Clinical Significance of Induced Atrial Tachycardia After Termination of Longstanding Persistent Atrial Fibrillation Using a Stepwise Approach

Atrial tachycardia occurring after a prior atrial fibrillation ablation procedure: Does non-inducibility matter?

Recurrent atrial tachycardia (AT) is a common phenomenon after catheter ablation for AF, particularly in the setting of additional substrate ablation, with many studies demonstrating gap-related macro re-entrant AT (predominantly mitral and roof dependent) to be the dominant mechanism. Although multiple inducible ATs after ablation of the clinical AT are commonly described at repeat procedures, the optimal ablation strategy, and procedural endpoints are unclear in this setting. A recent randomized study addressing the question of non-inducibility as a procedural endpoint demonstrated no additional benefits to the ablation of all induced, non-clinical ATs, but it was limited by small numbers and high rates of non-inducibility. Nevertheless, once ablation of the clinical AT has been successfully performed, ensuring durable linear block and PV isolation may be sufficient for the prevention of further AT. Durable linear block, particularly at the mitral isthmus, is difficult to achieve but may be facilitated by the real-time evaluation of lesion quality and contiguity and the novel technique of vein of Marshall ethanol infusion. Large-scale, randomized trials are needed, nonetheless, to fully assess the optimal ablation strategy in the setting of recurrent AT post-AF ablation.

Inducibility of atrial fibrillation after catheter ablation predicts recurrences of atrial fibrillation: a meta-analysis

BACKGROUND

Pulmonary vein isolation (PVI) is a component of standard care for patients with symptomatic atrial fibrillation (AF). Procedural inducibility of AF following PVI has been suggested as predictor of AF recurrence but is discussed controversially. This meta-analysis aimed at evaluating the relevance of electrophysiological inducibility of AF following PVI for future AF recurrences.

METHODS

A literature search of MEDLINE and Web of Science was performed until April 2020. Prospective trials of PVI in patients with AF and post-procedural atrial stimulation to test for inducibility of AF as well as adequate follow-up for AF recurrence (defined as AF >10 s to >10 min at follow-up) were included. Odds ratios (ORs) were analyzed using random-effects models.

RESULTS

A total of 11 trials with 1544 patients (follow-up 7-39 months, age 56 ± 6 years, predominantly male 74 ± 6%) were included. Inducibility of AF post-PVI was predictive for AF recurrence during follow-up (OR 2.08; 95% CI 1.25 to 3.46). Prediction for AF recurrence at follow-up was better for patients with paroxysmal AF (OR 4.06; 95% CI 1.39 to 11.91), stimulation in the CS (OR 2.82, 95% CI 1.17 to 6.79). A trend towards higher ORs was seen without the use of isoproterenol (OR 2.43; 95% CI 1.17 to 5.07), as well as few stimulations during induction and a short definition of AF in meta-regression analyses.

CONCLUSIONS

Electrophysiological inducibility of AF following PVI was predictive for future recurrence of AF, in particular in patients with paroxysmal AF, stimulation in only CS and no use of isoproterenol.

The extent of complex fractionated atrial electrograms in the left atrium reflects age-related electrical remodeling in patients with persistent atrial fibrillation

BACKGROUNDS

Alterations in the atrial structure and function associated with aging result in electric remodeling of the left atrium (LA) in patients with persistent atrial fibrillation (AF). We performed this study to evaluate the influence of age on electric remodeling as assessed by the extent of complex fractionated atrial electrograms (CFAEs) in the LA.

METHODS

A total of 122 patients (mean age, 55.9 ± 10.4 years; range, 31-79; 106 males) who underwent catheter ablation for drug-refractory persistent AF were included in the study. The extent of CFAE was measured by CFAE area and its index (CFAE area/LA surface area × 100) using three-dimensional automated software of NavX system.

RESULTS

The mean value of CFAE extent was significantly different among age groups; the CFAE area decreased significantly with increasing age (30 seconds [43.2 ± 14.5 mm2] vs 40 seconds [28.6 ± 6.0 mm2] vs 50 seconds [22.8 ± 3.4 mm2] vs 60 seconds [15.3 ± 2.6 mm2] vs 70 seconds [10.3 ± 3.2 mm2]; P = .010). A similar significant decrease was observed in the CFAE area index (30 seconds [22.9 ± 7.4] vs 40 seconds [14.9 ± 3.4] vs 50 seconds [10.4 ± 1.6] vs 60 seconds [6.9 ± 1.2] vs 70 seconds [4.6 ± 1.4]; P = .002). Age had a significantly negative correlation with the CFAE area (r = -0.322, P < .001) and CFAE area index (r = -0.357, P < .001).

CONCLUSIONS

Increasing age is associated with electric remodeling in the LA characterized by a decrease in the extent of CFAE area and its index.

Utility of acute arrhythmia termination as an ablation endpoint for induced atrial tachyarrhythmia after complete pulmonary vein isolation during catheter ablation for persistent atrial fibrillation

PURPOSE

The presence of inducible atrial tachyarrhythmia after pulmonary vein isolation (PVI) during radiofrequency catheter ablation (RFCA) for persistent atrial fibrillation (AF) may indicate the necessity of further substrate modification, but the optimal ablation endpoint is unknown. We sought to assess the impact of procedural termination of inducible atrial tachyarrhythmia after PVI in comparison with continued atrial tachyarrhythmia after PVI.

METHODS

Among patients who underwent RFCA for persistent AF, we enrolled 93 patients who were in sinus rhythm after PVI and had inducible atrial tachyarrhythmia and 157 patients with continued atrial tachyarrhythmia after PVI. The impact of acute arrhythmia termination during further substrate modification on recurrence was compared between the two groups.

RESULTS

Acute termination was achieved in 51 (54.8%) patients in the induced arrhythmia group and 61 (38.9%) in the continued arrhythmia group. During a mean 35.8 months, acute termination did not significantly reduce arrhythmia recurrence in the induced arrhythmia group (HR 0.712, 95% CI 0.400-1.266, p = 0.247), while it was associated with improved outcome in the continued arrhythmia group (HR 0.590, 95% CI 0.355-0.979, p = 0.038). Acute termination of either induced atrial tachycardia (AT) or induced AF was not associated with improved procedure outcome. Among the continued arrhythmia group, the benefit of acute termination was statistically significant in AT (HR 0.329, 95% CI 0.108-0.997, p = 0.039), but not in AF (HR 0.704, 95% CI 0.396-1.253, p = 0.233) after PVI.

CONCLUSIONS

Acute termination of induced rhythm is not a reliable ablation endpoint during substrate modification in patients with inducible arrhythmia after PVI.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.

Interatrial septal thickness is associated with the extent of left atrial complex fractionated atrial electrograms and acute procedural outcome in patients with persistent atrial fibrillation

AIMS

The interatrial septal thickness (IAST) reflects the changes of the atrial wall in patients with atrial fibrillation (AF). Complex fractionated atrial electrograms (CFAEs) were consistently positioned on the interatrial septum, especially in the remodelled left atrium (LA). We sought to characterize the relationship between IAST and LA CFAE area, as well as the acute procedural and clinical outcomes of catheter ablation in persistent AF patients.

METHODS AND RESULTS

This study included 71 patients who underwent catheter ablation for drug-refractory persistent AF. A stepwise ablation approach included circumferential pulmonary vein isolation followed by LA and right atrial CFAE-guided ablation. Interatrial septal thickness was measured 1 cm inferior to the fossa ovalis on cardiac computed tomography (CT). The extent of LA CFAEs was assessed by CFAE area and index (CFAE area/LA surface area × 100). Patients were grouped into tertiles according to the value of IAST. The mean IAST of the first, second, and third tertile was 4.69 ± 0.79, 6.44 ± 0.45, and 9.12 ± 1.42 mm, respectively (P < 0.001). The mean CFAE areas (5.6 ± 6.9, 18.5 ± 20.3, and 24.3 ± 26.6 mm(2), P = 0.005) and CFAE indexes (3.1 ± 4.2, 9.2 ± 10.7, and 11.8 ± 15.3, P = 0.025) in LA were significantly different among the three groups. More patients in the highest IAST tertile did not terminate AF during catheter ablation (12.5% vs. 26.1% vs. 37.5%, P = 0.048).

CONCLUSIONS

Interatrial septal thickness measured by cardiac CT is associated with the extent of CFAE area within the LA and is related to acute procedural success of catheter ablation. These findings suggest that IAST reflects the degree of atrial substrate and remodelling in patients with persistent AF.