Long-term results of pulmonary vein antrum isolation in patients with atrial fibrillation: an analysis in regards to substrates and pulmonary vein reconnections

Left Atrial Low-Voltage Zone Assessment and Voltage-Guided Ablation Outcome in Patients With Atrial Fibrillation-Induced Tachycardiomyopathy

BACKGROUND

Persistent atrial fibrillation (AF) patients with tachycardia-induced cardiomyopathy (TIC) undergoing catheter ablation have similar or even better outcomes than patients without TIC. Data regarding atrial substrate remodeling are scarce in cases of TIC. We assessed regional distribution of left atrial (LA) bipolar voltage, the extent of low-voltage zones (LVZs), and outcomes of voltage-guided ablation in AF patients with and without TIC.

METHODS AND RESULTS

In all, 139 patients with persistent AF presenting for a first voltage-guided catheter ablation were enrolled, 61 with TIC and 78 with structurally normal hearts. LA voltage maps were obtained using a 3-dimensional electroanatomical mapping system in sinus rhythm. LVZ was defined as <0.5 mV. Compared with non-TIC patients, TIC patients had a lower indexed LA volume (median [interquartile range] 58.6 [50.6-68.7] vs. 63.4 [60.1-76.1] mL/m2; P<0.01) and higher LA voltage (2.3 [1.5-2.8] vs. 1.7 [1-2.6] mV; P=0.02). LVZs were less frequently found in patients with than without TIC (8 [13.1%] vs. 30 [39%]; P<0.01). There was no significant difference in atrial tachyarrhythmia (AT)-free survival rate over a 36-month follow-up between the 2 groups (log-rank test, P=0.176). No predictor of AT recurrence was identified.

CONCLUSIONS

TIC patients exhibit less LA substrate remodeling with a smaller LA volume, higher bipolar voltage, and fewer LVZs than non-TIC patients. They have a similar favorable outcome after a single procedure.

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.

Atrial structural remodeling and atrial fibrillation substrate: A histopathological perspective

Atrial fibrillation (AF) substrate progresses with the advancement of atrial structural remodeling, resulting in AF perpetuation and recurrence. Although fibrosis is considered a hallmark of atrial structural remodeling, the histological background has not been fully elucidated because obtaining atrial specimens is difficult, especially in patients not undergoing open-heart surgery. Bipolar voltage reduction evaluated using electroanatomic mapping during AF ablation is considered a surrogate marker for the progression of structural remodeling; however, histological validation is lacking. We developed an intracardiac echocardiography-guided endomyocardial atrial biopsy technique to evaluate atrial structural remodeling in patients undergoing catheter ablation for nonvalvular AF. The histological factors associated with a decrease in bipolar voltage were interstitial fibrosis, as well as an increase in myocardial intercellular space preceding fibrosis, myofibrillar loss, and a decrease in cardiomyocyte nuclear density, which is a surrogate marker for cardiomyocyte density. Cardiomyocyte hypertrophy is closely associated with a decrease in cardiomyocyte nuclear density, suggesting that hypertrophic changes compensate for cardiomyocyte loss. Electron microscopy also revealed that increased intercellular spaces indicated the leakage of plasma components owing to increased vascular permeability. Additionally, amyloid deposition was observed in 4 % of biopsy cases. Only increased intercellular space and interstitial fibrosis were significantly higher for long-standing persistent AF than for paroxysmal AF and associated with recurrence after AF ablation, suggesting that this interstitial remodeling is the AF substrate. An increase in intercellular space that occurs early in AF formation is a therapeutic target for the AF substrate, which prevents irreversible interstitial degeneration due to collagen accumulation. This endomyocardial atrial biopsy technique will allow the collection of atrial tissue from a wide variety of patients and significantly facilitate the elucidation of the mechanisms of atrial cardiomyopathy, structural remodeling, and AF substrates.

Analysis of the success rate of conversion using ibutilide administration in radiofrequency catheter ablation of persistent atrial fibrillation and its effects on postoperative recurrence

OBJECTIVE

To assess the efficacy of ibutilide administration during radiofrequency catheter ablation of persistent atrial fibrillation (AF), to explore the success rate of conversion and related influential factors, and to analyze the effects of ibutilide on postoperative recurrence.

METHODS

A total of 192 patients with persistent AF who underwent catheter ablation from January 1, 2019, to December 31, 2021. These patients failed in conversion of AF to normal sinus rhythm by intraoperative catheter ablation. Patients were categorized into effective group (115 cases) and ineffective group (77 cases) based on whether sinus rhythm was restored after application of ibutilide.

RESULTS

The overall success rate of conversion using ibutilide administration was 59.9%. The success rate was associated with weight ((68.12 ± 11.72 vs. 72.83 ± 12.08) kg, P = 0.008), the duration of AF ((34.67 ± 55.68 vs. 66.52 ± 95.21) months, p = 0.008), diameter of left atrium (LAD) ((44.39 ± 5.80 vs. 47.36 ± 6.10) mm,P = 0.002), and N-terminal pro-brain natriuretic peptide (NT-proBNP) level ((854.85 ± 770.84 vs. 662.88 ± 659.18) pg/ml,P = 0.030). The results showed the duration of AF was associated with early recurrence, while early recurrence was not a risk factor for late recurrence. And duration of AF was associated with postoperative maintenance time of normal sinus rhythm, whereas successful conversion into normal sinus rhythm using ibutilide administration had no influence on postoperative maintenance time of normal sinus rhythm.

CONCLUSION

Ibutilide showed to be effective in catheter ablation of AF, the success rate of conversion was correlated with the duration of AF, LA diameter, and NT-proBNP level. Besides, the duration of AF was found as a risk factor for early postoperative recurrence, while ibutilide administration for successful conversion had no influence on predicting postoperative recurrence and had no influence on postoperative maintenance time of sinus rhythm.

Quantitative analysis of fractionated electrogram area of left atrium during right atrial pacing as an indicator of left atrial electrical remodeling in patients with atrial fibrillation

Background

The clinical significance of left atrial local electrogram fractionation after restoration of sinus rhythm in patients with atrial fibrillation (AF) has not been elucidated.

Methods

We evaluated ultrahigh-resolution maps of the left atrium (LA) during RA pacing acquired after pulmonary vein isolation in 40 patients with AF. The association between low-voltage area (LVA, <0.5 mV), fractionated electrogram area (FEA, the highlighted area with LUMIPOINT™ Complex Activation), the interval from onset of LA activation to wavefront collision at the mitral isthmus (LA activation time), and wave propagation velocity (WPV) was evaluated quantitatively.

Results

The total LVA, total FEA with ≥5.0 peaks or ≥7.0 peaks were 7.0 ± 7.9 cm2, 15.9 ± 12.9 cm2, and 5.2 ± 7.5 cm2, respectively. These areas were predominantly observed in the anteroseptal region. Total LVA, total FEA with ≥5.0 peaks, and total FEA with ≥5.0 peaks in the normal voltage area (NVA: ≥0.5 mV) correlated with LA activation time (R = 0.69, 0.75, and 0.71; each p < .0001). In the anterior wall, these areas correlated with regional mean WPV (R = -0.75, -0.83, and - 0.55; each p < .0001) and the extent of slow conduction area (SCA) with WPV <0.3 m/s (R = 0.89, 0.84, 0.33; p < .0001 for LVA and FEA, p < .05 for FEA located in NVA). The anterior wall FEA with ≥7.0 peaks and that in the NVA showed a better correlation in predicting anterior wall SCA (R = 0.92 and 0.86, each p < .0001).

Conclusion

Quantitative analysis of FEA together with LVA may facilitate the assessment of LA electrical remodeling.

Research progress on predicting atrial fibrillation recurrence after radiofrequency ablation based on electrocardiogram-related parameters

Atrial fibrillation (AF) is the most common arrhythmia. It is associated with increased stroke risks, thromboembolism, and other complications, which are great life and economic burdens for patients. In recent years, with the maturity of percutaneous catheter radiofrequency ablation (RFA) technology, it has become a first-line therapy for AF. However, some patients still experience AF recurrence (AFR) after RFA, which can cause serious consequences. Therefore, it is critical to identify appropriate parameters that are predictive of prognosis and to be able to translate the parameters easily into the clinical setting. Here, we reviewed possible predicting indicators for AFR, focusing on all the electrocardiogram indicators, such as P wave duration, PR interval and so on. It may provide valuable information for guiding clinical works.

Histological validation of atrial structural remodelling in patients with atrial fibrillation

BACKGROUND AND AIMS

This study aimed to histologically validate atrial structural remodelling associated with atrial fibrillation.

METHODS AND RESULTS

Patients undergoing atrial fibrillation ablation and endomyocardial atrial biopsy were included (n = 230; 67 ± 12 years old; 69 women). Electroanatomic mapping was performed during right atrial pacing. Voltage at the biopsy site (Vbiopsy), global left atrial voltage (VGLA), and the proportion of points with fractionated electrograms defined as ≥5 deflections in each electrogram (%Fractionated EGM) were evaluated. SCZtotal was calculated as the total width of slow conduction zones, defined as regions with a conduction velocity of <30 cm/s. Histological factors potentially associated with electroanatomic characteristics were evaluated using multiple linear regression analyses. Ultrastructural features and immune cell infiltration were evaluated by electron microscopy and immunohistochemical staining in 33 and 60 patients, respectively. Fibrosis, intercellular space, myofibrillar loss, and myocardial nuclear density were significantly associated with Vbiopsy (P = .014, P < .001, P < .001, and P = .002, respectively) and VGLA (P = .010, P < .001, P = .001, and P < .001, respectively). The intercellular space was associated with the %Fractionated EGM (P = .001). Fibrosis, intercellular space, and myofibrillar loss were associated with SCZtotal (P = .028, P < .001, and P = .015, respectively). Electron microscopy confirmed plasma components and immature collagen fibrils in the increased intercellular space and myofilament lysis in cardiomyocytes, depending on myofibrillar loss. Among the histological factors, the severity of myofibrillar loss was associated with an increase in macrophage infiltration.

CONCLUSION

Histological correlates of atrial structural remodelling were fibrosis, increased intercellular space, myofibrillar loss, and decreased nuclear density. Each histological component was defined using electron microscopy and immunohistochemistry studies.

Efficacy and safety of low voltage area ablation for atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Pulmonary vein isolation is the cornerstone of atrial fibrillation (AF) ablation. However, the recurrence rate of AF after pulmonary vein isolation (PVI) remains high. The efficacy and safety of low voltage area (LVA) ablation in the treatment of AF are uncertain.

METHODS

The studies comparing the efficacy and safety of LVA ablation and LVA non-ablation for AF were systematically reviewed and meta-analyzed. Outcomes of interest included recurrent event, procedure time, and fluoroscopy time. Continuous variables were evaluated with mean deviation (MD) and standard mean difference (SMD). Odds ratio (OR) values and its 95% confidence intervals (CI) were used in meta-analysis of binary variables.

RESULTS

Fourteen studies were eligible for inclusion. The AF recurrence was similar between the two groups, with no statistical difference (25.7% (67/346) vs. 28% (63/225), P = 0.49). LVA ablation did not increase the incidence of AT (8.7% (20/231) vs. 14.5% (28/193), P = 0.66). Fluoroscopy time was longer in the LVA ablation group (31.4 ± 8.4 min vs. 26.3 ± 7.8 min, P < 0.05). Complication rates were similar between the two groups (26.6% (17/64) vs. 21.7% (13/60), P = 0.53). Patients with LVA had higher AT/AF recurrence (32.9% (213/647) vs. 24.2% (229/948), P < 0.05).

CONCLUSIONS

Patients with left atrial LVA have a poor prognosis after catheter ablation. LVA ablation did not reduce the recurrence of AF nor did it increase the recurrence of atrial tachycardia.

Impact of gender on left atrial low-voltage zones in patients with persistent atrial fibrillation: results of a voltage-guided ablation

Background

Gender-related differences have been reported in atrial fibrotic remodeling and prognosis of atrial fibrillation (AF) patients after ablation. We assessed in persistent AF the regional distribution of left atrial (LA) bipolar voltage and the extent of low-voltage zones (LVZ) according to gender as well as the results of a voltage-guided substrate ablation.

Methods

Consecutive patients who underwent a voltage-guided AF ablation were enrolled. LA endocardial voltage maps were obtained using a 3D electro-anatomical mapping system in sinus rhythm. LVZ was defined as <0.5 mV.

Results

A total of 115 patients were enrolled (74 men, 41 women). The LA bipolar voltage amplitude was twice lower in the whole LA (p < 0.01) and in each atrial region in women compared with men, whereas the LA indexed volume was similar. LVZ were found in 56.1% of women and 16.2% of men (p < 0.01). LVZ were also more extensive in women (p = 0.01), especially in the anterior LA. Atrial voltage alteration occurred earlier in women than in men. In a multivariate analysis, the female sex (OR 12.99; 95% CI, 3.23-51.63, p = 0.0001) and LA indexed volume (OR 1.09; 95% CI, 1.04-1.16, p = 0.001) were predictive of LVZ. Atrial arrhythmia-free survival was similar in men and women 36 months after a single ablation procedure.

Conclusion

The study reports a strong relationship between the female gender and atrial substrate remodeling. The female gender was significantly associated with higher incidence, earlier occurrence, and greater extent of LVZ compared with men. Despite the female-specific characteristics in atrial remodeling, LVZ-guided ablation may improve the AF ablation outcome in women.

Interatrial conduction time is associated with left atrial low voltage area and predicts the recurrence after single atrial fibrillation ablation

Background

Interatrial conduction time (IACT) prolongs in fibrotic left atrium. We tested the hypothesis that IACT is related to left atrial low voltage area (LVA) and predicts the recurrence after single atrial fibrillation (AF) ablation.

Methods

One hundred sixty-four consecutive AF patients (79 non-paroxysmal) who underwent initial ablation in our institute were analyzed. IACT and LVA were defined as interval from the onset of P-wave to the basal left atrial appendage (P-LAA) activation, and area with bipolar electrogram < 0.5 mV covering over 5% of the total left atrial surface area during sinus rhythm, respectively. Pulmonary vein antrum isolation, non-PV foci ablation, and atrial tachycardia (AT) ablation were performed without substrate modification.

Results

LVA was frequently identified in patients with prolonged P-LAA ≥ 84 ms (n  = 28) compared with patients with P-LAA < 84 ms (n  = 136). Patients with P-LAA ≥ 84 ms were older (71 ± 10 vs. 65 ± 10 years, p  = .0061), and had more frequent non-paroxysmal AF (75% vs. 43%, p  = .0018), larger left atrial diameter (43.5 ± 4.5 vs. 39.3 ± 5.7 mm, p  = .0003), and higher E/e' ratio (14.4 ± 6.5 vs. 10.5 ± 3.7, p  < .0001) compared with P-LAA < 84 ms patients. After a mean follow-up period of 665 ± 153 days, Kaplan-Meier curve analysis showed that AF/AT recurrences was more frequently observed in patients with prolonged P-LAA (Log-rank p  = .0001). Additionally, univariate analysis revealed that P-LAA prolongation (OR = 1.055 per 1 ms, 95% CI: 1.028-1.087, p  < .0001) and the existence of LVA (OR = 5.000, 95% CI: 1.653-14.485 p  = .0053) were predictors of AF/AT recurrences after single AF ablation.

Conclusions

Our results suggested that prolonged IACT as measured by P-LAA was associated with LVA and predicts AT/AF recurrence after single AF ablation.

Alcohol Consumption Is Associated With Postablation Recurrence but Not Changes in Atrial Substrate in Patients With Atrial Fibrillation: Insight from a High-Density Mapping Study

Background

The association between alcohol consumption, atrial substrate, and outcomes after atrial fibrillation (AF) ablation remains controversial. This study evaluated the impacts of drinking on left atrial substrate and AF recurrence after ablation.

Methods and Results

We prospectively enrolled 110 patients with AF without structural heart disease (64±12 years) from 2 institutions. High‐density left atrial electroanatomic mapping was performed using a high‐density grid multipolar catheter. We investigated the impact of alcohol consumption on left atrial voltage, left atrial conduction velocity, and AF ablation outcome. Patients were classified as abstainers (<1 drink/wk), mild drinkers (1–7 drinks/wk), or moderate‐heavy drinkers (>7 drinks/wk). High‐density mapping (mean 2287±600 points/patient) was performed on 49 abstainers, 27 mild drinkers, and 34 moderate‐heavy drinkers. Low‐voltage zone and slow‐conduction zone were identified in 39 (35%) and 54 (49%) patients, respectively. There was no significant difference in the proportions of low‐voltage zone and slow‐conduction zone among the 3 groups. The success rate after a single ablation was significantly lower in drinkers than in abstainers (79.3% versus 95.9% at 12 months; mean follow‐up, 18±8 months; P=0.013). The success rate after a single or multiple ablations was not significantly different among abstainers and drinkers. In multivariate analysis, alcohol consumption (P=0.02) and the presence of a low‐voltage zone (P=0.032) and slow‐conduction zone (P=0.02) were associated with AF recurrence after a single ablation, while low‐voltage zone (P=0.023) and slow‐conduction zone (P=0.024) were associated with AF recurrence after a single or multiple ablations.

Conclusions

Alcohol consumption was associated with AF recurrence after a single ablation but not changes in atrial substrate.

Atrial Structural Remodeling in Patients With Atrial Fibrillation Is a Diffuse Fibrotic Process: Evidence From High-Density Voltage Mapping and Atrial Biopsy

Background

Low‐voltage areas (LVAs) in the atria of patients with atrial fibrillation are considered local fibrosis. We hypothesized that voltage reduction in the atria is a diffuse process associated with fibrosis and that the presence of LVAs reflects a global voltage reduction.

Methods and Results

We examined 140 patients with atrial fibrillation and 13 patients with a left accessory pathway (controls). High‐density bipolar voltage mapping was performed using a grid‐mapping catheter during high right atrial pacing. Global left atrial (LA) voltage (V_GLA) in the whole LA and regional LA voltage (V_RLA) in 6 anatomic regions were evaluated with the mean of the highest voltage at a sampling density of 1 cm². Patients with atrial fibrillation were categorized into quartiles by V_GLA. LVAs were evaluated at voltage cutoffs of 0.1, 0.5, 1.0, and 1.5 mV. Twenty‐eight patients with atrial fibrillation also underwent right atrial septum biopsy, and the fibrosis extent was quantified. Voltage at the biopsy site (V_biopsy) was recorded. V_GLA results by category were Q1 (<4.2 mV), Q2 (4.2–5.6 mV), Q3 (5.7–7.0 mV), and Q4 (≥7.1 mV). V_RLA at any region was reduced as V_GLA decreased. V_GLA and V_RLA did not differ between Q4 and controls. The presence of LVAs increased as V_GLA decreased at any voltage cutoff. Biopsies revealed 11±6% fibrosis, which was inversely correlated with both V_biopsy and V_GLA (r=–0.71 and –0.72, respectively). V_biopsy was correlated with V_GLA (r=0.82).

Conclusions

Voltage reduction in the LA is a diffuse process associated with fibrosis. Presence of LVAs reflects diffuse voltage reduction of the LA.

Reproducibility and predictive value of a simple novel method to measure atrial fibrillation cycle length in persistent atrial fibrillation - FARS-AF study

INTRODUCTION

Different methods are used for atrial fibrillation (AF) cycle length (CL) measurement with variable results. Previous studies of pulmonary vein (PV) CL measurement showed contradictory results on predicting PV isolation (PVI) efficacy. A novel simple method of measuring the average of 10 consecutive Fastest Atrial Repetitive Similar morphology signal (FARS₁₀ )-CL to characterize local atrial activity rate was evaluated prospectively.

METHODS

The intra-observer reproducibility of FARS₁₀ -CL and traditional AF-CL measurement of continuously fragmented coronary sinus (CS) signals were tested. We prospectively enrolled 100 consecutive patients (62±10 years, 72% male) undergoing wide antral PVI only ablation for persistent AF, measured PV-FARS₁₀ -CLs and evaluated long-term outcome.

RESULTS

The Kendall area correlation between repeated traditional AF-CL measurements was -0.006 and between repeated FARS₁₀ -CL measurements in the right and left atrial appendages, CS and PVs were 0.944, 0.859, 0.882, 0.675-0.955, respectively. Patients with recurrent atrial tachyarrhythmia had significantly longer Fastest PV-FARS₁₀ -CL (172±41 vs. 156±41 ms, p=0.047). Patients with high burden of spontaneous low voltage zone (LVZ) had significantly longer Fastest PV-FARS₁₀ -CL. Freedom from recurrent tachyarrhythmia at 24 months was 85% vs. 59% in patients with Fastest PV-FARS₁₀ -CL≤140 vs. >140 ms, p=0.0018, respectively. In multivariable analysis Fastest PV-FARS₁₀ -CL≤140 ms was the only significant predictor of freedom from recurrent tachyarrhythmia.

CONCLUSIONS

FARS₁₀ -CL measurements have a high reproducibility in contrast to traditional AF-CL measurement of continuously fragmented CS signals. Patients with high burden of LVZ have longer Fastest PV-FARS₁₀ -CLs. Fastest PV-FARS₁₀ -CL≤140 ms is associated with a high success of wide antral PVI-only ablation approach in persistent AF. This article is protected by copyright. All rights reserved.

Comparison of the empirical linear ablation and low voltage area-guided ablation in addition to pulmonary vein isolation in patients with persistent atrial fibrillation: a propensity score-matched analysis

Background

The efficacy of pulmonary vein isolation (PVI) alone is not guaranteed for persistent atrial fibrillation (PeAF), and it is unclear which type of ablation approach should be applied in addition to PVI. This study aimed to compare outcomes and prognosis between empirical linear ablation and low-voltage area (LVA) ablation after PVI for PeAF.

Methods

We enrolled 128 patients with PeAF who were assigned to the linear ablation group (n = 64) and the LVA ablation group (n = 64) using a propensity score-matched model. After PVI and cardioversion, the patients underwent either empirical linear ablation or LVA ablation during sinus rhythm. All patients in the linear ablation group underwent both roof line and mitral valve isthmus (MVI) ablations. An electrical-guided ablation targeting LVA (< 0.5 mV) was performed in the LVA group. When there was no LVA in the LVA group, only PVI was applied. We compared the procedural outcomes and recurrence after ablation between the two groups.

Results

The baseline characteristics were well-balanced between the two groups. Fifty patients had LVA (22 and 28 patients in the linear and LVA groups). The roof and MVI lines were completed in 100% and 96.9% of the patients. During the mean follow-up of 279.5 ± 161.3 days, the LVA group had significantly lower recurrence than the linear group (15 patients [23%] vs. 29 patients [45%], p = 0.014). Thirty-five patients were prescribed antiarrhythmic drugs during the follow-up period (linear group, n = 17; LVA group, n = 18); amiodarone and bepridil were administered to most of the patients (15 and 17 patients, respectively). The difference in the prognosis was relevant among the patients with LVA, while this trend was not observed in those without LVA. The LVA ablation group demonstrated significantly lower radiofrequency energy and shorter procedural time compared to the linear ablation group. The recurrence of atrial flutter was more likely to occur in the linear group than in the LVA group (14 [22%] vs. 6 [9.4%], p = 0.052).

Conclusion

The electrophysiological-guided LVA ablation is more effective than empirical linear ablation in PeAF patients with LVA. Unnecessary empirical linear ablation might have a risk of iatrogenic gap and atrial flutter recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02460-9.

Extensive Left Atrial Low-Voltage Area During Initial Ablation is Associated with A Poor Clinical Outcome Even Following Multiple Procedures

Background

Some patients fail to respond to persistent atrial fibrillation (PeAF) catheter ablation in spite of multiple procedures and ablation strategies, including low voltage area (LVA)-guided, linear, and complex fractionated atrial electrogram (CFAE)-guided ablation procedures. We hypothesized that LVA extent could predict non-responseto Pe AF catheter ablation in spite of multiple procedures.

Methods

This study included 510 patients undergoing initial ablation procedures for PeAF. LVAs were defined as regions with bipolar peak-to-peak voltages of <0.50 mV after PVI during sinus rhythm. Patients were categorized by LVA size into groups A(0-5 cm²), B (5-20 cm²), and C (over 20 cm²). The primary endpoint was AF-free survival after the last procedure.

Results

During a median follow-up of 25 (17, 36) months, AF recurrence was observed in 101 (20%) patients after 1.4±0.6 ablation procedures (maximum 4). Comparison of clinical outcomes after multiple procedures in the three groups showed that the results depended on the extent of LVA. Multivariate analysis of AF-free survival after the last procedure showed that LVAs > 20 cm2 was an independent factor associated with AF recurrence after the final procedure(Hazard ratio, 7.94; 95% confidence interval, 2.91 to 21.67, P <0.001).

Conclusions

Extensive LVA after initial PVI was associated with poor clinical benefit despite multiple catheter based ablations.

Left Atrial Hypertension, Electrical Conduction Slowing, and Mechanical Dysfunction - The Pathophysiological Triad in Atrial Fibrillation-Associated Atrial Cardiomyopathy

Background

Atrial fibrillation (AF) is the most common arrhythmia and a significant burden for healthcare systems worldwide. Presence of relevant atrial cardiomyopathy (ACM) is related to persistent AF and increased arrhythmia recurrence rates after pulmonary vein isolation (PVI).

Objective

To investigate the association of left atrial pressure (LAP), left atrial electrical [invasive atrial activation time (IAAT) and amplified p-wave duration (aPWD)] and mechanical [left atrial emptying fraction (LA-EF) and left atrial strain (LAS)] functional parameters with the extent of ACM and their impact on arrhythmia recurrence following PVI.

Materials and Methods

Fifty patients [age 67 (IQR: 61-75) years, 78% male] undergoing their first PVI for persistent AF were prospectively included. LAP (maximum amplitude of the v-wave), digital 12-lead electrocardiogram, echocardiography and high-density endocardial contact mapping were acquired in sinus rhythm prior to PVI. Arrhythmia recurrence was assessed using 72-hour Holter electrocardiogram at 6 and 12 months post PVI.

Results

Relevant ACM (defined as left atrial low-voltage extent ≥2 cm² at <0.5 mV threshold) was diagnosed in 25/50 (50%) patients. Compared to patients without ACM, patients with ACM had higher LAP [17.6 (10.6-19.5) mmHg with ACM versus 11.3 (7.9-14.0) mmHg without ACM (p = 0.009)]. The corresponding values for the electrical parameters were 166 (149-181) ms versus 139 (131-143) ms for IAAT (p < 0.0001), 163 (154-176) ms versus 148 (136-152) ms for aPWD on surface-ECG (p < 0.0001) and for the mechanical parameters 27.0 (17.5-37.0) % versus 41.0 (35.0-45.0) % for LA-EF in standard 2D-echocardiography (p < 0.0001) and 15.2 (11.0-21.2) % versus 29.4 (24.9-36.6) % for LAS during reservoir phase (p < 0.0001). Furthermore, all parameters showed a linear correlation with ACM extent (p < 0.05 for all). Receiver-operator-curve-analysis demonstrated a LAP ≥12.4 mmHg [area under the curve (AUC): 0.717, sensitivity: 72%, and specificity: 60%], a prolonged IAAT ≥143 ms (AUC: 0.899, sensitivity: 84%, and specificity: 80%), a prolonged aPWD ≥153 ms (AUC: 0.860, sensitivity: 80%, and specificity: 79%), an impaired LA-EF ≤33% (AUC: 0.869, sensitivity: 84%, and specificity: 72%), and an impaired LAS during reservoir phase ≤23% (AUC: 0.884, sensitivity: 84%, and specificity: 84%) as predictors for relevant ACM. Arrhythmia recurrence within 12 months post PVI was significantly increased in patients with relevant ACM ≥2 cm², electrical dysfunction with prolonged IAAT ≥143 ms and mechanical dysfunction with impaired LA-EF ≤33% (66 versus 20, 50 versus 23 and 55 versus 25%, all p < 0.05).

Conclusion

Left atrial hypertension, electrical conduction slowing and mechanical dysfunction are associated with ACM. These findings improve the understanding of ACM pathophysiology and may be suitable for risk stratification for new-onset AF, arrhythmia recurrence following PVI, and development of novel therapeutic strategies to prevent AF and its associated complications.

Benefit of ultra-high-density mapping-guided radiofrequency reablation in pulmonary vein isolation non-responders after initial cryoballoon procedure

AIMS

Symptomatic atrial arrhythmias despite complete pulmonary vein isolation (PVI) are common. The purpose was to evaluate ultra-high-density multi-electrode electroanatomical mapping-guided radiofrequency ablation (RFA) in PVI non-responders.

METHODS AND RESULTS

Ultra-high-density multi-electrode electroanatomical mapping-guided RFA in consecutive symptomatic atrial fibrillation (AF) patients after initial cryoballoon PVI was performed. Patients were included if all pulmonary veins (PVs) were still isolated. Radiofrequency targets were atrial tachycardia (AT), extra-PV trigger, and/or substrate. Procedural results and outcome were evaluated. Of 95 patients, 67 (70.5%) with complete PVI were included (70 years, CHA2DS2Vasc 2.9, left atrium 45 mm, persistent AF 45%, AT 45%). The median time to reablation was 26 months. One hundred and seven maps (1.6/patient) and 11.890 ± 9.018 electrograms were acquired in 33 ± 12 min. Twenty-eight percent of the left atrial (LA) wall showed pathological voltage signals, predominantly at the anterior (37%) and septal wall (26%). Atrial tachycardia (49 left, 4 right) were ablated in 35 patients (52%), extra-PV trigger in two patients (3%). One atrioventricular nodal re-entry tachycardia and seven right atrial isthmus ablation (10%) were performed. In 32 patients (48%), no AT was present and substrate-based ablation was performed. Mean LA area ablated was 7 ± 6 cm2 (7%). No major complication occurred. The mean follow-up time was 772 ± 317 days. Freedom from atrial arrhythmia recurrence off antiarrhythmic drugs was 49% at 12 months.

CONCLUSION

Pulmonary vein isolation non-responders are older, mainly suffering from complex atrial arrhythmias. Left atrial substrate is predominantly located at the anterior and septal wall. Ultra-high-density multi-electrode electroanatomical mapping-guided RFA is safe and effective. At 1 year, 5 out of 10 patients were in stable sinus rhythm off antiarrhythmic drugs.

Evaluation of left atrial remodeling by 2D-speckle-tracking echocardiography versus by high-density voltage mapping in patients with atrial fibrillation

BACKGROUND

Strain imaging during left atrial (LA) reservoir phase (LASr) is used as a surrogate for LA structural remodeling and fibrosis. Atrial fibrillation (AF) patients with >5% low-voltage zones (LVZs) obtained by 3D-electro-anatomical-mapping have higher recurrence rate post-ablation. We investigated the relationship between LA remodeling using two-dimensional-speckle-tracking echocardiography (2D-STE) and high-density voltage mapping in AF patients.

METHODS

A prospective study of 42 consecutive patients undergoing AF ablation. 2D-echo, 2D-STE, and high-density contact LA bipolar voltage maps were constructed before ablation. LVZs were determined with different bipolar amplitudes and their ratio per patient's LA area were investigated for correlation with LASr. We compared 2D-LASr results in patients with LVZs ≥ 5% (LVZs group) versus those with LVZ < 5% (non-LVZs group).

RESULTS

Compared with non-LVZs group (n = 15), LVZs group (n = 27) included significantly older patients, more women, more persistent AF, higher CHA₂ DS₂ -VASc score, higher E/A ratio and higher LA volume index (p < .05). LVZs group had lower %LASr values (12.4 ± 5.9% vs. 21.1 ± 6.3, respectively; p<.001). LVZs% in different amplitudes (<0.1 mV, <0.2 mV, and <0.5 mV) were negatively correlated with %LASr (r = -.63, r = -.68, and r = -.72, respectively; p< .001). Atrial strain thresholds for LVZs ≥ 5% in amplitudes <0.1 mV, <0.2 mV, and <0.5 mV were associated with %LASr 12.98, 16.16 and 19.55, respectively; p< .05). In a multivariate analysis, %LASr was the only independent indicator of LVZs (OR, 0.8; 95% CI, 0.6-0.9; p= .04).

CONCLUSIONS

LVZs ≥ 5% has a negative association with atrial %LASr. Thus, a simple 2D-STE measurement of %LASr can be used as a noninvasive method to evaluate significant LA remodeling and fibrosis in AF patients.

Atrial Fibrillation Structural Substrates: Aetiology, Identification and Implications

Atrial remodelling in AF underlines the electrical, structural and mechanical changes in the atria of patients with AF. Several risk factors for AF contribute to the development of the atrial substrate, with some evidence that atrial remodelling reversal is possible with targeted intervention. In this article, the authors review the electrophysiological changes that characterise the atrial substrate in patients with AF risk factors. They also discuss the pitfalls of mapping the atrial substrate and the implications for developing tailored ablation strategies to improve outcomes in patients with AF.

Voltage-guided ablation in persistent atrial fibrillation-favorable 1-year outcome and predictors

INTRODUCTION

Pulmonary vein isolation (PVI) in persistent atrial fibrillation (AF) has a low success rate. A newer ablation concept targets left atrial (LA) low voltage zones (LVZ) which correlate with fibrosis and predict recurrence after PVI. We aimed to determine the success of combined PVI- and LVZ-guided ablation and to identify the predictors for LVZ and for ablation success.

METHODS AND RESULTS

A total of 119 consecutive patients who underwent their first ablation procedure due to persistent AF were included. After acquisition of a high-resolution LA voltage map, PVI- and LVZ-guided ablation were performed. Mean age was 69 ± 8 years, 53% were men, and 8% had longstanding persistent AF. We found LVZ in 55% of patients. Twelve-month freedom from recurrences off drugs was 69%. The only independent predictor for recurrence was the existence of LVZ (OR 4.2, 95% CI 1.54-11.41, p = 0.005). Existence of LVZ was predicted positively by age ≥ 67 years (OR 4.4, 95% CI 1.4-13.7, p = 0.011), LA volume index ≥ 68 ml/m² (OR 3.9, 95% CI 1.4-10.5, p = 0.008), and GFR ≤ 85 ml/min/1.73 m² (OR 12.5, 95% CI 2.0-76.6, p = 0.006). BMI ≥ 26 kg/m² (OR 0.06, 95% CI 0.01-0.30, p = 0.001) was a negative predictor of LVZ.

CONCLUSION

LVZ-guided ablation in combination with PVI results in comparably high success rates. However, the existence of LVZ remains the strongest predictor of ablation success.

Advancements in Imaging for Atrial Fibrillation Ablation: Is There a Potential to Improve Procedural Outcomes?

Since the introduction of atrial fibrillation (AF) ablation in the 1990s, the procedure has continuously evolved, with gradual improvements in outcomes and safety. Recent technological advancements include the introduction of contact force catheters and high-resolution electroanatomical mapping systems, while imaging modalities including transesophageal echocardiography and fluoroscopy have become integral parts of AF ablation procedures. Further, intraprocedural intracardiac echocardiography and the integration of cardiac magnetic resonance and computed tomography images with electroanatomical mapping have shown promise to improve procedural outcomes by reducing radiation exposure and procedural times. However, available data on procedural utility and the reduction in AF recurrence rates associated with these modalities are mixed. This review therefore aims to discuss the current common imaging modalities used in AF ablation and their potential impact on outcomes. In particular, imaging is discussed with respect to the important information it offers before, during, and after the procedure. Perspectives on the future of imaging in AF ablation are also shared.

Atrial Fibrosis by Late Gadolinium Enhancement Magnetic Resonance Imaging and Catheter Ablation of Atrial Fibrillation: 5-Year Follow-Up Data

Background

Late gadolinium enhancement magnetic resonance imaging is an effective tool for assessment of atrial fibrosis. The degree of left atrial fibrosis is a good predictor of atrial fibrillation (AF) ablation success at 1 year, but the association between left atrial fibrosis and long‐term ablation success has not been studied.

Methods and Results

Late gadolinium enhancement magnetic resonance images of sufficient quality to quantify atrial fibrosis were obtained before the first AF ablation in 308 consecutive patients. Left atrial fibrosis was classified in 4 Utah stages (I, 0–10%; II, 10–20%; III, 20–30%; and IV, >30%). Patients were followed up for up to 5 years until the time of first arrhythmia recurrence or second ablation. A total of 308 patients were included; the mean age was 64.5±12.1 years, and 63.4% were men. During follow‐up, 157 patients experienced an arrhythmia recurrence and 106 patients underwent a repeated ablation. A graded effect was observed in which patients with more advanced atrial fibrosis were more likely to experience recurrent AF (hazard ratio for stage IV versus stage I, 2.73; 95% confidence interval, 1.57–4.75) and undergo a repeated ablation (proportional odds ratio for stage IV versus stage I, 5.19; 95% confidence interval, 2.12–12.69).

Conclusions

The degree of left atrial fibrosis predicts the success of AF ablation at up to 5 years follow‐up. In patients with advanced atrial fibrosis, AF ablation is associated with a high procedural failure rate.

Individualised Approaches for Catheter Ablation of AF: Patient Selection and Procedural Endpoints

Pulmonary vein isolation (PVI) is the cornerstone of AF ablation, but studies have reported improved efficacy with high rates of repeat procedures. Because of the large interindividual variability in the underlying electrical and anatomical substrate, achieving optimal outcomes requires an individualised approach. This includes optimal candidate selection as well as defined ablation strategies with objective procedure endpoints beyond PVI. Candidate selection is traditionally based on coarse and sometimes arbitrary clinical stratification such as AF type, but finer predictors of treatment efficacy including biomarkers, advanced imaging and electrocardiographic parameters have shown promise. Numerous ancillary ablation strategies beyond PVI have been investigated, but the absence of a clear mechanistic and evidence-based endpoint, unlike in other arrhythmias, has remained a universal limitation. Potential endpoints include functional ones such as AF termination or non-inducibility and substrate-based endpoints such as isolation of low-voltage areas. This review summarises the relevant literature and proposes guidance for clinical practice and future research.

Multiple factors influence the morphology of the bipolar electrogram: An in silico modeling study

Although bipolar electrograms (Bi-egms) are commonly used for catheter mapping and ablation of cardiac arrhythmias, the accuracy and reproducibility of Bi-egms have not been evaluated. We aimed to clarify the influence of the catheter orientation (CO), catheter contact angle (CA), local conduction velocity (CV), scar size, and catheter type on the Bi-egm morphology using an in silico 3-dimensional realistic model of atrial fibrillation. We constructed a 3-dimensional, realistic, in silico left atrial model with activation wave propagation including bipolar catheter models. Bi-egms were obtained by computing the extracellular potentials from the distal and proximal electrodes. The amplitude and width were measured on virtual Bi-egms obtained under different conditions created by changing the CO according to the wave direction, catheter-atrial wall CA, local CV, size of the non-conductive area, and catheter type. Bipolar voltages were also compared between virtual and clinically acquired Bi-egms. Bi-egm amplitudes were lower for a perpendicular than parallel CO relative to the wave direction (p<0.001), lower for a 90° than 0° CA (p<0.001), and lower for a CV of 0.13m/s than 0.48m/s (p<0.001). Larger sized non-conductive areas were associated with a decreased bipolar amplitude (p<0.001) and increased bipolar width (p<0.001). Among three commercially available catheters (Orion, Pentaray, and Thermocool), those with more narrowly spaced and smaller electrodes produced higher voltages on the virtual Bi-egms (p<0.001). Multiple factors including the CO, CA, CV, and catheter design significantly influence the Bi-egm morphology. Universal voltage cut-off values may not be appropriate for bipolar voltage-guided substrate mapping.

Cardiac arrhythmias are rhythm disorders of the heart leading to abnormal heart function. For the diagnosis and treatment of the arrhythmias, clinicians insert catheters into the heart and examine the electrical signal propagation in the heart. Among different type of catheters, bipolar catheters have two electrodes at the tip of the catheter with the signal being the difference between the two electrodes, which provides sharper signal than unipolar catheter. However, bipolar electrogram is dependent on many factors including catheter design and orientation, and consequently, knowledge of the determinants of the bipolar electrogram is needed for proper interpretation of the signal. In this study, we examined the effects of many factors on bipolar electrogram using computer simulation. Computer simulation is very useful in this type of study because, in clinical settings, it is not feasible to control each factor precisely. We quantitatively demonstrated the effects of catheter design and orientation, and cardiac wave propagation speed on bipolar electrogram.

The impact of the presence of left atrial low voltage areas on outcomes from pulmonary vein isolation

BACKGROUND

AF ablation (AFA) with pulmonary vein isolation (PVI) is highly successful for paroxysmal atrial fibrillation (PAF). However, success rates for persistent AF (PsAF) are significantly lower. In this study we evaluate the impact of left atrial (LA) low voltage areas (LVA) on response to AFA.

METHODS

Consecutive patients undergoing first-time radiofrequency AFA were included (n = 160, 53% PAF). PVI was performed followed by LA voltage mapping during sinus rhythm. Patients were categorized as having LVA based on the presence of LVA (0.2-0.5 mV) in the LA assessed visually by the operator intra-procedurally. Further adjunctive LA ablation was performed at the operators' discretion. The end-point was recurrence of any sustained atrial arrhythmia (atrial fibrillation/tachycardia/flutter) during 12 months follow-up.

RESULTS

All patients had PVI and 23 (14%) had adjunctive LA ablation. LVA were found in 49 (31%) patients and were an independent predictor of arrhythmia recurrence. Patients with LVA compared to those without had significantly lower 12-month arrhythmia-free survival in both PAF (38% vs 76%; P = 0.002) and PsAF (27% vs 61%; P = 0.015). PsAF patients without LVA (93% had PVI alone) had similar arrhythmia-free survival to patients with PAF (61% vs 67%, respectively; P = 0.42). Recurrence in patients with LVA compared to those without was more likely to be an organized atrial arrhythmia rather than AF (16/30 recurrences vs 2/26, P < 0.001).

CONCLUSIONS

The presence of LVA predicts AFA success as well as the type of arrhythmia recurrence. The absence of LVA identifies PsAF patients that respond well to a PVI-based ablation strategy.

Bipolar Voltage Mapping for the Evaluation of Atrial Substrate: Can We Overcome the Challenge of Directionality?

The relationship between atrial fibrosis and atrial fibrillation (AF) has been proven. Patient specific substrate ablation targeting fibrotic tissue estimated by bipolar voltage mapping has emerged as an alternative strategy for additional substrate modification beyond pulmonary vein isolation. The primary mechanism of a low-voltage electrogram has been suggested to be atrial fibrosis, however, no direct correlation between histological fibrosis and low-voltage zone has been confirmed. Furthermore, the definition of low-voltage zone is still controversial, and bipolar voltage amplitudes depend on multiple variables including electrodes orientation relative to direction of wavefront, electrode length, interelectrode spacing, and tissue contact. The aim of this article is to review the role and limitation of voltage mapping, and to share our initial experience of a newly released grid-pattern designed mapping catheter to make the voltage mapping more reliable to guide patient specific AF ablation.

Incidence of Atrial Fibrosis in Non-Valvular Atrial Fibrillation Patients and its Impact on Recurrence after Pulmonary Vein Antral Isolation

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia; it affects 1%-2% of the general population [1]. Many studies demonstrated an association between atrial fibrosis and AF [2]. There is increasing evidence that even in patients with lone AF; the AF is an arrhythmic manifestation of a structural atrial disease which has been described as fibrotic atrial cardiomyopathy [3]. It is unknown whether the presence of atrial fibrosis has any impact on post pulmonary vein antrum isolation outcome.

Purpose of the study

This study aims to determine the incidence of atrial fibrosis in patients with non-valvular AF and its impact on recurrence after pulmonary vein antrum isolation.

Patients and Methods

This study included twenty eight consecutive patients referred for first-time pulmonary vein antrum isolation for the treatment of symptomatic recurrent non-valvular AF not responding to medical treatment, Isolation of the pulmonary veins antra was performed using three dimensional electroanatomical mapping, detailed voltage map was done in the right and left atrium, before ablation and Low-voltage zones were identified. Follow up of the patients was done for 6 months after the procedure to detect recurrence of AF.

Results

Left atrium fibrosis was present in 6 (21.4%) cases, right atrium fibrosis was present only in 1 (3.6%) case and recurrence of atrial fibrillation after 6 months occurred in 12 (42.9%) cases. AF burden was significantly higher in the recurrence group [50.33 ±19.7 (48) (hour/month)] as compared to no recurrence group [29.5 ± 6.99 (32) (hour/month)] with P-value 0.002 and the incidence of left atrium fibrosis was significantly higher in the recurrence group as compared to no recurrence group with P-value 0.024. The only significant predictors of recurrence were the presence of left atrium fibrosis (OR 10.71, 95% CI 1.05 to 109.78; P=0.046) and AF burden (OR 1.14, 95% CI 1.02 to 1.27; P=0.023). The only significant predictor of the presence of left atrium fibrosis was AF burden (OR 1.06, 95% CI 1.01 to 1.13; P=0.031).

Conclusions

The presence of the atrial fibrosis in the left atrium is an independent predictor of atrial fibrillation recurrence after pulmonary vein antrum isolation after 6 months without left atium substrate modification.

Impact of the extent of low-voltage zone on outcomes after voltage-based catheter ablation for persistent atrial fibrillation

BACKGROUND

Low-voltage zones (LVZs), as measured by electroanatomic mapping, are thought to be associated with fibrosis. We reported the efficacy of atrial fibrillation (AF) ablation aiming to homogenize left atrial (LA) LVZ. The purpose of this study was to evaluate the impact of LVZ extension outcomes after LVZ homogenization in patients with nonparoxysmal AF.

METHODS

This prospective observational cohort study included 172 patients with nonparoxysmal AF undergoing their initial ablation. LVZ was defined as an area with bipolar electrograms <0.5mV during sinus rhythm. LVZ extent was calculated as the percentage of LA surface area, and subsequently, LVZ was categorized into stages I (<5%), II (≥5% to <20%), III (≥20% to <30%), and IV (≥30%). Patients with LVZs underwent LVZ ablation aimed at homogenization of ≥80% of LVZs following pulmonary vein isolation. The primary endpoint was atrial tachyarrhythmia recurrence-free survival after a single procedure at 18 months off antiarrhythmic drugs. The association of %LVZ with recurrence-free survival was examined using Cox proportional hazard models.

RESULTS

The survival rates were 76%, 74%, 57%, and 28% in patients with stages I, II, III, and IV LVZ, respectively. The difference was significant between stages I and IV (log-rank, p<0.001), while not significant between stages I vs. II and I vs. III (p=0.843, p=0.073, respectively). Cox proportional hazard model revealed that %LVZ was an independent predictor of recurrence-free survival (hazard ratio, 1.025 per 1% increase, p<0.001; unadjusted model). The results were similar after demographic and clinical covariate adjustments and after excluding 12 patients who did not achieve homogenization of ≥80% of LVZ.

CONCLUSIONS

The extent of LVZ is an independent predictor for recurrence even after LVZ homogenization.

Feasibility of total intravenous anesthesia by cardiologists with the support of anesthesiologists during catheter ablation of atrial fibrillation

BACKGROUND

The optimal methodology for sedation and anesthesia during atrial fibrillation (AF) ablation has not been well established. We assessed the feasibility of total intravenous anesthesia (TIVA) by cardiologists with support from anesthesiologists during AF ablation and quality of pulmonary vein isolation (PVI) and single procedure success rate at 12 months.

METHODS

TIVA was performed by cardiologists using IV propofol and fentanyl under controlled ventilation via i-gel™ without neuromuscular blocking drugs in 160 consecutive patients (80 nonparoxysmal) with no anticipated difficult airway or other severe diseases. Anesthesiologists were requested to be on standby during the procedure. The incidence of anesthesia-associated complications and ablation-associated complications were assessed. To evaluate the quality of PVI, the prevalence of acute adenosine triphosphate (ATP)-provoked PV reconnections and late PV reconnections among those requiring a redo procedure was analyzed.

RESULTS

TIVA was successfully completed in 152 patients (95%). In five (3%), we requested help from anesthesiologists, and in three (2%), TIVA was abandoned. No major anesthesia-associated complications were observed. Ablation-associated complications were observed in seven patients (4%). ATP provocation test was performed in 141 patients, and no acute PV reconnections were observed in 134 (95%). Success rates at 12 months were 85% of patients off antiarrhythmic drugs. Twenty-one of 24 patients with recurrence underwent a redo session, and 18 (86%) had no PV reconnections.

CONCLUSIONS

TIVA by cardiologists with support from anesthesiologists during AF ablation may be feasible. The success rate at 12 months was high, and prevalence of acute and late PV reconnection was very low.

Scar Homogenization in Atrial Fibrillation Ablation: Evolution and Practice

Atrial fibrillation (AF) ablation has emerged as the preferred rhythm control strategy for symptomatic paroxysmal AF refractory or intolerant to at least one class I or III antiarrhythmic medication. Since the initial observation by Haissaguerre and colleagues, of pulmonary vein triggers initiating atrial fibrillation (AF), pulmonary vein isolation (PVI) has become the cornerstone for paroxysmal AF ablation therapy.

Adenosine Testing After Atrial Fibrillation Ablation: Systematic Review and Meta-Analysis

BACKGROUND

Adenosine can be used to reveal dormant pulmonary vein (PV) conduction after pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). We performed a systematic review and meta-analysis to assess the impact of adenosine administration in patients undergoing PVI for AF.

METHODS

Meta-analysis of 22 studies was performed to assess the rates of freedom from AF in 1) patients with dormant PV conduction versus patients without dormant PV conduction, and 2) patients given routine adenosine post PVI versus patients not given adenosine. Relative-risks (RR) were calculated using random effects modelling.

RESULTS

In 18 studies, 3038 patients received adenosine and freedom from AF in those patients with dormant PV reconnection was significantly lower (62.9%) compared to patients without PV reconnection (67.2%) (RR 0.87; 95% CI: 0.78-0.98). In seven studies with 3049 patients, the freedom from AF was significantly higher in patients who received adenosine (67%) versus those patients who did not receive adenosine (63%) (RR: 1.11; 95% CI: 1.01-1.22).

CONCLUSIONS

The present study showed clear benefits of adenosine testing for freedom from AF recurrence. Adenosine-guided dormant conduction is associated with higher AF recurrence despite further ablation. Future studies should investigate the optimal methodology, including dosage and waiting time between PVI and adenosine administration.

Clinical, electrophysiological and imaging predictors of atrial fibrillation ablation outcome

INTRODUCTION

Significant technological advances for catheter ablation of atrial fibrillation (AF) have occurred over the last decade, with a consequent increase in numbers of patients referred for AF ablation worldwide. Despite this, long-term success rates, particularly in those with persistent AF, remain modest. The patient population presenting for AF ablation are heterogeneous with regard to age, type of AF and presence of associated cardiovascular disease. Improved understanding of factors predicting response to AF ablation may therefore help to improve patient selection for ablation procedures. Areas covered: This review outlines the clinical, electrophysiological and imaging predictors of response to radiofrequency ablation for AF in contemporary practice. Recently developed scoring systems incorporating these parameters are examined, as are factors identified thus far which may predict the outcome of cryoballoon ablation. Expert commentary: Traditional clinical factors associated with ablation outcomes serve as surrogates rather than direct measures of the underlying arrhythmia substrate. An improved understanding of this substrate could improve the prediction of response to radiofrequency ablation. Continued development of methods for characterising the arrhythmia substrate, including atrial cardiac magnetic resonance imaging and invasive voltage mapping, may inform patient risk assessment and help guide selection for catheter ablation on an increasingly individualistic basis.

Advanced Mapping Systems To Guide Atrial Fibrillation Ablation: Electrical Information That Matters

Catheter ablation is an established and widespread treatment for atrial fibrillation (AF). Contemporary electroanatomical mapping systems (EAMs) have been developed to facilitate mapping processes but remain limited by spatiotemporal and processing restrictions. Advanced mapping systems emerged from the need to better understand and ablate complex AF substrate, by improving the acquisition and illustration of electrophysiological information. In this review, we present you the recently advanced mapping systems for AF ablation in comparison to the established contemporary EAMs.

Adenosine testing after second-generation cryoballoon ablation (ATSCA) study improves clinical success rate for atrial fibrillation

AIMS

Adenosine administration after pulmonary vein (PV) isolation using radiofrequency, laser, and cryoablation can cause acute recovery of conduction to the PVs and predict atrial fibrillation (AF) recurrence. This study evaluates whether ablation of dormant potentials post-adenosine administration following second-generation cryoballoon (CB-2G) ablation may improve the success rate for AF.

METHODS AND RESULTS

In 45 of 90 patients after a waiting period of 30 min, a bolus 15-21 mg of adenosine was administered followed by rapid saline flush. The response was assessed for each PV using a circular octapolar catheter. If needed, further ablation using a cryoballoon and/or cryocatheter was performed until no reconduction was observed after repeat adenosine administration. The remaining 45 patients did not receive adenosine after the procedure. Acute PV isolation was achieved in 352 of 358 PVs (98.3%) of 86 of 90 patients (95.6%) using CB-2G. The adenosine group showed dormant reconduction in 5 of 45 patients (11%), 8 of 179 PVs (4.5%), including 1 left superior pulmonary vein, 3 left inferior pulmonary vein, 1 right superior pulmonary vein, and 3 right inferior pulmonary vein. The success rate for adenosine and without adenosine group was 84 and 79%, respectively, after a mean follow-up of 397 ± 47 and 349 ± 66 days, without any AF recurrence in patients in whom adenosine-induced dormant conduction was ablated.

CONCLUSION

Adenosine testing after second-generation cryoballoon ablation study showed that reablation of initially isolated PVs increases the clinical success rate for AF.

Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate

Cardiac electrophysiology has moved a long way forward during recent decades in the comprehension and treatment of complex cardiac arrhythmias. Contemporary electroanatomical mapping systems, along with state-of-the-art technology in the manufacture of electrophysiology catheters and cardiac imaging modalities, have significantly enriched our armamentarium, enabling the implementation of various mapping strategies and techniques in electrophysiology procedures. Beyond conventional mapping strategies, ablation of complex fractionated electrograms and rotor ablation in atrial fibrillation ablation procedures, the identification and modification of the underlying arrhythmogenic substrate has emerged as a strategy that leads to improved outcomes. Arrhythmogenic substrate modification also has a major role in ventricular tachycardia ablation procedures. Optimisation of contact between tissue and catheter and image integration are a further step forward to augment our precision and effectiveness. Hybridisation of existing technologies with a reasonable cost should be our goal over the next few years.

Unmasking the dormant pulmonary vein conduction with adenosine administration after pulmonary vein isolation with laser energy

AIMS

The isolation of the pulmonary veins (PVs) is the mainstay of atrial fibrillation (AF) ablation, which with current ablation techniques can be achieved in almost all cases. Reconnection of PVs constitutes the most frequent cause of AF recurrence. Visually guided laser balloon ablation (VGLA) is a novel system with very high rate of persistence of pulmonary vein isolation (PVI) three months after the first procedure shown in preclinical and clinical studies. We aimed to determine the acute efficiency of the laser energy during PVI with the help of adenosine provocation.

METHODS AND RESULTS

Twenty-six patients (19 male; mean age 64 ± 9 years) with symptomatic paroxysmal AF were included in the study. Pulmonary vein isolation was performed using the VGLA system. After successful PVI, we studied the effects of intravenous adenosine (18 mg) on activation of each PV at least 20 min after PVI. A total of 104 PVs were targeted. The balloon catheter could not be placed in two PVs. Of the remaining 102 PVs 99 (97% of the ablated PVs) could be successfully isolated. Adenosine was administered for each isolated PV in 25 patients. Only six PVs (6.7%) in five patients (20%) showed a PV reconnection during adenosine provocation.

CONCLUSION

Pulmonary vein isolation with VGLA is a feasible technique for PVI with a very effective acute lesion formation. The clinical significance of this low reconnection rate has to be determined.

Electroanatomical mapping of atrial fibrillation: Review of the current techniques and advances

The number of atrial fibrillation (AF) catheter ablations performed annually has been increasing exponentially in the western countries in the last few years. This is clearly related to technological advancements, which have greatly contributed to the improvements in catheter ablation of AF. In particular, state-of-the-art electroanatomical mapping systems have greatly facilitated mapping processes and have enabled complex AF ablation strategies. In this review, we outline contemporary and upcoming electroanatomical key technologies focusing on new mapping tools and strategies in the context of AF catheter ablation.