Continuous monitoring of atrial fibrillation in heart failure

In patients with atrial fibrillation (AF) undergoing cardiac resynchronization therapy (CRT) for heart failure, continuous monitoring of the percentage of biventricular BiV% pacing has shown that the greatest improvement and reduction in mortality occur with a BiV pacing greater than 98%. Continuous monitoring of BiV pacing has improved the CRT management of patients with AF. Continuous monitoring has generated important new questions about anticoagulant therapy, which require randomized trials. Anticoagulant therapy should probably be considered in patients who have a high risk of thromboembolism according to standard scoring systems.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

CLINICAL TRIAL REGISTRATION

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

Ganglionated plexus ablation vs linear ablation in patients undergoing pulmonary vein isolation for persistent/long-standing persistent atrial fibrillation: a randomized comparison

BACKGROUND

The optimal ablation technique for persistent and long-standing persistent atrial fibrillation (AF) is unclear. Both linear lesion (LL) and ganglionated plexus (GP) ablation have been used in addition to pulmonary vein isolation (PVI), but no direct comparison of the 2 methods exists.

OBJECTIVE

The aim of this study is to assess the comparative safety and efficacy of 2 different ablation strategies-PVI+LL vs PVI+GP ablation -in patients with persistent or long-standing persistent AF.

METHODS

Two hundred sixty-four consecutive patients with persistent/long-standing persistent AF were randomly assigned to 2 different ablation schemes: PVI+LL (n = 132) and PVI+GP (n = 132) ablation. Consistent sinus rhythm (SR) off antiarrhythmic drug was assessed after follow-up of at least 3 years with the use of an implanted monitoring device.

RESULTS

All procedural end points were acutely achieved. At 12 months after a single procedure, 47% of the patients treated with PVI+LL were in SR compared to 54% of the patients treated with PVI+GP (P = .29). At 3 years, 34% of the patients with PVI+LL and 49% of the patients with PVI+GP maintained SR (P = .035). Atrial flutter was more frequent in the PVI+LL group than in PVI+GP group (18% vs 6%; P = .002). After a second procedure in 78 patients of the PVI+LL group and 55 patients of the PVI+GP group, the long-term overall success rate was 52% and 68%, respectively (P = .006).

CONCLUSIONS

PVI+GP ablation confers superior clinical results with less ablation-related left atrial flutter and reduced AF recurrence compared to PVI+LL ablation at 3 years of follow-up.

Acute termination of human atrial fibrillation by identification and catheter ablation of localized rotors and sources: first multicenter experience of focal impulse and rotor modulation (FIRM) ablation

INTRODUCTION

Catheter ablation of atrial fibrillation (AF) currently relies on eliminating triggers, and no reliable method exists to map the arrhythmia itself to identify ablation targets. The aim of this multicenter study was to define the use of Focal Impulse and Rotor Modulation (FIRM) for identifying ablation targets.

METHODS

We prospectively enrolled the first (n = 14, 11 males) consecutive patients undergoing FIRM-guided ablation for persistent (n = 11) and paroxysmal AF at 5 centers. A 64-pole basket catheter was used for panoramic right and left atrial mapping during AF. AF electrograms were analyzed using a novel system to identify sustained rotors (spiral waves), or focal beats (centrifugal activation to surrounding atrium). Ablation was performed first at identified sources. The primary endpoints were acute AF termination or organization (>10% cycle length prolongation). Conventional ablation was performed only after FIRM-guided ablation.

RESULTS

Twelve out of 14 cases were mapped. AF sources were demonstrated in all patients (average of 1.9 ± 0.8 per patient). Sources were left atrial in 18 cases, and right atrial in 5 cases, and 21/23 were rotors. FIRM-guided ablation achieved the acute endpoint in all patients, consisting of AF termination in n = 8 (4.9 ± 3.9 minutes at the primary source), and organization in n = 4. Total FIRM time for all patients was 12.3 ± 8.6 minutes.

CONCLUSIONS

FIRM-guided ablation revealed localized AF rotors/focal sources in patients with paroxysmal, persistent and longstanding persistent AF. Brief targeted FIRM-guided ablation at a priori identified sites terminated or substantially organized AF in all cases prior to any other ablation.

A randomized comparison of pulmonary vein isolation with versus without concomitant renal artery denervation in patients with refractory symptomatic atrial fibrillation and resistant hypertension

OBJECTIVES

The aim of this prospective randomized study was to assess the impact of renal artery denervation in patients with a history of refractory atrial fibrillation (AF) and drug-resistant hypertension who were referred for pulmonary vein isolation (PVI).

BACKGROUND

Hypertension is the most common cardiovascular condition responsible for the development and maintenance of AF. Treating drug-resistant hypertension with renal denervation has been reported to control blood pressure, but any effect on AF is unknown.

METHODS

Patients with a history of symptomatic paroxysmal or persistent AF refractory to ≥2 antiarrhythmic drugs and drug-resistant hypertension (systolic blood pressure >160 mm Hg despite triple drug therapy) were eligible for enrolment. Consenting patients were randomized to PVI only or PVI with renal artery denervation. All patients were followed ≥1 year to assess maintenance of sinus rhythm and to monitor changes in blood pressure.

RESULTS

Twenty-seven patients were enrolled, and 14 were randomized to PVI only, and 13 were randomized to PVI with renal artery denervation. At the end of the follow-up, significant reductions in systolic (from 181 ± 7 to 156 ± 5, p < 0.001) and diastolic blood pressure (from 97 ± 6 to 87 ± 4, p < 0.001) were observed in patients treated with PVI with renal denervation without significant change in the PVI only group. Nine of the 13 patients (69%) treated with PVI with renal denervation were AF-free at the 12-month post-ablation follow-up examination versus 4 (29%) of the 14 patients in the PVI-only group (p = 0.033).

CONCLUSIONS

Renal artery denervation reduces systolic and diastolic blood pressure in patients with drug-resistant hypertension and reduces AF recurrences when combined with PVI.

ISHNE/EHRA expert consensus on remote monitoring of cardiovascular implantable electronic devices (CIEDs)

We are in the midst of a rapidly evolving era of technology-assisted medicine. The field of telemedicine provides the opportunity for highly individualized medical management in a way that has never been possible before. Evolving medical technologies using cardiac implantable devices with capabilities for remote monitoring permit evaluation of multiple parameters of cardiovascular physiology and risk, including cardiac rhythm, device function, blood pressure values, the presence of myocardial ischaemia, and the degree of compensation of congestive heart failure. Cardiac risk, device status, and response to therapies can now be assessed with these electronic systems of detection and reporting. This document reflects the extensive experience from investigators and innovators around the world who are shaping the evolution of this rapidly expanding field, focusing in particular on implantable pacemakers, implantable cardioverter defibrillators, devices for cardiac resynchronization therapy (both with and without defibrillation properties), loop recorders, and hemodynamic monitoring devices. This document covers the basic methodologies, guidelines for their use, experience with existing applications, and the legal and reimbursement aspects associated with their use. To adequately cover this important emerging topic, the International Society for Holter and Noninvasive Electrocardiology and the European Heart Rhythm Association combined their expertise in this field. We hope that the development of this field can contribute to improve care of our cardiovascular patients.

Predictors of response to cardiac resynchronization therapy in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT)

BACKGROUND

We hypothesized that combined assessment of factors that are associated with favorable reverse remodeling after cardiac resynchronization-defibrillator therapy (CRT-D) can be used to predict clinical response to the device.

METHODS AND RESULTS

The study population comprised 1761 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT). Best-subset regression analysis was performed to identify factors associated with echocardiographic response (defined as percent reduction in left ventricular end-diastolic volume 1 year after CRT-D implantation) and to create a response score. Cox proportional hazards regression analysis was used to evaluate the CRT-D versus defibrillator-only reduction in the risk of heart failure or death by the response score. Seven factors were identified as associated with echocardiographic response to CRT-D and made up the response score (female sex, nonischemic origin, left bundle-branch block, QRS ≥150 milliseconds, prior hospitalization for heart failure, left ventricular end-diastolic volume ≥125 mL/m(2), and left atrial volume <40 mL/m(2)). Multivariate analysis showed a 13% (P<0.001) increase in the clinical benefit of CRT-D per 1-point increment in the response score (range, 0-14) and a significant direct correlation between risk reduction associated with CRT-D and response score quartiles: Patients in the first quartile did not derive a significant reduction in the risk of heart failure or death with CRT-D (hazard ratio=0.87; P=0.52); patients in the second and third quartiles derived 33% (P=0.04) and 36% (P=0.03) risk reductions, respectively; and patients in the upper quartile experienced a 69% (P<0.001) risk reduction (P for trend=0.005).

CONCLUSION

Combined assessment of factors associated with reverse remodeling can be used for improved selection of patients for cardiac resynchronization therapy. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.

Cardiac Resynchronization Therapy and Atrial Fibrillation

Cardiac resynchronization therapy (CRT) is an important advance for the treatment of end--stage heart failure (HF). About 15-50% of HF is complicated by atrial fibrillation (AF) and associated with worsened outcomes. Meta-analyses from observational studies suggest that patients with AF derive similar benefits to CRT as patients in sinus rhythm (SR). The presence of AF, however, may interfere with optimal delivery of CRT due to competition with biventricular (BiV) capture by conducted beats. Atrioventricular junction (AVJ) ablation with permanent pacing eliminates interference by conducted beats and provides complete BiV capture. Catheter ablation of AF is an alternative to antiarrhythmic drugs to maintain sinus rhythm in patients with AF and HF. Randomized trial comparing catheter ablation, AVJ ablation and pharmacologic therapy are needed.

Cardiac resynchronization therapy: an updateimpaired left ventricular systolic function

Cardiac resynchronization therapy has been shown to reduce hospitalization and mortality, and to improve heart failure symptoms, in patients with systolic dysfunction and ventricular dyssynchrony. We review the current guidelines for cardiac resynchronization therapy, the underlying evidence, the latest developments in the field and directions of future research.

Time-dependent benefit of preventive cardiac resynchronization therapy after myocardial infarction

AIMS

Cardiac remodelling is a progressive process after myocardial infarction (MI). However, currently there are no data regarding the effect of s:elapsed time from MI on the benefit of cardiac resynchronization therapy with defibrillator (CRT-D). The present study was designed to evaluate the relationship between elapsed time from MI and the benefit of preventive CRT-D therapy in patients with ischaemic cardiomyopathy (ICM).

METHODS AND RESULTS

The risk of heart failure (HF) or death as a function of elapsed time from MI to enrolment, by treatment with CRT-D vs. implantable cardioverter defibrillator (ICD)-only therapy, was assessed among 704 ICM patients with a documented MI enrolled in MADIT-CRT, and separately in a subset of ICM patients without a documented prior MI (n = 237). In ICD patients, the adjusted risk of HF or death increased by 4% (P = 0.01) for each year elapsed from MI. Multivariate analysis demonstrated that patients with remote MI [categorized at the median value (≥8 years)] derived a significantly greater benefit from CRT-D [HR = 0.42 (P < 0.001)] than those with a more recent MI [HR = 1.26 (P = 0.35); P-value for interaction <0.001]. Consistently, the benefit of CRT-D was directly related to increasing quartiles of elapsed time from MI [Q(1) (<3 years): HR = 1.67; P = 0.20, Q(2) (3-8 years): HR = 1.12; P = 0.71, Q(3) (8-15 years): HR = 0.47; P = 0.02, and Q(4) (≥15 years): HR = 0.38; P = 0.001]. The ICM subgroup with no documented MI also derived enhanced benefit from CRT-D (HR = 0.43; P = 0.003).

CONCLUSION

In patients with ischaemic cardiomyopathy, the risk of HF or death and the magnitude of CRT-D benefit are directly related to elapsed time from MI.

Long-term implications of cumulative right ventricular pacing among patients with an implantable cardioverter-defibrillator

BACKGROUND

Limited data regarding the effect of right ventricular pacing (RVP) on long-term survival following implantable cardioverter-defibrillator (ICD) implantation are available.

OBJECTIVE

The purpose of this study was to evaluate the effect of RVP on the long-term survival benefit of primary ICD therapy.

METHODS

Mortality data were obtained for all patients enrolled in the Multicenter Automatic Defibrillator Trial-II (MADIT-II) during an extended follow-up period of 8 years. The cumulative percent RVP during the trial was categorized as low (≤ 50% [n = 369]) and high (>50% [n = 198]). The benefit of ICD versus non-ICD therapy (n = 490) was evaluated in the two pacing categories during the early (0-3 years) and late (4-8 years) phases of the extended follow-up period.

RESULTS

During the early phase of the extended follow-up period, ICD therapy was associated with similar benefits in the low-RVP and high-RVP subgroups (hazard ratio [HR] = 0.35 and 0.38, respectively, P <.001 for both). In contrast, during the late phase, the long-term survival benefit of the ICD was maintained among patients with low RVP (HR = 0.60, P <.001) and attenuated among those with the high RVP (HR = 0.89, P = .45). An increased risk for late mortality associated with high versus low RVP was evident only among patients without left bundle branch [LBBB] at enrollment (HR = 1.63, P = .002).

CONCLUSION

Among ICD recipients, high RVP is associated with a significant increase in the risk of long-term mortality and with attenuated device efficacy. The deleterious effects of RVP are pronounced mainly in non-LBBB patients, suggesting a possible role for combined cardiac resynchronization-defibrillator therapy in this population.

Value of the signal-averaged electrocardiogram in arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited disease that causes structural and functional abnormalities of the right ventricle (RV). The presence of late potentials as assessed by the signal-averaged electrocardiogram (SAECG) is a minor task force criterion.

OBJECTIVE

The purpose of this study was to examine the diagnostic and clinical value of the SAECG in a large population of genotyped ARVC/D probands.

METHODS

We compared the SAECGs of 87 ARVC/D probands (age 37 ± 13 years, 47 males) diagnosed as affected or borderline by task force criteria without using the SAECG criterion with 103 control subjects. The association of SAECG abnormalities was also correlated with clinical presentation, surface ECG, ventricular tachycardia (VT) inducibility at electrophysiologic testing, implantable cardioverter-defibrillator therapy for VT, and RV abnormalities as assessed by cardiac magnetic resonance imaging (cMRI).

RESULTS

Compared with controls, all three components of the SAECG were highly associated with the diagnosis of ARVC/D (P <.001). They include the filtered QRS duration (97.8 ± 8.7 ms vs 119.6 ± 23.8 ms), low-amplitude signal (24.4 ± 9.2 ms vs 46.2 ± 23.7 ms), and root mean square amplitude of the last 40 ms of the QRS (50.4 ± 26.9 μV vs 27.9 ± 36.3 μV). The sensitivity of using SAECG for diagnosis of ARVC/D was increased from 47% using the established 2 of 3 criteria (i.e., late potentials) to 69% by using a modified criterion of any 1 of 3 criteria, while maintaining a high specificity of 95%. Abnormal SAECG as defined by this modified criterion was associated with a dilated RV volume and decreased RV ejection fraction detected by cMRI (P <.05). SAECG abnormalities did not vary with clinical presentation or reliably predict spontaneous or inducible VT and had limited correlation with ECG findings.

CONCLUSION

Using 1 of 3 SAECG criteria contributed to increased sensitivity and specificity for the diagnosis of ARVC/D. This finding is incorporated in the recent modification of the task force criteria.

Pulmonary vein isolation alone in patients with persistent atrial fibrillation: an ablation strategy facilitated by antiarrhythmic drug induced reverse remodeling

INTRODUCTION

Pulmonary vein isolation (PVI) alone has been thought to be insufficient in patients with persistent atrial fibrillation (PersAF). We hypothesized that preablation treatment of PersAF with a potent antiarrhythmic drug (AAD) would facilitate reverse atrial remodeling and result in high procedural efficacy after PVI alone.

METHODS AND RESULTS

Seventy-one consecutive patients (59.4 ± 9.8 years) with PersAF and prior AAD failure were treated with oral dofetilide (768 ± 291 mcg/day) for a median of 85 days pre-PVI. P-wave duration (Pdur) on ECG was used to assess reverse atrial remodeling. Thirty-five patients with paroxysmal (P) AF not treated with an AAD served as controls. All patients underwent PVI alone; dofetilide was discontinued 1-3 mos postablation. In the PersAF patients, the Pdur decreased from 136.3 ± 21.7 ms (assessed postcardioversion on dofetilide) to 118.6 ± 20.4 ms (assessed immediately prior to PVI) (P < 0.001). In contrast, no change in Pdur (122.6 ± 11.5 ms vs. 121.3 ± 13.7 ms, P = NS) was observed in PAF patients. The 6 and 12 mos AAD-free response to ablation was 76% and 70%, respectively, in PersAF patients, similar to the 80% and 75%, response in PAF patients (P = NS). A decline in Pdur in response to dofetilide was the only predictor of long-term clinical response to PVI in patients with PersAF.

CONCLUSIONS

Pre-treatment with AAD resulted in a decrease in Pdur suggesting reverse atrial electrical remodeling in PersAF patients. This may explain the excellent clinical outcomes using PVI alone, and may suggest an alternative ablation strategy for PersAF.