Pulsed Field or Conventional Thermal Ablation for Paroxysmal Atrial Fibrillation

BACKGROUND

Catheter-based pulmonary vein isolation is an effective treatment for paroxysmal atrial fibrillation. Pulsed field ablation, which delivers microsecond high-voltage electrical fields, may limit damage to tissues outside the myocardium. The efficacy and safety of pulsed field ablation as compared with conventional thermal ablation are not known.

METHODS

In this randomized, single-blind, noninferiority trial, we assigned patients with drug-refractory paroxysmal atrial fibrillation in a 1:1 ratio to undergo pulsed field ablation or conventional radiofrequency or cryoballoon ablation. The primary efficacy end point was freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation. The primary safety end point included acute and chronic device- and procedure-related serious adverse events.

RESULTS

A total of 305 patients were assigned to undergo pulsed field ablation, and 302 were assigned to undergo thermal ablation. At 1 year, the primary efficacy end point was met (i.e., no events occurred) in 204 patients (estimated probability, 73.3%) who underwent pulsed field ablation and 194 patients (estimated probability, 71.3%) who underwent thermal ablation (between-group difference, 2.0 percentage points; 95% Bayesian credible interval, -5.2 to 9.2; posterior probability of noninferiority, >0.999). Primary safety end-point events occurred in 6 patients (estimated incidence, 2.1%) who underwent pulsed field ablation and 4 patients (estimated incidence, 1.5%) who underwent thermal ablation (between-group difference, 0.6 percentage points; 95% Bayesian credible interval, -1.5 to 2.8; posterior probability of noninferiority, >0.999).

CONCLUSIONS

Among patients with paroxysmal atrial fibrillation receiving a catheter-based therapy, pulsed field ablation was noninferior to conventional thermal ablation with respect to freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation and with respect to device- and procedure-related serious adverse events at 1 year. (Funded by Farapulse-Boston Scientific; ADVENT ClinicalTrials.gov number, NCT04612244.).

Influence of monitoring and atrial arrhythmia burden on quality of life and health care utilization in patients undergoing pulsed field ablation: A secondary analysis of the PULSED AF trial

BACKGROUND

Freedom from atrial arrhythmia (AA) recurrence ≥30 seconds after pulsed field ablation (PFA) in patients with atrial fibrillation (AF) was reported in PULSED AF (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF; ClinialTrials.gov Identifier: NCT04198701). AA burden may be a more clinically meaningful endpoint.

OBJECTIVE

The purpose of this study was to determine the influence of monitoring strategies on AA detection and AA burden association with quality of life (QoL) and health care utilization (HCU) after PFA.

METHODS

Patients underwent 24-hour Holter monitoring at 6 and 12 months and weekly, and symptomatic transtelephonic monitoring (TTM). AA burden post-blanking was calculated as the greater of (1) percentage of AA on total Holter time; or (2) percentage of weeks with ≥1 TTM with AA out of all weeks with ≥1 TTM.

RESULTS

Freedom from all AAs varied by >20% when differing monitoring strategies were used. PFA resulted in zero burden in 69.4% of paroxysmal atrial fibrillation (PAF) and 62.2% of persistent atrial fibrillation (PsAF) patients. Median burden was low (<9%). Most PAF and PsAF patients had ≤1 week of AA detection on TTM (82.6% and 75.4%) and <30 minutes of AA per day of Holter monitoring (96.5% and 89.6%), respectively. Only PAF patients with <10% AA burden averaged a clinically meaningful (>19 point) QoL improvement. PsAF patients experienced clinically meaningful QoL improvements irrespective of burden. Repeat ablations and cardioversions significantly increased with higher AA burden (P <.01).

CONCLUSION

The ≥30-second AA endpoint is dependent on the monitoring protocol used. PFA resulted in low AA burden for most patients, which was associated with clinically relevant improvement in QoL and reduced AA-related HCU.

Pulsed Field Ablation for the Treatment of Atrial Fibrillation: PULSED AF Pivotal Trial

BACKGROUND

Pulsed field ablation uses electrical pulses to cause nonthermal irreversible electroporation and induce cardiac cell death. Pulsed field ablation may have effectiveness comparable to traditional catheter ablation while preventing thermally mediated complications.

METHODS

The PULSED AF pivotal study (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF) was a prospective, global, multicenter, nonrandomized, paired single-arm study in which patients with paroxysmal (n=150) or persistent (n=150) symptomatic atrial fibrillation (AF) refractory to class I or III antiarrhythmic drugs were treated with pulsed field ablation. All patients were monitored for 1 year using weekly and symptomatic transtelephonic monitoring; 3-, 6-, and 12-month ECGs; and 6- and 12-month 24-hour Holter monitoring. The primary effectiveness end point was freedom from a composite of acute procedural failure, arrhythmia recurrence, or antiarrhythmic escalation through 12 months, excluding a 3-month blanking period to allow recovery from the procedure. The primary safety end point was freedom from a composite of serious procedure- and device-related adverse events. Kaplan-Meier methods were used to evaluate the primary end points.

RESULTS

Pulsed field ablation was shown to be effective at 1 year in 66.2% (95% CI, 57.9 to 73.2) of patients with paroxysmal AF and 55.1% (95% CI, 46.7 to 62.7) of patients with persistent AF. The primary safety end point occurred in 1 patient (0.7%; 95% CI, 0.1 to 4.6) in both the paroxysmal and persistent AF cohorts.

CONCLUSIONS

PULSED AF demonstrated a low rate of primary safety adverse events (0.7%) and provided effectiveness consistent with established ablation technologies using a novel irreversible electroporation energy to treat patients with AF.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04198701.

Hybrid epicardial-endocardial ablation for long-standing persistent atrial fibrillation: A subanalysis of the CONVERGE Trial

Background

Favorable clinical outcomes are difficult to achieve in long-standing persistent atrial fibrillation (LSPAF) with catheter ablation (CA). The CONVERGE (Convergence of Epicardial and Endocardial Ablation for the Treatment of Symptomatic Persistent Atrial FIbrillation) trial evaluated the effectiveness of hybrid convergent (HC) ablation vs endocardial CA.

Objective

The study sought to evaluate the safety and effectiveness of HC vs CA in the LSPAF subgroup from the CONVERGE trial.

Methods

The CONVERGE trial was a prospective, multicenter, randomized trial that enrolled 153 patients at 27 sites. A post hoc analysis was performed on LSPAF patients. The primary effectiveness was freedom from atrial arrhythmias off new or increased dose of previously failed or intolerant antiarrhythmic drugs (AADs) through 12 months. The primary safety endpoint was major adverse event incidence through 30 days with HC. Key secondary effectiveness measures included (1) percent of patients achieving ≥90% AF burden reduction vs baseline and (2) AF freedom.

Results

Sixty-five patients (42.5% of total enrollment) had LSPAF; 38 in HC and 27 in CA. Primary effectiveness was 65.8% (95% confidence interval [CI] 50.7%-80.9%) with HC vs 37.0% (95% CI 5.1%-52.4%) with CA (P = .022). Through 18 months, these rates were 60.5% (95% CI 50.0%-76.1%) with HC vs 25.9% (95% CI 9.4%-42.5%) with CA (P = .006). Secondary effectiveness rates were higher than CA with HC at 12 and 18 months. Freedom from atrial arrhythmias off AADs was 52.6% (95% CI 36.8%-68.5%) and 47.4% (95% CI 31.5%-63.2%) with HC at 12 and 18 months vs 25.9% (95% CI 9.4%-42.5%) and 22.2% (95% CI 6.5%-37.9%) with CA, respectively (12 months: P = .031; 18 months: P = .038). Three (7.9%) major adverse events occurred within 30 days of HC.

Conclusion

Post hoc analysis demonstrated effectiveness and acceptable safety of HC compared with CA in LSPAF.

Contact force catheter ablation for the treatment of persistent atrial fibrillation: Results from the PERSIST-END study

INTRODUCTION

Use of a novel magnetic sensor enabled optical contact force ablation catheter has been established to be safe and effective for treatment of symptomatic drug-refractory paroxysmal atrial fibrillation (AF) but has yet to be demonstrated in the persistent AF (PersAF) population.

METHODS

PERSIST-END was a multicenter, prospective, nonrandomized, investigational study designed to demonstrate the safety and effectiveness of TactiCath™ Ablation Catheter, Sensor Enabled™(SE) (TactiCath SE) for use in the treatment of subjects with documented PersAF refractory or intolerant to at least one Class I/III AAD. The ablation strategy included pulmonary vein isolation and additional targets at physician discretion. Follow-up through 15-months, including a 3-month blanking period and 3-month therapy consolidation period, was performed with cardiac event and Holter monitoring. Primary safety, primary effectiveness, clinical success, and quality of life (QOL) endpoints were analyzed.

RESULTS

Of 224 subjects enrolled at 21 investigational sites in the United States and Australia, 223 underwent ablation with the investigational catheter. The primary safety event rate was 3.1% (seven events in seven subjects). The Kaplan-Meier estimate of freedom from AF/atrial flutter/atrial tachycardia recurrence at 15-months was 61.6% and clinical success at 15 months was 89.8%. Subject QOL significantly improved following ablation as assessed via AFEQT (31.6 point increase, p < .0001) and EQ-5D-5L (10.7 point increase, p < .0001) and was met with a 53% reduction in all cause cardiovascular healthcare utilization.

CONCLUSION

The sensor-enabled force-sensing catheter is safe and effective for the treatment of drug refractory recurrent symptomatic PersAF, reducing arrhythmia recurrence while improving QOL and healthcare utilization.

The Hybrid Convergent Procedure for Persistent and Long-Standing Persistent Atrial Fibrillation From an Electrophysiologist's Perspective

In atrial fibrillation (AF), the pulmonary veins (PV) are central to arrhythmogenicity and are targeted by PV isolation (PVI). As AF progresses, triggers become more prevalent in non-PV areas including the left atrial posterior wall (LAPW). Reported benefits of LAPW isolation in Cox-maze IV led to exploration of ablation strategies using endocardial catheters. However, no single approach to endocardial LAPW isolation exists. Relative success in comparison to PVI alone has been mixed. The hybrid convergent procedure was developed to combine minimally invasive surgical and electrophysiology techniques to accomplish effective PVI and LAPW isolation. Epicardial LAPW isolation is performed by a cardiothoracic surgeon followed by endocardial ablation by an electrophysiologist who ensures PVI completion and targets any remaining gaps. Safety and effectiveness of hybrid convergent was evaluated in the prospective, multi-center, randomized controlled trial, Convergence of Epicardial and Endocardial Ablation for the Treatment of Symptomatic Persistent AF (CONVERGE). CONVERGE compared the effectiveness of the hybrid convergent procedure to endocardial catheter ablation for treatment of drug-refractory persistent and longstanding persistent AF and demonstrated primary effectiveness of higher freedom from atrial arrhythmias absent new/increased dose previously failed/intolerant anti-arrhythmic drugs through 12 months compared to endocardial catheter ablation. Greater freedom from AF and proportion of patients experiencing ≥90% burden reduction with hybrid convergent ablation were seen through 18 months follow-up. Improved electrophysiology lab efficiency was demonstrated by the reduction in endocardial ablation time with addition of epicardial ablation. This multi-disciplinary heart team procedure may improve outcomes in difficult-to-treat patients with advanced AF. This article is protected by copyright. All rights reserved.

Hybrid Convergent Procedure for the Treatment of Persistent and Long-standing Persistent Atrial Fibrillation

Recent advances have been made in AF treatment, including the role of early rhythm control and landmark clinical trials using ablation therapy. However, some treatment gaps remain, including the creation of durable lesions outside the pulmonary veins and effective treatment of longstanding persistent AF. A novel epicardial-endocardial ablation approach - the hybrid convergent procedure - was developed to combine surgical and catheter ablation techniques into a collaborative, multidisciplinary approach to managing AF. In this review, the authors discuss recently published data on hybrid convergent ablation, including results of the CONVERGE clinical trial, in the context of current challenges to treatment of persistent and long-standing persistent AF. The review also aims to provide perspective on outstanding questions and future directions in this area.

Convergence of Epicardial and Endocardial RF Ablation for the Treatment of Symptomatic Persistent AF (CONVERGE Trial): Rationale and design

Atrial fibrillation is the most common sustained arrhythmia affecting over 33 million people worldwide. Approximately 70% of AF patients have non-paroxysmal AF. As AF progresses from paroxysmal to non-paroxysmal forms, the prevalence of comorbidities increases. The efficacy of catheter ablation for persistent and long standing persistent (LSP) AF is <40%, often requiring multiple ablation procedures with greater cost and potentially more complications. There is an unmet need to effectively treat such patients. METHODS: CONVERGE is an investigational device exempt, prospective, multi-center, open label 2:1 randomized controlled pivotal study to evaluate the overall success of the Convergent hybrid procedure compared to endocardial catheter ablation for the treatment of symptomatic persistent AF refractory or intolerant to at least one Class I and /or III anti-arrhythmic drug (AAD). A total of 153 subjects at 27 centers are treated in the study. The CONVERGE study is differentiated from other studies currently being conducted on the persistent AF population, because a) there is no time restriction on the duration of diagnosed AF in the patients being studied and b) the trial allows patients with left atrial sizes up to 6 centimeters. The ongoing trials are limited to either 6 months, 12 months or 3-years of continuous AF making CONVERGE the only ablation trial thus far to include a substantial portion of patients with longstanding persistent AF. The convergent procedure involves combination of minimally invasive pericardioscopic epicardial ablation with endocardial left atrial ablation. The primary endpoint is freedom from AF/AFL/AF absent class I/III AAD, except for a previously failed class I/ III AAD with no increase in dosage following 3-months through 12-months. The primary safety endpoint is the incidence of major adverse events from the procedure through 30-days post procedure. CONCLUSION: CONVERGE AF compares the overall success of the Convergent hybrid procedure to endocardial catheter ablation for the treatment of persistent and longstanding persistent AF. By providing objective comparative data, the study aims to provide guidance on the treatment of such patients.

Left Atrial Appendage Occlusion, Shared Decision-Making, and Comprehensive Atrial Fibrillation Management

The epidemic of atrial fibrillation (AF) requires a comprehensive management strategy that uses the full force of available data and technology, including anticoagulation, ablative therapy, and left atrial appendage occlusion. Patient-centered care with an emphasis on shared decision-making is particularly relevant to the authors' understanding of the complexity of AF and has helped them tailor therapy in this ever-growing patient population.

Heart sounds based measures of cardiac status for heart failure patient management

Heart sounds based measurements such as S3 amplitude and systolic timing intervals (STIs) are known to be indicative of cardiac dysfunction. In this paper we investigate the correlation of these measurements from pacemaker device implant locations to echocardiographic hemodynamic metrics of E wave deceleration time (EDT), Ejection Fraction (EF) and Stroke Volume (SV). Simultaneous heart sounds and echocardiography measurements were made in 6 heart failure patients with cardiac resynchronization therapy (CRT) devices prior to CRT activation (baseline) and at 3 and 6 months post-CRT. In N=17 datasets, S3 amplitude was correlated to EDT (r=-0.86, p<0.05). Similarly STIs such as heart sounds based pre-ejection period (HSPEP) was correlated with EF (r = -0.81, p<0.01) and ejection time (HSET) with SV (r = 0.65, p=0.01). Longitudinal analysis in each patient showed consistent changes between % increase in S3 vs. % decrease in EDT (r= -0.83, p<0.01), % change in HSPEP vs. % change in EF (r= -0.80, p=0.03) and % change in SV (r= -0.72, p< 0.01). These results show proof of concept for using pacemaker derived measurements for monitoring HF patients. Further study is needed to determine their efficacy for chronic monitoring of HF patients.

The Impact of Cardiac Resynchronization Therapy on Ventricular Tachycardia/Fibrillation: An Analysis from the Combined Contak-CD and InSync-ICD Studies

OBJECTIVES

To determine the potential influence of cardiac resynchronization therapy (CRT) on the frequency and types of ventricular arrhythmia (VA) in patients with an indication for the implantable cardioverter-defibrillator (ICD), we performed a retrospective electrogram (EGM) analysis of stored VA events from the two largest CRT-ICD trials.

BACKGROUND

Previous reports suggest that CRT might promote polymorphic VT (PVT), while a beneficial effect of CRT on ventricular function might reduce the frequency of monomorphic VT (MVT). Theoretically, a balanced effect produces no change in overall VA.

METHODS

We analyzed stored EGMs from patients in the Contak-CD and Insync-ICD studies receiving appropriate therapy for VA. EGM inspection distinguishes MVT and PVT using morphologic criteria rather than cycle length classification alone.

RESULTS

Of 1,041 subjects entering the two trials, 880 were randomized CRT (N = 439) or control (N = 441). We were able to analyze 840 EGMs in 150 patients with VA, including 678 MVT episodes and 162 PVT episodes. These events were distributed among 68 patients with active CRT (390 MVT vs 111 PVT) and 82 patients assigned to control (288 MVT compared to 51 PVT). The apparent increase in PVT episodes in the CRT group is not significant and can be explained by a disproportionate number of episodes in a few patients. We were unable to identify clinical variables predictive of PVT during CRT.

CONCLUSIONS

CRT is not associated with a measurable increase in the incidence of PVT, or in a reduction in MVT in the combined InSync-ICD and Contak-CD populations.

Usefulness of the peak velocity difference by tissue Doppler imaging technique as an effective predictor of response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) improves symptoms and functional status in heart failure patients; however, current selection criteria need improvement. A novel tissue Doppler imaging parameter, the peak velocity difference (PVD), defined as the greatest difference in time to peak velocity between any of 6 left ventricular regions, may better select responders to CRT. Subjects were divided into 2 groups based on the PVD. Clinical and echocardiographic parameters significantly improved in subjects with dyssynchrony by the baseline PVD and had a better overall response to CRT.

Benefits of cardiac resynchronization therapy in outpatients with indicators for heart transplantation

BACKGROUND

Despite several new advances in the treatment of end-stage congestive heart failure (CHF) the number of patients moving onto the heart transplant list continues to rise. Recently, cardiac resynchronization therapy (CRT) has become a Food and Drug Administration (FDA)-approved therapy for advanced CHF. Currently, there are no available data on CRT in cardiac transplant candidates.

METHODS

To determine the effects of CRT on potential transplant candidates we retrospectively reviewed patients (n = 34) enrolled in resynchronization trials at our center who met accepted criteria for transplantation. Ventricular function, oxygen uptake and New York Heart Association (NYHA) class were compared at baseline and after 6 months of active therapy for each patient.

RESULTS

CRT reduced QRS duration from 178 +/- 29 to 143 +/- 17 msec (p < 0.0001) and NYHA class from 3.1 +/- 0.3 to 1.8 +/- 0.7 (p < 0.0001). Ejection fraction (EF) increased from 18.4 +/- 5.1 to 25.1 +/- 8.4% (p < 0.0001) and maximum VO(2) increased from 11.9 +/- 1.8 to 15.3 +/- 3 ml/kg/min (p < 0.0001). Only 2 of the initial 34 patients still met the criteria for transplantation at 6 months.

CONCLUSIONS

CRT improves ventricular function, oxygen uptake and NYHA class in ambulatory patients who have a QRS of >130 msec and might be considered candidates for cardiac transplantation. Transplantation can be prevented or deferred in the majority of patients. Outpatients with chronic CHF and a widened QRS should be evaluated for CRT before being listed for cardiac transplantation.

Effect of cardiac resynchronization therapy on left ventricular size and function in chronic heart failure

BACKGROUND

Cardiac resynchronization therapy (CRT) has recently emerged as an effective treatment for patients with moderate to severe systolic heart failure and ventricular dyssynchrony. The purpose of the present study was to determine whether improvements in left ventricular (LV) size and function were associated with CRT.

METHODS AND RESULTS

Doppler echocardiograms were obtained at baseline and at 3 and 6 months after therapy in 323 patients enrolled in the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial. Of these, 172 patients were randomized to CRT on and 151 patients to CRT off. Measurements were made of LV end-diastolic and end-systolic volumes, ejection fraction, LV mass, severity of mitral regurgitation (MR), peak transmitral velocities during early (E-wave) and late (A-wave) diastolic filling, and the myocardial performance index. At 6 months, CRT was associated with reduced end-diastolic and end-systolic volumes (both P<0.001), reduced LV mass (P<0.01), increased ejection fraction (P<0.001), reduced MR (P<0.001), and improved myocardial performance index (P<0.001) compared with control. beta-Blocker treatment status did not influence the effect of CRT. Improvements with CRT were greater in patients with a nonischemic versus ischemic cause of heart failure.

CONCLUSIONS

CRT in patients with moderate-to-severe heart failure who were treated with optimal medical therapy is associated with reverse LV remodeling, improved systolic and diastolic function, and decreased MR. LV remodeling likely contributes to the symptomatic benefits of CRT and may herald improved longer-term survival.

Cardiac resynchronization in patients with congestive heart failure and chronic atrial fibrillation: effect of upgrading to biventricular pacing after chronic right ventricular pacing

OBJECTIVES

This study assessed the effects of biventricular pacing (BVP) on ventricular function, functional status, quality of life and hospitalization in patients with congestive heart failure (CHF), prior atrioventricular (AV) junction ablation and right ventricular (RV) pacing performed for chronic atrial fibrillation (AF).

BACKGROUND

Although the benefit of BVP in CHF should theoretically extend to the patient with chronic RV pacing and AF, to our knowledge, no study has determined the effects of BVP on symptoms and ventricular function in these patients. This patient population allows for the evaluation of ventricular resynchronization independent of any BVP-induced changes on the AV interval.

METHODS

Twenty consecutive patients with severe CHF (ejection fraction < or = 0.35, New York Heart Association [NYHA] functional class III or IV), prior AV junction ablation and RV pacing performed for permanent AF of at least six months' duration were studied. Electrocardiograms, echocardiograms, functional status evaluations and quality of life surveys were completed before and at three to six months after implant.

RESULTS

The NYHA functional classification improved 29% (p < 0.001). The left ventricular (LV) ejection fraction increased 44% (p < 0.001), the LV diastolic diameter decreased 6.5% (p <0.003) and the end-systolic diameter decreased 8.5% (p < 0.01). The number of hospitalizations decreased by 81% (p < 0.001). The scores on the Minnesota Living with Heart Failure survey improved by 33% (p < 0.01).

CONCLUSIONS

We conclude that BVP improves the LV function and the symptoms of CHF in patients with permanent AF and chronic RV pacing. These benefits are comparable to those described for patients in sinus rhythm suggesting that BVP acts through ventricular resynchronization rather than optimization of the AV delay.

Transvenous cardioverter defibrillator lead malfunction due to terminal connector damage in pectoral implants

Lead failure places patients with implantable cardioverter defibrillators (ICD) at risk for sudden cardiac death or results in delivery of inappropriate shocks. This study describes a mechanism of lead malfunction occurring at the junction of the terminal ring with the conductor coil of the rate sensing terminal connector in one specific model of a transvenous ICD lead. We detected the problem in a population of 179 patients with a mean age of 61 +/- 10 years and a mean lead implant duration of 16 +/- 11 months. All patients underwent pectoral ICD implantation using a submuscular approach. The implanting physician chose to place the ICD on the left side in 155 patients (87%) and on the right side in 24 patients (13%). Cephalic vein cutdown provided central venous access in 147 patients (82%), and subclavian vein puncture provided access in 32 patients (18%). Follow-up examination detected lead failure in six patients (3.5% over 31 months) due to insulation damage with or without conductor coil fracture at the junction of the terminal ring and conductor coil of the IS-1 rate sense terminal. We detected lead disruption 17 +/- 9 months (range 5-31 months) after implantation. Multiple nonsustained arrhythmia episodes exhibiting nonphysiologic intervals associated with noisy rate sensing electrograms during pocket manipulation led to discovery in three patients. The other three patients presented with inappropriate device discharges confirmed by stored high-energy lead electrograms showing normal rhythm. Pacing lead impedance abnormally dropped in two patients. Impedance remained stable in the other four patients. In conclusion, the generator pocket represents an important site of ICD transvenous lead vulnerability. Lead failure may result from conductor coil and/or insulation disruption at the interface with the rate sensing terminal connector.

A comparison of ventricular function during high right ventricular septal and apical pacing after his-bundle ablation for refractory atrial fibrillation

This study compares LV performance during high right ventricular septal (RVS) and apical (RVA) pacing in patients with LV dysfunction who underwent His-bundle ablation for chronic AF. We inserted a passive fixation pacing electrode into the RVA and an active fixation electrode in the RVS. A dual chamber, rate responsive pulse generator stimulated the RVA through the ventricular port and the RVS via the atrial port. Patients were randomized to initial RVA (VVIR) or RVS (AAIR) pacing for 2 months. The pacing site was reversed during the next 2 months. At the 2 and 4 month follow-up visit, each patient underwent a transthoracic echocardiographical study and a rest/exercise first pass radionuclide ventriculogram. We studied nine men and three women (mean age of 68 +/- 7 years) with congestive heart failure functional Class (NYHA Classification): I (3 patients), II (7 patients), and III (2 patients). The QRS duration was shorter during RVS stimulation (158 +/- 10 vs 170 +/- 11 ms, P < 0.001). Chronic capture threshold and lead impedance did not significantly differ. LV fractional shortening improved during RVS pacing (0.31 +/- 0.05 vs 0.26 +/- 0.07, P < 0.01). RVS activation increased the resting first pass LV ejection fraction (0.51 +/- 0.14 vs 0.43 +/- 0.10, P < 0.01). No significant difference was observed during RVS and RVA pacing in the exercise time (5.6 +/- 3.2 vs 5.4 +/- 3.1, P = 0.6) or the exercise first pass LV ejection fraction (0.58 +/- 0.15 vs 0.55 +/- 0.16, P = 0.2). The relative changes in QRS duration and LV ejection fraction at both pacing sites showed a significant correlation (P < 0.01). We conclude that RVS pacing produces shorter QRS duration and better chronic LV function than RVA pacing in patients with mild to moderate LV dysfunction and chronic AF after His-bundle ablation.

Frequency analysis of human atrial fibrillation using the surface electrocardiogram and its response to ibutilide

This study assesses a technique for quantifying the frequency spectrum of atrial fibrillation (AF) using the surface electrocardiogram. Electrocardiograhic recordings were obtained in 61 patients during AF. After bandpass filtering, the QRST complexes were subtracted using a template-matching algorithm. The resulting fibrillatory baseline signal was subjected to Fourier transformation and displayed as a frequency power spectrum. These frequency spectra were compared to direct measurements from the right atrium and coronary sinus in 35 patients undergoing electrophysiologic study. The clinical use of this technique was explored by correlating fibrillatory frequency with the behavior of the arrhythmia in 26 patients referred for cardioversion. The electrocardiographic frequency spectrum during AF was characterized by a single peak that varied widely between patients (range 228 to 480 beats/min). There was a strong correlation between electrocardiographic peak frequency and that measured in the right atrium and coronary sinus (r = 0.79 to 0.98, p <0.0001). Episodes of AF that terminated in < 5 minutes had a lower frequency than those that persisted > 5 minutes (324 +/- 36 vs 402 +/- 78 beats/min, p = 0.001). Chronic AF (< 3 months in duration) had a lower frequency than chronic AF (present > 3 months) (336 +/- 48 vs 408 +/- 60 beats/ min, p = 0.012). Fibrillation frequency was an accurate predictor of conversion with ibutilide. Success rate was 100% in patients with peak frequency < 360 beats/min versus 29% in patients with frequencies > or = 360 beats/min (p = 0.003). Automatic analysis of the frequency content of the fibrillatory baseline on the surface electrocardiogram accurately reflects the average rate of AF. This measurement correlates with the clinical pattern of the arrhythmia and predicts the response to administration of ibutilide.

Anatomy of atrioventricular nodal reentry investigated by intracardiac echocardiography

Intracardiac echocardiography was used to evaluate posteroseptal space anatomy in patients with atrioventricular nodal reentrant tachycardia compared with patients with other mechanisms of tachycardia. The posteroseptal space was found to be significantly wider in patients with atrioventricular nodal reentry, suggesting an anatomic basis for dual atrioventricular nodal physiology.

Implantable defibrillators for high-risk patients with heart failure who are awaiting cardiac transplantation

The objective of this study was to assess the operative risk and efficacy of implantable defibrillators for preventing sudden death in patients with heart failure awaiting transplantation. The average waiting time for elective cardiac transplantation is 6 months to 1 year. Sudden cardiac death is the major source of mortality in outpatients in stable condition awaiting cardiac transplantation. The efficacy of implantable defibrillator therapy in this population is not established. We analyzed the operative risk, time to appropriate shock, and sudden death in 15 patients determined to be at high risk of sudden death who were accepted onto the outpatient cardiac transplant waiting list. Nonfatal postoperative complications occurred in two (13%) subjects with epicardial defibrillating lead systems and in none with transvenous lead systems. Defibrillation energies were 16 +/- 2 J versus 24 +/- 2 J with epicardial and transvenous lead systems, respectively. Sudden death free survival until transplantation was 93%. Most of the patients (60%) had an appropriate shock during a mean follow-up of 11 +/- 12 months. The mean time to an appropriate shock was 3 +/- 3 months. Hospital readmission was required in three (20%) subjects to await transplantation on an urgent basis. However, two of these subjects had received appropriate shocks before readmission. In selected patients at high risk for sudden death while on the outpatient cardiac transplant waiting list, the operative risk is low and adequate defibrillation energies can be obtained to allow implantable defibrillator placement. Most subjects will have an appropriate shock as outpatients before transplantation, and sudden death free survival is excellent.(ABSTRACT TRUNCATED AT 250 WORDS)