High-density mapping in catheter ablation for persistent atrial fibrillation

Funding Acknowledgements

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

Background

Pulmonary vein isolation (PVI) is an established treatment option for persistent atrial fibrillation (PersAF). Corresponding long-term success rates remain modest however, advancements in high-density (HD) mapping may better identify substrates. The HD grid-style mapping catheter (HD Grid) allows for simultaneous analysis of adjacent orthogonal bipolar signals that may assist in ablation strategy decisions to achieve favorable outcomes in treating PersAF.

Objective

This was a prospective, multi-center, observational study to quantify and characterize the use of a market-released HD mapping catheter in PersAF subjects.

Methods

HD Grid was used in PersAF subjects undergoing radiofrequency (RF) ablation across 25 sites to gather data regarding safety, mapping efficiency and quality, ablation strategies, and procedural outcomes.

Results

334 PersAF subjects (average age: 64.2 years; 76% male) were enrolled in this study. Types of maps generated included peak-to-peak voltage (78%; 322/413), local activation time (LAT) (11.4%; 47/413), and complex fractionated electrogram (CFE) mean (7.7%; 32/413). Median total mapping points collected and used were 8428.0 (IQR 4845.0-13366.0) and 2099.0 (IQR 1219.0-2947.0), respectively, in a median of 11.0 (IQR 7.3-16.0) minutes per map. Low voltage, scar/fibrosis, and CFE were searched for in 90.4% (302/334), 53.6% (179/334), and 15.9% (53/334) of subjects, respectively. A PVI approach was used in 93.1% of all ablation procedures and 34.1% (114/334) of subjects received PVI plus additional lesions. HD Grid identified signals of interest not identified by the ablation catheter in 80.4% (205/255) of subjects. The total procedure time was 134.3 ± 51.3 minutes with a fluoroscopy time of 14.5 ± 11.3 minutes and RF ablation time of 32.4 ± 29.6 minutes. Of the subjects in atrial fibrillation (AF) (59.6%; 199/334), AF was terminated in 80.4% (160/199). 87.4% (173/198) of subjects were free from recurrent atrial arrhythmias as detected by 48-hour Holter monitoring at 12 months. 13.8% (46/334) of subjects experienced any adverse event through 12 months including 1 death unrelated to the procedure and 1 event deemed related to HD Grid by the investigator.

Conclusion

This study demonstrated the use of the HD Grid mapping catheter to create detailed maps and to guide ablation strategies to treat PersAF while maintaining an adequate safety profile.

Simultaneous orthogonal bipole mapping compared to conventional electrode configurations and impact on ablation strategies: results from a real world observational study

Funding Acknowledgements

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

Background

3D mapping systems are pivotal to identify low voltage areas and to define ablation strategies. In this context, high-density multipolar mapping catheters with varying electrode configurations are used for accurate myocardial substrate definition. High density mapping using a grid shaped catheter allows for use of simultaneous analysis of adjacent orthogonal bipolar signals that may assist in more accurate substrate characterization and ablation strategy decisions.

Purpose

This was a prospective, multicenter observational study to characterize the utility of electroanatomical mapping with a high density grid-style mapping catheter (HD Grid) in subjects undergoing catheter ablation for persistent atrial fibrillation (PersAF) or ventricular tachycardia (VT) in real-world clinical settings.

Methods

Mapping was performed with the HD Grid catheter to generate high-density maps of cardiac chambers in order to assess the potential influence of the simultaneous orthogonal bipole configuration on PersAF and VT ablation strategies. Differences in substrate identification between simultaneous orthogonal bipole configuration and standard along-the-spline electrode configuration, and potential effects on ablation strategies were investigated.

Results

During the study period (January 2019 through April 2020), 367 subjects underwent catheter ablation for PersAF (N = 333, average age 64.1yr, 75% male) or VT (N = 34, average age = 64.3yr, 85.3% male).

In total, 494 maps were generated to treat patients undergoing PersAF ablation and 57 to treat patients undergoing VT ablation. Compared to standard along-the-spline configuration, mapping with the simultaneous orthogonal bipole configuration showed differences in 57.8% (178/308) of maps generated, with the greatest difference noticed in surface area of low voltage (62.9%) and location of low voltage (55.6%).

In comparisons performed live during the procedure (n = 50), simultaneous orthogonal bipole configuration assisted in identification of ablation targets in 70.0% of cases, changing the ablation strategy compared to that identified with along-the-spline configuration in 34.3%.

In comparisons performed retrospectively after the procedure (n = 258), the ablation strategy identified with simultaneous orthogonal bipole configuration differed from along-the-spline configuration in 21.7% of maps. Even compared to a higher-density electrode configuration using all-bipoles rather than along-the-spline bipoles, simultaneous orthogonal bipole configuration identified differences in 57.1% of maps.

Conclusion

The HD grid catheter combined with simultaneous orthogonal bipole configuration can define myocardial substrate more accurately compared to standard along-the-spline configuration. The difference in substrate identification has potential impact on ablation strategy. Further clinical trials are needed to elucidate the role of orthogonal bipole configuration mapping and improved ablation success rates.

Impact of high density mapping using a grid shaped catheter with orthogonal signal analysis on ventricular tachycardia ablation strategy

Funding Acknowledgements

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

Background

Ventricular tachycardia (VT) in patients with structural heart disease (SHD) is related to scar and slow conduction areas. Substrate-based ablation has become the gold standard treatment in patients with SHD-related refractory VT. A new high-density grid shaped catheter that allows simultaneous analysis of adjacent orthogonal bipolar signals can allow better understanding of these slow conduction areas with the potential to improve ablation results.

Purpose

This was a prospective, multicenter observational study to characterize the utility of electroanatomical mapping with a high density grid-style mapping catheter (HD Grid) in subjects undergoing catheter ablation for ventricular tachycardia (VT) in real-world clinical settings.

Methods

During the study period, patients who underwent VT ablation using the HD Grid catheter as the primary mapping catheter were included. Comparisons both during the procedure and retrospectively were performed between conventional electrode configuration maps and simultaneous orthogonal bipole electrode configuration maps. The influence of these different configurations on ablation strategy was analyzed.

Results

  During study period (January 2019 – April 2020) 57 maps were performed in 34 VT subjects (average age: 64.3yr, male: 85.3%, ischemic cardiomyopathy: 70.6%). The left ventricle was mapped in 94.1% of subjects, including left ventricular outflow tract and papillary muscles in 20.6% and 8.8% respectively, reporting minimal or no ectopic beats in 97.1% of the subjects. The total number of mapping points collected was 14172.0 ± 15174.8 in 24.3 ± 17.9 min per map.

Simultaneous orthogonal bipole mapping identified differences in 67.6% of maps compared to linear along-the-spline electrode configurations. The differences consisted mainly in the surface area (92%) and location of low voltage (40%). When compared during the procedure, simultaneous orthogonal bipole mapping was used to identify ablation strategy in 100% of cases. When compared to a standard along-the-spline configuration retrospectively, the ablation strategy identified with simultaneous orthogonal bipoles was different in 30.1% of cases.  The ablation strategy used in these subjects was mainly substrate ablation (late potentials and low voltage areas in scar regions) with an acute success rate of 97.1%.

Conclusions

The use of the HD Grid catheter with the ability to analyze orthogonal signals is feasible and has the potential to change the ablation strategy in one third of VT patients with a high acute success rate.