Low-Voltage-Area Ablation in Paroxysmal Atrial Fibrillation - Extended Follow-up Results of the VOLCANO Trial

Association between left atrial low-voltage area and induction and recurrence of macroreentrant atrial tachycardia in pulmonary vein isolation for atrial fibrillation

BACKGROUND

The relationship between induction and recurrence due to atrial tachycardia (AT) and left atrial (LA) matrix progression after atrial fibrillation (AF) ablation remains unclear.

METHODS

One hundred fifty-two consecutive patients with paroxysmal and persistent AF who underwent pulmonary vein isolation (PVI) and cavo-tricuspid isthmus (CTI) ablation and achieved sinus rhythm before the procedure were classified into three groups according to the AT pattern induced after the procedure: group N (non-induced), F (focal pattern), and M (macroreentrant pattern) in 3D mapping.

RESULTS

The total rate of AT induction was 19.7% (30/152) in groups F (n = 13) and M (n = 17). Patients in group M were older than those in groups N and F, with higher CHADS2/CHA2DS2-VASc values, left atrial enlargement, and low-voltage area (LVA) size of LA. The receiver operating characteristic curve determined that the cut-off LVA for macroreentrant AT induction was 8.8 cm2 (area under the curve [AUC]: 0.86, 95% confidence interval [CI]: 0.75-0.97). The recurrence of AT at 36 months in group N was 4.1% (5/122), and at the second ablation, all patients had macroreentrant AT. Patients with AT recurrence in group N had a wide LVA at the first ablation, and the cut-off LVA for AT recurrence was 6.5 cm2 (AUC 0.94, 95%CI 0.88-0.99). Adjusted multivariate analysis showed that only LVA size was associated with the recurrence of macroreentrant AT (odds ratio 1.21, 95%CI 1.04-1.51).

CONCLUSIONS

It is important to develop a therapeutic strategy based on the LVA size to suppress the recurrence of AT in these patients.

The effect of high-power short-duration pulmonary vein isolation on PWPT-a predictor of paroxysmal atrial fibrillation

BACKGROUND

The P wave peak time (PWPT) is a predictor of paroxysmal atrial fibrillation (PAF). High-power short-duration ablation has been associated with improved durability of circumferential pulmonary vein electrical isolation (PVI). We investigated the effect of high-power short-duration PVI on PWPT in patients with PAF.

METHODS

Out of 111 patients with PAF, 91 received radiofrequency ablation (ablation group) and 20 received medication treatment (control group). A VIZIGO sheath and an STSF catheter (Biosense Webster, CA, USA) were used together for high-power short-duration circumferential PVI at ablation index values of 500 and 400 for the anterior and posterior walls, respectively. The patients were followed up for 12 months.

RESULTS

The preoperative PWPT in the ablation group was similar to that in the control group: PWPT II = 54.38 ± 6.18 ms vs. 54.35 ± 6.12 ms (p > 0.05), PWPT V1 = 54.19 ± 6.21 ms vs. 54.31 ± 6.08 ms (p > 0.05), respectively. Circumferential PVI was achieved for all patients in the ablation group during the operation. At the 12-month follow-up, there were seven cases of AF recurrence. The PWPT in the ablation group 12 months postoperatively was shorter than the preoperative value: PWPT II = 49.39 ± 7.11 ms vs. 54.38 ± 6.18 ms (p < 0.001), PWPT V1 = 47.69 ± 7.01 ms vs. 54.19 ± 6.21 ms (p < 0.001). The PWPT in the patients with AF recurrence was significantly longer than that in the non-recurrence patients: PWPT II = 50.48 ± 7.12 ms vs. 47.33 ± 6.21 ms (p < 0.001), PWPT V1 = 50.84 ± 7.05 ms vs. 47.19 ± 6.27 ms, (p < 0.001). The PWPT of the control group at the 12-month follow-up was similar to the baseline level: PWPT II = 54.32 ± 6.20 ms vs. 54.35 ± 6.12 ms (p > 0.05), PWPT V1 = 53.89 ± 6.01 ms vs. 54.31 ± 6.08 ms (p > 0.05).

CONCLUSION

The results showed that high-power short-duration PVI had a positive effect on PWPT, which is a predictor of PAF.

Recurrence as isthmus-related atrial tachycardia: A cautionary point of low-voltage area homogenization of persistent atrial fibrillation

A 66-year-old female underwent persistent atrial fibrillation ablation. After pulmonary vein isolation and homogenization of low-voltage areas (LVAs), atrial tachycardia (AT) was not induced at the first session; however, it recurred one year after the procedure. During the second session, the extensive LVAs were distributed in the same area of the left atrial anterior wall and expanded possibly due to the previous LVA homogenization. The activation map revealed a macroreentrant AT circuit with the critical isthmus between the isolated right superior pulmonary vein and homogenized LVAs. Although the Ripple map algorithm failed to visualize dynamic bars, extremely low voltage and fractionated potentials (amplitude, 0.04 mV) were observed at the isthmus. Currently, there are various procedural endpoints of LVA-guided ablation (e.g. local electrogram reduction > 50 % or <0.1 mV in amplitude). In this case, incomplete transmural lesions may have led to slow conduction, which could have become an AT substrate. In cases with extensive LVAs on the left atrial anterior wall, eliminating any potential channels may be important for preventing future iatrogenic ATs. LVA-guided ablation should be performed on an individual basis, considering the potential benefits and harms based on the extent and location of LVAs.

Learning objective

Currently, the procedural endpoint of low-voltage area (LVA)-guided ablation varies across studies. Because any low-voltage potentials, except scars, can cause slow conduction, LVA-guided ablation with an endpoint of local electrogram voltage reduction can unintentionally generate an iatrogenic slow conduction isthmus. LVA-guided ablation should be individually performed, considering the potential benefits and harms based on the extent and location of LVAs.

Long-Term Impact of Additional Ablation After Pulmonary Vein Isolation: Results From EARNEST-PVI Trial

Background An optimal strategy for left atrial ablation in addition to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF) has not been determined. Methods and Results We conducted an extended follow-up of the multicenter randomized controlled EARNEST-PVI (Efficacy of Pulmonary Vein Isolation Alone in Patients With Persistent Atrial Fibrillation) trial, which compared 12-month rhythm outcomes in patients with persistent AF between patients randomized to a PVI-alone strategy (n=248) or PVI-plus strategy (n=248; PVI followed by left atrial additional ablation, including linear ablation or ablation targeting areas with complex fractionated electrograms). The present study extended the follow-up period to 3 years after enrollment. Outcomes were compared not only between randomly allocated groups but also between on-treatment groups categorized by actually created ablation lesions. Recurrence rate of AF or atrial tachycardia (AT) was lower in the randomly allocated to PVI-plus group than the PVI-alone group (29.0% versus 37.5%, P=0.036). On-treatment analysis revealed that patients with PVI+linear ablation (n=205) demonstrated a lower AF/AT recurrence rate than those with PVI only (26.3% versus 37.8%, P=0.007). In contrast, patients with PVI+complex fractionated electrograms ablation (n=37) had an AF/AT recurrence rate comparable to that of patients with PVI only (40.5% versus 37.8%, P=0.76). At second ablation in 126 patients with AF/AT recurrence, ATs excluding common atrial flutter were more frequent in patients with PVI+linear ablation than in those with PVI only (32.6% versus 5.7%, P<0.0001). Conclusions Left atrial ablation in addition to PVI was efficacious during 3-year follow-up. Linear ablation was superior to other ablation strategies but may increase iatrogenic ATs. Registration URL: http://www.umin.ac.jp/ctr/index-j.htm; Unique identifier: UMIN000019449.

Structural characteristics of patients with superior vena cava foci initiating atrial fibrillation: Analysis with electrocardiogram-triggered computed tomography

INTRODUCTION

The superior vena cava (SVC) is the most common source of non-pulmonary vein foci in atrial fibrillation (AF); therefore, predicting the existence of non-pulmonary vein foci before the catheter ablation procedure helps construct a proper ablation strategy in preparation for SVC isolation. This study aimed to clarify the structural characteristics of patients with SVC foci initiating AF.

METHODS

We enrolled 331 consecutive patients with AF who underwent cardiac computed tomography imaging before radiofrequency catheter ablation treatment, and they were divided into SVC (+) and (-) groups based on the presence or absence of SVC foci initiating AF.

RESULTS

The SVC (+) group (n = 27) exhibited SVC crescent signs-defined as a curve-shaped SVC with two narrow pointed ends-more frequently (37% vs. 9%, p < .001), and larger right atrial volume (95.6 ± 20.8 vs. 80.5 ± 26.1 mL, p = .004) than the SVC (-) group (n = 304). Multivariate logistic regression analysis revealed that the SVC crescent sign (odds ratio, 8.88; 95% confidence interval [CI], 3.21-24.60) and right atrial volume (odds ratio, 1.03; 95% CI, 1.01-1.04) were independent predictors of SVC foci.

CONCLUSION

Patients with SVC foci exhibited more frequent SVC crescent signs and larger right atrial volumes, and these characteristics may help clinicians choose the appropriate ablation technology.

Risk and benefit of extrapulmonary vein ablation in atrial fibrillation

PURPOSE OF REVIEW

This review aims to summarize the recent development, benefit, and safety of extrapulmonary vein ablation for atrial fibrillation.

RECENT FINDING

Studies have shown that extrapulmonary vein ablation can help maintain normal sinus rhythm for patients with persistent atrial fibrillation. As prior strategies targeting anatomical lines and triggers are well utilized, novel techniques for substrate mapping have been rapidly developing. These strategies are well tolerated and could be chosen based on patients' conditions and physicians' experience.

SUMMARY

Extrapulmonary vein ablation could be safely and effectively performed for patients with atrial fibrillation. It provides further consolidation of normal sinus rhythm.

Findings from repeat ablation using high-density mapping after pulmonary vein isolation with pulsed field ablation

AIMS

Pulsed-field ablation (PFA) can offer a novel perspective for atrial fibrillation (AF) ablation. We aimed to characterize the incidence of pulmonary vein (PV) reconnection, types of recurrent atrial tachyarrhythmia (ATa) and lesion quality after PFA-guided PV isolation (PVI).

METHODS AND RESULTS

Patients undergoing second ablation for recurrent ATa following the initial PVI using the pentaspline PFA catheter were investigated. The rate of PV reconnection, the features of recurrent ATa, and the amount of isolated posterior wall (PW) surface area (ISAPW%) (ratio of the isolated- to total surface area on PW) were analyzed.

RESULTS

Among 360 patients treated with PFA, 25 patients (paroxysmal AF, n = 19) with 99 PVs underwent a second procedure 6.1 ± 4.0 months after the initial procedure. The rate of PV reconnection was 9.1% (9 PVs). Patients presented with atrial tachycardia (AT) (n = 16), AF (n = 8) and typical atrial flutter (n = 1). The mechanism of all but one AT was macro-reentry. The critical isthmus was found to be linked to the initial lesion set at the left atrial (LA) PW in eight patients and linked to pre-existing substrate at the LA anterior wall in four patients. One AT had a focal origin at the septum. In three patients, AT were unmappable. Mean ISAPW% was 72.7 ± 19.0%.

CONCLUSION

We revealed a remarkable low reconnection rate with a large antral lesion at the PW after pentaspline PFA catheter-guided PVI. However, macro-reentrant AT with a critical isthmus at the LAPW linked to the PVI lesion set was commonly observed.

Efficacy of left atrial low-voltage area-guided catheter ablation of atrial fibrillation: An updated systematic review and meta-analysis

Aims

This study aimed to evaluate the efficacy of low-voltage area (LVA)-guided substrate modification catheter ablation in patients with atrial fibrillation (AF).

Methods

Systematic searches of the PubMed, EMBASE, and Cochrane databases were performed from inception to July 2022 for all available studies. The effect estimates were combined with the Mantel–Haenszel random-effects model. Subgroup analyses, sensitivity analysis, and meta-regression were conducted to explore the sources of statistical heterogeneity.

Results

A total of 16 studies involving 1942 subjects (mean age: 61 ± 10 years, 69% male) were identified. All studies included patients with paroxysmal AF, non-paroxysmal AF, or both. At a mean follow-up of 18.9 months, patients who underwent LVA-guided substrate modification ablation had significantly higher freedom from all-atrial tachycardia recurrence than patients who underwent control ablation [67.7% vs. 48.9%, risk ratios (RR) 0.64, 95% confidence interval (CI) 0.55–0.76, P &lt; 0.001], with 36% relative risk and 18.7% absolute risk reductions in all-atrial tachycardia recurrence. Subgroup analysis based on AF types demonstrated that the decreased risk of all-atrial tachycardia recurrence was present predominantly in non-paroxysmal AF compared with paroxysmal AF (RR 0.60, 95% CI 0.52–0.69 vs. RR 0.96, 95% CI 0.81–1.13).

Conclusion

Low-voltage area-guided substrate modification ablation combined with PVI appears to have a significant beneficial effect of improving freedom from all-atrial tachycardia recurrence, especially in patients with non-paroxysmal AF.

Mapping Atrial Fibrillation After Surgical Therapy to Guide Endocardial Ablation

BACKGROUND

Surgical ablation for atrial fibrillation (AF) can be effective, yet has mixed results. It is unclear which endocardial lesions delivered as part of hybrid therapy' will best augment surgical lesion sets in individual patients. We addressed this question by systematically mapping AF endocardially after surgical ablation and relating findings to early recurrence, then performing tailored endocardial ablation as part of hybrid therapy.

METHODS

We studied 81 consecutive patients undergoing epicardial surgical ablation (stage 1 hybrid), of whom 64 proceeded to endocardial catheter mapping and ablation (stage 2). Stage 2 comprised high-density mapping of pulmonary vein (PV) or posterior wall (PW) reconnections, low-voltage zones (LVZs), and potential localized AF drivers. We related findings to postsurgical recurrence of AF.

RESULTS

Mapping at stage 2 revealed PW isolation reconnection in 59.4%, PV isolation reconnection in 28.1%, and LVZ in 42.2% of patients. Postsurgical recurrence of AF occurred in 36 patients (56.3%), particularly those with long-standing persistent AF (P=0.017), but had no relationship to reconnection of PVs (P=0.53) or PW isolation (P=0.75) when compared with those without postsurgical recurrence of AF. LVZs were more common in patients with postsurgical recurrence of AF (P=0.002), long-standing persistent AF (P=0.002), advanced age (P=0.03), and elevated CHA₂DS₂-VASc (P=0.046). AF mapping revealed 4.4±2.7 localized focal/rotational sites near and also remote from PV or PW reconnection. After ablation at patient-specific targets, arrhythmia freedom at 1 year was 81.0% including and 73.0% excluding previously ineffective antiarrhythmic medications.

CONCLUSIONS

After surgical ablation, AF may recur by several modes particularly related to localized mechanisms near low voltage zones, recovery of posterior wall or pulmonary vein isolation, or other sustaining mechanisms. LVZs are more common in patients at high clinical risk for recurrence. Patient-specific targeting of these mechanisms yields excellent long-term outcomes from hybrid ablation.