Low voltage area as a predictor of recurrence after a single pulmonary vein isolation procedure: results of the WAVE-MAP AF study

Background/Introduction

Pulmonary vein isolation (PVI) is a recommended approach for atrial fibrillation (AF) ablation procedures. Substrate modification beyond PVI has mixed results but identifying and ablating low voltage zones and ablating those targets in addition to PVI may be beneficial. Electroanatomic mapping is critical to identify subjects that may require further substrate modification. Low voltage area may be predictive of optimal treatment approach.

Purpose

This was a prospective, multicenter, interventional study of a high-density grid-style mapping catheter (HD Grid) to characterize left atrial low voltage substrate during sinus rhythm (SR) and AF and identify associations with 12 month recurrence rates after a single de novo radiofrequency (RF) ablation using a PVI only approach.

Methods

This study (NCT03882021) enrolled 300 subjects at 18 centers in Europe and Israel. Subjects underwent de novo RF ablation for paroxysmal AF (PAF) (N=113), early persistent AF (PsAF; AF sustained 7 days to 3 months) (N=86) or non-early PsAF (AF sustained >3 months to 12 months) (N=101). High density voltage maps were collected with HD Grid. Two pre-ablation maps, in SR and AF, were created for each subject (N=196) followed by PVI only ablation. Low voltage area (using cutoffs of 0.1 mV to 1.5 mV) was investigated in SR and AF. Follow up visits were at 3, 6 and 12 months post-ablation, with a 24-hour Holter monitor at 12 months. A Cox proportional hazards model was used to identify associations between mapping data and 12 month AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence after a single PVI procedure.

Results

At 12 months, 75.5% of subjects were free from AF/AFL/AT recurrence. On average, PsAF subjects had more low voltage area than PAF subjects in SR and AF. However, while univariate analysis found no correlation between recurrence and PAF or PsAF diagnosis (p=0.1261), those with recurrence had a significantly larger percent left atrial low voltage area under 0.5 mV with simultaneous orthogonal bipole wave configuration (HDW) in both AF (p=0.0011) and SR (p=0.0210) than those without recurrence. Using HDW, low voltage area (identified as <0.5 mV) greater than 28% of the left atrium in SR (HR: 4.82, 95% CI: 2.08–11.18, p=0.0003) and greater than 72% in AF (HR: 5.66, 95% CI: 2.34–13.69, p=0.0001) were associated with a higher risk of AF/AFL/AT recurrence at one year.

Conclusion(s)

Using a standard cutoff of 0.5 mV, a larger percent low voltage area was associated with increased risk of recurrence in both SR and AF. Future analyses will explore optimal low voltage cutoffs and thresholds predictive of recurrence that may necessitate additional substrate modification beyond PVI.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Abbott

High density wave mapping to characterize low voltage substrate in sinus rhythm and atrial fibrillation: acute results from the WAVE-MAP AF study

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

Pulmonary vein isolation (PVI) is a recommended approach for all atrial fibrillation (AF) ablation procedures, but PVI alone does not cure all AF. Supplementary substrate modification beyond PVI has mixed results. Identifying low voltage zones and ablating those targets in addition to PVI may be beneficial. Electroanatomic mapping is critical to identify subjects that may require further substrate modification. The amount of low voltage area may be predictive of the optimal treatment approach.

Purpose

This was a prospective, multicenter, interventional study of a high-density grid-style mapping catheter (HD Grid) to characterize left atrial (LA) low voltage substrate during sinus rhythm (SR) and AF in subjects undergoing de novo radiofrequency (RF) ablation for paroxysmal AF (PAF), early persistent AF (PsAF) (7 days-3 months) or non-early PsAF (>3 months-12 months) using a PVI only approach.

Methods

High-density voltage maps were collected with HD Grid during both SR and AF prior to ablation. Differences in low voltage area between (1) SR and AF and (2) simultaneous orthogonal bipole wave configuration (HDW) and standard along-the-spline linear electrode configuration (SD) were investigated.

Results

Three hundred subjects, enrolled at 18 centers in Europe and Israel, underwent PVI only RF ablation for PAF (N=113), early PsAF (N=79), and non-early PsAF (N=108). The average age was 62.0 ± 9.5 years and 70.3% (211/300) were male. SR maps and AF maps were available and evaluated in HDW and SD for 196 subjects (65.3%) (63 PAF, 65 early PsAF, 68 non-early PsAF). Mean LA surface area was 108.8 cm² and mean mapped surface area ranged from 83.2 to 89.5 cm².

HDW maps showed less low voltage area compared to SD in all subgroups, both in AF and in SR (Figure). For example, in AF with a low voltage cutoff of 0.5 mV, mean low voltage area was 49.8 cm² using SD and only 45.6 cm² using HDW (p<.0001). Similarly, in SR with a low voltage cutoff of 0.5 mV, mean low voltage area was 16.1 cm² using SD and only 12.6 cm² using HDW (p<.0001). HDW showed significantly less low voltage area than SD in SR for all measured voltage cutoffs from 0.1 mV to 1.5 mV.

On average, non-early PsAF subjects had a larger low voltage area than early PsAF subjects and PAF subjects in both SR and AF. In SR HDW, non-early PsAF subjects had 15.6 cm² under 0.5 mV, early PsAF subjects had 12.4 cm², and PAF subjects had 9.2 cm² (p=.0316). In AF HDW, non-early PsAF subjects had 56.6 cm² under 0.5 mV, early PsAF had 42.8 cm² and PAF subjects had 35.4 cm² (p<.0001).

Conclusion

Non-early PsAF subjects had the largest low voltage area on average compared to both early PsAF and PAF subjects in this study. Using HD grid, HDW provided better low voltage area characterization compared to SD in both SR and AF. The final results of this study will suggest whether an HDW substrate characterization of low voltage area can predict recurrences after a single PVI-only strategy procedure.

P343Comparison of Focal Impulse and Rotor Modulation Ablation (FIRM) only versus second-generation cyroballoon ablation in patients with paroxysmal atrial fibrillation

Background

Rotors have been postulated to be a major driver of atrial fibrillation (AF). Initial studies demonstrated, that focal impulse and rotor modulation (FIRM) might be an effective therapy for the treatment of paroxysmal AF (PAF). However, data about FIRM-guided ablation strategies without PVI is sparse.

Objective

To compare the safety and efficacy of FIRM-guided catheter ablation (without PVI; FIRM arm) and second generation cryoballoon (CB2, CB2 arm) based PVI in patients with paroxysmal atrial fibrillation (PAF) and de-novo catheter ablation of AF.

Methods

In this retrospective single-center study patients with PAF undergoing de-novo ablation of PAF between February 2016 and January 2017 were enrolled. Patients treated with FIRM-guided AF ablation as a standalone therapy without PVI were included and compared with patients undergoing CB2 based PVI. All patients in the FIRM arm were part of the randomized multicenter FIRMAP AF trial (results of this trial will be presented at this meeting). In patients undergoing FIRM-guided ablation, 3D electroanatomical mapping of both atria was performed. Rotor mapping using FIRM technology was conducted in spontaneous or induced AF. The procedural endpoint was the elimination of all rotors and focal impulses; no PVI was performed in those patients. In the CB2 arm, CB based PVI with the procedural endpoint of isolation of all veins was performed. Procedural data and arrhythmia-free survival after 12 months were compared.

Results

FIRM-guided and CB2 based AF ablation was performed in 22 and 86 patients, respectively. Follow up was completed in 20 and 79 patients LA diameter differed between groups. Otherwise, baseline characteristics did not differ between the FIRM group (mean age 60±11 years, 59.1% males) and the CB2 group (mean age 62±13, 62.4% male).

Arrhythmia-free survival including a 90-day blanking period was 25.0% (15/20) in the FIRM group and 86.1% (11/79) in the CB2 PVI group (p=0.000; Figure 1). Procedure duration was significantly longer in the FIRM group (152 [120; 176] minutes) compared to the CB2 PVI group (122 [110; 145] minutes) (p=0.031), whereas radiation dose was lower in the FIRM group (1266 [1027; 2281] cGy·cm2 vs. 3020 [1677; 4215] cGy·cm2). Adverse events (groin complications) occurred in 1 patient (1.2%) in the CB2 PVI group and 5 patients (22.7%) in the FIRM group.

Figure 1. Kaplan-Meier-survival curve dem

Conclusion

De novo ablation of PAF using a FIRM-guided AF ablation only (without PVI) is associated with poor arrhythmia-free survival after 12 months compared to CB2 PVI. These results underline the importance of PVI as the first-line approach in catheter ablation of AF.

Transesophageal vs. intracardiac echocardiographic screening in patients undergoing atrial fibrillation ablation with uninterrupted rivaroxaban

BACKGROUND

Patients with atrial fibrillation (AF) routinely undergo different imaging modalities for the evaluation of the left atrial (LA) appendage to rule out thrombus prior to the AF ablation procedure. Recently, uninterrupted novel oral anticoagulants were introduced for patients undergoing atrial fibrillation (AF) ablation to minimize the peri-procedural thromboembolism risk. We performed a retrospective analysis to evaluate the safety of uninterrupted rivaroxaban and whether transesophageal (TEE) or intracardiac echocardiography (ICE) is necessary for patients undergoing AF ablation.

METHODS

Data from 332 consecutive patients (42% females, aged 64 ± 11 years) with AF undergoing either TEE (n = 115) prior to catheter ablation or ICE (n = 217) for the detection of LA thrombus were analyzed. All patients were on uninterrupted rivaroxaban during, and for at least, 4 weeks before the procedure. Heparin bolus was administered in all patients before transseptal puncture to maintain a target activated clotting time of >350 s.

RESULTS

A total of 277 patients (80.4%) had paroxysmal AF. The average CHA2DS2-VASc score was 2.11 ± 0.91 in the TEE group and 2.46 ± 0.61 in the ICE group. The CHA2DS2-VASc score was ≥2 in 64 (55.7%) and 214 (98.6%) patients in the TEE and ICE groups, respectively. The left atrial appendage was adequately visualized in all cases. None of the patients have an identifiable LA thrombus either in the TEE group or the ICE group. One (0.3%) thromboembolic periprocedural stroke occurred in a patient with long-standing persistent AF in the TEE group.

CONCLUSIONS

This study illustrates that performing AF ablation with ICE guidance on uninterrupted rivaroxaban for at least 4 weeks even without TEE is feasible and safe.