recorder. Device ECGs and EGMs were compared for AF burden. A total of 20 744 and 11 238 arrhythmia episodes were identified in the ICM and PPM groups, respectively. Correct identification of AF was significantly better in the PPM group (97 vs. 55% P < 0.001). In the ICM group, 26% of ECGs were un-interpretable. Sensitivity and specificity for each episode of AF was significantly better in the PPM group (100 vs. 79% and 98 vs. 66%, respectively, P < 0.001). The positive predictive value for the detection of any AF was significantly better in the PPM than the ICM (100 vs. 58%, P = 0.03). The negative predictive value for the absence of all AF was not significantly different between the PPM and ICM (100% vs. 92%, P = 0.76).

CONCLUSION

Permanent pacemakers Holters are the most accurate method of evaluating arrhythmia burden and the therapeutic efficacy of novel AF therapies. ICM has a high degree of artefact, which reduces its specifity and sensitivity. Despite the deficiencies of ICM monitoring the negative predictive value of the ICM is satisfactory if zero AF burden is the aim of therapy.

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.

Detection of paroxysmal atrial fibrillation by prolonged electrocardiographic recording after ischaemic stroke in patients aged<60years: a study with 21-day recording using the SpiderFlash(®) monitor

BACKGROUND

Many studies have suggested that longer duration of cardiac monitoring is suitable for the detection of occult paroxysmal atrial fibrillation (AF) after stroke; however, most studies involved patients aged≥65years - a population with a high stroke rate.

AIMS

To assess the incidence of paroxysmal AF in unselected young patients presenting with stroke.

METHODS

We included consecutive patients aged<60years with a stroke diagnosis on magnetic resonance imaging. Aetiological screening included clinical history and examination, and biological and cardiac tests. Patients were included if they had no history of AF and if a 24-hour electrocardiogram recording detected no AF or atrial flutter. Patients wore the SpiderFlash(®) monitor for 21days after discharge from hospital. The primary outcome was detection of paroxysmal AF episodes lasting>30seconds during monitoring. The secondary outcome was detection of paroxysmal AF episodes lasting<30seconds and any arrhythmia during monitoring.

RESULTS

Among the 56 patients included (mean age 48±9years), 39 had cryptogenic stroke (CS) and 17 had stroke of known cause (SKC). Cardiac monitoring was achieved in 54 patients (37 CS, 17 SKC); one CS patient had a paroxysmal AF episode lasting>30seconds and one CS patient had a paroxysmal AF episode lasting<30seconds (versus no patients in the SKC group). Two CS patients and one SKC patient presented numerous premature atrial complexes. Non-sustained ventricular tachycardia was detected in one CS patient.

CONCLUSION

This prospective observational study showed a low rate of paroxysmal AF among young patients presenting with stroke, on the basis of 21-day cardiac monitoring. This result highlights the need to identify patients who would benefit from such long monitoring.

Accuracy of patient perception of their prevailing rhythm: a comparative analysis of monitor data and questionnaire responses in patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) guidelines recommend that symptom relief be a primary goal in management. However, patient perception of their prevailing rhythm is often inaccurate, complicating symptom-targeted treatment.

OBJECTIVE

The purpose of this study was to evaluate the accuracy of patient perception of their prevailing rhythm and identify factors that predict inaccuracies.

METHODS

Demographic and health status data were captured by questionnaires for 458 outpatients with documented AF. AF burden (%) was captured by 1-week continuous heart monitors. Patients estimated the length and frequency of their AF episodes by completing the AF Symptom Severity questionnaire. Patient reports were compared to AF burden, and outliers were identified and broken into 2 groups: patients with AF burden <10% who indicated near-continuous AF (overestimators) and patients with AF burden >90% who estimated little to no AF (underestimators). Multinomial logistic regression was used to identify predictors of inaccuracies (over- or underestimators).

RESULTS

By continuous monitor, 15% of patients were found to be over- or underestimators. Persistent AF, female sex, older age, anxiety, and depression were predictive of inaccurate patient perception. Persistent AF, female sex, and older age were predictive of underestimating, while mood disorders (anxiety and depression) were predictive of overestimating. The prevalence of underestimators was nearly twice that of overestimators.

CONCLUSION

Sex, age, and mood disorders are among factors that lead to inaccurate patient perception of their prevailing rhythm in patients with AF. Such modulating factors should be considered when evaluating treatment strategies. Consideration should be given to more liberal use of heart monitors in these patient populations to better target therapy.

The cold facts of long-term ECG monitoring

Two recently published trials have provided evidence in favor of longer ECG monitoring among patients with cryptogenic stroke (CS). In the CRYSTAL-AF trial, new atrial fibrillation (AF) was detected in 12.4% of patients with implantable monitor when compared with 2% among those receiving standard follow-up. A similar result was observed in the EMBRACE trial in which AF was detected in 16.1% of patients who received 30-day event recorder (3.2% in controls). These data are compelling in convincing us that long-term ECG technologies have superior sensitivity for the detection of AF in CS; however, clinical specificity for the definition of CS etiology of such findings cannot be established and can be lower than expected, leaving open questions about the etiologic weight of AF in CS. The causative role of AF in this subpopulation remains to be proven, and diagnostic routes cannot be solely unbalanced toward the research of AF.

Autonomic dysfunction is associated with brief episodes of atrial fibrillation in type 2 diabetes

BACKGROUND AND AIMS

This study aimed to investigate the relationship between asymptomatic episodes of atrial fibrillation (AF) and abnormalities of the autonomic nervous system in type 2 diabetic patients who did not have evidence of atrial fibrillation at baseline.

METHODS AND RESULTS

In a multicentric cross-sectional controlled study, 1992 patients with type 2 diabetes were screened. All underwent ambulatory ECG recording for 48-hour at 3, 6, 9, and 12months. Heart rate variability (HRV) was used as indicator of autonomic activity. One hundred seventy-six diabetics with silent atrial fibrillation episodes (SAFE group) and 288 without silent atrial fibrillation (non-SAFE group) were enrolled. These selected diabetics were matched on clinical and anthropometric data to 120 control subjects without diabetes of the control group. HRV analysis evidenced that LF/HF ratio was significantly higher in the SAFE group than in the non-SAFE group (P<0.05) in the whole period of HM analysis. AF absolute burdens were positively correlated with LF/HF ratio (r=0.31, P<0.001). Multiple regression analysis showed that LF/HF ratio was an independent determinant of AF episodes.

CONCLUSIONS

This study originally showed a strong relationship between autonomic dysfunction and silent atrial fibrillation in type 2 diabetes.

Pulse pressure is not an independent predictor of incident atrial fibrillation in 60-year-old men and women

AIM

To evaluate if pulse pressure (PP) is a risk predictor for atrial fibrillation (AF) in a longitudinal study of 60-year-old men and women from Stockholm (n = 4,232), free from AF at baseline, with primary end-point incident AF.

METHODS

AF diagnoses were obtained from the national hospital discharge register. The estimated risk of AF associated with increasing PP values was calculated according to PP values above median (>52.5 mmHg) and according to 1-SD increase (14 mmHg) in PP, using a crude and an adjusted Cox proportional hazard regression model.

RESULTS

During a mean follow-up of 13.6 years, 286 incident AF cases were recorded. The number of AF cases increased significantly with increasing PP quartile in men but not in women. PP values above median were associated with increased AF risk (crude HR 1.63, 95% CI 1.28-2.06; p < 0.001), but risk estimates were attenuated after adjustment for common AF risk factors. When PP was entered in the Cox regression model as a continuous variable, the risk of AF did not change by 1-SD PP increase (adjusted HR 1.04, 95% CI 0.91-1.20; p = 0.560).

CONCLUSIONS

PP seems not to be associated with incident AF in a Swedish population of 60-year-old men and women.

Clinical predictors of risk for atrial fibrillation: implications for diagnosis and monitoring

OBJECTIVE

To create a risk score using clinical factors to determine whom to screen and monitor for atrial fibrillation (AF).

PATIENTS AND METHODS

The AF risk score was developed based on the summed odds ratios (ORs) for AF development of 7 accepted clinical risk factors. The AF risk score is intended to assess the risk of AF similar to how the CHA2DS2-VASc score assesses stroke risk. Seven validated risk factors for AF were used to develop the AF risk score: age, coronary artery disease, diabetes mellitus, sex, heart failure, hypertension, and valvular disease. The AF risk score was tested within a random population sample of the Intermountain Healthcare outpatient database. Outcomes were stratified by AF risk score for OR and Kaplan-Meier analysis.

RESULTS

A total of 100,000 patient records with an index follow-up from January 1, 2002, through December 31, 2007, were selected and followed up for the development of AF through the time of this analysis, May 13, 2013, through September 6, 2013. Mean ± SD follow-up time was 3106±819 days. The ORs of subsequent AF diagnosis of patients with AF risk scores of 1, 2, 3, 4, and 5 or higher were 3.05, 12.9, 22.8, 34.0, and 48.0, respectively. The area under the curve statistic for the AF risk score was 0.812 (95% CI, 0.805-0.820).

CONCLUSION

We developed a simple AF risk score made up of common clinical factors that may be useful to possibly select patients for long-term monitoring for AF detection.

Atrial fibrillation in patients with cryptogenic stroke

BACKGROUND

Atrial fibrillation is a leading preventable cause of recurrent stroke for which early detection and treatment are critical. However, paroxysmal atrial fibrillation is often asymptomatic and likely to go undetected and untreated in the routine care of patients with ischemic stroke or transient ischemic attack (TIA).

METHODS

We randomly assigned 572 patients 55 years of age or older, without known atrial fibrillation, who had had a cryptogenic ischemic stroke or TIA within the previous 6 months (cause undetermined after standard tests, including 24-hour electrocardiography [ECG]), to undergo additional noninvasive ambulatory ECG monitoring with either a 30-day event-triggered recorder (intervention group) or a conventional 24-hour monitor (control group). The primary outcome was newly detected atrial fibrillation lasting 30 seconds or longer within 90 days after randomization. Secondary outcomes included episodes of atrial fibrillation lasting 2.5 minutes or longer and anticoagulation status at 90 days.

RESULTS

Atrial fibrillation lasting 30 seconds or longer was detected in 45 of 280 patients (16.1%) in the intervention group, as compared with 9 of 277 (3.2%) in the control group (absolute difference, 12.9 percentage points; 95% confidence interval [CI], 8.0 to 17.6; P<0.001; number needed to screen, 8). Atrial fibrillation lasting 2.5 minutes or longer was present in 28 of 284 patients (9.9%) in the intervention group, as compared with 7 of 277 (2.5%) in the control group (absolute difference, 7.4 percentage points; 95% CI, 3.4 to 11.3; P<0.001). By 90 days, oral anticoagulant therapy had been prescribed for more patients in the intervention group than in the control group (52 of 280 patients [18.6%] vs. 31 of 279 [11.1%]; absolute difference, 7.5 percentage points; 95% CI, 1.6 to 13.3; P=0.01).

CONCLUSIONS

Among patients with a recent cryptogenic stroke or TIA who were 55 years of age or older, paroxysmal atrial fibrillation was common. Noninvasive ambulatory ECG monitoring for a target of 30 days significantly improved the detection of atrial fibrillation by a factor of more than five and nearly doubled the rate of anticoagulant treatment, as compared with the standard practice of short-duration ECG monitoring. (Funded by the Canadian Stroke Network and others; EMBRACE ClinicalTrials.gov number, NCT00846924.).

The Role of Continuous Monitoring in Atrial Fibrillation Management

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is strongly associated with stroke risk and a variety of cardiovascular conditions. AF early detection is of paramount importance, in order to define proper medical treatment. This can be challenging due to the often silent and intermittent nature of the rhythm disturbance. Long-term external ECG monitoring may be very helpful, but if less than fully continuous and of long duration it will be not reliable. For this reason continuous monitoring is of increased importance, and outcome measurements of AF treatment trials will be based on the AF burden detected by insertable cardiac monitors (ICM) or therapeutic devices such as pacemakers or ICDs, leading to the paradigm that the detection of AF in the presence of thromboembolic risk factors should be performed wherever possible in order to improve patients' chances.

AF burden is important - fact or fiction?

Asymptomatic atrial fibrillation (AF) is common and in view of its prognostic impact (the same as of clinically overt AF) knowledge of the overall AF burden (defined as the amount of time spent in AF) appears to be important, both for scientific and clinical reasons. Data collected on more than 12,000 patients indicate that cardiac implantable electrical devices (CIEDs) are validated tools for measuring AF burden and that AF burden is associated with an increased risk of stroke. A maximum daily AF burden of ≥ 1 h carries important negative prognostic implications and may be a clinically relevant parameter for improving risk stratification for stroke. Decision-making should primarily consider the context in which asymptomatic, subclinical arrhythmias are detected (i.e. primary or secondary prevention of stroke and systemic embolism) and the risk profile of every individual patient with regard to thromboembolic and haemorrhagic risk, as well as patient preferences and values. Continuous monitoring using CIEDs with extensive data storage capabilities allow in-depth study of the temporal relationship between AF and ischaemic stroke. The relationships between AF and stroke are complex. AF is certainly a risk factor for cardioembolic stroke, with a cause-effect relationship between the arrhythmia and a thromboembolic event, the latter being related to atrial thrombi. However, AF can also be a simple 'marker of risk', with a non-causal association between the arrhythmia and stroke, the latter being possibly related to atheroemboli from the aorta, the carotid arteries or from other sources.

A prospective randomized controlled trial on the incidence and predictors of late-phase postoperative atrial fibrillation up to 30 days and the preventive value of biatrial pacing

BACKGROUND

Postoperative atrial fibrillation (POAF) is considered to be a transient arrhythmia in the first week after cardiac surgery.

OBJECTIVE

To determine the 30-day incidence and predictors of POAF and the value of postoperative overdrive biatrial pacing in the prevention of POAF.

METHODS

Patients (n = 148) without a history of atrial fibrillation undergoing aortic valve replacement or coronary artery bypass graft (CABG) were randomized into a pacing group (n = 75) and a control group. Patients were treated with standardized sotalol postoperatively. Rhythm was continuously monitored for 30 days by a transtelephonic event recorder.

RESULTS

POAF occurred in 73 (49.3%) patients, of whom 60 (40.5%) patients showed POAF during postoperative days (PODs) 0-5 and 37 (25%) patients during PODs 6-30. Prolonged aortic cross-clamp time was an important univariate predictor of 30-day and of late POAF (PODs 6-30; P = .017 and P = .03, respectively). Best-fit model analysis using 15 predetermined risk factors for POAF showed different positive interactive effects for early POAF (ie, baseline C-reactive protein levels with a history of myocardial infarction or low body mass index) and late POAF (ie, high body mass index, diabetes mellitus, baseline C-reactive protein, early POAF, creatinine levels, type of operation, smoking, and male gender). Biatrial pacing reduced the late POAF incidence in patients with aortic cross-clamp time >50 minutes (P = .006).

CONCLUSION

POAF is not limited to the first week after cardiac surgery but also occurs frequently in the postoperative month. It is desirable to regularly follow patients with POAF for atrial fibrillation recurrences after discharge.

Rationale and design of REVEAL AF: a prospective study of previously undiagnosed atrial fibrillation as documented by an insertable cardiac monitor in high-risk patients

BACKGROUND

Atrial fibrillation (AF) is associated with substantial morbidity and mortality. Sometimes, AF exists but is undiagnosed; yet, its risk for consequences still exists. Identifying unrecognized episodes of AF in patients without known AF but at high risk for AF is critical for guiding preventative therapy decisions. The incidence of AF in high-risk patients, understanding how physicians manage these patients once AF has been detected, and knowing which patient characteristics are most predictive of developing AF are all unknown.

METHODS

REVEAL AF is a prospective, single-arm, open-label, multicenter, interventional study to evaluate the incidence of AF ≥6 minutes in patients without known AF but who may be at high risk for AF based on symptoms and/or demographic criteria. The Reveal Insertable Cardiac Monitor will be implanted in 400 patients, and these patients will be followed up for a minimum of 18 months to monitor for the detection of AF, up to a maximum of 30 months or until the last patient has completed their 18-month follow-up visit.

CONCLUSIONS

REVEAL AF will determine the incidence rate of AF lasting ≥6 minutes in patients who are at high risk for having AF. Secondary outcomes include observations regarding physician actions in response to detected AF and determination of risk markers for AF development.

Device-detected atrial fibrillation and risk for stroke: an analysis of >10,000 patients from the SOS AF project (Stroke preventiOn Strategies based on Atrial Fibrillation information from implanted devices)

Objective

The aim of this study was to assess the association between maximum daily atrial fibrillation (AF) burden and risk of ischaemic stroke.

Background

Cardiac implanted electronic devices (CIEDs) enhance detection of AF, providing a comprehensive measure of AF burden.

Design, setting, and patients

A pooled analysis of individual patient data from five prospective studies was performed. Patients without permanent AF, previously implanted with CIEDs, were included if they had at least 3 months of follow-up. A total of 10 016 patients (median age 70 years) met these criteria. The risk of ischaemic stroke associated with pre-specified cut-off points of AF burden (5 min, 1, 6, 12, and 23 h, respectively) was assessed.

Results

During a median follow-up of 24 months, 43% of 10 016 patients experienced at least 1 day with at least 5 min of AF burden and for them the median time to the maximum AF burden was 6 months (inter-quartile range: 1.3–14). A Cox regression analysis adjusted for the CHADS₂ score and anticoagulants at baseline demonstrated that AF burden was an independent predictor of ischaemic stroke. Among the thresholds of AF burden that we evaluated, 1 h was associated with the highest hazard ratio (HR) for ischaemic stroke, i.e. 2.11 (95% CI: 1.22–3.64, P = 0.008).

Conclusions

Device-detected AF burden is associated with an increased risk of ischaemic stroke in a relatively unselected population of CIEDs patients. This finding may add to the basis for timely and clinically appropriate decision-making on anticoagulation treatment.

Assessment of concomitant paroxysmal atrial fibrillation ablation in mitral valve surgery patients based on continuous monitoring: does a different lesion set matter?

OBJECTIVES

The efficacy of concomitant ablation techniques in patients with paroxysmal atrial fibrillation (AF) undergoing mitral valve surgery remains under debate. The aim of this prospective, randomized, single-centre study was to compare pulmonary vein isolation (PVI) only versus a left atrial maze (LAM) procedure in patients with paroxysmal AF during mitral valve surgery.

METHODS

Between February 2009 and June 2011, 52 patients with a mean age of 54.2 (standard deviation 7.2 years) underwent mitral valve surgery and concomitant bipolar radiofrequency ablation for paroxysmal AF. Patients were randomized into the PVI group (n = 27) and the LAM group (n = 25). After surgery, an implantable loop recorder for continuous electrocardiography (ECG) monitoring was implanted. Patients with an AF burden (AF%) of <0.5% were considered AF free (responders). The mean follow-up was 18.6 months (standard deviation 2.1 months), and the patient' data were evaluated every 3 months.

RESULTS

All patients were alive at discharge. No procedure-related complications occurred for either the ablation or the loop recorder implantation. Mean aortic clamping and ablation times were significantly longer in the LAM group than in the PVI group. The incidence of early AF paroxysm recurrence was significantly higher in the PVI group than in the LAM group (62.9 vs 24.0%, P < 0.001). At 20 months after surgery, 15 (55.6%) of the 27 patients in the PVI group and 22 (88.0%) of the 25 patients in the LAM group had no documented atrial arrhythmias and were considered responders (AF burden <0.5%). The mean AF burden during all follow-up periods was significantly lower in the LAM group (23.6 ± 8.7%) than in the PVI group (6.8 ± 2.2%) (P < 0.001).

CONCLUSIONS

According to continuous ECG monitoring data, freedom from AF was significantly higher after the concomitant LAM procedure than after PVI in patients with paroxysmal AF who underwent mitral valve surgery.

Hybrid Therapy for Atrial Fibrillation: where the Knife meets the Catheter

During the past decades there has been a consistent evolution of both surgical and catheter-based techniques for the treatment of stand-alone atrial fibrillation, as alternatives or in combination with anti-arrhythmic drugs. Transcatheter ablation has significantly improved outcomes, despite often requiring multiple procedures and with limited success rates especially in presence of persistent atrial fibrillation. Surgical procedures have dramatically evolved from the original cut-and-sew Maze operation, allowing nowadays for closed-chest epicardial ablations on the beating heart. Recently, the concept of a close collaboration between the cardiac surgeon and the electrophysiologist has emerged as an intriguing option in order to overcome the drawbacks and suboptimal results of both techniques; therefore, the hybrid approach has been proposed as a potentially more successful strategy, allowing for a patient-tailored therapeutical approach. We reviewed the recent advancements either from the transcatheter and surgical standpoint, with a peculiar focus on the current option to merge both techniques along with an up-to-date review of the preliminary clinical experiences with the hybrid, surgical-transcatheter treatment of stand-alone atrial fibrillation.

Progression of atrial fibrillation after a failed initial ablation procedure in patients with paroxysmal atrial fibrillation: a randomized comparison of drug therapy versus reablation

BACKGROUND

The aim of this prospective randomized study was to assess whether an early reablation was superior to antiarrhythmic drug (AAD) therapy in patients with previous failed pulmonary vein isolation.

METHODS AND RESULTS

Patients with paroxysmal atrial fibrillation (AF) eligible for AAD therapy or reablation after a previously failed initial pulmonary vein isolation procedure were eligible for this study and were followed up for 3 years to assess rhythm by means of an implanted cardiac monitor. After the blanking period postablation, 154 patients had symptomatic AF recurrences and were randomized to AAD (n=77) or repulmonary vein isolation (n=77). At the end of follow-up, 61 (79%) patients in the AAD group and 19 (25%) patients in the reablation group demonstrated AF% progression (P<0.01). The AF% at 36 months was significantly greater in the AAD group compared with patients in the reablation group (18.8±11.4% versus 5.6±9.5%, respectively; P<0.01). In addition, 18 (23%) patients in the AAD group and 3 (4%) patients in the reablation group progressed to persistent AF (P<0.01). Furthermore, 45 (58%) of the 77 reablation group patients were free of AF/atrial tachycardia on no AADs; in contrast, in the AAD group, only 9 (12%) of the 77 patients were free of AF/atrial tachycardia (P<0.01) throughout follow-up.

CONCLUSIONS

Redo AF ablation was substantially more effective than AAD in reducing the progression and prevalence of AF after the failure of an initial ablation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01709682.