Accuracy of Mode Switch Algorithms for Detection of Atrial Tachyarrhythmias

Impact of Atrial Fibrillation Burden on Health Care Costs and Utilization

BACKGROUND

Integrating patient-specific cardiac implantable electronic device (CIED)-detected atrial fibrillation (AF) burden with measures of health care cost and utilization allows for an accurate assessment of the AF-related impact on health care use.

OBJECTIVES

The goal of this study was to assess the incremental cost of device-recognized AF vs no AF; compare relative costs of paroxysmal atrial fibrillation (pAF), persistent atrial fibrillation (PeAF), and permanent atrial fibrillation (PermAF) AF; and evaluate rates and sources of health care utilization between cohorts.

METHODS

Using the de-identified Optum Clinformatics U.S. claims database (2015-2020) linked with the Medtronic CareLink database, CIED patients were identified who transmitted data ≥6 months postimplantation. Annualized per-patient costs in follow-up were analyzed from insurance claims and adjusted to 2020 U.S. dollars. Costs and rates of health care utilization were compared between patients with no AF and those with device-recognized pAF, PeAF, and PermAF. Analyses were adjusted for geographical region, insurance type, CHA2DS2-VASc score, and implantation year.

RESULTS

Of 21,391 patients (mean age 72.9 ± 10.9 years; 56.3% male) analyzed, 7,798 (36.5%) had device-recognized AF. The incremental annualized increased cost in those with AF was $12,789 ± $161,749 per patient, driven by increased rates of health care encounters, adverse clinical events associated with AF, and AF-specific interventions. Among those with AF, PeAF was associated with the highest cost, driven by increased rates of inpatient and outpatient hospitalization encounters, heart failure hospitalizations, and AF-specific interventions.

CONCLUSIONS

Presence of device-recognized AF was associated with increased health care cost. Among those with AF, patients with PeAF had the highest health care costs. Mechanisms for cost differentials include both disease-specific consequences and physician-directed interventions.

Impact of Atrial Fibrillation Ablation on Activity Minutes in Patients With Cardiac Implantable Electronic Devices

BACKGROUND

Impaired quality of life due to atrial fibrillation (AF), which often includes decreased activity level, is an indication for ablation. However, the impact of ablation for AF on activity is poorly understood.

OBJECTIVE

To assess the impact of ablation on activity minutes per day using continuous accelerometer data from cardiac implantable electronic devices (CIED).

METHODS

Using the Optum® Health Record dataset (2007-2019) linked with the Medtronic CareLink® database, we identified patients who had a CIED with AF detection and accelerometer capabilities. Patients with a device that transmitted heart rhythm and activity data ≥ 3 months prior to- and ≥ 12 months following ablation were included in analysis. The associations between ablation and activity minutes were assessed in each CIED type.

RESULTS

Of 4297 eligible patients who underwent AF ablation, 409 (9.5%) (65% Male, 67.3±9.8 years, 64% paroxysmal AF) were included in analysis. The average AF burden and activity minutes per day pre-ablation were 30.9±37.4% and 175±99 minutes, respectively. Following ablation, relative AF burden decreased by 75.1±53.2% (p<0.001). There was no change in activity minutes per day following ablation in the entire cohort (average change: -0.10±36.2 min, p=0.96). There were also no clinically significant changes in activity minutes post-ablation in subgroups based on CIED, season of ablation, quartile of AF burden change, and quartile of age at the time of ablation.

CONCLUSION

There were no clinically significant changes in activity minutes per day in patients with CIEDs following ablation for AF.

Association of kidney function and atrial fibrillation progression to clinical outcomes in patients with cardiac implantable electronic devices

BACKGROUND

Kidney function may promote progression of AF.

OBJECTIVE

We evaluated the association of kidney function to AF progression and resultant clinical outcomes in patients with cardiac implantable electronic devices (CIED).

METHODS

We performed a retrospective cohort study using national clinical data from the Veterans Health Administration linked to CIED data from the Carelink® remote monitoring data warehouse (Medtronic Inc, Mounds View, MN). All devices had atrial leads and at least 75% of remote monitoring transmission coverage. Patients were included at the date of the first AF episode lasting ≥6 minutes, and followed until the occurrence of persistent AF in the first year, defined as ≥7 consecutive days with continuous AF. We used Cox regression analyses with persistent AF as a time-varying covariate to examine the association to stroke, myocardial infarction, heart failure and death.

RESULTS

Of, 10,323 eligible patients, 1,771 had a first CIED-detected AF (mean age 69 ± 10 years, 1.2% female). In the first year 355 (20%) developed persistent AF. Kidney function was not associated with persistent AF after multivariable adjustment including CHA₂DS₂-VASc variables and prior medications. Only higher age increased the risk (HR: 1.37 per 10 years; 95% CI:1.22-1.54). Persistent AF was associated to higher risk of heart failure (HR: 2.27; 95% CI: 1.88-2.74) and death (HR: 1.60; 95% CI: 1.30-1.96), but not stroke (HR: 1.28; 95% CI: 0.62-2.62) or myocardial infarction (HR: 1.43; 95% CI: 0.91-2.25).

CONCLUSION

Kidney function was not associated to AF progression, whereas higher age was. Preventing AF progression could reduce the risk of heart failure and death.

Temporal patterns and short-term progression of paroxysmal atrial fibrillation: data from RACE V

Aims

Atrial fibrillation (AF) often starts as a paroxysmal self-terminating arrhythmia. Limited information is available on AF patterns and episode duration of paroxysmal AF. In paroxysmal AF patients, we longitudinally studied the temporal AF patterns, the association with clinical characteristics, and prevalence of AF progression.

Methods and results

In this interim analysis of the Reappraisal of AF: Interaction Between HyperCoagulability, Electrical Remodelling, and Vascular Destabilisation in the Progression of AF (RACE V) registry, 202 patients with paroxysmal AF were followed with continuous rhythm monitoring (implantable loop recorder or pacemaker) for 6 months. Mean age was 64 ± 9 years, 42% were women. Atrial fibrillation history was 2.1 (0.5–4.4) years, CHA₂DS₂-VASc 1.9 ± 1.3, 101 (50%) had hypertension, 69 (34%) heart failure. One-third had no AF during follow-up. Patients with long episodes (>12 hours) were often men with more comorbidities (heart failure, coronary artery disease, higher left ventricular mass). Patients with higher AF burden (>2.5%) were older with more comorbidities (worse renal function, higher calcium score, thicker intima media thickness). In 179 (89%) patients, 1-year rhythm follow-up was available. On a quarterly basis, average daily AF burden increased from 3.2% to 3.8%, 5.2%, and 6.1%. Compared to the first 6 months, 111 (62%) patients remained stable during the second 6 months, 39 (22%) showed progression to longer AF episodes, 8 (3%) developed persistent AF, and 29 (16%) patients showed AF regression.

Conclusions

In paroxysmal AF, temporal patterns differ suggesting that paroxysmal AF is not one entity. Atrial fibrillation burden is low and determined by number of comorbidities. Atrial fibrillation progression occurred in a substantial number.

Trial registration number

Clinicaltrials.gov identifier NCT02726698.

The Importance of Arrhythmia Burden for Outcomes and Management Related to Catheter Ablation of Atrial Fibrillation

Atrial fibrillation (AF) ablation has been shown to be an effective treatment for AF, although our understanding of AF ablation outcomes until now, has been based on AF recurrence as a dichotomous variable. Reduction in AF burden, defined as the proportion of time that an individual is in AF during a monitoring period, has been already correlated to an improvement in quality of life and is likely a better assessment of success. Clinically, many patients may still have a few short recurrences of AF but feel much better. In addition, several studies have related higher AF burden with poorer health outcomes and a higher risk of stroke. Despite the growing understanding of AF burden, it is not clear yet which threshold of AF burden would be considered an appropriate outcome measure for AF ablation. Further investigations are needed to address that question. However, the reduction of AF burden seems to be a more accurate reflection of procedural success and a better predictor of prognosis and stroke risk than a single measure of AF.

Use of Oral Anticoagulation in a Real-World Population With Device Detected Atrial Fibrillation

Background

Guideline recommendations for oral anticoagulation (OAC) in patients with atrial fibrillation (AF) are based on CHA₂DS₂‐VASc score alone. Patients with cardiac implantable electronic devices provide an opportunity to assess how the interaction between AF duration and CHA₂DS₂‐VASc score influences OAC prescription rates.

Methods and Results

Data from the Optum de‐identified Electronic Health Record data set were linked to the Medtronic CareLink database of cardiac implantable electronic devices. An index date was assigned as the later of 6 months after device implant or 1 year after Electronic Health Record data availability. Maximum daily AF duration (no AF, 6 minutes–23.5 hours, and >23.5 hours) was assessed for 6 months before index date. OAC prescription rates were computed as a function of both AF duration and CHA₂DS₂‐VASc score. A total of 35 779 patients with CHA₂DS₂‐VASc scores ≥1 were identified, including 27 198 not prescribed OAC. Overall OAC prescription rate among the 12 938 patients with device‐detected AF >6 minutes was 36.7% and significantly higher in those with a maximum daily AF duration >23.5 hours (45.4%) compared with those with 6 minutes to 23.5 hours (28.7%). OAC prescription rates increased monotonically with both increasing AF duration and CHA₂DS₂‐VASc score, reaching a maximum of 67.2% for patients with AF >23.5 hours and a CHA₂DS₂‐VASc score ≥5.

Conclusions

Real‐world prescription of OAC increased with both increasing duration of AF and CHA₂DS₂‐VASc score. This highlights the need for further research into the role of AF duration, stroke risk, and the need for anticoagulation in patients with devices capable of long‐term AF monitoring.

Interatrial Block Predicts Atrial Fibrillation and Total Mortality in Patients with Cardiac Resynchronization Therapy

BACKGROUND

Interatrial block (IAB) and abnormal P-wave terminal force in lead V1 (PTFV1) are electrocardiographic (ECG) abnormalities that have been shown to be associated with new-onset atrial fibrillation (AF) and death. However, their prognostic importance has not been proven in cardiac resynchronization therapy (CRT) recipients.

OBJECTIVE

To assess if IAB and abnormal PTFV1 are associated with new-onset AF or death in CRT recipients.

METHODS

CRT recipients with sinus rhythm ECG at CRT implantation and no AF history were included (n = 210). Automated analysis of P-wave duration (PWD) and morphology classified patients as having either no IAB (PWD <120 ms), partial IAB (pIAB: PWD ≥120 ms, positive P waves in leads II and aVF), or advanced IAB (aIAB: PWD ≥120 ms and biphasic or negative P wave in leads II or aVF). PTFV1 >0.04 mm•s was considered abnormal. Adjusted Cox regression analyses were performed to assess the impact of IAB and abnormal PTFV1 on the primary endpoint new-onset AF, death, or heart transplant (HTx) and the secondary endpoint death or HTx at 5 years of follow-up.

RESULTS

IAB was found in 45% of all patients and independently predicted the primary endpoint with HR 1.9 (95% CI 1.2-2.9, p = 0.004) and the secondary endpoint with HR 2.1 (95% CI 1.2-3.4, p = 0.006). Abnormal PTFV1 was not associated with the endpoints.

CONCLUSIONS

IAB is associated with new-onset AF and death in CRT recipients and may be helpful in the risk stratification in the context of heart failure management. Abnormal PTFV1 did not demonstrate any prognostic value.

Over- and undersensing-pitfalls of arrhythmia detection with implantable devices and wearables

Cardiac implantable electronic devices (CIEDs) are a cornerstone of arrhythmia and heart failure detection as well as management. In recent years new kinds of devices have emerged which can be used subcutaneously or worn on the skin. In particular for large-scale arrhythmia monitoring, small, unobtrusive gadgets seem positioned to upend paradigms and care delivery. However, the performance of CIEDs and wearables is only as good as their sensing and detection capacities. Whether for pacing, defibrillation or diagnostic monitoring, the device must be able to process and filter the sensed signal to reduce noise and to exclude irrelevant physiological signals. The demands on sensing and detection quality will differ depending on how the information is applied. With a pacemaker or implantable cardioverter/defibrillator, withheld or erroneous therapy can have severe consequences and accurate and reliable detection of cardiac function is crucial. Monitoring devices are usually used in risk assessment and management, with greater tolerance for isolated artefacts or lower quality of readings. This review discusses sensing and detection and the performance to date by CIEDs as well as subcutaneous and wearable devices.

Atrial fibrillation burden and subsequent heart failure events in patients with cardiac resynchronization therapy devices

BACKGROUND

Atrial fibrillation (AF) and heart failure (HF) often coexist but little is known on how AF burden associates with subsequent episodes of HF.

OBJECTIVE

The aim of this study was to quantitatively assess the short- and long-term association of AF burden with subsequent episodes of HF events in patients with reduced ejection fraction.

METHODS

Patients with cardiac resynchronization therapy (CRT) devices with at least 90 days of device data were included in the study. Time-dependent Cox regression with a 7-day window was used to evaluate the association of short- and long-term AF burden with subsequent HF events. Each patient with HF was matched to two control patients without an HF event based on age, gender, year of implant and CRT defibrillation capability.

RESULTS

In our cohort with 2:1 matching (N = 549), 183 patients developed HF events and 275 (50.1%) had AF over an average follow-up of 24 ± 11 months. A 1-hour increase in short-term AF burden was associated with a 3% increased risk of HF events (HR, 1.034; 95% confidence interval [CI], 1.012-1.056; P = .01; HR for 24-hour = 2.23). In contrast, the association between long-term AF burden and subsequent HF events was not statistically significant (HR, 1.009; 95% CI, 0.992-1.026; P = .373).

CONCLUSION

A 24-hour increase in AF burden is associated with a more than two-fold increased risk of HF events over the subsequent week while the long-term AF burden is not significantly associated with HF events.

Stroke Risk as a Function of Atrial Fibrillation Duration and CHA 2 DS 2 -VASc Score

Background:

Studies of patients with cardiovascular implantable electronic devices show a relationship between atrial fibrillation (AF) duration and stroke risk, although the interaction with CHA 2 DS 2 -VASc score is poorly defined. The objective of this study is to evaluate rates of stroke and systemic embolism (SSE) in patients with cardiovascular implantable electronic devices as a function of both CHA 2 DS 2 -VASc score and AF duration.

Methods:

Data from the Optum electronic health record deidentified database (2007–2017) were linked to the Medtronic CareLink database of cardiovascular implantable electronic devices capable of continuous AF monitoring. An index date was assigned as the later of either 6 months after device implantation or 1 year after electronic health record data availability. CHA 2 DS 2 -VASc score was assessed using electronic health record data before the index date. Maximum daily AF burden (no AF, 6 minutes–23.5 hours, and >23.5 hours) was assessed over the 6 months before the index date. SSE rates were computed after the index date.

Results:

Among 21 768 nonanticoagulated patients with cardiovascular implantable electronic devices (age, 68.6±12.7 years; 63% male), both increasing AF duration ( P <0.001) and increasing CHA 2 DS 2 -VASc score ( P <0.001) were significantly associated with annualized risk of SSE. SSE rates were low in patients with a CHA 2 DS 2 -VASc score of 0 to 1 regardless of device-detected AF duration. However, stroke risk crossed an actionable threshold defined as >1%/y in patients with a CHA 2 DS 2 -VASc score of 2 with >23.5 hours of AF, those with a CHA 2 DS 2 -VASc score of 3 to 4 with >6 minutes of AF, and patients with a CHA 2 DS 2 -VASc score ≥5 even with no AF.

Conclusions:

There is an interaction between AF duration and CHA 2 DS 2 -VASc score that can further risk-stratify patients with AF for SSE and may be useful in guiding anticoagulation therapy.

Validation of the modified Microlife blood pressure monitor in patients with paroxysmal atrial fibrillation

AIMS

Undiagnosed atrial fibrillation (AF) accounts for 6% of all strokes, therefore early detection and treatment of the arrhythmia are paramount. Previous research has illustrated that the Microlife WatchBPO3 AFIB, an automated blood pressure (BP) monitor with an inbuilt AF algorithm, accurately detects permanent AF. Currently, limited data exist on whether the modified BP monitor is able to detect paroxysmal AF (PAF). Therefore, this study aims to assess the accuracy of the Microlife WatchBPO3 AFIB monitor to detect PAF against a pacemaker reference standard over a 24-h period.

METHODS AND RESULTS

Forty-eight patients with a pacemaker implanted for sick sinus syndrome and previously documented fast AF participated. Sensitivity of the atrial pacemaker lead was set to allow detection of signals of ≥ 0.5 mV. Patients engaged in their normal daily routine whilst wearing the modified BP monitor. The modified BP monitor demonstrated an overall sensitivity of 76.0% and specificity of 80.8% for detecting PAF. This sensitivity and specificity increased to 100% and 83.1%, respectively, for patients that achieved more than 80% successful BP readings. Compared to day-time readings, night-time readings also demonstrated a lower proportion of movement artefact (14.4% vs. 3.4%), and therefore, a higher sensitivity and specificity of 100% and 84.9%, respectively, for detecting PAF.

CONCLUSION

The Microlife WatchBPO3 AFIB device has an acceptable diagnostic accuracy to detect PAF; however, movement artefact affects the accuracy of the readings. This modified BP monitor may potentially be useful as a screening tool for AF in patients at high risk of developing stroke.

Atrial Fibrillation Burden Signature and Near-Term Prediction of Stroke: A Machine Learning Analysis

BACKGROUND

Atrial fibrillation (AF) increases the risk of stroke 5-fold and there is rising interest to determine if AF severity or burden can further risk stratify these patients, particularly for near-term events. Using continuous remote monitoring data from cardiac implantable electronic devices, we sought to evaluate if machine learned signatures of AF burden could provide prognostic information on near-term risk of stroke when compared to conventional risk scores.

METHODS AND RESULTS

We retrospectively identified Veterans Health Administration serviced patients with cardiac implantable electronic device remote monitoring data and at least one day of device-registered AF. The first 30 days of remote monitoring in nonstroke controls were compared against the past 30 days of remote monitoring before stroke in cases. We trained 3 types of models on our data: (1) convolutional neural networks, (2) random forest, and (3) L1 regularized logistic regression (LASSO). We calculated the CHA₂DS₂-VASc score for each patient and compared its performance against machine learned indices based on AF burden in separate test cohorts. Finally, we investigated the effect of combining our AF burden models with CHA₂DS₂-VASc. We identified 3114 nonstroke controls and 71 stroke cases, with no significant differences in baseline characteristics. Random forest performed the best in the test data set (area under the curve [AUC]=0.662) and convolutional neural network in the validation dataset (AUC=0.702), whereas CHA₂DS₂-VASc had an AUC of 0.5 or less in both data sets. Combining CHA₂DS₂-VASc with random forest and convolutional neural network yielded a validation AUC of 0.696 and test AUC of 0.634, yielding the highest average AUC on nontraining data.

CONCLUSIONS

This proof-of-concept study found that machine learning and ensemble methods that incorporate daily AF burden signature provided incremental prognostic value for risk stratification beyond CHA₂DS₂-VASc for near-term risk of stroke.

Atrial fibrillation incidence and impact of biventricular pacing on long-term outcome in patients with heart failure treated with cardiac resynchronization therapy

Background

In patients with cardiac resynchronization therapy (CRT), atrial fibrillation (AF) is associated with an unfavorable outcome and may cause loss of biventricular pacing (BivP). An effective delivery of BivP of more than 98% of all ventricular beats has been shown to be a major determinant of CRT-success.

Methods

At a Swedish tertiary referral center, data was retrospectively obtained from patient registers, medical records and preoperative electrocardiograms. Data regarding AF and BivP during the first year of follow-up was assessed from CRT-device interrogations. No intra-cardiac electrograms were studied. Kaplan-Meier curves and Cox-regression analyses adjusted for age, etiology of heart failure, left ventricular ejection fraction, left bundle branch block and NYHA class were performed to assess the impact of AF and BivP on the risk of death or heart transplantation (HTx) at 10-years of follow-up.

Results

Preoperative AF-history was found in 54% of the 379 included patients and was associated with, but did not independently predict death or HTx. The one-year incidence of new device-detected AF was 22% but not associated with poorer prognosis. At one-year, AF-history and BivP≤98%, was associated with a higher risk of death or HTx compared to patients without AF (HR 1.9, 95%CI 1.2–3.0, p = 0.005) whereas AF and BivP> 98% was not (HR 1.4, 95%CI 0.9–2.3, p = 0.14).

Conclusions

In CRT-recipients, AF-history is common and associated with poor outcome. AF-history does not independently predict mortality and is probably only a marker of a more severe underlying disease. BivP≤98% during first-year of CRT-treatment independently predicts poor outcome thus further supporting the use of 98% threshold of BivP, which should be attained to maximize the benefits of CRT.

Long-term efficacy and safety of radiofrequency catheter ablation of atrial fibrillation in patients with cardiac implantable electronic devices and transvenous leads

INTRODUCTION

Long-term efficacy and safety are uncertain in patients with cardiac implantable electronic devices (CIED) and transvenous leads (TVL) undergoing radiofrequency catheter ablation of atrial fibrillation (AF). Thus, we assessed the outcome of AF ablation in those patients during long-term follow-up using continuous atrial rhythm monitoring (CARM).

METHODS AND RESULTS

A total of 190 patients (71.3 ± 10.7 years; 108 (56.8% men) were included in this study. At index procedure 81 (42.6%) patients presented with paroxysmal AF and 109 (57.4%) with persistent AF. The ablation strategy included pulmonary vein isolation in all patients and biatrial ablation of complex fractionated electrograms with additional ablation lines, if appropriate. AF recurrences were assessed by CARM- and CIED-related complications by device follow-up. After a mean follow-up of 55.4 ± 38.1 months, freedom of AF was found in 86 (61.4%) and clinical success defined as an AF burden less than or equal to 1% in 101 (72.1%) patients. Freedom of AF was reported in 74.6% and 51.9% (P = 0.006) and clinical success in 89.8% and 59.3% (P < 0.001) of patients with paroxysmal and persistent AF, respectively. In 3 of 408 (0.7%) ablation procedures, a TVL malfunction occurred within 90 days after catheter ablation. During long-term follow-up 9 (4.7%) patients showed lead dislodgement, 2 (1.1%) lead fracture, and 2 (1.1%) lead insulation defect not related to the ablation procedure.

CONCLUSION

Our findings using CARM demonstrate long-term efficacy and safety of radiofrequency catheter ablation of AF in patients with CIED and TVL.

Upper rate behavior in six dogs with dual-chamber pacemakers

INTRODUCTION

This report provides clinical examples of upper rate behavior in dogs with dual-chamber pacemakers, with suggestions for programming alterations to avoid detrimental upper rate behavior.

ANIMALS

Six dogs with dual-chamber pacemakers displaying upper rate behavior at upper atrial tracking rates.

METHODS

Medical records of dogs with dual-chamber pacemakers with evidence of upper rate behavior were reviewed retrospectively from two institutions. Two of the six dogs were followed prospectively, and 24 h Holter monitors were placed to evaluate upper rate behavior correlated to programming settings.

RESULTS

Pacemaker Wenckebach or 2:1 atrioventricular block was documented in four of six dogs, and automatic mode switch was documented in two of six dogs. Twenty-four-hour Holter monitors placed on two dogs after pacemaker optimization documented a pacemaker Wenckebach window at increased atrial rates with neither dog reaching their respective 2:1 block point throughout the recording period.

CONCLUSIONS

Clinicians who implant dual-chamber pacemakers should be aware of upper rate behavior in animal species with high heart rates. Optimal programming of dual-chamber pacemakers can be achieved by selecting programmed timing intervals to limit deleterious upper rate behavior and create a more physiologic ventricular response at maximum tracking rates.

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.

When is Device-Detected Atrial Fibrillation Actionable?

Device-detected atrial high-rate episodes (AHREs) are frequently encountered in patients with no history of atrial fibrillation (AF) and represent a challenge for clinicians because patients with device-only documented AF have not been included in clinical trials of anticoagulants and other AF therapies. For patients with known history of AF, wireless continuous rhythm monitoring and rapidly acting oral anticoagulants offer the possibility of tailored anticoagulation in response to AHREs, with studies ongoing to evaluate the safety of this approach. This article provides an overview of current evidence on device-detected AHREs and evolving areas of investigation.

The Influence of Cardiac Pacemaker Programming Modes on Exercise Capacity

BACKGROUND/AIM

The cardiac pacing mode influences the atrioventricular synchronicity and the response of the heart rate to physical exercise. The aim of this study was to compare the influence of the most common pacemaker programming modes on exercise capacity.

PATIENTS AND METHODS

Fifty-two pacemaker-wearing patients were clinically evaluated and submitted to an exercise stress test.

RESULTS

Symptoms of heart failure were more frequently met in the single-chamber pacemaker group compared to the dual-chamber group. The parameters recorded during the exercise stress test were significantly better with the rate responsive function (RRF) activated. The effort time was higher by an average of 2.1 minutes and the exercise capacity was higher by 0.92 metabolic equivalents.

CONCLUSION

Dual-chamber pacing is superior to single-chamber (ventricular) pacing and the activation of the RRF in single-chamber pacemakers has similar impact on exercise capacity as the preservation of atrioventricular synchronicity by dual-chamber pacemakers.

Association between paced QRS duration and atrial fibrillation after permanent pacemaker implantation: A retrospective observational cohort study

Right ventricular pacing often results in prolonged QRS duration (QRSd) as the result of right ventricular stimulation, and atrial fibrillation (AF) may result. The association of pacing-induced prolonged QRSd and AF in patients with permanent pacemakers is unknown.We selected 180 consecutive patients who underwent pacemaker implantation for complete/advanced atrioventricular block. All of the patients were paced from the right ventricular septum. Electrocardiography recordings were obtained at the beginning and the end of pacemaker implantation. QRSd was measured in all 12 leads. The QRSd variation was calculated by subtracting the preimplantation QRSd from the postimplantation QRSd.The occurrence of AF was observed in 64 (35.56%) patients (follow-up 33.62 ± 21.47 mo). No significant differences in preimplantation QRSd were observed between the AF occurrence and nonoccurrence groups. The QRSd variation in leads V4 (54.22 ± 29.03 vs 42.66 ± 33.79 ms, P = .022), and V6 (64.62 ± 23.16 vs 48.45 ± 34.40 ms, P = .001) differed significantly between the occurrence and nonoccurrence groups. More QRSd variation in lead V6 (P = .005, HR = 1.822, 95% CI 1.174-2.718, interval scale of QRSd was 40 ms) and left atrial diameter (P = .045, HR = 1.042, 95% CI 1.001-1.086) were independent risk factors for AF occurrence. Receiver operating characteristic curve suggested that QRSd variation in lead V6 could predict AF occurrence, especially for patients with long preimplantation QRSd (≥120 ms, area under the curve was 0.826, 95% CI 0.685-0.967).QRSd variation in lead V6 might be positively correlated with postimplantation AF occurrence. In patients with pacemaker implantation, QRSd could be a complementary criterion for optimizing the right ventricular septal pacing site, and smallest QRSd might be worth pursuing.

Atrial fibrillation variability on long-term monitoring of implantable cardiac rhythm management devices

BACKGROUND

Atrial fibrillation (AF) burden and duration are predictors of thromboembolic events. The random nature of these measures may affect clinical decision making. The objective of this study was to determine temporal changes in AF burden as detected by continuous monitoring.

HYPOTHESIS

AF burden changes over time when detected by continuous monitoring.

METHODS

A post hoc analysis of patients enrolled in the TRENDS (A Prospective Study of the Clinical Significance of Atrial Arrhythmias Detected by Implanted Device Diagnostics) study with ≥1 stroke risk factor(s) who were implanted with a dual-chamber cardiac rhythm management device (CRMD) and had AF burden data available for ≥2 years was performed. AF burden was defined as no AF, low AF (<5.5 hours on any given day), or high AF burden (≥5.5 hours in a day), and was first assessed over the initial 30 days following enrollment and then reassessed at 6-month intervals for 2 years.

RESULTS

Among 394 patients included, the average age was 70.2 ± 10.9 years, 71% were male, and mean CHA2 DS2- VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke or TIA, vascular disease, age 65-74 years, sex category) score was 3.7 ± 1.6. In the 30-day baseline period, 75.1% of patients had no AF, 11.2% had low AF, and 13.7% had high AF. Over the subsequent 2 years, 40.0% of patients initially classified as no AF or low AF experienced periods with high AF, whereas 59.3% of patients initially classified as high AF experienced ≥6 consecutive months with no AF or low AF. Advanced age was the sole predictor of AF progression.

CONCLUSIONS

Significant temporal variability in AF burden exists when measured continuously with an implantable CRMD.

Atrial high-rate episodes predict clinical outcome in patients with cardiac resynchronization therapy

OBJECTIVES

Up to 50% of patients qualified for cardiac resynchronization therapy (CRT) have documented atrial fibrillation (AF) prior to CRT-implantation. This finding is associated with worse prognosis but few studies have evaluated the importance of post-implant device-detected AF. This study aimed to assess the prognostic impact of device-detected atrial high-rate episodes (AHRE), as a surrogate for AF.

DESIGN

Data were retrospectively obtained from consecutive patients receiving CRT. Baseline clinical data and data from CRT device-interrogations, performed at a median of 12.2 months after CRT-implantation, were evaluated with regard to prediction of the composite endpoint of death, heart transplant or appropriate shock therapy. Median follow-up time was 51 months post-implant.

RESULTS

The study included 377 patients. Preoperative AF was present in 49% and associated with worse outcome. The cumulative burden of AHRE at 12 months post-implant was an independent predictor of the primary endpoint. During the first 12 months after CRT-implantation, AHRE were detected in 25% of the patients with no preoperative diagnosis of AF. This finding was not associated with worse outcome.

CONCLUSIONS

In CRT recipients, the cumulative burden of AHRE during the first year of follow-up was associated with worse long-term clinical outcome. Prospective trials are needed to determine if a rhythm control strategy is to be preferred in patients with CRT.

Performance of an Implantable Cardiac Monitor to Detect Atrial Fibrillation: Results of the DETECT AF Study

INTRODUCTION

Reliable detection and monitoring of atrial fibrillation (AF) is essential for accurate clinical decision making, which can now be done continuously with the introduction of implantable cardiac monitors (ICM) The DETECT AF study evaluated the performance of the Confirm DM2102 ICM (St. Jude Medical, St. Paul, MN, USA) to accurately detect and monitor AF.

METHODS

Ninety patients previously implanted with the ICM and with either suspected or known paroxysmal AF were enrolled at 12 centers in Germany and The Netherlands. At least 2 weeks after ICM implant, patients wore a Holter monitor for 4 days, while the ICM monitored for AF episodes lasting at least 2 minutes. Holter monitor data was analyzed by a blinded, independent core laboratory and compared to the ICM AF detections. Patient and episode sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive (NPV) were calculated using standard analysis and a generalized estimation equation method where appropriate.

RESULTS

A total of 79/90 subjects (61% male, 65.7 ± 9.6 years old) were included in the analysis, totaling 6,894 hours of Holter monitoring. Using a per patient analysis SE was 100%, PPV was 64.0%, SP was 85.7%, and NPV was 100%. Using a per episode analysis, SE was 94.0% and PPV was 64.0%. With an AF duration analysis, the SE was 83.9%, PPV was 97.3%, SP was 99.4% with an NPV of 98.5%.

CONCLUSION

The SJM Confirm DM2102 can accurately and repeatedly detect paroxysmal AF episodes of at least 2 minutes in length.

Clinical, Echocardiographic, and Electrocardiographic Predictors of Persistent Atrial Fibrillation after Dual-Chamber Pacemaker Implantation: An Integrated Scoring Model Approach

Persistent atrial fibrillation (PeAF) predictors after dual-chamber pacemaker (PM) implantation remain unclear. We sought to determine these predictors and establish an integrated scoring model. Data were retrospectively reviewed for 649 patients (63.8 ± 12.3 years, 48.6% male, mean CHA₂DS₂–VASC score 2.7 ± 2.0) undergoing dual-chamber PM implantation. PeAF was defined as documented AF on two consecutive electrocardiograms acquired ≥7 days apart. During a 7.1-year median follow-up (interquartile range 4.5–10.1 years), 67 (10.3%) patients had PeAF. Multivariable analysis showed the following independent predictors of future PeAF: ischemic stroke or transient ischemic accident history (hazard ratio [HR] 2.03, 95% confidence interval [CI] 1.03–3.50, p = 0.040), atrial fibrillation/flutter history (HR 1.80, 95% CI 1.01–3.20, p = 0.046), sinus node disease (HR 2.24, 95% CI 1.16–4.35, p = 0.016), left atrial enlargement (>45 mm, HR 2.14, 95% CI 1.26–3.63, p = 0.005), and time in automatic mode switching >1% at first follow-up interrogation (HR 2.58, 95% CI 1.51–4.42, p < 0.001). An integrated scoring model combining these predictors showed good discrimination performance at the seven-year follow-up. (C-statistic 0.716, 95% CI 0.629–0.802, p < 0.001). Significantly greater seven-year PeAF incidences were seen in patients with higher scores (2–5) than in those with lower scores (0–1) (22.8% ± 3.8% vs. 5.3% ± 1.7%, p < 0.001). In conclusion, an integrated scoring model combining clinical, echocardiographic, and electrocardiographic characteristics is useful for predicting future PeAF in patients with a dual-chamber PM.

Automatic Mode Switch (AMS) Causes Less Synchronization

INTRODUCTION

Cardiac resynchronization devices are part of modern heart failure management. After implantation, we analyze and program devices in an attempt to ensure their success. Biventricular pacing should be 98% or more for the lowest mortality and best symptom improvement.

CASE PRESENTATION

In this case series, we present a combination of far field sensing and automatic mode switching (AMS) in six patients. It is found that this combination causes ventricular sensing (VS) episodes with wide QRS and no synchronization. We turn off the AMS and alleviate the problem.

CONCLUSIONS

Switching AMS off may increase biventricular pacing in some patients.

Management of device-detected atrial high-rate episodes

Atrial tachyarrhythmias are common in patients with cardiac implantable electronic devices (CIEDs) with atrial leads. These atrial tachyarrhythmias are detected as atrial high-rate episodes (AHREs) by the CIED. AHREs may be brief, infrequent, and asymptomatic, and may be detected before clinical arrhythmia is apparent. These subclinical device-detected AHREs are associated with an increased stroke risk, similar to, but to a lesser degree than, clinically apparent atrial fibrillation detected by routine methods. Whether a specific duration of AHREs is needed before the risk of stroke increases and whether treatment with anticoagulation for subclinical device-detected AHREs reduces stroke risk is unclear.

The Impact of Early Detection of Atrial Fibrillation on Stroke Outcomes

Early detection of atrial fibrillation (AF) before an AF-related stroke potentially allows for prevention, but the best methods are uncertain. Population screening trials have demonstrated the ability to increase detection in older individuals by systematic screening. The subset of patients with implantable cardiac rhythm management devices are at particular risk. Remote monitoring has substantially reduced the time to detection. Although primary prevention of stroke is a priority, detection in patients with cryptogenic stroke represents another opportunity for therapeutic intervention. Evidence that early detection actually leads to improved stroke outcomes is still being gathered.

How often should we monitor for reliable detection of atrial fibrillation recurrence? Efficiency considerations and implications for study design

Objective

Although atrial fibrillation (AF) recurrence is unpredictable in terms of onset and duration, current intermittent rhythm monitoring (IRM) diagnostic modalities are short-termed and discontinuous. The aim of the present study was to investigate the necessary IRM frequency required to reliably detect recurrence of various AF recurrence patterns.

Methods

The rhythm histories of 647 patients (mean AF burden: 12±22% of monitored time; 687 patient-years) with implantable continuous monitoring devices were reconstructed and analyzed. With the use of computationally intensive simulation, we evaluated the necessary IRM frequency to reliably detect AF recurrence of various AF phenotypes using IRM of various durations.

Results

The IRM frequency required for reliable AF detection depends on the amount and temporal aggregation of the AF recurrence (p<0.0001) as well as the duration of the IRM (p<0.001). Reliable detection (>95% sensitivity) of AF recurrence required higher IRM frequencies (>12 24-hour; >6 7-day; >4 14-day; >3 30-day IRM per year; p<0.0001) than currently recommended. Lower IRM frequencies will under-detect AF recurrence and introduce significant bias in the evaluation of therapeutic interventions. More frequent but of shorter duration, IRMs (24-hour) are significantly more time effective (sensitivity per monitored time) than a fewer number of longer IRM durations (p<0.0001).

Conclusions

Reliable AF recurrence detection requires higher IRM frequencies than currently recommended. Current IRM frequency recommendations will fail to diagnose a significant proportion of patients. Shorter duration but more frequent IRM strategies are significantly more efficient than longer IRM durations.

Clinical Trial Registration URL

Unique identifier: NCT00806689.

AF Detected on Implanted Cardiac Implantable Electronic Devices: Is There a Threshold for Thromboembolic Risk?

OPINION STATEMENT

Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with elevated thromboembolism risk caused by multiple pathophysiologies, including a hypercoagulable state, structural heart changes, left atrial appendage stasis, inflammation, and endothelial dysfunction. With the exception of lone AF, most other categories of AF, whether paroxysmal or persistent, have been shown to share a high thromboembolism risk. Risk stratification schemes such as CHADS2 and CHA2DS2-VASc scores help to identify the level at which anticoagulation may mitigate thromboembolism risk. AF may be episodic and asymptomatic; therefore, AF diagnosis that depends entirely on office electrocardiogram (ECG) may be easily missed. With the increasing use of pacemakers, implantable cardioverter defibrillators (ICDs), and insertable loop recorders (ILRs) for diagnosis and treatment of arrhythmias, AF has been incidentally detected with increasing frequency. However, the sensitivity and specificity for detection of AF, especially brief episodes, vary from one type of device to another, and rhythm confirmation should be considered. Several recent studies have examined device-detected AF and have tried to follow associated clinical outcomes. In this paper, we review studies that have addressed device-detected AF and associated thromboembolism risk to try to identify the burden of AF that is associated with an elevated risk of thromboembolism and may therefore warrant anticoagulation therapy.

Does atrial fibrillation detected by cardiac implantable electronic devices have clinical relevance?

The precise role atrial fibrillation (AF) plays in increasing the risk of stroke is less well understood; this is especially true for the implanted device population. Current cardiac implanted electronic devices have a very high sensitivity and specificity for true AF detection. It does not seem to matter if the AF episode is proximal to the stroke event, and risk seems to be increased by relatively brief AF episodes. The appearance of new atrial high-rate episodes increases thromboembolic event rates. Until larger trials or registries are conducted, it is important to follow established guidelines regarding anticoagulation.

A rare cause of pacemaker failure: interatrial block

Pacemaker and implantable cardioverter defibrillators (ICD) systems are useful in detection and differentiation of many symptomatic and asymptomatic arrhythmias. In this report, we described a rare condition that caused by failure in detection of a clinical tachyarrhythmia by a dual chamber pacemaker that implanted because of intermittent atrioventricular (AV) block and sinus node disease in a 46-year-old patient. In our case, bidirectional interatrial block was demonstrated; and the symptoms associated with high ventricular rate caused by left atrial tachyarrhythmias relieved after AV node ablation.

Effects of long-term ω-3 polyunsaturated fatty acid supplementation on paroxysmal atrial tachyarrhythmia burden in patients with implanted pacemakers: results from a prospective randomised study

BACKGROUND

Sino-atrial node disease and aging increase AF risk. We investigated if long-term fish oil supplementation reduces paroxysmal atrial tachycardia/fibrillation (AT/AF) burden in patients aged ≥60 years with sinoatrial node disease and dual chamber pacemakers.

METHODS

Following a run-in period of 6 months (p1) where AT/AF burden was logged,78 patients were randomised to control or fish oil group (total omega-3 6 g/d) and AT/AF burden evaluated after 6 months (p2; 39 controls, 39 fish oil) and 12 months (p3; 39 controls; 18 fish oil). A subset of 21 fish oil patients crossed over to controls in the final 6 months (crossover group).

RESULTS

Median AT/AF burden increased significantly in controls (1.5%, 3.2%, 4.3%, P<.001) but not in fish oil patients at 6 months (1.4% to 2%, P=.46) or those continuing for 12 months (1.5%, 0.98%, 1%, P=.16). Time to first episode of AT/AF >1 min was not significantly different between the groups (P=.9). There was a rebound increase in AT/AF burden in p3 in cross over patients (2.2% to 5.8%, P=.01) reaching a level similar to controls (crossover vs. controls, 5.8% vs. 4.3%, P=.63) and higher than those who continued fish oil for 12 months (crossover vs. continued intake 5.8% vs. 1.2%, P=.02). Fish oil patients had shorter duration episodes of AT/AF with no difference in frequency compared to controls.

CONCLUSION

Long-term fish oil supplementation did not suppress AT/AF burden but may have attenuated its temporal progression related to aging and sinus node disease.

The potential role of nonpharmacologic electrophysiology-based interventions in improving outcomes in patients hospitalized for heart failure

Hospitalization for heart failure (HHF) is commonly associated with symptomatic improvement in response to standard medical therapy, yet there remains a substantial risk of rehospitalization and death. Clinically stable outpatients and decompensated inpatients represent two types of patients with chronic heart failure. In the former, treatment of common heart rhythm disorders with nonpharmacologic electrophysiology-based interventions is of substantial benefit in select patients. The potential benefits of these interventions in the hospitalized setting are not well studied. In this review, current knowledge is discussed and future research directions are suggested with nonpharmacologic electrophysiology-based interventions to reduce the morbidity and mortality associated with patients with HHF.

Detection of previously undiagnosed atrial fibrillation in patients with stroke risk factors and usefulness of continuous monitoring in primary stroke prevention

The detection of undiagnosed atrial tachycardia/atrial fibrillation (AT/AF) among patients with stroke risk factors could be useful for primary stroke prevention. We analyzed newly detected AT/AF (NDAF) using continuous monitoring in patients with stroke risk factors but without previous stroke or evidence of AT/AF. NDAF (AT/AF >5 minutes on any day) was determined in patients with implantable cardiac rhythm devices and ≥1 stroke risk factors (congestive heart failure, hypertension, age ≥75 years, or diabetes). All devices were capable of continuously monitoring the daily cumulative time in AT/AF. Of 1,368 eligible patients, NDAF was identified in 416 (30%) during a follow-up of 1.1 ± 0.7 years and was unrelated to the CHADS(2) score (congestive heart failure, hypertension [blood pressure consistently >140/90 mm Hg or hypertension treated with medication], age ≥75 years, diabetes mellitus, previous stroke or transient ischemic attack). The presence of AT/AF >6 hours on ≥1 day increased significantly with increased CHADS(2) scores and was present in 158 (54%) of 294 patients with NDAF and a CHADS(2) score of ≥2. NDAF was sporadic, and 78% of patients with a CHADS(2) score of ≥2 with NDAF experienced AT/AF on <10% of the follow-up days. The median interval to NDAF detection in these higher risk patients was 72 days (interquartile range 13 to 177). In conclusion, continuous monitoring identified NDAF in 30% of patients with stroke risk factors. In patients with NDAF, AT/AF occurred sporadically, highlighting the difficulty in detecting paroxysmal AT/AF using traditional monitoring methods. However, AT/AF also persisted for >6 hours on ≥1 days in most patients with NDAF and multiple stroke risk factors. Whether patients with CHADS(2) risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anticoagulation for primary stroke prevention merits additional investigation.