Atrial Fibrillation Burden During the Post-Implant Period After CRT Using Device-Based Diagnostics

Cardiac resynchronization therapy in the presence of total atrioventricular block reduces long-lasting atrial fibrillation episodes

Background

There is an ongoing debate on how cardiac resynchronization therapy (CRT) in the presence of total AV block affects atrial fibrillation (AF) episodes and symptoms in patients with AF.

Methods

Seventy-five patients with symptomatic, drug and ablation refractory AF received, irrespective of their left ventricular ejection fraction (EF), either a CRT device and underwent subsequent atrioventricular node (AVN) ablation or already had a total AV block and underwent CRT upgrade. Long-lasting AF episodes (>48 h), left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), left atrial diameter (LAD), NTproBNP levels, EHRA score, and NYHA class had been monitored on the follow-up.

Results

The number of patients experiencing long-lasting AF episodes (>48 h) and symptoms decreased significantly within 24 months after CRT implantation in the presence of total AV block (p < .001) from 57 (76%) to 25 (33.3%). Mean LAD decreased from 52 mm (IQR 48.0-56.0) to 48 mm (IQR 42.0-52.0, p < .001) and LVEDD from 54 mm (IQR 49.0-58.0) to 51 mm (IQR 46.5-54.0, p < .001).

Conclusion

A combination of total AVN block and biventricular pacing markedly reduces long-lasting AF episodes, symptoms, left atrial diameter, and left ventricular end-diastolic diameter.

Atrial fibrillation associated with heart failure treated by a 2-lead CRT-DX system (BIO-AffectDX): Study design and clinical protocol

Background

Evidence to support use of cardiac resynchronization therapy (CRT) among patients with both heart failure (HF) and atrial fibrillation (AF) is largely limited to retrospective or post hoc subanalyses. Data from a prospectively enrolled and contemporary cohort are needed.

Objective

We aim to better characterize the changes from baseline in HF patients with concomitant AF subsequently implanted with a 2-lead CRT-DX system capable of sensing in the atrium, aggregating diagnostics, and delivering CRT therapy. The primary objective of this study is to evaluate the percentage of all HF subjects with an improvement in a clinical composite score from pre-CRT implant to 12 months.

Methods

The study is a US-based, prospective, observational multicenter clinical trial conducted at up to 50 sites and enrolling approximately 400 subjects with a follow-up period of 1 year. Multiple subject assessments, atrial rhythm status, and device interrogation will be collected at follow-up visits occurring at 3, 6, and 12 months postimplant.

Results

A Clinical Events Committee will adjudicate subject HF events, arrhythmia events, death events, and all device-classified ventricular tachycardia and ventricular fibrillation episodes with treatment that are collected throughout the follow-up period. Their decisions are based on independent physician review of the data from sites and device interrogation.

Conclusion

The BIO-AffectDX study aims to provide further insight into the expected outcomes from CRT treatment in patients with HF and AF.

Nonpharmacological Treatment of Atrial Fibrillation: What Is the Role of Device Therapy?

Atrial fibrillation is the most common arrhythmia in the adult population, and its incidence and prevalence are still rising. Cardiac devices are widely used in clinical practice in the management of various rhythm disturbances and heart failure treatment. Many patients who receive a pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy also experience atrial fibrillation in the course of their life. Therefore, this review aims to describe the role of these devices in the treatment and prevention of atrial fibrillation in the device recipients. In addition, all these implantable devices also serve as permanent ECG (electrocardiogram) monitors, thus providing important information about the presence and characteristics of atrial fibrillation that may or may not be detected by the patient but can modify our therapeutical approach with regard to the stroke prevention.

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.

Atrial Fibrillation in Patients with Heart Failure: Current State and Future Directions

Heart failure affects nearly 26 million people worldwide. Patients with heart failure are frequently affected with atrial fibrillation, and the interrelation between these pathologies is complex. Atrial fibrillation shares the same risk factors as heart failure. Moreover, it is associated with a higher-risk baseline clinical status and higher mortality rates in patients with heart failure. The mechanisms by which atrial fibrillation occurs in a failing heart are incompletely understood, but animal studies suggest they differ from those that occur in a healthy heart. Data suggest that heart failure-induced atrial fibrosis and atrial ionic remodeling are the underlying abnormalities that facilitate atrial fibrillation. Therapeutic considerations for atrial fibrillation in patients with heart failure include risk factor modification and guideline-directed medical therapy, anticoagulation, rate control, and rhythm control. As recommended for atrial fibrillation in the non-failing heart, anticoagulation in patients with heart failure should be guided by a careful estimation of the risk of embolic events versus the risk of hemorrhagic episodes. The decision whether to target a rate-control or rhythm-control strategy is an evolving aspect of management. Currently, both approaches are good medical practice, but recent data suggest that rhythm control, particularly when achieved through catheter ablation, is associated with improved outcomes. A promising field of research is the application of neurohormonal modulation to prevent the creation of the "structural substrate" for atrial fibrillation in the failing heart.

Comparative Effectiveness of Cardiac Resynchronization Therapy Among Patients With Heart Failure and Atrial Fibrillation: Findings From the National Cardiovascular Data Registry's Implantable Cardioverter-Defibrillator Registry

BACKGROUND

Atrial fibrillation is common in patients with heart failure, but outcomes of patients with both conditions who receive cardiac resynchronization therapy with defibrillator (CRT-D) compared with an implantable cardioverter-defibrillator (ICD) alone are unclear.

METHODS AND RESULTS

Using the National Cardiovascular Data Registry's ICD Registry linked with Medicare claims, we identified 8951 patients with atrial fibrillation who were eligible for CRT-D and underwent first-time device implantation for primary prevention between April 2006 and December 2009. We used Cox proportional hazards models and inverse probability-weighted estimates to compare outcomes with CRT-D versus ICD alone. Cumulative incidence of mortality (744 [33%] for ICD; 1893 [32%] for CRT-D) and readmission (1788 [76%] for ICD; 4611 [76%] for CRT-D) within 3 years and complications within 90 days were similar between groups. After inverse weighting for the probability of receiving CRT-D, risks of mortality (hazard ratio, 0.83; 95% confidence interval, 0.75-0.92), all-cause readmission (hazard ratio, 0.86; 95% confidence interval, 0.80-0.92), and heart failure readmission (hazard ratio, 0.68; 95% confidence interval, 0.62-0.76) were lower with CRT-D compared with ICD alone. There was no significant difference in the 90-day complication rate (hazard ratio, 0.88; 95% confidence interval, 0.60-1.29). We observed hospital-level variation in the use of CRT-D among patients with atrial fibrillation.

CONCLUSIONS

Among eligible patients with heart failure and atrial fibrillation, CRT-D was associated with lower risks of mortality, all-cause readmission, and heart failure readmission, as well as with a similar risk of complications compared with ICD alone.

Analyses of inappropriate shocks in a Spanish ICD primary prevention population: Predictors and prognoses

BACKGROUND

ICDs have been demonstrated to be highly effective in the primary prevention of sudden death, but inappropriate shocks (IS) occur frequently and represent one of the most important adverse effects of ICDs. The aim of this study was to analyze IS and identify the clinical predictors and prognostic implications of ISs in a real-world primary prevention ICD population.

METHODS

This multicenter retrospective study was performed in 13 centers with experience in the field of ICD implantation (at least 30 per year) and ICD follow-up in Spain. All consecutive patients who underwent ICD implantation for primary prevention between January 2008 and May 2014 were included.

RESULTS

One-thousand-sixteen patients were included, and 4 (0.39%) were lost to follow-up. Two-hundred-seventeen (21.4%) patients suffered from shock; 69 (6.8%) of these patients experienced IS, and 154 (15.4%) experienced appropriate shocks (AS). Age (<65 years, hazard ratio (HR) 2.588 [95% CI 1.282-5.225]; p=0.008), history of atrial fibrillation (HR 2.252 [95% CI 1.230-4.115]; p=0.009), non-ischemic myocardiopathy (HR 2.258 [95% CI 1.090-4.479]; p=0.028), and cardiac resynchronization therapy (HR 0.385 [95% CI 0.200-0.740]; p=0.004) were identified as IS predictors in a multivariate analysis. IS was not associated with rehospitalization due to heart failure, myocardial infarction, cardiovascular mortality or all-cause mortality.

CONCLUSIONS

This analysis of our national registry identified the independent IS predictors of age, atrial fibrillation history and cardiac resynchronization therapy and suggests that ISs are not linked to poorer clinical endpoints.

Is cardiac resynchronization therapy an antiarrhythmic therapy for atrial fibrillation? A systematic review and meta-analysis

The impact of cardiac resynchronization therapy (CRT) on atrial fibrillation (AF) burden is poorly characterized. To assess the influence of CRT on AF, we performed a systematic literature search in MEDLINE using the MeSH headings "cardiac resynchronization therapy" or "cardiac pacing, artificial" and "atrial fibrillation." Selected studies were peer-reviewed and written in English. Most studies enrolled patients meeting traditional CRT criteria. Ten observational studies and two secondary analyses of clinical trials were identified. Although ten studies suggest that CRT favorably impacts AF, one secondary analysis of a clinical trial showed no effect of CRT on new-onset AF. In a meta-analysis of three studies examining the effect of CRT on persistent or permanent AF, the combined rate of conversion from persistent or permanent AF to sinus rhythm was 0.107 (95 % confidence interval 0.069-0.163). Prospective studies, particularly among patients not meeting traditional CRT criteria, are needed.

Feasibility and efficacy of electrical cardioversion after cardiac resynchronization implantation in patients with permanent atrial fibrillation

PURPOSE

Patients with permanent atrial fibrillation (AF) who undergo cardiac resynchronization therapy (CRT) may spontaneously recover sinus rhythm during follow-up. We tested the feasibility and efficacy of electrical cardioversion attempted after 3 months of CRT in patients with permanent AF and measured the long-term maintenance of sinus rhythm.

METHODS

Twenty-eight consecutive patients with permanent AF in whom CRT defibrillators had been implanted were scheduled for internal electrical cardioversion after 3 months (group A) and were compared with a control group of 27 patients (group B).

RESULTS

In group A, 22 patients (79 %) were eligible for cardioversion; sinus rhythm was restored in 18 (82 %) of these, with no procedural complications. After 12 months, 16 patients (58 %) in group A were in sinus rhythm, compared with one group B patient who spontaneously recovered sinus rhythm (4 %, p < 0.001). On 12-month evaluation, ejection fraction had improved in both groups, but a reduction in left ventricular end-systolic volume was recorded only in group A patients (p = 0.018 versus baseline).

CONCLUSIONS

In patients with permanent AF, the rhythm control strategy consisting of internal cardioversion, performed by means of the implanted cardioverter-defibrillator after 3 months of CRT, was associated with a high rate of sinus rhythm resumption on long-term follow-up and with a better echocardiographic response to CRT than that seen in patients treated according to a rate control strategy.

Impact of chronic atrial fibrillation in patients with severe heart failure and indication for CRT: data of two registries with 711 patients (1999-2006 and 2007-6/2008)

AIMS

Atrial fibrillation (AF) is a relevant comorbidity in heart failure (HF) patients. In milestone cardiac resynchronization therapy (CRT) studies, patients with AF were excluded. We sought to investigate the influence of chronic atrial fibrillation (AF) on patients with CRT. AV node (AVN) ablation is frequently recommended. Converting AF to sinus rhythm (SR) is not a standard concept.

METHODS

A total of 584 consecutive patients with CRT devices were included in a single-center registry from 1999-2006 (retrospective registry) and 127/324 patients from 2007-06/2008 (prospective registry). The impact of persistent AF (group 1) on clinical and echocardiographic improvement compared with patients in SR (group 2) after 12 (6) months follow-up were analyzed. Re-establishing SR after initial cardioversion or need for AVN ablation was examined.

RESULTS

In the retrospective registry, 139 (24%) patients presented with AF (group 1) and 445 with SR (group 2). The groups differed in age, gender, and left atrium (LA) size but not in NYHA class, ejection fraction (EF), left ventricular end-diastolic dimension (LVEDD), B-type natriuretic peptide (BNP) levels, QRS width, and underlying disease. After 1 year, CRT improvement of NYHA class and EF was similar with higher mortality in group 1 (12% vs. 7%; OR 1.80; 95% confidence interval 0.95-3.4). The AF group presented with SR in 33/82 (40%) patients and 11% needed AVN ablation. The prospective data showed 27 (21%) patients in AF with conversion to SR in 41% after 6 months.

CONCLUSION

Patients with severe HF and chronic AF had a comparable improvement with CRT as those in SR. CRT is a successful treatment option in patients with chronic AF offering the potential to restore SR in a significant number of patients.

Cardiac resynchronization therapy for patients with atrial fibrillation

Atrial fibrillation and chronic heart failure are two major and even growing cardiovascular conditions that often coexist. Cardiac resynchronization therapy is an important, device-based, non-pharmacological approach in a selected group of chronic heart failure patients that has been shown to improve left ventricular function and to reduce both morbidity and mortality in large randomized trials. The latest European and American guidelines have considered atrial fibrillation patients with heart failure eligible for cardiac resynchronization therapy. This review summarizes current literature concerning the following topics: prognostic relevance of atrial fibrillation in heart failure, effects of cardiac resynchronization therapy in atrial fibrillation, relevance and strategies of rhythm and rate control in this group of patients. Authors explain how atrial fibrillation may interfere with the delivery of adequate cardiac resynchronization therapy, how to reduce the burden of atrial tachyarrhythmias, and finally present a brief overview. Orv. Hetil., 2011, 152, 1757–1763.

Mesoporous silica as a membrane for ultra-thin implantable direct glucose fuel cells

The design, fabrication and characterization of an inorganic catalyst based direct glucose fuel cell using mesoporous silica coating as a functional membrane is reported. The desired use of mesoporous silica based direct glucose fuel cell is for a blood vessel implantable device. Blood vessel implantable direct glucose fuel cells have access to higher continuous glucose concentrations. However, reduction in the implant thickness is required for application in the venous system as part of a stent. We report development of an implantable device with a platinum thin-film (thickness: 25 nm) deposited on silicon substrate (500 μm) to serve as the anode, and graphene pressed on a stainless steel mesh (175 μm) to serve as the cathode. Control experiments involved the use of a surfactant-coated polypropylene membrane (50 μm) with activated carbon (198 μm) electrodes. We demonstrate that a mesoporous silica thin film (270 nm) is capable of replacing the conventional polymer based membranes with an improvement in the power generated over conventional direct glucose fuel cells.

Treatment of atrial fibrillation with a dual defibrillator in heart failure patients (TRADE HF): protocol for a randomized clinical trial

Background

Heart failure(HF) and atrial fibrillation(AF) frequently coexist in the same patient and are associated with increased mortality and frequent hospitalizations. As the concomitance of AF and HF is often associated with a poor prognosis, the prompt treatment of AF in HF patients may significantly improve outcome.

Methods/design

Recent implantable cardiac resynchronization (CRT) devices allow electrical therapies to treat AF automatically. TRADE-HF (trial registration: NCT00345592; http://www.clinicaltrials.gov) is a prospective, randomized, double arm study aimed at demonstrating the efficacy of an automatic, device-based therapy for treatment of atrial tachycardia and fibrillation(AT/AF) in patients indicated for CRT. The study compares automatic electrical therapy to a traditional more usual treatment of AT/AF: the goal is to demonstrate a reduction in a combined endpoint of unplanned hospitalizations for cardiac reasons, death from cardiovascular causes or permanent AF when using automatic atrial therapy as compared to the traditional approach involving hospitalization for symptoms and in-hospital treatment of AT/AF.

Discussion

CRT pacemaker with the additional ability to convert AF as well as ventricular arrhythmias may play a simultaneous role in rhythm control and HF treatment. The value of the systematic implantation of CRT ICDs with the capacity to deliver atrial therapy in HF patients at risk of AF has not yet been explored. The TRADE-HF study will assess in CRT patients whether a strategy based on automatic management of atrial arrhythmias might be a valuable option to reduce the number of hospital admission and to reduce the progression the arrhythmia to a permanent form.

Trial registration

NCT00345592

Frequency of atrial tachyarrhythmias in patients treated by cardiac resynchronization (from the Prospective, Multicenter Mona Lisa Study)

The continuous measurement of sustained atrial tachyarrhythmia (AT) is now possible with some permanently implanted devices. Data on this subject remain controversial. The aim of this study was to evaluate the incidence of sustained AT in patients treated with cardiac resynchronization therapy using pacemakers without backup defibrillators (CRT-P), within the first year after implantation, using strict definition criteria for sustained AT and a systematic review of all high-quality electrographically recorded episodes. The Mona Lisa study was a prospective, multicenter, cohort study carried out from February 2004 to February 2006, with a 12-month follow-up period. Sustained AT was defined as an episode lasting > or =5 minutes; episodes were confirmed by a systematic review of electrograms in the whole study population. Of the 198 patients who underwent CRT-P device implantation and were enrolled in the study, 173 were in stable sinus rhythm at baseline and were included in the analysis (mean age 70 +/- 9 years, 66% men, 91% in New York Heart Association class III, mean QRS duration 164 +/- 26 ms, mean left ventricular ejection fraction 25 +/- 7%). During a mean follow-up period of 9.9 +/- 3.6 months, 34 patients experienced > or =1 episode of sustained AT, for an incidence rate of 27.5% (95% confidence interval 18.2 to 36.7). Only a history of AT was independently associated with the occurrence of sustained AT within the 12 months after CRT-P device implantation (hazard ratio 2.3, 95% confidence interval 1.2 to 4.4, p = 0.02). In conclusion, this first prospective electrogram-based evaluation of AT incidence demonstrated that 27% of patients developed > or =1 episode of sustained AT lasting > or =5 minutes in the 12 months after CRT-P device implantation.

Incidence of paroxysmal atrial tachycardias in patients treated with cardiac resynchronization therapy and continuously monitored by device diagnostics

AIMS

Little is known about the incidence of paroxysmal atrial tachycardias (PAT) in patients with heart failure (HF). The availability of cardiac resynchronization therapy (CRT) devices with extended diagnostics for AT enables continuous monitoring of PAT episodes. The aim of the study was to assess the incidence over time of PAT in HF patients treated with CRT.

METHODS AND RESULTS

Consecutive patients in NYHA functional class III or IV despite optimal drug therapy, QRS duration > or = 130 ms, left ventricular ejection fraction < or = 35%, and left ventricular end-diastolic dimension > or = 55 mm were eligible for enrolment. Patients with permanent or persistent atrial fibrillation (AF) were not included in the study. The first follow-up examination was performed 2 weeks after implantation, to optimize atrial sensing and CRT. Subsequent follow-up examinations were carried out 15 and 28 weeks after implantation, to collect the telemetric data. A total of 173 patients (67 +/- 11 years, M 116) were enrolled. Complete arrhythmia monitoring data were available from 120 patients over a mean follow-up of 183 +/- 23 days. Atrial tachycardia episodes were detected through telemetry in 25 of 120 patients (21%) during at least one follow-up examination. Atrial tachycardia episodes were recorded in 29 and 17% (P = NS) of patients with and without previous history of AF, respectively.

CONCLUSION

More than 20% of the overall HF patient population treated with CRT suffer PAT episodes. Paroxysmal atrial tachycardia may interfere with response to CRT. Therefore, telemetric data may be relevant to drive the appropriate therapy in each patient.

Improvement of P wave dispersion after cardiac resynchronization therapy for heart failure

OBJECTIVE

The purpose of this study is to investigate the effect of cardiac resynchronization therapy (CRT) on P wave maximum duration (PWM) and P wave dispersion (PWD) in patients with advanced heart failure.

METHODS

Forty-six patients (33 men; mean age, 60 +/- 11 years) with CRT were enrolled in the present study. PWM and PWD were measured using 12-lead surface electrocardiography (ECG) at a paper speed of 50 mm/s and 20 mm/mV. Serial ECG, echocardiography, clinical assessment, and device interrogations were performed at baseline and 3 months after CRT.

RESULTS

After 3 months of follow-up, PWM and PWD values were significantly decreased (129.6 +/- 11.3 to 120.7 +/- 10.7 milliseconds, P < .001; 42.6 +/- 8.0 to 32.3 +/- 10.1 milliseconds; P < .001, respectively). It showed a significant reduction in left atrial diameter (LAD) (46.5 +/- 5.2 to 44.9 +/- 5.6 mm, P = .021) and an improvement in left ventricular ejection fraction (LVEF) (29.0% +/- 7.5% to 36.2% +/- 8.0%, P < .001). The decrease of PWM and PWD was positively correlated with the reduction of LAD and negatively correlated with the improvement of LVEF. The reduction in atrial fibrillation burden was observed after 3 months of follow-up.

CONCLUSIONS

Cardiac resynchronization therapy decreases PWM and PWD along with an improvement of LVEF and a reduction of LAD. Further studies are needed to evaluate the clinical implications of decrease of PWD on prevention of atrial fibrillation.

Atrial fibrillation in heart failure: current treatment of patients with remodeled atria

Atrial fibrillation (AF) and chronic heart failure (CHF) can be caused by each other, and therefore constitute a vicious circle. The prevalence of both conditions is about 1% in industrialized countries and increases with age. Although mortality is increased in heart failure, the additional prognostic relevance of AF in these patients is less clear. AF in patients with CHF can worsen heart failure symptoms, cause complications (eg, stroke), and is difficult to treat. Thus, prevention of AF entirely is an important goal. This review summarizes recent data concerning prognostic relevance, treatment, and means of primary and secondary prevention of AF in patients with CHF.

Effect of cardiac resynchronization therapy on conversion of persistent atrial fibrillation to sinus rhythm

BACKGROUND

Spontaneous conversion of persistent atrial fibrillation to sinus rhythm (SR) has anecdotally been reported following cardiac resynchronisation therapy.

OBJECTIVE

This monocenter observational study was designed to estimate the incidence of spontaneous conversion of persistent atrial fibrillation to SR in consecutive patients implanted with a cardiac resynchronisation device.

METHODS AND RESULTS

A total of 46 patients with persistent atrial fibrillation (> or =4 weeks pre-implant), left bundle branch block (QRS > 130 ms), left ventricular ejection fraction <0.35 and NYHA III or IV heart failure were implanted with a cardiac resynchronisation pacemaker or defibrillator and followed for at least 6 months between 6/2000 to 12/2006. During 22 +/- 9 (7-34) months of follow-up, eight out of 46 patients (17%) converted to SR. Spontaneous conversion was encountered in seven cases, whereas one patient converted due to an ICD shock delivered for ventricular tachycardia; in the latter patient, previous ICD shocks had not converted atrial fibrillation. The time interval from device implantation to conversion was 12 +/- 11 (3-31) months. In patients converting to SR, the duration of atrial fibrillation before device implantation was significantly shorter than in patients remaining in atrial fibrillation (15 +/- 13 vs. 53 +/- 58 months, P = 0.001). Echocardiographic parameters such as left ventricular ejection fraction, left ventricular end-diastolic diameter, left atrial diameter did not differ significantly between converting and non-converting patients. However, patients converting to SR showed a significant reduction in systolic pulmonary artery pressure on CRT vs. before CRT (45 +/- 13 vs. 29 +/- 5 mmHg, P = 0.008).

CONCLUSIONS

This pilot study suggests that CRT favors spontaneous conversion of persistent AF to SR in a minority of patients. If confirmed by larger clinical studies, atrial lead implantation would be encouraged in these patients, in order to provide AV synchronous pacing in case of spontaneous conversion or successful cardioversion to SR on cardiac resynchronisation therapy.

Atrial fibrillation in recipients of cardiac resynchronization therapy device: 1-year results of the randomized MASCOT trial

BACKGROUND

Atrial fibrillation (AF) is associated with increased morbidity and mortality in patients suffering from heart failure (HF). Patients in New York Heart Association HF classes III or IV, with systolic dysfunction and a wide QRS, are candidates for cardiac resynchronization therapy (CRT), and might benefit from atrial overdrive pacing (AOP).

METHODS

The Management of Atrial fibrillation Suppression in AF-HF COmorbidity Therapy (MASCOT) trial enrolled 409 CRT device recipients (79% men), who were randomly assigned to AOP ON (n = 197), versus AOP OFF (n = 197) and followed up for 1 year. Their mean age was 68 +/- 10 years, left ventricular ejection fraction 25 +/- 6%, QRS duration 163 +/- 29 milliseconds. New York Heart Association class III was present in 86% of patients and 19% had a history of paroxysmal AF. The primary study end point was incidence of permanent AF at 1 year.

RESULTS

Atrial overdrive pacing increased the percentage of atrial pacing from 30% to 80% (P < .0001), was well tolerated, and did not interfere with (a) delivery of CRT (95% mean ventricular pacing in both groups), (b) response to CRT (70% responders in the control vs 67% in the treatment group), or (c) cardiac function (left ventricular ejection fraction increased from 24.5% +/- 6.2% to 32.7% +/- 10.9% in the control and from 25.8% +/- 6.8% to 33.1% +/- 12.6% in the treatment group). The incidence of permanent AF was 3.3% in both groups. By logistic regression analysis, a history of AF (P < .001) and absence of antiarrhythmic drugs (P = .002) were associated with permanent AF.

CONCLUSIONS

In this first trial of a specific AF prevention algorithm in CRT recipients, AOP was safe and did not worsen HF. The prevention algorithm did not lower the 1-year incidence of AF.

Burden of atrial fibrillation after cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) may diminish atrial fibrillation (AF) burden in patients with chronic heart failure (HF). Each of 27 patients without permanent AF in whom CRT implantation was unsuccessful was paired with 2 active CRT patients-1 responder and 1 nonresponder-based on age, gender, cause of HF, and history of paroxysmal AF. Device-documented high atrial rates and mode-switching episodes were tabulated during a median follow-up of 386 days. CRT responders had significantly improved left ventricular (LV) ejection fraction and New York Heart Association functional class compared with nonresponders and controls. Left atrial dimension change was similar among the groups (+0.03 +/- 0.92 cm controls; -0.18 +/- 0.80 cm responders; -0.11 +/- 1.01 cm nonresponders) despite a significant reduction in mitral regurgitation in responders compared with nonresponders. There was no significant difference in AF burden between controls and patients who underewent CRT when indexed over time. Median AF-free follow-up was significantly longer in patients who underwent CRT without a history of AF (log-rank p = 0.04), but no differences were seen in the overall cohorts. In conclusion, despite inducing LV reverse remodeling and clinical improvement, CRT does not appear to decrease AF burden in responders compared with nonresponders or matched controls in whom CRT implantation failed. CRT may, however, delay onset of new AF.

Resynchronization therapy in the context of atrial fibrillation: Benefits and limitations

Atrial fibrillation (AF) and heart failure often coexist and are believed to directly predispose to each other. Cardiac resynchronization does not prevent or increase the induction of AF. However, new onset of AF does not seem to diminish the beneficial effects of CRT on symptoms, cardiac function and, more importantly, all-cause mortality if appropriate ventricular rate control by beta-blockers and digoxin is being achieved. While a pharmacological approach to control ventricular rate may be sufficient in most patients with paroxysmal AF or AF of shorter duration in those with permanent AF ablation strategies may be necessary. Observational studies and one randomized trial indicate a potential benefit of CRT in heart failure patients with chronic AF; particularly, biventricular pacing was superior compared to conventional right-univentricular stimulation. However, recent results suggest that even relatively high percentage biventricular capture may be inadequate, and that the benefits of CRT may only be extended to chronic AF patients with previous AV junctional ablation. Well designed and powered clinical trials are required before pacemaker dependency is created in large numbers of heart failure patients.