Substrate-guided ablation of haemodynamically tolerated and untolerated ventricular tachycardia in patients with structural heart disease: effect of cardiomyopathy type and acute success on long-term outcome.

AIMS: The purpose of this study was to evaluate the outcomes of purely substrate-guided ventricular tachycardia (VT) ablation in patients with non-ischaemic dilated cardiomyopathy (NIDCM) and ischaemic cardiomyopathy (ICM) and the impact of acute procedural success on long-term outcome. METHODS AND RESULTS: One hundred and forty-two patients (65 ± 12 years old, 72% male) with ICM (n = 87) and with NIDCM (n = 55) underwent substrate-guided VT ablation. The ablation approach involved eliminating all LP regions and ablating all scar border zone regions with 10 or more out of 12 pace-matching. All patients were followed with regular implantable defibrillator interrogations for mean 641 ± 301 days. Complete acute success (no inducible VT) was achieved in 60 patients with ICM (69%) and in 29 patients with NIDCM (53%) (P = 0.03). Partial success (elimination of clinical VT only) was obtained in nine patients with ICM (10%) and in four patients with NIDCM (7%) (P = 0.14). Procedural failure (clinical VT still inducible) occurred in 18 patients within the ICM group (21%) and in 22 patients of the NIDCM (40%) (P = 0.04). Overall, 51 patients presented with recurrence of ventricular arrhythmias: 23 in the group with ICM (26%) and 28 in the group with NIDCM (51%) (P = 0.03). Long-term success was related to acute procedural outcome. CONCLUSIONS: Substrate-guided ablation is an effective approach in the treatment of VT with long-term outcome directly related to acute procedural success. Success rates are significantly lower in patients with NIDCM compared with those with ICM.

Point-by-point pulmonary vein antrum isolation guided by intracardiac echocardiography and 3D mapping and duty-cycled multipolar AF ablation: effect of multipolar ablation on procedure duration and fluoroscopy time.

PURPOSE: Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. Single-catheter multipolar ablation holds the promise to reduce these parameters. This study examined the effect of the conventional point-by-point PVAI with that of single-catheter multipolar ablation on the procedural characteristics and clinical outcomes of atrial fibrillation ablation. METHODS: Referred patients underwent PVAI guided by a magnetic-based 3D mapping (CARTO 3(®) System; group 1) or duty-cycled multipolar AF ablation using the pulmonary vein ablation catheter (PVAC, group 2) between June 2010 and May 2011. RESULTS: Data were analyzed from 19 patients in group 1 and 31 patients in group 2. There was no significant difference in the length of the procedure between the two groups (135 ± 26 vs 125 ± 25 min, P = 0.20). Patients who underwent ablation using PVAC spent significantly less time in the procedure room pre- and post-procedure than those who underwent conventional PVAI (205 ± 38 vs 179 ± 30 min, P = 0.02) and had a significantly shorter fluoroscopy exposure (50 ± 16 vs 36 ± 14 min, P = 0.003) and radiofrequency energy delivery time (54 ± 26 vs 32 ± 33 min, P = 0.02). No differences in safety and efficacy were seen between the groups. CONCLUSIONS: Single-catheter multipolar AF ablation was associated with significantly lower fluoroscopy duration, radiofrequency energy delivery time, and the time the patient spent in the procedure room before and after ablation, although measured short-term clinical outcomes were similar.

Clinical predictors of arrhythmia recurrences following pulmonary vein antrum isolation for atrial fibrillation: predicting arrhythmia recurrence post-PVAI.

INTRODUCTION: Pulmonary vein antrum isolation (PVAI) is an accepted treatment for atrial fibrillation (AF) refractory to medical therapy. The purpose of this study was to identify the patient, procedural, and follow-up factors associated with arrhythmia recurrences following PVAI. METHODS AND RESULTS: Clinical data were prospectively collected on all 385 consecutive patients who had 530 PVAI (age 58 ± 11 years, 63% paroxysmal AF-PAF, follow-up 2.8 ± 1.2 years) between February 2004 and March 2009. ECGs were recorded at each follow-up visit with Holter monitoring 1, 3, 6, and 12 months following PVAI and every 6 months thereafter. Recurrences < 3 months post-PVAI were defined as early, 3 months-1 year post-PVAI as late, and > 1 year post-PVAI as very late. Relationship between predictor variables and outcomes was modeled using Cox proportional hazards analysis. Late recurrences occurred in 42% with a lower rate among PAF versus non-PAF patients (39% vs 56%, P = 0.001). Of the 256 patients with ≥ 1-year follow-up, 121 (47%) had no arrhythmia off antiarrhythmic drugs (AADs) 1 year post-PVAI; 36 (30%) of these had a very late recurrence. In multivariate analysis, non-PAF, hypertension, and prior AAD failure predicted recurrence. When entered into the model, early recurrences remained the only predictor of late recurrences. CONCLUSION: Patients with non-PAF, hypertension, and prior failure of multiple AAD were more likely to experience arrhythmia recurrence post-PVAI. Early recurrences were the strongest predictor of late recurrences. Late and very late recurrences following PVAI were common and should be considered when planning long-term AF patient management.

Adjusting the timing of left-ventricular pacing using electrocardiogram and device electrograms.

AIMS: Left-ventricular (LV) pacing with optimized atrio-ventricular (AV) timing may provide similar or greater benefit in comparison with bi-ventricular (BiV) pacing in a subset of cardiac resynchronization therapy (CRT) patients with sinus rhythm and preserved AV conduction. We hypothesized that the optimal device AV delays during LV pacing can be predicted using electrocardiogram (ECG) and device electrograms. METHODS AND RESULTS PATIENTS: (n= 55) with sinus rhythm and PR interval < 300 ms had their CRT devices programmed to atrial and LV pacing with a range of AVs as well as to echocardiographically optimized BiV and no ventricular pacing. At each setting, LV function was evaluated using echocardiography and AVs corresponding to the highest LV ejection fraction (LVEF), lowest LV end-systolic volume (LVESV), and the average of the two (by EF and ESV) were determined. Correlation between the optimal AVs and the following intervals was investigated: intrinsic QRS duration (QRSs), intervals from atrial pacing (Ap) to right-ventricular (RV) sensing (Ap-RVs), from RV sensing to LV activation (RVs-LVs), and from LV pacing to RV sensing (LVp-RVs). Optimal AVs moderately correlated with intrinsic Ap-RVs interval, whereas other parameters showed weak or no correlation. The best correlation (R = 0.66, P< 0.0001) was between the optimal AV delay according to EF and ESV, and Ap-RVs interval. Programming of AVs during LV pacing to the shortest of 70% of the intrinsic Ap-RVs interval, or Ap-RVs--40 ms resulted in significant improvement in LV function similar to that in case of BiV. CONCLUSION: Optimal AV during LV pacing can be approximated from the intrinsic AV conduction time.

CARTO-guided vs. NavX-guided pulmonary vein antrum isolation and pulmonary vein antrum isolation performed without 3-D mapping: effect of the 3-D mapping system on procedure duration and fluoroscopy time.

PURPOSE: Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. This study examined the effect of two different mapping systems on the procedural characteristics and clinical outcomes of PVAI for atrial fibrillation. METHODS: Referred patients underwent PVAI using a magnetic-based 3-dimensional (3-D) mapping (CARTO® System; group 1), a current-based system (EnSite NavX™; group 2), or fluoroscopy without 3-D mapping (group 3) between February 2004 and November 2009. RESULTS: Data were analyzed from 71 patients in group 1, 165 patients in group 2, and 197 patients in group 3. Baseline characteristics and measured long-term outcomes did not differ between the groups. Although patients in group 1 were more likely to undergo a concurrent flutter ablation (P = 0.01), they had significantly shorter procedure time, fluoroscopy time, and radiofrequency energy delivery time compared with group 2 and 3 patients. No difference was detected among the groups with respect to recurrence, mean time to recurrence, or number of PVAI procedures. CONCLUSIONS: Use of a magnetic-based 3-D mapping system, which allows precise spatial localization of the ablation catheter, was associated with significantly lower procedure time, fluoroscopy duration, and radiofrequency energy delivery time during catheter ablation for atrial fibrillation compared with a current-based system and ablation performed without 3-D mapping, although measured short- and long-term clinical outcomes were similar.

Atrial fibrillation termination as a procedural endpoint during ablation in long-standing persistent atrial fibrillation.

BACKGROUND: Ablation of long-standing persistent atrial fibrillation (AF) remains challenging, with a lower success rate than paroxysmal AF. A reliable ablation endpoint has not been demonstrated yet, although AF termination during ablation may be associated with higher long-term maintenance of sinus rhythm (SR). OBJECTIVE: The purpose of this study was to determine whether the method of AF termination during ablation predicts mode of recurrence or long-term outcome. METHODS: Three hundred six patients with long-standing persistent AF, free of antiarrhythmic drugs (AADs), undergoing a first radiofrequency ablation (pulmonary vein [PV] antrum isolation and complex fractionated atrial electrograms) were prospectively included. Organized atrial tachyarrhythmias (AT) that occurred during AF ablation were targeted. AF termination mode during ablation was studied in relation to other variables (characteristics of arrhythmia recurrence, redo procedures, the use of adenosine/isoproterenol for redo, and comparison of focal versus macroreentrant ATs). Long-term maintenance of SR was assessed during the follow-up. RESULTS: During AF ablation, six of 306 patients converted directly to SR, 172 patients organized into AT (with 38 of them converting in SR with further ablation), and 128 did not organize or terminate and were cardioverted. Two hundred eleven of 306 patients (69%) maintained in long-term SR without AADs after a mean follow-up of 25 +/- 6.9 months, with no statistical difference between the various AF termination modes during ablation. Presence or absence of organization during ablation clearly predicted the predominant mode of recurrence, respectively, AT or AF (P = .022). Among the 74 redo ablation patients, 24 patients (32%) had extra PV triggers revealed by adenosine/isoproterenol. Termination of focal ATs was correlated with higher long-term success rate (24/29, 83%) than termination of macroreentrant ATs (20/35, 57%; P = .026). CONCLUSION: AF termination during ablation (conversion to AT or SR) could predict the mode of arrhythmia recurrence (AT vs. AF) but did not impact the long-term SR maintenance after one or two procedures. AT termination with further ablation did not correlate with better long-term outcome, except with focal ATs, for which termination seems critical.

Spatial and temporal stability of complex fractionated electrograms in patients with persistent atrial fibrillation over longer time periods: relationship to local electrogram cycle length.

BACKGROUND: Atrial fibrillation (AF) ablation guided by complex fractionated electrograms (CFE) has been described, but the spatial and temporal stability of the electrograms (EGMs) has been questioned. OBJECTIVE: The purpose of this study was to prospectively assess the spatial and temporal stability of CFE in patients with persistent AF. METHODS: Twenty-four patients were studied. For 12 patients, two high-density CFE maps were performed during AF at baseline (0 minute) and 20 minutes later using the EnSite NavX system. Six-second bipolar EGMs were collected throughout the left atrium (LA) using a circular mapping catheter. Automated software measured the time between discrete local EGM deflections yielding a mean local cycle length (CL). EGMs with mean CL <120 ms were considered CFE. The LA was divided into six regions. Spatial distribution of EGMs at 0 and 20 minutes was compared in each region across three different CL ranges (A = 50-120 ms, B = 121-200 ms, C = 200-500 ms). The 0- and 20-minute CFE maps were directly superimposed offline in MATLAB, and the mean CL value for each point that was sampled in both maps was compared in each CL range (A-C). For the other 12 patients, repetitive measurements (1-minute intervals for 5 minutes) of mean CL were obtained at a sample point for each CL range (A-C) in each patient and compared for consistency. RESULTS: A total of 324 +/- 65 points were collected per map. Globally in the LA, the distribution of CLs did not change from 0 to 20 minutes (A: 47.1% vs 45.0%; B: 35.3% vs 36.5%; C: 16.0% vs 16.9%; P = .6). The CL distribution in each of the six regions of the LA also did not change significantly from 0 to 20 minutes. There was no significant change in repetitive CL measures for range A (mean DeltaCL 12 +/- 4 ms, P = .4). However, there was significant variation over 5 minutes for ranges B and C (mean DeltaCL 39 +/- 19 ms and 48 +/- 22 ms, respectively, P <.05 for both). Superimposing maps showed 74.7% point-to-point match for range A, 39.3% for range B, and 14.2% for range C (within 30 ms), with a significant correlation seen only for range A (r = 0.82, P <.001). CONCLUSION: CFE show a high degree of spatial and temporal stability. Greater temporal variation is seen in progressively longer CL regions that are outside of the CFE region of interest.

Complications associated with defibrillation threshold testing: the Canadian experience.

BACKGROUND: Defibrillation threshold (DFT) testing has traditionally been a routine part of implantable cardioverter-defibrillator (ICD) implantation, despite a lack of compelling evidence that it predicts or improves outcomes. In the past, when devices were much less reliable, DFT testing seemed prudent; however, modern ICD systems have such a high rate of successful defibrillation that many electrophysiologists now question whether DFT testing is still worthwhile, particularly since DFT testing may now be the highest acute risk component of ICD implantation. OBJECTIVE: The purpose of this study was to systematically document complications directly attributable to intraoperative DFT testing. METHODS: We obtained data on DFT-related complications from all 21 adult ICD implant centers in Canada, covering the period from January 1, 2000, to September 30, 2006. RESULTS: There were a total of 19,067 ICD implants in Canada during the study period. There were three DFT testing-related deaths, five DFT testing-related strokes, and 27 episodes that required prolonged resuscitation. Two patients had significant clinical sequelae after prolonged resuscitation. CONCLUSIONS: The risk of severe complications from intraoperative DFT testing appears small, even allowing for the underestimation of its true rate with the current study methodology. These slight but measurable risks must be considered when assessing the risk-benefit ratio of the procedure. Additional data from ongoing prospective ICD registries and/or clinical trials are required.