Adjunctive low-voltage area ablation for patients with atrial fibrillation: An updated meta-analysis of randomized controlled trials.

BACKGROUND: The efficacy and safety of adjunctive low-voltage area (LVA) ablation on outcomes of catheter ablation (CA) for atrial fibrillation (AF) remains uncertain. METHODS: PubMed, Embase, Cochrane Library, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) comparing CA with versus without LVA ablation for patients with AF. Risk ratios (RR) with 95% confidence intervals (CI) were pooled with a random-effects model. Our primary endpoint was recurrence of atrial tachyarrhythmia (ATA), including AF, atrial flutter, or atrial tachycardia. We used R version 4.3.1 for all statistical analyses. RESULTS: Our meta-analysis included 10 RCTs encompassing 1780 patients, of whom 890 (50%) were randomized to LVA ablation. Adjunctive LVA ablation significantly reduced recurrence of ATA (RR 0.76; 95% CI 0.67-0.88; p < .01) and reduced the number of redo ablation procedures (RR 0.54; 95% CI 0.35-0.85; p < .01), as compared with conventional ablation. Among 691 (43%) patients with documented LVAs on baseline substrate mapping, adjunctive LVA ablation substantially reduced ATA recurrences (RR 0.57; 95% CI 0.38-0.86; p < .01). There was no significant difference between groups in terms of periprocedural adverse events (RR 0.78; 95% CI 0.39-1.56; p = .49). CONCLUSIONS: Adjunctive LVA ablation is an effective and safe strategy for reducing recurrences of ATA among patients who undergo CA for AF.

Percutaneous mechanical support in catheter ablation of ventricular arrhythmias: hype or hope?

Catheter ablation (CA) has become an established treatment strategy for managing recurrent ventricular tachycardias (VTs) in patients with structural heart disease. In recent years, percutaneous mechanical circulatory support (PMCS) devices have been increasingly used intra-operatively to improve the ablation outcome. One indication would be rescue therapy for patients who develop haemodynamic deterioration during the ablation. However, more efforts are focused on identifying subjects who are at high risk of such deterioration and could benefit from the pre-emptive use of the PMCS. The third reason to use PMCS could be the inability to identify diffuse substrate, especially in non-ischaemic cardiomyopathy. This paper reviews available experiences using various types of PMCS in different clinical scenarios. Although PMCS allows mapping during VT, it does not significantly influence acute outcomes and not convincingly long-term outcomes. On the contrary, the complication rate appears to be higher in PMCS cohorts. Our data suggest that even in patients with severe left ventricular dysfunction, the substrate modification can be performed without the need for general anaesthesia and risk of haemodynamic decompensation. In end-stage heart failure associated with the electrical storm, implantation of a left ventricular assist device (or PMCS with a transition to the left ventricular assist device) might be the preferred strategy before CA. In high-risk patients who are not potential candidates for these treatment options, radiotherapy could be considered as a bail-out treatment of recurrent VTs. These approaches should be studied in prospective trials.

Low voltage area guided substrate modification in nonparoxysmal atrial fibrillation: A systematic review and meta-analysis.

BACKGROUND: Low voltage areas (LVAs) on left atrial (LA) bipolar voltage mapping correlate with areas of fibrosis. LVAs guided substrate modification was hypothesized to improve the success rate of atrial fibrillation (AF) ablation particularly in nonparoxysmal AF population. However, randomized controlled trials (RCTs) and observational studies yielded mixed results. METHODS: The databases of Pubmed, EMBASE and Cochrane Central databases were searched from inception to August 2022. Relevant studies comparing LVA guided substrate modification (LVA ablation) versus conventional AF ablation (non LVA ablation) in patients with nonparoxysmal AF were identified and a meta-analysis was performed (Graphical Abstract image). The efficacy endpoints of interest were recurrence of AF and the need for repeat ablation at 1-year. The safety endpoint of interest was adverse events for both groups. Procedure related endpoints included total procedure time and fluoroscopy time. RESULTS: A total of 11 studies with 1597 patients were included. A significant reduction in AF recurrence at 1-year was observed in LVA ablation versus non LVA ablation group (risk ratio [RR] 0.63 (27% vs. 36%),95% confidence interval [CI] 0.48-0.62, p < .001]. Also, redo ablation was significantly lower in LVA ablation group (RR 0.52[18% vs. 26.7%], 95% CI 0.38-0.69, p < .00133). No difference was found in the overall adverse event (RR 0.7 [4.3% vs. 5.4%], 95% CI 0.36-1.35, p = .29). CONCLUSION: LVA guided substrate modification provides significant reduction in recurrence of all atrial arrhythmias at 1-year compared with non LVA approaches in persistent and longstanding persistent AF population without increase in adverse events.

Low-voltage area substrate modification for atrial fibrillation ablation: a systematic review and meta-analysis of clinical trials.

AIMS: The value of additional ablation beyond pulmonary vein isolation for atrial fibrillation (AF) ablation is unclear, especially for persistent AF. The optimal target for substrate modification to improve outcomes is uncertain. We investigate the utility of low-voltage area (LVA) substrate modification in patients undergoing catheter ablation for AF. METHODS AND RESULTS: This meta-analysis was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Medline, Scopus and Cochrane Central Register of Controlled Trials were systematically searched to identify relevant studies. Risk of bias was assessed using the Cochrane risk of bias tool. Only randomized studies were included. AF patients who underwent catheter ablation with voltage-guided substrate modification targeting LVA (LVA group) vs. conventional ablation approaches not targeting LVA (non-LVA group) were compared. Four studies comprising 539 patients were included (36% female). Freedom from arrhythmia (FFA) in patients with persistent AF was greater in the LVA group [risk ratio (RR) 1.30; 95% confidence interval (CI) 1.03-1.64]. There was no difference in FFA in patients with paroxysmal AF between groups (RR 1.30; 95% CI 0.89-1.91). There was no difference in total procedural time (mean difference -17.54 min; 95% CI -64.37 to 29.28 min) or total ablation time (mean difference -36.17 min; 95% CI -93.69 to 21.35 min) in all included patients regardless of AF type between groups. There was no difference in periprocedural complications between groups in all included patients regardless of AF type (RR 0.93; 95% CI 0.22-3.82). CONCLUSION: This meta-analysis demonstrates improved FFA in persistent AF patients who underwent voltage-guided substrate modification targeting LVA.

Beneficial effects of atrial fibrillation ablation in patients with angina pectoris and coronary sinus reducer.

Limited data exists about the effectiveness of the coronary sinus reducer (CSR) device in patients with angina pectoris and atrial fibrillation (AF). This case demonstrates beneficial effects of AF ablation in a patient with CSR. We report four major findings: Rhythm control has a relevant effect on angina pectoris symptoms in patients with coronary artery disease and AF. In these patients, AF ablation should be considered at an early stage. Patients with persistent angina pectoris and CSR may require sinus rhythm for an optimal effect of the device. Selected coronary sinus (CS) interventions can still be performed through the mesh of the CSR device.

Splitting the P-Wave: Improved Evaluation of Left Atrial Substrate Modification after Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation.

Atrial substrate modification after pulmonary vein isolation (PVI) of paroxysmal atrial fibrillation (pAF) can be assessed non-invasively by analyzing P-wave duration in the electrocardiogram (ECG). However, whether right (RA) and left atrium (LA) contribute equally to this phenomenon remains unknown. The present study splits fundamental P-wave features to investigate the different RA and LA contributions to P-wave duration. Recordings of 29 pAF patients undergoing first-ever PVI were acquired before and after PVI. P-wave features were calculated: P-wave duration (PWD), duration of the first (PWDon-peak) and second (PWDpeak-off) P-wave halves, estimating RA and LA conduction, respectively. P-wave onset (PWon-R) or offset (PWoff-R) to R-peak interval, measuring combined atrial/atrioventricular and single atrioventricular conduction, respectively. Heart-rate fluctuation was corrected by scaling. Pre- and post-PVI results were compared with Mann-Whitney U-test. PWD was correlated with the remaining features. Only PWD (non-scaling: Δ=-9.84%, p=0.0085, scaling: Δ=-17.96%, p=0.0442) and PWDpeak-off (non-scaling: Δ=-22.03%, p=0.0250, scaling: Δ=-27.77%, p=0.0268) were decreased. Correlation of all features with PWD was significant before/after PVI (p<0.0001), showing the highest value between PWD and PWon-R (ρmax=0.855). PWD correlated more with PWDon-peak (ρ= 0.540-0.805) than PWDpeak-off (ρ= 0.419-0.710). PWD shortening after PVI of pAF stems mainly from the second half of the P-wave. Therefore, noninvasive estimation of LA conduction time is critical for the study of atrial substrate modification after PVI and should be addressed by splitting the P-wave in order to achieve improved estimations.

Electrophysiological findings during atrial fibrillation reablation: Extending from pulmonary vein reconnection to sequential bipolar voltage map information.

BACKGROUND: Left atrial substrate modification targeting low voltage zones (LVZ) is an ablation strategy that-in addition to pulmonary vein (PV) isolation-tries to eliminate arrhythmogenic mechanisms harbored in such tissue. Electrophysiological findings at reablation include (a) PV reconnection, (b) reconnection over previous substrate ablation, and (c) de-novo LVZ. OBJECTIVE: To study, prevalence and contribution of these arrhythmogenic electrophysiological entities in patients with atrial fibrillation (AF) recurrences. METHODS: Consecutive patients with highly symptomatic AF undergoing index and reablation were included (n = 113). In all patients' PV reconnection, reconnection over previous substrate ablation and spontaneous de-novo LVZ were quantitatively assessed and integrated into an individual reablation strategy. Follow-up was based on continuous device monitoring. RESULTS: At re-do procedure, 45 out of 113 (39.8%) patients showed PV reconnection as the only electrophysiological abnormality. Reconduction over previous lines was the only electrophysiological abnormality in 8 out of 113 (7.1%) patients. Spontaneous de-novo LVZ was the only electrophysiological abnormality in 12 out of 113 (10.6%) patients. Combined findings of PV reconnection, line reconduction, and/or spontaneous de-novo LVZ were seen in 40 out of 113 (35.4%) patients. No detectable electrophysiological abnormality was observed in 8 out of 113 (7.1%) patients. In univariate analysis, none of the tested electrophysiological characteristics independently predicted the outcome after re-do. CONCLUSIONS: In patients undergoing reablation, we could show that reconduction over previous substrate ablation as well as the development of new low voltage areas are frequent findings besides classical PV reconnection-without a clear leading cause for recurrences. These findings impact reablation strategies as well as the strategic focus during index procedures.

Sustained and self-terminating atrial fibrillation induced immediately after pulmonary vein isolation exhibit differences in coronary sinus electrical activity from onset.

INTRODUCTION: Little data exists on the electrophysiological differences between sustained atrial fibrillation (sAF; >5 minutes) vs self-terminating nonsustained AF (nsAF; <5 minutes). We sought to investigate the electrophysiological characteristics of coronary sinus (CS) activity during postpulmonary vein isolation (PVI) sAF vs nsAF. METHODS AND RESULTS: We studied 142 patients post-PVI for paroxysmal AF (PAF). In a 50-patient subset, CS electrograms in the first 30 seconds of induced AF were analyzed manually. A custom-made algorithm for automated electrogram annotation was derived for validation on the whole patient set. In patients with sAF post-PVI, CS fractionated potentials were ablated. Manual analysis showed that patients with sAF exhibited higher activation pattern variability (2.1 vs 0.5 changes/sec; P < .001); fewer proximal-to-distal wavefronts (25 vs 61%; P < .001); fewer unidirectional wavefronts (60 vs 86%; P < .001); more pivot locations (4.3 vs 2.1; P < .001); shorter cycle lengths (190 vs 220 ms; P < .001); and shorter cumulative isoelectric segments (35 vs 44%; P = .045) compared to nsAF. These observations were confirmed on the whole study population by automated electrogram annotation and sample entropy computation (SampEn: 0.29 ± 0.15 in sAF vs 0.15 ± 0.05 in nsAF; P < .0001). The derived model predicted sAF with 78% sensitivity, 88% specificity; agreement with manual model: 88% (Cohen's kappa= 0.76). CS defragmentation resulted in AF termination or noninducibility in 49% of sAF. CONCLUSION: In PAF patients post-PVI, induced sAF shows greater activation sequence variability, shorter cycle length, and higher SampEn in the CS compared to nsAF. Automated electrogram annotation confirmed these results and accurately distinguished self-terminating nsAF episodes from sAF based on 30-second recordings at AF onset.

Identification of circumferential pulmonary vein isolation responders among patients with persistent atrial fibrillation: clinical value of the sequential low-dose ibutilide test.

AIMS: Circumferential pulmonary vein isolation can be effective as sole treatment for persistent atrial fibrillation. However, identifying those patients who will respond to this therapy remains a challenge. We investigated the clinical value of the sequential low-dose ibutilide test for identifying patients with persistent atrial fibrillation in whom pulmonary vein isolation is effective as sole therapy. METHODS AND RESULTS: In a prospective cohort of 180 consecutive patients with persistent atrial fibrillation, intravenous low-dose (0.004 mg/kg) ibutilide was administered 3 days before ablation and after the completion of circumferential pulmonary vein isolation. In patients in whom ibutilide did not terminate atrial fibrillation pre-procedurally, but successfully terminated it intraprocedurally, no further atrial substrate modification was performed. Pre-procedural low-dose ibutilide failed to terminate the arrhythmia in all patients with persistent atrial fibrillation, while pulmonary vein isolation ± low-dose ibutilide terminated persistent atrial fibrillation in 55 (30.6%) of them (PsAF group 1). The remaining 125 (69.4%) patients underwent electrogram-based ablation (PsAF Group 2). The control group comprised 379 consecutive patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation over the same period. At 24 months follow-up, 39 (70.9%) patients in PsAF Group 1 and 276 (72.8%) patients in the control group were free from atrial tachyarrhythmias (P = NS); the arrhythmia-free rates in both groups were higher than that in PsAF group 2 (58.4%, P = 0.005). CONCLUSION: The sequential low-dose ibutilide test is a simple method for identifying patients with persistent atrial fibrillation in whom pulmonary vein isolation alone is an appropriate treatment strategy.

Dynamic voltage threshold adjusted substrate modification technique for complex atypical atrial flutters with varying circuits.

BACKGROUND: Atypical atrial flutter (AFL) is common in patients with postsurgical atrial scar, with macro- or microscopic channels in the scar acting as substrate for reentry. Heterogeneous atrial scarring can cause varying flutter circuits, which makes mapping and ablation challenging, and recurrences common. AIM: We hypothesize that dynamically adjusting voltage thresholds can identify heterogeneous atrial scarring, which can then be effectively homogenized to eliminate atypical AFLs. METHODS: We studied consecutive patients who presented to Electrophysiology laboratory for atypical AFL ablation with history of atriotomy and included the patients with multiple, varying flutter circuits during mapping in our study. We excluded patients with stable flutter circuit that was sustained and could be localized using traditional entrainment and activation mapping strategy. In the included patients, we performed detailed high-density voltage map of the atrium of interest. We adjusted voltage thresholds as needed to identify heterogeneity and channels in the scarred regions. A thorough scar homogenization was performed with irrigated smart-touch ablation catheter. Re-inducibility of tachycardia, and immediate and long-term outcomes were studied. RESULTS: Of five studied cases, one was female; age 66 ± 10 years. All five had prior surgical substrate. All the patients had multiple flutter morphologies, which varied as we mapped the AFL. After scar homogenization, tachycardia was not inducible in any patient. No recurrence of flutter was noted during a mean follow-up duration of 450 ± 27 days. CONCLUSION: High-density voltage mapping and homogenization of the scar can be an effective strategy in eliminating complex scar-mediated atypical AFL with multiple circuits.

Efficacy and Safety of Adjunctive Substrate Modification During Pulmonary Vein Isolation for Atrial Fibrillation: A Meta-Analysis.

BACKGROUND: The efficacy and safety of adjuvant substrate modification (SM; either linear ablation [LA] or complex fractionated atrial electrogram [CFAE] ablation) in addition to pulmonary vein isolation (PVI) for the treatment of symptomatic, drug-refractory atrial fibrillation (AF), have still not been clarified and need further assessment. METHOD: We systematically searched the PubMed, MEDLINE, and Cochrane databases for studies comparing PVI with adjunctive SM versus PVI alone for treatment of drug-refractory AF. RESULTS: Twenty-six (26) studies including 3,409 patients (1,975 PVI + SM; 1,434 PVI alone) were included for further analysis. Atrial fibrillation/atrial tachycardia-free survival of patients with PVI + SM was comparable with that of PVI alone (relative risk [RR], 1.06; 95% confidence interval [CI], 0.98-1.14; p = 0.143). In line with this, the primary clinical outcomes were robust, irrespective of additional LA (RR, 1.07; 95% CI, 0.97-1.18; p = 0.194) or CFAE ablation (RR, 1.04; 95% CI, 0.93-1.16; p = 0.534). Adjuvant SM is associated with longer procedural time (weighted mean difference, 20.72; 95% CI, 10.25-31.20; p = 0.0) and fluoroscopy time (weighted mean difference, 6.66; 95% CI, 1.74-11.58; p = 0.000); surprisingly, it presented similar procedure-related complications as PVI alone during AF catheter ablation (RR, 1.01; 95% CI, 0.68-1.50; p = 0.946). CONCLUSIONS: Adjuvant LA or CFAE ablation do not provide incremental benefit over PVI alone. Although substrate-based ablation markedly prolonged procedural and fluoroscopic duration, there was no evidence of increased risk of procedure-related complications.

An automated fractionation mapping algorithm for mapping of scar-based ventricular tachycardia.

BACKGROUND: Mapping and ablation of fractionated electrograms is a common treatment for scar-based ventricular tachycardia (VT). An automated algorithm has been developed for rapid "fractionation mapping." METHODS: Electroanatomic maps from 21 ablation procedures (14 scar-based VT and seven control idiopathic VT/premature ventricular contractions with normal voltage) were retrospectively analyzed using the Ensite Precision fractionation map (fMap; Abbott Laboratories; Abbott Park, IL, USA) algorithm. For each study, voltage maps and 30 fMaps were generated using combinations of parameters: width (5, 10, 20 ms), refractory time (15, 30 ms), sensitivity (0.1, 0.2 mV), and fractionation threshold (2, 3, 5). Parameter sensitivity was assessed by overlap of fractionated areas (fArea) with successful VT ablation sites (defined by entrainment and/or pace mapping). Specificity was assessed by presence of fractionated areas in control patients. RESULTS: Of the 30 fMap parameter sets tested, seven identified >50% of scar-based VT ablation sites, and 26 contained <5 cm2 fractionation on control fMaps. Three combinations of fMap width/refractory/sensitivity/threshold parameters met both of the above criteria, and 20/30/0.1/2 identified the most VT ablation sites (79%) and generated 42.3 ± 28.2 cm2 of fArea on scar-based VT maps compared with 4.9 ± 3.2 cm2 on control maps (P = .001). None of the control patients and 23% of the scar-based VT patients had VT recurrence at mean 15 month follow-up. CONCLUSION: Careful selection of signal processing parameters optimizes sensitivity and specificity of automated fractionation mapping for scar-based VT. Real-time use of fMap algorithms may reduce VT ablation procedure time and improve substrate modification, which may improve outcomes.

Impact of left atrial box surface ratio on the recurrence after ablation for persistent atrial fibrillation.

BACKGROUND: The posterior wall of the left atrium (LA) is a well-known substrate for atrial fibrillation (AF) maintenance. Isolation of the posterior wall between the pulmonary veins (box lesion) may improve ablation success. Box lesion surface area size varies depending on the individual anatomy. This retrospective study evaluates the influence of box lesion surface area as a ratio of total LA surface area (box surface ratio) on arrhythmia recurrence. METHODS: Seventy consecutive patients with persistent AF (63 ± 11 years, 53 men) undergoing computed tomography (CT) imaging and ablation procedure consisting of a first box lesion were included in this study. Box lesion surface area was measured on electroanatomical maps and total LA surface area was derived from CT. Patients were followed with 24-h electrocardiography and exercise tests at 3, 6, and 12 months after AF ablation. Arrhythmia recurrence was defined as any AF/atrial tachycardia (AT) beyond 3 months without antiarrhythmic drugs. RESULTS: During a median follow-up of 13 (interquartile range = 10-17) months, 42 (60%) patients had AF/AT recurrence. Multivariate Cox proportional regression analysis showed that a larger box surface ratio protected against recurrence (hazard ratio [HR] = 0.81; 95% confidence interval [CI] = 0.690-0.955; P = 0.012). Left atrial volume index (HR = 1.01 [0.990-1.024, P = 0.427] and a history of mitral valve surgery (HR = 2.90; 95% CI = 0.970-8.693; P = 0.057) were not associated with AF recurrence in multivariate analysis. CONCLUSION: A larger box lesion surface area as a ratio of total LA surface area is protective for AF/AT recurrence after ablation for persistent AF.

Silver Nanoparticles Based Ink with Moderate Sintering in Flexible and Printed Electronics.

Printed electronics on flexible substrates has attracted tremendous research interest research thanks its low cost, large area production capability and environmentally friendly advantages. Optimal characteristics of silver nanoparticles (Ag NPs) based inks are crucial for ink rheology, printing, post-print treatment, and performance of the printed electronics devices. In this review, the methods and mechanisms for obtaining Ag NPs based inks that are highly conductive under moderate sintering conditions are summarized. These characteristics are particularly important when printed on temperature sensitive substrates that cannot withstand sintering of high temperature. Strategies to tailor the protective agents capping on the surface of Ag NPs, in order to optimize the sizes and shapes of Ag NPs as well as to modify the substrate surface, are presented. Different (emerging) sintering technologies are also discussed, including photonic sintering, electrical sintering, plasma sintering, microwave sintering, etc. Finally, applications of the Ag NPs based ink in transparent conductive film (TCF), thin film transistor (TFT), biosensor, radio frequency identification (RFID) antenna, stretchable electronics and their perspectives on flexible and printed electronics are presented.

A novel ablation approach in atrial fibrillation patients undergoing fibrotic-based substrate modification: Targeting the Bachmann's bundle?

INTRODUCTION: Box isolation of fibrotic areas (BIFA) is a promising ablation approach for atrial fibrillation (AF) patients. However, complete isolation of fibrotic anteroseptal left atrial area, where Bachmann's bundle is blending into the left atrial myocardium, is very specific and complex. METHODS AND RESULTS: In 34 AF patients with anteroseptal fibrosis, circumferential BIFA was performed in addition to pulmonary vein isolation. In 8 of 34 patients, complete isolation of the fibrotic area was achieved with BIFA alone. In 26 of 34 patients, a decrease in voltage amplitude with or without conduction delay was observed after box ablation but no complete isolation. Activation mapping and characteristic unipolar potentials revealed earliest activation inside the box from one (73%), two (15%), or three (12%) remaining inputs, in the region of Bachmann's bundle insertion. Focal ablation inside the box (mean radiofrequency impulses: 1.7 ± 0.4, mean radiofrequency time: 70 ± 19 seconds) led to complete isolation of the fibrotic area in 25 of 26 patients. Overall, 97% of anteroseptal boxes were completely isolated with additional focal ablation in the study group compared to 21% in the control group with BIFA alone (33/34 vs. 7/34, P < 0.001). Time of left atrial activation decreased significantly by 25% after complete box isolation (P < 0.001). After a single procedure, 12-month arrhythmia-free survival was 82% with additional focal ablation compared to 71% in the control group (P = 0.2). CONCLUSION: Targeted and focal ablation in the region of Bachmann's bundle is a novel and feasible technique to achieve complete isolation of the left atrial anteroseptal fibrotic area.

Long-term outcomes of different ablation strategies for ventricular tachycardia in patients with structural heart disease: systematic review and meta-analysis.

Aims: To compare the long-term outcomes of standard ablation of stable ventricular tachycardia (VT) vs. substrate modification, and of complete vs. incomplete substrate modification in patients with structural heart disease (SHD) presenting with VT. Methods and results: An electronic search was performed using major databases. The main outcomes were a composite of long-term ventricular arrhythmia (VA) recurrence and all-cause mortality of standard ablation of stable VT vs. substrate modification, and long-term VA recurrence in complete vs. incomplete substrate modification. Six studies were included for the comparison of standard ablation of stable VT vs. substrate modification, with a total of 396 patients (mean age 63 ± 10 years, 87% males), and seven studies were included to assess the impact of extensive substrate modification, with a total of 391 patients (mean age 64 ± years, 90% males). More than 70% of all the patients included had ischaemic cardiomyopathy. Substrate modification was associated with decreased composite VA recurrence/all-cause mortality compared to standard ablation of stable VTs [risk ratio (RR) 0.57, 95% confidence interval (CI) 0.40-0.81]. Complete substrate modification was associated with decreased VA recurrence as compared to incomplete substrate modification (RR 0.39, 95% CI 0.27-0.58). Conclusion: In patients with SHD who had VT related mainly to ischaemic substrates, there was a significantly lower risk of the composite primary outcome of long-term VA recurrence and all-cause mortality among those undergoing substrate modification compared to standard ablation. Long-term success is improved when performing complete substrate modification.

Catheter ablation of paroxysmal atrial fibrillation using high-density mapping-guided substrate modification.

BACKGROUND: This study aimed to evaluate the effect of substrate modification in paroxysmal atrial fibrillation (AF) patients prior to circumferential pulmonary vein isolation (CPVI). METHODS: Patients without left atrial low-voltage and/or scar areas were defined as Group A. Patients with left atrial low-voltage and/or scar areas underwent regular CPVI (Group B) or substrate modification after CPVI (Group C). The procedural success rate and differences in the left atrial diameter (LAD) among groups were compared at 1 year postoperatively. RESULTS: The procedural success rate in Group C was comparable to that in Group A (P > 0.05) and was significantly higher than that in Group B (P < 0.01). The LAD of patients in Groups A and C significantly decreased at 1 year postoperatively compared to that prior to the surgery (P < 0.05). However, no significant difference was noted in Group B. CONCLUSIONS: Our study demonstrated that substrate modification could contribute to the single catheter ablation surgery success rate in patients with paroxysmal AF and narrow LAD.