Ablation of Complex Fractionated Atrial Electrograms for Atrial Fibrillation Rhythm Control: A Systematic Review and Meta-analysis

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 < 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.

Impact of advanced liver fibrosis on atrial fibrillation recurrence after ablation in non-alcoholic fatty liver disease patients

Aim

Advanced liver fibrosis is independently associated with new onset of atrial fibrillation (AF). Non-invasive liver fibrosis scores are considered an effective strategy for assessing liver fibrosis. This study aimed to investigate the association between advanced liver fibrosis and AF recurrence after ablation in patients with non-alcoholic fatty liver disease (NAFLD).

Materials and methods

A total of 345 AF patients with NAFLD who underwent de novo ablation between 2019 and 2020 at two large hospitals in China were included in this study. AF recurrence was defined as the occurrence of atrial arrhythmia for more than 30 s by electrocardiogram or 24 h Holter monitoring after the first 3 months of ablation. Predictive values of non-alcoholic fatty liver disease fibrosis score (NFS) and Fibrosis-4 (FIB-4) scores for AF burden and recurrence after ablation were assessed.

Results

At the 1 year follow-up after ablation, 38.8% of patients showed recurrence. Patients with recurrence who had higher FIB-4 and NFS scores were more likely to have persistent AF and a duration of AF ≥ 3 years. In Kaplan-Meier analysis, patients with intermediate and high NFS and FIB-4 risk categories had a higher risk of AF recurrence. Compared to patients with the low risk, intermediate and high NFS, and FIB-4 risk were independently associated with AF recurrence in multivariate Cox regression analysis (high risk: NFS, hazard ratio (HR): 3.11, 95% confidence interval (CI): 1.68∼5.76, p < 0.001; FIB-4, HR: 3.91, 95% CI: 2.19∼6.98, p < 0.001; intermediate risk: NFS, HR: 1.85, 95% CI: 1.10∼3.10, p = 0.020; FIB-4, HR: 2.08, 95% CI: 1.27∼3.41, p = 0.003).

Conclusion

NFS and FIB-4 scores for advanced liver fibrosis are associated with AF burden. Advanced liver fibrosis is independently associated with AF recurrence following ablation. Advanced liver fibrosis might be meaningful in risk classification for patients after AF ablation.

Additional complex fractionated atrial electrogram ablation does not improve the outcomes of non-paroxysmal atrial fibrillation: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Non-paroxysmal atrial fibrillation (AF) has a complex pathophysiological process. The standard catheter ablation approach is pulmonary vein isolation (PVI). The additional value of complex fractionated electrogram (CFAE) ablation is still unclear. We aimed to investigate the additional value of CFAE ablation for non-paroxysmal AF.

METHODS

We performed a systematic review and meta-analysis of randomized controlled studies up to May 2020. Articles comparing pulmonary vein isolation (PVI) plus CFAE ablation and PVI alone for AF were obtained from the electronic scientific databases. The pooled mean difference (MD) and pooled risk ratio (RR) were assessed.

RESULTS

A total of 8 randomized controlled trials (RCTs) including 1034 patients were involved. Following a single catheter ablation procedure, the presence of any atrial tachyarrhythmia (ATA) with or without the use of antiarrhythmic drugs (AADs) between both groups were not significantly different (RR = 1.1; 95% confidence interval [CI] = 0.97-1.24; p = 0.13). Similar results were also obtained for the presence of any ATA without the use of AADs (RR = 1.08; 95% CI = 0.96-1.22; p = 0.2). The additional CFAE ablation took longer procedure times (MD = 46.95 min; 95% CI = 38.27-55.63; p = < 0.01) and fluoroscopy times (MD = 11.69 min; 95% CI = 8.54-14.83; p = < 0.01).

CONCLUSION

Additional CFAE ablation failed to improve the outcomes of non-paroxysmal AF patients. It also requires a longer duration of procedure times and fluoroscopy times.

Catheter Ablation of Low-Voltage Areas for Persistent Atrial Fibrillation: Procedural Outcomes Using High-Density Voltage Mapping

BACKGROUND

Several approaches have been proposed to address the challenge of catheter ablation of persistent atrial fibrillation (AF). However, the optimal ablation strategy is unknown. We sought to evaluate the efficacy of pulmonary vein isolation (PVI) plus low-voltage area (LVA) ablation using contemporary high-density mapping to identify LVA in patients with persistent AF.

METHODS

Consecutive patients accepted for AF catheter ablation were studied. High-density bipolar voltage mapping data were acquired in sinus rhythm using multipolar catheters to detect LVA (defined as bipolar voltage < 0.5 mV). Semiautomated impedance-based software was used to ensure catheter contact during data collection. Patients underwent PVI + LVA ablation (if LVA present).

RESULTS

A total of 145 patients were studied; 95 patients undergoing PVI + LVA ablation were compared with 50 controls treated with PVI only. Average age was 61 ± 10 years, and 80% were male. Baseline characteristics were comparable. Freedom from atrial tachycardia/AF at 18 months was 72% after PVI + LVA ablation vs 58% in controls (P = 0.022). Median procedure duration (273 [240, 342] vs 305 [262, 360] minutes; P = 0.019) and radiofrequency delivery (50 [43, 63] vs 55 [35, 68] minutes; P = 0.39) were longer in the PVI + LVA ablation group. Multivariable analysis showed that the ablation strategy (PVI + LVA) was the only independent predictor of freedom from atrial tachycardia/AF (hazard ratio, 0.53; 95% confidence interval, 0.29-0.96; P = 0.036). There were no adverse safety outcomes associated with LVA ablation.

CONCLUSIONS

An individualized strategy of high-density mapping to assess the atrial substrate followed by PVI combined with LVA ablation is associated with improved outcomes. Adequately powered randomized clinical trials are needed to determine the role of PVI + LVA ablation for persistent AF.

The role of the autonomic nervous system in cardiac arrhythmias: The neuro-cardiac axis, more foe than friend?

The autonomic nervous system (ANS) with its two limbs, the sympathetic (SNS) and parasympathetic nervous system (PSNS), plays a critical role in the modulation of cardiac arrhythmogenesis. It can be both pro- and/or anti-arrhythmic at both the atrial and ventricular level of the myocardium. Intricate mechanisms, different for specific cardiac arrhythmias, are involved in this modulatory process. More data are available for the arrhythmogenic effects of the SNS, which, when overactive, can trigger atrial and/or ventricular "adrenergic" arrhythmias in susceptible individuals (e.g. in patients with paroxysmal atrial fibrillation-PAF, ventricular pre-excitation, specific channelopathies, ischemic heart disease or cardiomyopathies), while it can also negate the protective anti-arrhythmic drug effects. However, there is also evidence that PSNS overactivity may be responsible for triggering "vagotonic" arrhythmias (e.g. PAF, Brugada syndrome, idiopathic ventricular fibrillation). Thus, a fine balance is necessary to attain in these two limbs of the ANS in order to maintain eurhythmia, which is a difficult task to accomplish. Over the years, in addition to classical drug therapies, where beta-blockers prevail, several ANS-modulating interventions have been developed aiming at prevention and management of arrhythmias. Among them, techniques of cardiac sympathetic denervation, renal denervation, vagal stimulation, ganglionated plexi ablation and the newer experimental method of optogenetics have been employed. However, in many arrhythmogenic diseases, ANS modulation is still an investigative tool. Initial data are encouraging; however, further studies are needed to explore the efficacy of such interventions. These issues are herein reviewed and old and recent literature data are discussed, tabulated and pictorially illustrated.

Efficacy of Ablation Lesion Sets in Addition to Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation: Findings From the SMASH - AF Meta-Analysis Study Cohort

Background

The objective was to explore the efficacy of ablation lesion sets in addition to pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation. The optimal strategy for catheter ablation of paroxysmal atrial fibrillation is debated.

Methods and Results

The SMASH‐AF (Systematic Review and Meta‐analysis of Ablation Strategy Heterogeneity in Atrial Fibrillation) study cohort includes trials and observational studies identified in PubMed, Scopus, and Cochrane databases from January 1 1990, to August 1, 2016. We included studies reporting single procedure paroxysmal atrial fibrillation ablation success rates. Exclusion criteria included insufficient reporting of outcomes, ablation strategies that were not prespecified and uniform, and a sample size of fewer than 40 patients. We analyzed lesion sets performed in addition to PVI (PVI plus) using multivariable random‐effects meta‐regression to control for patient, study, and procedure characteristics. The analysis included 145 total studies with 23 263 patients (PVI‐only cohort: 115 studies, 148 treatment arms, 16 500 patients; PVI plus cohort: 39 studies; 46 treatment arms, 6763 patients). PVI plus studies, as compared with PVI‐only studies, included younger patients (56.7 years versus 58.8 years, P=0.001), fewer women (27.2% versus 32.0% women, P=0.002), and were more methodologically rigorous with longer follow‐up (29.5 versus 17.1 months, P 0.004) and more randomization (19.4% versus 11.8%, P<0.001). In multivariable meta‐regression, PVI plus studies were associated with improved success (7.6% absolute improvement [95% CI, 2.6–12.5%]; P<0.01, I²=88%), specifically superior vena cava isolation (4 studies, 4 treatment arms, 1392 patients; 15.1% absolute improvement [95% CI, 2.3–27.9%]; P 0.02, I²=87%). However, residual heterogeneity was large.

Conclusions

Across the paroxysmal atrial fibrillation ablation literature, PVI plus ablation strategies were associated with incremental improvements in success rate. However, large residual heterogeneity complicates evidence synthesis.

Persistent Atrial Fibrillation Ablation: Where Do We Go From Here?

Catheter ablation is being used increasingly for the treatment of atrial fibrillation (AF). Pulmonary vein antral isolation is considered the "cornerstone" for the ablation of AF. This approach has demonstrated consistent rates of success for paroxysmal AF, but the rates of success for persistent AF are lower. There has long been a hypothesis that additional ablation beyond pulmonary vein isolation is required to achieve better outcomes in the population with persistent AF. However, large clinical trials have demonstrated recently that such approaches as empiric linear ablation and/or ablation of complex fractionated electrograms may add no benefit over pulmonary vein isolation alone in persistent AF. Furthermore, new technologies are improving the durability and outcome of pulmonary vein isolation alone. These observations have endorsed a search for new potential targets for adjuvant ablation, which currently include ablation of dynamic phenomena during AF such as rotational and focal activations, ablation of scar regions in the atria, isolation of the left atrial posterior wall, and ablation of nonpulmonary vein triggers. Whether any of these additional approaches will add to the success of ablation for persistent AF is unknown. Smaller study results are mixed. Only the performance of large-scale randomized trials will definitively answer whether additional ablation over pulmonary vein isolation alone with improve outcomes for persistent AF.

The Extent of Left Atrial Low-Voltage Areas Included in Pulmonary Vein Isolation Is Associated With Freedom from Recurrent Atrial Arrhythmia

BACKGROUND

The extent of left atrial (LA) baseline low-voltage areas (LVA-B), which may be a surrogate for fibrosis, is associated with recurrent atrial fibrillation (AF) after ablation. This study aimed to assess the relationship between the extent of LVA-B isolated by ablation (LVA-I) and AF recurrence.

METHODS

The study cohort included 159 consecutive patients with drug-refractory AF who underwent an initial AF ablation with LA voltage mapping during sinus rhythm. The extent of LVA-B was quantified while excluding the pulmonary veins, LA appendage, and mitral valve area. LVA-I was quantified as the percentage of LVA-B encircled by pulmonary vein isolation. Surveillance and symptom-prompted electrocardiograms, Holter monitors, and event monitors were used to document atrial arrhythmia recurrence for a median follow-up of 712 days (1.95 years).

RESULTS

Of 159 patients, 72% were men and 27% had persistent AF. The mean number of sampled bipolar voltage points was 119 ± 56. The mean LA surface area was 102.3 ± 37.3 cm², and the mean LVA-B was 1.9 ± 3.8 cm². The mean LVA-I was 51.05% ± 36.8% of LVA-B. In the multivariable Cox proportional hazards model adjusted for LA volume, CHA₂DS₂-VASc (Congestive Heart Failure, Hypertension, Age [≥ 75 years], Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age [65-74 years], Sex [Female] score), LVA-B, and AF type, LVA-I was inversely associated with recurrent atrial arrhythmia after the blanking period (hazard ratio, 0.42/percent LVA isolated; P = 0.037).

CONCLUSIONS

The extent of LVA-I is independently associated with freedom from atrial arrhythmias after AF ablation, supporting ongoing efforts to target low LA voltage areas and other fibrosis indicators to improve ablation outcomes.

Electrogram Fractionation-Guided Ablation in the Left Atrium Decreases the Frequency of Activation in the Pulmonary Veins and Leads to Atrial Fibrillation Termination: Pulmonary Vein Modulation Rather Than Isolation

OBJECTIVES

This study sought to evaluate the impact of a complex fractionated atrial electrogram (CFAE)-guided ablation strategy on atrial fibrillation (AF) dynamics in patients with persistent AF.

BACKGROUND

It is still unclear whether complete pulmonary vein isolation (PVI) is required or if the ablation of well-delineated pulmonary vein (PV) subregions could achieve similar outcomes in persistent AF.

METHODS

CFAE-guided ablations were performed in 76 patients (65.2 ± 10 years of age) with persistent AF. In 47 patients, we measured mean PVs and left atrial appendage (LAA) cycle length (CL) values (PV-CL and LAA-CL), before ablation and before AF termination. We defined "active" PVs as PV-CL ≤ LAA-CL, "rapid fires" as PV-CL ≤80% of LAA-CL, and "PV-LAA CL gradient" as a significant CL difference between the 2 regions.

RESULTS

AF termination (sinus rhythm [SR] or atrial tachycardia [AT] conversion) occurred in 92% and SR conversion in 75%. The radiofrequency time for AF termination and total radiofrequency time were 26 ± 25 min and 61.1 ± 21.6 min, respectively. Thirty of 47 patients had active PV (with 19 PV "rapid fires"). Ablation significantly increased median CL, both at PVs and LAA from 188 ms (interquartile range [IQR]: 161 to 210 ms) to 227.5 ms (IQR: 200 to 256 ms) (p < 0.0001) and from 197 ms (IQR: 168 to 220 ms) to 224 ms (IQR: 193 to 250 ms) (p < 0001), respectively. After ablation, PV-LAA CL gradients were withdrawn and all PV "rapid fires" were extinguished (without PVI). After 17.2 ± 10 months of follow-up and 1.61 ± 0.75 procedures, 86.3% and 73% of the patients were free from AF and from any arrhythmia (AF/AT), respectively.

CONCLUSIONS

CFAE-guided ablation leads to a large decrease in PV frequency of activation, preceding AF termination. A PV modulation approach, rather than complete PVI, may be preferable for persistent AF.