Lower Atrial Fibrillation Burden Research Articles

Atrial fibrillation burden: a new outcome predictor and therapeutic target.

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is not a dichotomous disease trait. Technological innovations enable long-term rhythm monitoring in many patients and can estimate AF burden. These technologies are already used to detect and monitor AF. This review describes the relation between AF burden and outcomes and potential effects of AF burden reduction. A lower AF burden is associated with a lower risk of stroke and heart failure in patients with AF: stroke risk without anticoagulation is lower in patients with device-detected AF and a low AF burden (stroke rate 1%/year) than in patients with persistent and permanent AF (stroke rate 3%/year). Paroxysmal AF shows intermediate stroke rates (2%/year). Atrial fibrillation burden-reducing interventions can reduce cardiovascular outcomes in patients with AF: early rhythm control reduces cardiovascular events including stroke and heart failure in patients with recently diagnosed AF and cardiovascular conditions. In patients with heart failure and AF, early rhythm control and AF ablation, interventions that reduce AF burden, reduce mortality and heart failure events. Recent technological innovations allow to estimate AF burden in clinical care, creating opportunities and challenges. While evidence remains limited, the existing data already suggest that AF burden reduction could be a therapeutic goal. In addition to anticoagulation and treatment of cardiovascular conditions, AF burden reduction emerges as a therapeutic goal. Future research will define the AF burden that constitutes a relevant risk of stroke and heart failure. Technologies quantifying AF burden need careful validation to advance the field.

Preprocedural atrial fibrillation burden is associated with recurrence in patients undergoing atrial fibrillation ablation: findings from the ISOLATION AF Ablation Cohort Study

Abstract Background Non-invasive quantification of electrophysiological properties of the atria is increasingly used for outcome prediction in atrial fibrillation (AF) patients. Data on the benefit of the current classification of AF compared to AF burden based on single lead ECG measurements to predict AF recurrences are scarce. Objective This study sought to assess the predictive performance of low versus high AF burden compared to the conventional AF classification for predicting recurrences after AF catheter ablation. Methods A cross-sectional analysis was conducted in AF patients scheduled for catheter ablation included in the prospective multicenter ISOLATION cohort study between July 2020 and November 2022. Clinical characteristics, routine tests, blood tests and rhythm monitoring through single lead ECGs were collected prior to ablation. ECGs were recorded three times daily for four weeks, with additional measurements in case of the onset or relief of symptoms. The primary endpoint was "ablation success" defined as freedom from documented arrhythmia after the blanking period. Of 650 included patients, pre-procedural rhythm monitoring was available in 580. 261 patients had at least 14 days of ECG measurements and completed 12 months of follow-up. In these patients, we compared the recurrences after 12 months between paroxysmal and persistent AF and high versus low AF burden through survival analysis. Maximally selected rank statistics were used to determine the best cut-off value for AF burden. Results In 261 patients, the mean age was 64 ± 9 years, and 33.7% were female. Physicians classified 170 patients (65.1%) as paroxysmal AF and 91 (34.9%) as persistent AF based on medical history. The AF burden is shown in Figure 1. The optimal calculated cut-off value for AF burden was 42%. Out of 170 patients with paroxysmal AF, 17 (10%) had a burden of > 42%. Of the 91 patients with persistent AF, 35 (38%) had a burden of < 42%. After 12 months, a significant difference in recurrences was observed between patients with paroxysmal AF versus persistent AF (p= 0.015). Patients with high AF burden, had more recurrences after 12 months, than patients with a low AF burden (p= 0.006) (Figure 2). Conclusion Our preliminary results suggest that the addition of a new classification of AF based on burden might provide additional benefit in predicting AF recurrences after catheter ablation compared to the current existing classification and may improve prognostication. Completion of patient follow-up is necessary to determine the predictive value of AF burden derived from single lead ECGs for the prediction of AF recurrence.Figure 2.

Longer and better lives for patients with atrial fibrillation: the 9th AFNET/EHRA consensus conference.

Recent trial data demonstrate beneficial effects of active rhythm management in patients with atrial fibrillation (AF) and support the concept that a low arrhythmia burden is associated with a low risk of AF-related complications. The aim of this document is to summarize the key outcomes of the 9th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Eighty-three international experts met in Münster for 2 days in September 2023. Key findings are as follows: (i) Active rhythm management should be part of the default initial treatment for all suitable patients with AF. (ii) Patients with device-detected AF have a low burden of AF and a low risk of stroke. Anticoagulation prevents some strokes and also increases major but non-lethal bleeding. (iii) More research is needed to improve stroke risk prediction in patients with AF, especially in those with a low AF burden. Biomolecules, genetics, and imaging can support this. (iv) The presence of AF should trigger systematic workup and comprehensive treatment of concomitant cardiovascular conditions. (v) Machine learning algorithms have been used to improve detection or likely development of AF. Cooperation between clinicians and data scientists is needed to leverage the potential of data science applications for patients with AF. Patients with AF and a low arrhythmia burden have a lower risk of stroke and other cardiovascular events than those with a high arrhythmia burden. Combining active rhythm control, anticoagulation, rate control, and therapy of concomitant cardiovascular conditions can improve the lives of patients with AF.

Sex-based differences in obstructive sleep apnea and atrial fibrillation: Implication of atrial fibrillation burden

BackgroundObstructive sleep apnea (OSA) is a risk factor for atrial fibrillation (AF); however, it is unclear whether AF increases the risk of OSA. Furthermore, sex differences among patients with both AF and OSA remain unclear. We aimed to determine the association between an increased AF burden and OSA and investigate the differences in clinical characteristics between women and men with AF and OSA. MethodsThis was a descriptive, cross-sectional analysis from a prospective cohort study. Patients with non-valvular AF were recruited from the cardiac electrophysiology clinic of a tertiary center; they underwent a home sleep apnea test and 14-day ambulatory electrocardiography. Moderate-to-severe OSA was defined as an apnea-hypopnea index of ≥15. ResultsOf 320 patients with AF, 53.4% had moderate-to-severe OSA, and the mean body mass index (BMI) was 25.6 kg/m2. Less women (38.2%) had moderate-to-severe OSA than men (59.3%) (p < 0.001). In the multivariate analysis, age, being a man, and BMI were significantly associated with moderate-to-severe OSA. AF burden was associated with moderate-to-severe OSA only in men (odds ratio: 1.008; 95% confidence interval: 1.001–1.014). Women and men with OSA had similar BMI (p = 0.526) and OSA severity (p = 0.754), but women were older than men (70.1 ± 1.3 vs. 63.1 ± 0.9 years, p < 0.001). Women with moderate-to-severe OSA had a lower AF burden than men did (27.6 ± 7.1 vs. 49.5 ± 3.9%, p = 0.009). ConclusionsAF burden is a sex-specific risk factor for OSA and is limited to men. In contrast, women with both AF and OSA have a lower AF burden than men, despite being older and having similar OSA severity and body habitus. Thus, AF may develop later in women with OSA than in men.

Atrial fibrillation burden and timing of anticoagulation therapy in patients with screen-detected and clinically-diagnosed AF

Abstract Purpose We evaluated the impact of atrial fibrillation (AF) burden and timing of oral anticoagulation (OAC) therapy initiation on stroke risk in patients with screen-detected and clinically-diagnosed AF. Methods Consecutive patients aged ≥65 years attending medical outpatient clinics with or without known AF were prospectively enrolled for AF-screening using handheld single-lead ECG (AliveCor) from 12/2014 to 12/2017 (NCT02409654). Repeated screening was performed in patients with &amp;gt;1 visit during this period. Patients who participated in repeat screening were included in final analysis. Patients with previously known AF who were in AF in the initial screening and those with repeat screen-positivity were considered probably persistent AF, otherwise paroxysmal AF (single screen-positivity) or no AF (never screen-positive). Time from AF detection to initiation of OAC (Dx-to-Rx) was divided into two exposure levels, Dx-to-Rx ≤ 1 and &amp;gt;1 month. Ischemic stroke risk was estimated using adjusted sub-distribution hazard ratios (aSHR) derived from Fine and Gray regression models, accounting for death as competing risk, adjusting for components of CHA2DS2VASC score and chronic renal disease, with no AF as reference and stratified according to AF burden and Dx-to-Rx. Results Of 11,972 patients enrolled, 3,853(32.2%) received repeated screening (mean age 76.7±7.3, female 47.5%), of which 3.7% (n=144) had screened-detected AF, 25.2% (n=972) previously known AF, 5.9% (n=226) clinically-diagnosed AF during follow-up, and 65.2% (n=2,511) no AF. Persistent AF was identified in 16.7% (n=644/3,853). Of patients with all AF categories, 55.1% (n=739/1,342) initiated OAC within 1 month after AF diagnosis. During a median follow-up period of 7.2(IQR: 6.1-7.5) years, compared to no AF, patients with paroxysmal AF and Dx-to-Rx ≤ 1m (aSHR=1.40, 95%CI:0.80-2.47) had similar low risk of ischemic stroke, while aSHR was highest for persistent AF and Dx-to-Rx &amp;gt;1m (aSHR=2.42, 95%CI:1.38-4.26), followed by persistent AF with Dx-to-Rx≤ 1m (aSHR=2.19,95%:1.47-3.28), and paroxysmal AF with Dx-to-Rx &amp;gt;1m (aSHR=2.00,95%CI:1.32-3.02) (Figure). Subgroup analysis revealed the effect of early initiation of OAC (P for interaction=0.936) and higher AF burden (P for interaction=0. 863) were consistent across screen-detected and clinically-diagnosed AF. Conclusion Among patients with screen-detected AF or clinically-diagnosed AF, lower AF burden and immediate initiation of OAC therapy were associated with reduction in risk of ischemic stroke. Early detection of AF by screening facilitating early OAC prophylaxis might improve clinical outcomes.Cumulative risk of ischemic stroke

Abstract 13214: Arrhythmic Burden After Bruton's Tyrosine Kinase Inhibitor Initiation and Major Cardiovascular Events

Background: Bruton’s tyrosine kinase inhibitors (BTKi) have dramatic efficacy against B cell malignancies. BTKi’s also cause cardiotoxic arrhythmias, including atrial fibrillation (AF) and ventricular arrhythmias (VA). Yet, the true burden and long term effects of arrhythmias after BTKi therapy are unknown. Research Question: In patients with suspected BTKi related arrhythmias, what is the relative AF burden? Does it prognosticate future events? Methods: Leveraging a cohort of consecutive B cell malignancy patients initiated on BTKi from 2009-2020, we identified patients with available ambulatory rhythm monitors. The primary outcome was AF burden after BTKi initiation. Secondary outcomes included VA burden, conduction blocks, and other arrhythmias of probable or definite BTKi association. Observed incident AF rates and burden with next generation BTKi’s were compared to ibrutinib. Multivariable regression and survival analysis were used to define factors associated with AF related hospitalizations and major adverse cardiac events (MACE), as well as the relationship between AF burden and mortality. Outcomes were stratified by high (≥5%) vs low (&lt;5%) AF burden. Results: Of 890 BTKi treated patients, 98 wore ambulatory rhythm monitors, including 38 on next generation BTKi’s [age 67.7 years, 24.2% prior AF]. Median duration BTKi use was 34 months. Among next generation BTKi treated patients, 8.7% developed incident AF compared to 25.5% with ibrutinib ( P =0.048). Ten patients (26.3%) developed symptomatic or &gt;1% PVCs, at a mean burden of 7.1% compared to eight patients (13.3%) with mean burden 9.4% on ibrutinib. In a multivariable model accounting for traditional CV risk factors, prior AF associated with increased post BTKi AF burden. In follow up, high AF burden associated with increased MACE (HR 3.49, P =0.001) and mortality (HR 3.2, P =0.002); Figure . Conclusions: In BTKi treated patients, cardiotoxic AF burden prognosticates future MACE and mortality.

Predictors of New Onset Atrial Fibrillation Burden in the Critically Ill

Introduction: Atrial fibrillation (AF) is common in the intensive care unit (ICU) setting and has been associated with adverse outcomes. In this context, there is increasing research interest in AF burden as a predictor of subsequent adverse events. However, the pathophysiology and drivers of AF burden in the ICU are poorly understood. This study sought to evaluate the predictors of AF burden in critical illness-associated new-onset AF (CI-NOAF). Methods: Out of 7,030 admissions in a tertiary general ICU between December 2015 and September 2018, 309 patients developed CI-NOAF. AF burden was defined as the percentage of monitored time in AF, as extracted from hourly interpretations of continuous ECG monitoring. Low and high AF burden groups were defined relative to the median AF burden. Clinical, laboratory, and echocardiographic parameters were extracted, and multivariable modelling with binary logistic regression was performed to evaluate for independent associations with AF burden. Results: The median AF burden was 7.0%. Factors associated with increased AF burden were age, dyslipidaemia, chronic kidney disease, increased creatinine, CHA₂DS₂-VASc score, ICU admission diagnosis category, amiodarone administration, and left atrial area (LAA). Factors associated with lower AF burden were previous alcohol excess, burden of ventilation, the use of inotropes/vasopressors, and beta blockers. On multivariate analysis, increased LAA, chronic kidney disease, and amiodarone use were independently associated with increased AF burden, whereas beta blocker use was associated with lower AF burden. Conclusion: Left atrial size and chronic cardiovascular comorbidities appear to be the primary drivers of CI-NOAF burden, whereas factors related to acute illness and critical care intervention paradoxically did not appear to be a substantial driver of arrhythmia burden. Further research is needed regarding drivers of AF and the efficacy of rhythm control intervention in this unique setting.

Patients and Their Physician’s Perspectives About Oral Anticoagulation in Patients With Atrial Fibrillation Not Receiving an Anticoagulant

The underuse of oral anticoagulation in patients with nonvalvular atrial fibrillation (AF) is a major issue that is not well understood. To understand the lack of anticoagulation by assessing the perceptions of patients with AF who are not receiving anticoagulation and their physician's about the risk of stroke and the benefits and risks of anticoagulation. This cohort study included patients with nonvalvular AF and a CHA2DS2-VASc score of 2 or more (calculated as congestive heart failure, hypertension, age 75 years and older, diabetes, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, and sex category) who were not receiving anticoagulation and were enrolled from 19 sites within the National Cardiovascular Data Registry (NCDR) Practice Innovation and Clinical Excellence Registry (PINNACLE Registry) between January 18, 2017, and May 7, 2018. Data were collected from January 18, 2017, to September 30, 2019, and analyzed from April 2022 to March 2023. Each patient enrolled in the study completed a survey, and their treating physician then conducted a clinical review of their care. Assessment of willingness for anticoagulation treatment and its appropriateness after central review by a panel of 4 cardiologists. Use of anticoagulation at 1 year follow-up was compared vs similar patients at other centers in the PINNACLE Registry. Of the 817 patients enrolled, the median (IQR) age was 76.0 (69.0-83.0) years, 369 (45.2%) were women, and the median (IQR) CHA2DS2-VASc score was 4.0 (3.0-6.0). The top 5 reasons physicians cited for no anticoagulation were low AF burden or successful rhythm control (278 [34.0%]), patient refusal (272 [33.3%]), perceived low risk of stroke (206 [25.2%]), fall risk (175 [21.4%]), and high bleeding risk (167 [20.4%]). After rereview, 221 physicians (27.1%) would reconsider prescribing oral anticoagulation as compared with 311 patients (38.1%), including 67 (24.6%) whose physician cited patient refusal. Of 647 patients (79.2%) adjudicated as appropriate or may be appropriate for anticoagulation, physicians would reconsider anticoagulation for only 177 patients (21.2%), while 527 patients (64.5%) would either agree to starting anticoagulation (311 [38.1%]) or were neutral (216 [27.3%]) to starting anticoagulation. Upon follow-up, 119 patients (14.6%) in the BOAT-AF study were prescribed anticoagulation, as compared with 55 879 of 387 975 similar patients (14.4%) at other centers in the PINNACLE Registry. The findings of this cohort study suggest that patients with AF who are not receiving anticoagulation are more willing to consider anticoagulation than their physicians. These data emphasize the need to revisit any prior decision against anticoagulation in a shared decision-making manner.

Optimizing Anticoagulation Management in Atrial Fibrillation: Beyond the Guidelines. How and for Whom?

Anticoagulation therapy (AT) is the cornerstone of atrial fibrillation (AF) treatment for thromboembolic event prevention. The AF burden, however, is of predictive relevance and may be used as a foundation for therapeutic decisions in individuals with paroxysmal or persistent AF. Remote rhythm monitoring devices can provide early detection of the arrhythmia, long-term rhythm monitoring, and the development of anticoagulation strategies based on AF recurrence profile and the total burden of the arrhythmia. Although the exact thromboembolic cut-off value for the AF burden has not yet been established, targeted anticoagulation treatments in the new oral anticoagulants era have shown encouraging outcomes. The combined evaluation of AF burden and patient thromboembolic risk reported in some studies supports the concept of tailored anticoagulation management, at least in a subset of patients with low AF burden and intermediate thromboembolic risk, for whom the guidelines recommend that AT should be individualized based on net clinical benefit and patient values and preferences. Although it is still premature to derive firm conclusions or algorithms diverging from the current guidelines, the combination of a patient's AF burden, thromboembolic risk, and bleeding risk can lead in the future to an individualized management of patients with a congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke, vascular disease, age 65-74 years sex category (female) (CHA 2 DS 2 -VASc) score of 1 (2 for female patients), in whom the guidelines do not strictly recommend long-term AT. In this study, we provide an algorithm regarding the individualized implementation of anticoagulation strategies in AF in different patients' thromboembolic risk profiles, based on the available data on the so far tailored anticoagulation strategies in AF.

Association between atrial fibrillation burden and cognitive function in patients with atrial fibrillation

BackgroundAccumulating evidence has demonstrated an association between clinical atrial fibrillation (AF) and cognitive impairment. This study aimed to further clarify the impact of AF burden on cognitive function based on detailed electrophysiological recordings and standardized assessments of cognitive function. MethodsThis prospective cohort study, conducted at the Cardiac Electrophysiology Clinic of a tertiary center, included patients with non-valvular AF. AF burden was evaluated using 14-day patch-based electrocardiography. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). ResultsEnrolled patients (n = 253) were grouped according to the median AF burden (13.52%). Patients with higher AF burden were significantly older and had larger left atrium size, a worse ejection fraction, and a lower MoCA score than those with lower AF burden. Predictors of MoCA score included age, CHA2DS2-VASc score, AF burden, and Center for Epidemiologic Studies Depression Scale scores. The association between MoCA scores and AF burden remained significant after adjustment for demographic characteristics, underlying diseases, and echocardiographic parameters (standardized beta coefficient: −0.159, 95% confidence interval: −0.020 to −0.004, p = 0.004). ConclusionAF burden is associated with cognitive function in patients with AF. Further studies are required to determine whether reducing AF burden can preserve cognitive function in these patients.

Abstract 10428: Probability of Atrial Fibrillation (AF) Diagnosis and Error in Estimation of Burden in People With Paroxysmal AF Based on the Duration of Monitoring

Introduction: In individuals with paroxysmal atrial fibrillation (PAF) undergoing heart rhythm monitoring, total duration of monitoring can influence both the probability of recognizing AF and estimation of burden. We estimate the probability of AF detection and quantify the error in burden estimation based on the duration of monitoring up to 10 days. Methods: Data included 5361 ECG patch recordings up to 14 days long with at least 1 episode of AF. 100 samples of pre-specified lengths were drawn at random from each recording. For each sample length, the probability of identifying any AF, and the AF burden over shorter periods of monitoring were determined. The absolute error in burden estimation over short monitoring divided by the true AF burden during up to 14 days of monitoring was used to determine relative deviation. We stratified the expected relative deviation and probability of detecting AF by high (&gt;10%), moderate (2-10%), or low (&lt;2%) true AF burden. Results: Estimated probability of detecting any AF was significantly affected by duration of monitoring (Fig): 1 day of monitoring identified 76% [75-77%], 52% [51-54%] and 35% [33-36%] of individuals with high, moderate, and low burden of AF. Relative deviation in the estimation of AF burden is also significantly impacted by monitoring duration with 1 day recording, with 0.89 [0.87-0.91], 1.45 [1.43-1.47], and 1.65 [1.63-1.67] for high, moderate, and low burden. Even for 7 days recording, the expected deviation is significant, with 0.31 [0.30-0.33], 0.60 [0.58-0.61], 0.79 [0.78-0.80] for high, moderate, and low burden (Fig). Conclusions: In people with PAF, known or unknown, the duration of continuous ECG recording can significantly impact both ability to diagnosis AF and accurate determination of AF burden. Even in individuals with true AF burden &gt;10%, 24 hours of monitoring will not detect AF in &gt;20% of people and provide an almost 90% relative error in the estimate of AF burden.

Abstract 14899: Ten Year Performance of Convergent Cryoballoon Hybrid Ablation With Left Atrial Appendage Exclusion in Persistent and Long Standing Persistent Atrial Fibrillation: A Trac-Af Registry Outcome Study

Introduction: Catheter ablation (CA) efficacy in persistent and long standing persistent atrial fibrillation (AF) remains poor. The Convergent procedure with endocardial cryoballoon and left atrial appendage exclusion (LAAE) addresses multiple epicardial/endocardial targets offering a comprehensive approach. We report clinical outcomes in a prospectively collected registry supplemented by continuous device monitoring in a diseased AF patient population. Methods: Single center patient data were retrospectively analyzed in the TRAC-AF registry (NCT05111015) between November 2011-November 2021. Epicardial ablations were performed by cardiothoracic surgeon and endocardial CA performed by electrophysiologist. Clinical follow up was performed at 3, 6, and 12 months and every 6 months thereafter. AF burden was determined from patients with ≥30 days of 24 hr continuous rhythm monitoring following a 90 day blanking period. Results: A total of 228 patients (69% male) received hybrid Convergent ablation. Mean age was 66 yrs, mean BMI was 30.2 ± 6.2, and in 70% of patients, CHA2DS2-VASc was ≥2. Baseline AF types were paroxysmal (7%), persistent (43%), and longstanding persistent (50%). Mean AF duration was 5.1 ± 6.2 yrs. Fifty-seven percent of patients had failed CA prior to hybrid ablation and 30.6% had LAAE with an epicardial clip. Of 228 patients, 114 (50%) had continuous rhythm monitoring. Mean residual AF burden was 5.2 ± 16.3% and of those, 77% had ≤1% mean residual AF burden, and 88% had ≤5% mean residual AF burden. A repeat CA after hybrid Convergent occurred in 23% (53/228) of patients at a mean 645.8 ± 511.4 days from the index procedure with 4.4% requiring &gt;1; 88.5% of all repeat ablations included a mitral annular line. Conclusions: The hybrid Convergent ablation with endocardial cryoballoon and LAAE provides long term sustainable low AF burden despite rigorous endpoint surveillance in a significantly diseased AF population which includes prior failed CA patients over a decade of follow up.

Abstract TP193: Atrial Fibrillation Burden Is Not Associated With Recurrent Cerebrovascular Events In Anticoagulated Stroke Patients: An Arest Trial Sub-study

Introduction: The burden of Atrial Fibrillation (AF) has previously been associated with a higher stroke risk in non-anticoagulated patients. We aim to find whether there is also an association between AF burden and recurrent cerebrovascular events in anticoagulated AF patients after their initial acute ischemic stroke (AIS) or transient ischemic attacks (TIA). Methods: The AREST study (Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation) was a multi-center, randomized controlled trial of early apixaban versus warfarin at one week post-TIA or two weeks post-AIS, in AF patients from 2015 to 2019. Subjects received either 30-day continuous electrocardiographic monitoring or an implantable device (i.e., pacemaker, loop recorder, or defibrillator). Logistic regression and Kendall's tau-b test were utilized to identify an association between AF burden and the proportion of subjects who developed recurrent cerebrovascular events. Results: Of 91 subjects enrolled into AREST, heart rhythm monitoring was assessed in 49 (54%); over half (59%) clustered at the extreme ends of the distribution, at either low (≤1%) or high (≥99%) AF burden. Higher AF burden was not significantly correlated with an increased risk of recurrent stroke or TIA (Odds Ratio = 0.99 [95% confidence interval (CI), 0.98-1.0]; p=0.518). Moreover, there was no statistically significant association between AF burden and the composite outcomes after adjusting for either apixaban or warfarin. Conclusions: AF Burden was not found to be associated with recurrent cerebrovascular events in patients taking oral anticoagulant after an AIS or TIA. Further research is needed to confirm these findings.

Role of long-term continuous cardiac monitoring in oral anticoagulation management of patients with known atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic OnBehalf Reveal LINQ Registry Investigators Background Monitoring atrial fibrillation (AF) with an insertable cardiac monitor (ICM) provides objective data for clinicians to make decisions on oral anticoagulation (OAC) management, based on individual risk profiles. Whether ICM data is being used for that purpose has not been widely explored. Purpose To show the impact of AF burden measured by an ICM on OAC treatment initiation and discontinuation in patients with known AF. Methods Patients from the prospective, ongoing, multi-center Reveal LINQ Registry monitored for AF management, or pre- or post-ablation monitoring were eligible. Follow-up was scheduled every 6 months for up to 3 years. Patients were excluded if they had no AF data available within the last 6 months of follow-up (FU), or less than 6 months of FU and no change to their OAC treatment compared to baseline. AF burden was defined as the percentage of time in AF 6 months prior to last FU, excluding the first 3 months post-ablation for patients who had an ablation. Results The analysis included 225 patients (65 ± 10 years, 72% male, mean CHA2DS2-VASc score 2.1 ± 1.4) monitored with an ICM for 21.8 ± 7.9 months. At baseline, 164 (73%) were taking OAC therapy, 147 (65%) had a history of paroxysmal AF and 79 (35%) had persistent AF. Forty percent of patients had a history of atrial ablation prior to ICM insertion and 37% had ≥1 AF ablation procedure after ICM. Patients were grouped according to OAC status at baseline, CHA2DS2-VASc score and AF burden (Figure: bars show percentage of patients with a change in OAC status during monitoring). Patients at high risk of stroke and AF burden &amp;gt;0.5% were more likely to initiate OAC therapy, whereas patients with higher AF burden were less likely to discontinue OAC, regardless of their risk score. Among those with no AF burden detected during the last 6 months of follow-up and on OAC at baseline, approximately half discontinued OAC, whereas 1/3 of patients with high risk score had initiated OAC, despite having no AF detected. Conclusion Our results derived from real-world practice show that AF detected and quantified by an ICM influences OAC therapy management in patients with known AF. Many patients with a low CHA2DS2-VASc score and no AF or low AF burden have had OAC therapy discontinuation, whereas a high proportion of patients with high AF burden have initiated OAC, regardless of their risk score. Abstract Figure. OAC according to risk and AF burden

Atrial Fibrillation Burden and Clinical Outcomes in HeartFailure: The CASTLE-AF Trial.

This subanalysis of the CASTLE-AF (Catheter Ablation vs. Standard Conventional Treatment in Patients With LV Dysfunction and AF) trial aimed to address the association between atrial fibrillation (AF) recurrence, AF burden, and hard clinical outcomes in heart failure (HF) patients with AF. The CASTLE-AF trial demonstrated the benefit of CA compared to pharmacological treatment in decreasing mortality and CV hospitalizations in patients with AF and HFrEF. However, the impact of AF recurrence and AF burden after ablation on long-term treatment benefit remains unknown. The CASTLE-AF protocol randomized 363 patients with coexisting HF and AF in a multicenter prospective controlled fashion to catheter ablation (n=179) versus pharmacological therapy (n=184). Two hundred eighty patients were included in this subanalysis (as-treated), 128 of them underwent ablation and 152 received pharmacological treatment. All patients had implanted dual chamber or biventricular implantable defibrillators with activated home monitoring capabilities. The individual AF burden was calculated as the percentage of the atrial arrhythmia time per day. AF burden at baseline was not predictive of the primary endpoint (p=0.473) or all-cause mortality (p=0.446). AF recurrence (defined as any episode >30 s) did not show any relationship with the primary endpoints of mortality and occurrence of HF, irrespective of the treatment arm. An AF burden below 50% after 6months of catheter ablation, was associated with a significant decrease in primary composite outcome (hazard ratio [HR]: 0.33; 95% confidence interval [CI]: 0.15 to 0.71; p=0.014) and all-cause mortality (HR: 0.23; 95% CI: 0.07 to 0.71; p=0.031). The risk of the primary endpoint or mortality was directly related to a low (<50%) or high (≥50%) AF burden at 6months post-ablation. AF burden at 6months was predictive of hard clinical outcomes in HF patients with AF. The first recurrent atrial tachyarrhythmia episode >30s after ablation was not associated with improvement in mortality andhospitalization for HF. (Catheter Ablation vs. Standard Conventional Treatment in Patients With LV DysfunctionandAF [CASTLE-AF]; NCT00643188).

Left atrial function assessed by speckle tracking echocardiography predicts atrial fibrillation burden after catheter ablation independently of reconduction: a RACE-AF echocardiographic sub-study

Abstract Funding Acknowledgements Type of funding sources: None. Background Left atrial (LA) function assessed by 2D speckle tracking echocardiography (STE) has demonstrated to be a useful predictor of recurrence of atrial fibrillation (AF) following catheter ablation (CA). Pulmonary vein reconduction (PVR) is one of the most important causes of recurrent paroxysmal AF (PAF) after ablation. The purpose of this study was to evaluate the association between AF burden (% of time in AF) following CA and LA strain measurements independently of PVR. Methods This prospective study included 66 patients with PAF who underwent CA (mean age 60 ± 8 years, 65% male). STE was performed during sinus rhythm prior to CA. AF burden was recorded by continuous rhythm monitoring using implantable loop recorders during a follow-up period of 4-6 months, excluding a blanking period of 3 months. After follow-up, all patients underwent an invasive assessment of pulmonary vein isolation to test for PVR. Multivariable linear regression analysis was used to assess the association between AF burden and peak atrial longitudinal reservoir strain (PALS), peak atrial contraction strain (PACS) and peak atrial conduit strain (PCS). Results Prior to CA, median AF burden was 3.8% (IQR: 0.5, 17). During follow-up, 37 patients (56%) were free of AF while median AF burden was 0.7% (IQR: 0.2, 1.6) in patients with an AF burden of more than 0%. A total of 35 patients (54%) were found to have PVR after ablation. Patients with AF recurrence had significantly lower PACS compared to patients with no AF during follow-up (10% ± 6% vs. 14% ± 5%, p = 0.004). No differences in PALS and PCS were observed. Increased PACS remained independently associated with low AF burden following CA after multivariable adjustments for clinical characteristics, comorbidities, and PVR (β=-0.262, p = 0.049) (Figure 1). PALS and PCS did not remain significantly associated with AF burden. Conclusion Increased PACS is strongly associated with low AF burden after CA even after adjusting for PVR. This suggests that an analysis of LA function could be useful to stratify patients prior to CA and improve treatment strategies. Abstract Figure.

Using 5D flow MRI to decode the effects of rhythm on left atrial 3D flow dynamics in patients with atrial fibrillation.

This study used a 5D flow framework to explore the influence of arrhythmia on thrombogenic hemodynamic parameters in patients with atrial fibrillation (AF). A fully self-gated, 3D radial, highly accelerated free-running 5D flow sequence with interleaved four-point velocity-encoding was acquired using an in vitro arrhythmic flow phantom and in 25 patients with a history of AF (68 ± 8 y, 6 female). Self-gating signals were used to calculate AF burden, bin data, and tag each k-space line with its RRLength . Data were binned as an RR-resolved dataset with four RR-interval bins (RR1-RR4, short-to-long) for compressed sensing reconstruction. AF burden was calculated as interquartile range of all intrascan RR-intervals divided by median RR-interval, and left atrial (LA) stasis as the percent of the cardiac cycle where the velocity was <0.1 m/s. In vitro results demonstrated successful recovery of RR-binned flow curves using RR-resolved 5D flow compared to a real-time PC reference standard. In vivo, 5D flow was acquired in 8:48 minutes. AF burden was significantly correlated with 5D flow-derived peak (PV) and mean (MV) velocity and stasis (|ρ| = 0.54-0.75, P < .001). Sensitivity analyses determined a threshold for low versus high AF burden at 9.7%. High burden patients had increased LA mean stasis (up to +42%, P < .01), and lower MV and PV (-30%, -40.6%, respectively, P < .01). RR4 deviated furthest from respiratory-resolved reconstruction (end-expiration) with increased mean stasis (7.6% ± 14.0%, P = .10) and decreased PV (-12.7 ± 14.2%, P = .09). RR-resolved 5D flow can capture temporal and RR-resolved 3D hemodynamics in <10 minutes and offers a novel approach to investigate arrhythmias.

Surgical ablation of atrial fibrillation in hypertrophic obstructive cardiomyopathy: Outcomes of a tailored surgical approach.

To assess outcomes of concomitant ablation for atrial fibrillation (AF) in patients with preoperative AF undergoing septal myectomy for hypertrophic obstructive cardiomyopathy. From 2005 to 2016, 67 patients underwent concomitant ablation for AF and septal myectomy and had a follow-up beyond a 3-month blanking period. Ablation strategy (pulmonary vein isolation [PVI], modified Cox-maze III [CM-III], or Cox-maze IV [CM-IV]) was tailored to preoperative AF burden, with high AF burden defined as persistent AF or need for cardioversion. AF recurrence was analyzed as a time-related event and predictors of recurrence identified using a random forest methodology. A total of 38 patients (57%) had low AF burden and 29 (43%) high burden. Patients with low AF burden most frequently underwent PVI (68%). Patients with high AF burden more frequently underwent CM-III (62%) or CM-IV (35%). Besides the preoperative AF burden, baseline characteristics were similar between patients receiving CM-III, CM-IV, and PVI. After surgery, the maximum provoked left ventricular outflow tract (LVOT) gradient decreased from 99 ± 34 to 18 ± 11mm Hg (P < .001). Eight patients (12%) required a permanent pacemaker. Cumulative AF recurrence at 1, 2, and 5 years was 11%, 22%, and 48%, respectively. Age, low preoperative resting LVOT gradient, and large left atrial diameter were predictors of AF recurrence. Surgical outcomes of concomitant ablation for AF and septal myectomy are good, although recurrence of AF by 5 years is frequent.

TREAT AF (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress Atrial Fibrillation)

This study was a sham-controlled, double-blind, randomized clinical trial to examine the effect of chronic low level tragus stimulation (LLTS) in patients with paroxysmal AF. Low-level transcutaneous electrical stimulation of the auricular branch of the vagus nerve at the tragus (LLTS) acutely suppresses atrial fibrillation (AF) in humans, but the chronic effect remains unknown. LLTS (20Hz, 1 mA below the discomfort threshold) was delivered using an ear clip attached to the tragus (active arm) (n=26) or the ear lobe (sham control arm) (n=27) for 1h daily over 6months. AF burden over 2-week periods was assessed by noninvasive continuous electrocardiogram monitoring at baseline, 3months, and 6months. Five-minute electrocardiography and serum were obtained at each visit to measure heart rate variability and inflammatory cytokines, respectively. Baseline characteristics were balanced between the 2 groups. Adherence to the stimulation protocol (≤4sessions lost per month) was 75% in the active arm and 83% in the control arm (p > 0.05). At 6months, the median AF burden was 85% lower in the active arm compared with the control arm (ratio of medians: 0.15; 95% confidence interval: 0.03 to 0.65; p=0.011). Tumor necrosis factor-alpha was significantly decreased by 23% in the active group relative to the control group (ratio of medians: 0.77; 95% confidence interval: 0.63 to 0.94; p=0.0093). Frequency domain indices of heart rate variability were significantly altered with active versus control stimulation (p<0.01). No device-related side effects were observed. Chronic, intermittent LLTS resulted in lower AF burden than did sham control stimulation, supporting its use to treat paroxysmal AF in selected patients. (Transcutaneous Electrical Vagus Nerve Stimulation to Suppress AtrialFibrillation [TREAT-AF]; NCT02548754).

Forecasting episodes of atrial fibrillation using a new machine learning algorithm

The performance of preventive pacing algorithms (PPA) that can reduce atrial fibrillation (AF) burden in cardiac electronic implanted devices (CEID's) has been disappointing. This can be due to the fact that the time frame between the start of AF and the implementation of preventive stimulation and anti-tachycardia pacing algorithms is too short. Nowadays, machine learning algorithms are powerful tools and have proven their ability to anticipate events. Therefore, we assessed forecasting of paroxysmal AF minutes before its onset using machine learning techniques. To forecast an oncoming AF episode in individual patients using machine learning techniques and to assess when a change in heart rate indicates the beginning of a possible forecast. We analysed retrospectively the raw data of a data set of 10484 ECG Holter monitorings searching for AF episodes of more than 30 sec. A hundred and forty patients presented paroxysmal AF (286 recorded AF episodes). We used only RR intervals to predict the presence of AF. It should be emphasized that we did not integrate clinical variables. We developed a deep and recurrent neural net machine learning algorithm. This algorithm was trained on using 90% of patients records and tested on the remaining 10%. Rather than attempting to predict the exact RR-interval at which AF would or would not happen our algorithm attempted to predict if AF would happen within windows of time of 30 RR intervals ( Table 1 ). The performance figures are summarized in the table. Based upon this retrospective study, AF can be forecasted thirty beats before its onset with a reasonable sensitivity, using our machine learning algorithm. We believe that its embedding in CEID's could lower AF burden by improving results of PPA in selected patients.