Mehul Dhinoja

A Randomized Controlled Trial of Catheter Ablation Versus Medical Treatment of Atrial Fibrillation in Heart Failure (The CAMTAF Trial)

Background—Restoring sinus rhythm in patients with heart failure (HF) and atrial fibrillation (AF) may improve left ventricular (LV) function and HF symptoms. We sought to compare the effect of a catheter ablation strategy with that of a medical rate control strategy in patients with persistent AF and HF. Methods and Results—Patients with persistent AF, symptomatic HF, and LV ejection fraction <50% were randomized to catheter ablation or medical rate control. The primary end-point was the difference between groups in LV ejection fraction at 6 months. Baseline LV ejection fraction was 32±8% in the ablation group and 34±12% in the medical group. Twenty-six patients underwent catheter ablation, and 24 patients were rate controlled. Freedom from AF was achieved in 21/26 (81%) at 6 months off antiarrhythmic drugs. LV ejection fraction at 6 months in the ablation group was 40±12% compared with 31±13% in the rate control group (P=0.015). Ablation was associated with better peak oxygen consumption (22±6 versus 18±6 mL/kg per minute; P=0.014) and Minnesota living with HF questionnaire score (24±22 versus 47±22; P=0.001) compared with rate control. Conclusions—Catheter ablation is effective in restoring sinus rhythm in selected patients with persistent AF and HF, and can improve LV function, functional capacity, and HF symptoms compared with rate control. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01411371

Catheter Ablation for Atrial Fibrillation on Uninterrupted Warfarin: Can It Be Done Without Echo Guidance?

AF Ablation on Uninterrupted Warfarin. Introduction: Catheter ablation for atrial fibrillation is an effective treatment for symptomatic patients who have failed drug therapy. Recent studies using intracardiac echocardiography have demonstrated that ablation can be performed safely on uninterrupted warfarin and may be superior to bridging low molecular weight heparin (LMWH). We sought to assess the safety of an uninterrupted warfarin protocol using a simplified ablation protocol in a prospective controlled study.

Cryoablation versus radiofrequency ablation for treatment of atrioventricular nodal reentrant tachycardia: Cryoablation with 6-mm-tip catheters is still less effective than radiofrequency ablation

BACKGROUND The treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT) is catheter ablation of the atrioventricular nodal slow pathway. OBJECTIVE The purpose of this study was to ascertain whether cryoablation (Cryo) with 6-mm-tip catheters is as effective as radiofrequency ablation (RF). METHODS Patients who had catheter ablation for AVNRT between 2005 and 2008 were identified. The main outcome measure was overall success without the use of an alternative energy source and no recurrence. RESULTS Two hundred eighty-eight procedures in 272 patients were identified; 184 were female (68%), and the mean age was 53 +/- 14 (17-88) years. There were 123 Cryo and 149 RF procedures. Cryo had a lower overall success rate (83% vs. 93%; P = .02). Mean procedure times were similar in both groups (90 minutes; P = .5). Fluoroscopy time was longer with Cryo: 16 (7-48) versus 14 (5-50) minutes (P = .04). Only one case of atrioventricular block was observed in the RF group (0.7%). Cryo was more expensive than RF ( pounds sterling 3141 vs. pounds sterling 2153). CONCLUSION Even when delivering multiple lesions with 6-mm-tip catheters, Cryo is less effective than RF. RF is recommended as a first-line treatment, although the only major complication occurred in the RF group.

Target Indices for Clinical Ablation in Atrial Fibrillation Insights From Contact Force, Electrogram, and Biophysical Parameter Analysis

Background—In animal studies of radiofrequency ablation, lesion sizes plateau as the maximum lesion size is reached for an ablation. Lesion parameters are not available in clinical ablations, but preclinical work suggests that these correlate with impedance drop and electrogram attenuation. Characterization of the relationships between catheter contact force, ablation duration, and these surrogate markers of lesion formation may allow us to define targets for effective ablation. Methods and Results—Fifteen patients undergoing first-time radiofrequency ablation for nonparoxysmal atrial fibrillation were studied. All were in atrial fibrillation at the time of the procedure. Ablations were performed with an irrigated-tip contact force–sensing catheter in temperature-controlled mode (temperature limited to 48°C, power to 30 W). Included were 285 left atrial static ablations, 247 with additional impedance data. The ablation force time integral (FTI) correlated with the attenuation of the electrogram with ablation (Spearman &rgr;, –0.14; P=0.02): the relationship plateauing from 500 g·s, a reduction in the electrogram amplitude of 20%. The FTI also correlated with the impedance drop during ablation (Spearman &rgr;, 0.79; P<0.0005): the relationship was logarithmic, the reduction in the impedance with an increasing FTI also plateauing from 500 g·s, an impedance drop of 7.5%. The ablation duration affected the impedance drop at an FTI if the duration was <10 s. Beyond this time point, the FTI achieved rather than the ablation duration or mean contact force applied determined the impedance drop. Conclusions—During nonparoxysmal atrial fibrillation ablation, an FTI of 500 g·s should be targeted with ablation duration of ≥10 s. Clinical Trials Registration—URL: http://clinicaltrials.gov/. Unique Identifier: NCT01587404.

Impact of angiotensin-converting enzyme-inhibitors and angiotensin receptor blockers on long-term outcome of catheter ablation for atrial fibrillation

AIMS We hypothesized that modulation of the renin-angiotensin-aldosterone system (RAAS) improves success following catheter ablation for atrial fibrillation (AF). METHODS AND RESULTS We examined a prospective registry of consecutive patients undergoing catheter ablation of paroxysmal or persistent AF between November 2004 and December 2008. Patients were divided based on whether they were taking RAAS modulators at the time of their first procedure and examined on an intention to treat basis. There were 419 patients (222 paroxysmal and 197 persistent AF) who underwent 1.8 ± 0.9 procedures. Median follow-up from the last procedure was 1.7 (range 0.9-5.0) years. There were 142 patients on RAAS modulators; they were older, more likely to suffer from hypertension, diabetes, coronary disease, or left ventricular impairment. Overall, sinus rhythm was maintained in 73.2% of those taking RAAS modulators vs. 77.6% of those taking none (P = 0.304). Multivariate analysis showed no impact of RAAS modulators [hazard ratios (HR): 1.97, CI: 0.56-6.89, P = 0.290] but also no effect of hypertension, ischaemic heart disease, left ventricular impairment, or diabetes that should have confounded results (persistent AF was found to predict failure; HR: 0.34, CI: 0.14-0.84, P = 0.020). Subgroup analysis of patients with risk factors for developing AF (hypertension, coronary artery disease, left ventricular impairment, or diabetes) found no benefit in this context, with sinus rhythm maintained in 73.2% of those taking RAAS modulators compared with 69.9% of those taking none (P = 0.574). CONCLUSION Modulation of the RAAS does not appear to affect maintenance of sinus rhythm following catheter ablation of AF.

Point-by-Point Radiofrequency Ablation Versus the Cryoballoon or a Novel Combined Approach: A Randomized Trial Comparing 3 Methods of Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation (The Cryo Versus RF Trial).

Catheter ablation of paroxysmal AF using the Cryoballoon (CRYO) has yielded similar success rates to conventional wide encirclement using radiofrequency catheter ablation (RFCA), but randomized data are lacking. Pilot data suggested a high success rate with a combined approach (COMBINED) using wide encirclement with RFCA followed by 2 CRYO applications to each vein. We compared these 3 strategies in a randomized controlled trial.

Comparison of Robotic and Manual Persistent AF Ablation Using Catheter Contact Force Sensing: An International Multicenter Registry Study

Catheter‐based contact force sensing (CFS) technology gives detailed information regarding contact between the catheter tip and myocardium. This may result in more effective ablation procedures. The primary objective of this study was comparison of remote robotic navigation (RRN) and Manual CFS ablation. The secondary objective was to compare CFS with non‐CFS ablation for both navigation modes.

Randomized trial comparing robotic to manual ablation for atrial fibrillation

BACKGROUND Catheter ablation of atrial fibrillation (AF) is a physically demanding procedure for the operator, involving radiation exposure, and has limited success rates. Remote robotic navigation (RRN) may offer benefit to the procedure, though only 1 previous small randomized trial has assessed this. OBJECTIVE This study aimed to investigate the impact of RRN on 1-year single-procedure success rates. METHODS RRN was compared to manual ablation in a randomized control trial setting by using an intention-to-treat analysis. RESULTS A total of 157 patients underwent ablation (116/157 (74%) persistent AF; 67/116 (58%) of these long-standing persistent AF). There were no significant differences between the RRN and manual groups with respect to 1-year single-procedure success rates (19/78 (24%) and 26/78 (33%), respectively; P = .29), acute wide area circumferential ablation reconnection rates, complication rates, or procedure times. On multivariable analysis, fluoroscopy times were significantly shorter in the RRN group. The number of catheter displacements during ablation was lower in the RRN group, as was subjectively assessed operator fatigue. The crossover rate from RRN to manual ablation was 11/78 (14%), mainly secondary to technical problems with the RRN system. A learning curve was evident for RRN ablation: the fluoroscopy and procedure times were significantly lower after the first 10 cases in an operators experience. CONCLUSION This randomized trial showed no difference in the success rate for catheter ablation of AF between a RRN and manual approach. The results highlight the learning curve for RRN ablation and suggest that the use of this technology leads to an improvement in fluoroscopy times, catheter stability, and operator fatigue.

Uninterrupted Warfarin for Periprocedural Anticoagulation in Catheter Ablation of Typical Atrial Flutter: A Safe and Cost‐Effective Strategy

Uninterrupted Warfarin for Periprocedural Anticoagulation in Catheter Ablation of Typical Atrial Flutter. Introduction: Many patients undergoing catheter ablation of atrial flutter (AFL) require periprocedural anticoagulation. We compared a strategy of conversion to low molecular weight heparin (LMWH) periprocedure to uninterrupted warfarinization in a nonrandomized, case‐controlled study.

Factors Affecting Catheter Contact in the Human Left Atrium and Their Impact on Ablation Efficacy

Preclinical work suggests factors including catheter orientation and contact consistency during individual radiofrequency ablations influence lesion size. Our aim was to investigate factors affecting catheter contact in the left atrium (LA) and their effects on ablation.