Atrial fibrillation ablation workflow optimization facilitated by high-power short-duration ablation and high-resolution mapping

Abstract

Aims

Pulmonary vein isolation (PVI) for catheter ablation of atrial fibrillation (AF) is a time-demanding procedure. High-power short-duration (HPSD) ablation protocols and high-density mapping catheters have recently been introduced to clinical practice. We investigated the impact of high-density mapping and HPSD ablation protocols on procedural timing, efficacy, and safety by comparing different standardized set-ups.

Methods and results

Three electrophysiology (EP) laboratory set-ups were analysed: (i) circular catheter for mapping and HPSD ablation with 30/35 W guided by an ablation index (AI); (ii) pentaspline catheter for mapping an HPSD ablation with 50 W guided by an AI; and (iii) pentaspline catheter for mapping and HPSD ablation with 90 W over 4 s using a novel ablation catheter. All patients underwent PVI without additional left atrial ablation strategies. Procedural data and operating intervals in the EP laboratory were systematically analysed. Three hundred seven patients were analysed (30/35 W AI: n = 102, 50 W AI: n = 102, 90 W/4 s: n = 103). Skin-to-skin times [105.3 ± 22.7 (30/35 W AI) vs. 81.4 ± 21.3 (50 W AI) vs. 69.5 ± 12.2 (90 W/4 s) min, P ≤ 0.001] and total laboratory times (132.8 ± 42.1 vs. 107.4 ± 25.7 vs. 95.2 ± 14.0 min, P < 0.001) significantly differed among the study groups. Laboratory interval analysis revealed significant shortening of mapping and ablation times. Arrhythmia-free survival after 12 months was not different among the study groups (log-rank P = 0.96).

Conclusion

The integration of high-density mapping and HPSD protocols into an institutional AF ablation process resulted in reduced procedure times without compromising safety or efficacy.

Graphical Abstract

Graphical Abstract.

What’s new?

• Recent technical development facilitated incorporation of novel energy settings and high-density multi-polar mapping catheters into atrial fibrillation (AF) ablation procedures.

• This study is a systematic analysis of workflow optimization adopting high-power short-duration (HPSD) ablation and modern high-resolution mapping for AF ablation.

• Combination of HPSD ablation and high-resolution mapping resulted in significantly shortened mapping and ablation times as well as total procedure duration.

• There was no effect on peri-procedural safety and efficacy in terms of arrhythmia-free survival during workflow optimization.

Introduction

Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for atrial fibrillation (AF). Increasing operator experience and technical innovations have led to improved efficacy of ablation with regard to reduced procedure durations and favourable long-term arrhythmia-free survival after catheter ablation.^1,2 The use of higher energy settings applied for shorter application times is a noteworthy development in ablation procedures.³ It has recently been shown that high-power short-duration (HPSD) ablation can be carried out safely and effectively. A novel ablation catheter has been introduced into the market enabling temperature-controlled ablation utilizing very high-energy settings up to 90 W. Although preliminary research indicated that ablation using a 90 W/4 s strategy was safe and effective,^4,5 comprehensive head-to-head comparisons with traditional ablation protocols are currently unavailable.

In this study, we systematically assessed the implementation of novel energy settings and use of modern high-resolution mapping catheters in our institutional workflow for PVI. We report on acute procedural success as well as safety and long-term efficacy. Additionally, the impact of the workflow evolution on electrophysiology (EP) laboratory efficacy was systematically assessed.

Methods

Patient population

Consecutive patients suffering from symptomatic paroxysmal or persistent AF undergoing first-time catheter ablation aiming at PVI between April 2021 and February 2022 at our centre were prospectively enrolled. Patients were enrolled in our institutional registry for all-comers undergoing catheter ablation at our centre. The study was approved by the local ethics board (ethical review board file number 2019-563) according to the Declaration of Helsinki. Pre-procedural transoesophageal echocardiography was performed in patients with interrupted oral anticoagulation and a risk for thromboembolism or in patients with previous stroke to rule out intra-cardiac thrombi. All patients underwent pre-procedural imaging by computed tomography or cardiac magnetic resonance imaging.

Ablation procedure workflow

All procedures were performed with an electroanatomical mapping system (CARTO 3 V7, Biosense Webster, Irvine, CA, USA). The use of a steerable sheath was at the operator’s discretion. Three laboratory set-ups were used: first setting: before June 2021, the set-up consisted of utilization of a circular mapping catheter (Lasso Nav, Biosense Webster) and use of contact force sensing catheters with a surround flow irrigation technique (ThermoCool SmartTouch SF, Biosense Webster) with power settings of 30 W at the posterior wall and 35 W at the anterior wall under the guidance of a lesion quality index [ablation index (AI), Biosense Webster; (30/35 W AI group]; second setting: from June 2021 until November 2021, a 50 W power-controlled ablation mode guided by AI and mapping with a high-resolution pentaspline multi-polar mapping catheter (Pentaray, Biosense Webster) was utilized (50 W AI group); and third setting: after November 2021, a novel ablation catheter (QDOT, Biosense Webster) enabling high-energy temperature-controlled ablation with 90 W over 4 s in conjunction with the pentaspline mapping catheter was implemented into routine clinical workflow (90 W/4 s group; Figure 1). Block of the cavotricuspid isthmus (CTI) was performed in patients with known CTI-dependent atrial flutter. The institutional workflow aimed at left atrial (LA) substrate modification guided by results of electroanatomical mapping. In general, substrate modification additional to PVI is conducted in our institution in patients with LA low-voltage areas. Low voltage was defined as areas with a bipolar voltage <0.5 mV assessed during mapping in sinus rhythm. Severity of low-voltage areas was categorized by judgement of the operator. Usually, confluent areas of low voltage were judged to be clinically relevant to the necessity of substrate modification.

Figure 1.

Procedural workflow optimization. The workflow changed in three steps during the study course. In the first setting, conventional ablation settings and a circular mapping catheter were utilized. In the second setting, a high-resolution multi-polar mapping catheter and a high-power short-duration ablation protocol (50 W AI-guided, power-controlled ablation) were used. In the third setting, a high-resolution multi-polar mapping catheter and a very high-energy ablation protocol (90 W over 4 s, temperature-controlled ablation) with a novel ablation catheter were utilized. AI, ablation index.

To allow for better comparison of ablation set-ups, only patients who underwent PVI without additional ablation strategies (with or without CTI block) as a result of repeat mapping in sinus rhythm after PVI demonstrating absence of low-voltage areas were analysed in this study. Figure 2 shows the representative images of electroanatomical mapping with the three different EP laboratory set-ups.

Figure 2.

Representative images of electroanatomical mapping with different laboratory set-ups: (A) first setting, (B) second setting, and (C) third setting. LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; PA, postero-anterior; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein.

The EP laboratory staff consisted of two electrophysiologists (at least one board-certified cardiologist) and two nurses with training in management of deep sedation during cardiological procedures. Ablations were carried out by six different first operators with a median range of invasive EP experience of 10 years (range 6–18 years). Procedures were performed on uninterrupted vitamin K antagonist therapy (international normalized ratio [INR] goal of 2.0–3.0). In the case of direct oral anticoagulant therapy, medication was withheld on the day of the procedure and restarted 6 h after catheter ablation. Procedures were performed under deep sedation with boli of midazolam and sufentanil and propofol infusion. Drug administration and monitoring were carried out by the nurses under the supervision of physicians. Heparin was administered targeting an activated clotting time >300 s. Double transseptal puncture was performed under fluoroscopic guidance with a BRK-XS needle (St. Jude Medical, St Paul, MN, USA). Electroanatomical 3D mapping was performed via fast anatomical mapping (FAM). Voltage mapping was performed before and after ablation to assess patients’ anatomy and to detect low-voltage areas in sinus rhythm. In patients who were in AF, electrical cardioversion was performed after PVI. A steerable sheath was used in all patients; a sheath that enables visualization inside the electroanatomical mapping system (Vizigo, Biosense Webster) was used in a subset of patients.⁶ Mapping of the right atrium (RA) was performed in patients in which a 3D visualized steerable sheath was used to enable building of a matrix for sheath visualization.⁶ Ablation settings in the 30/35 W AI group used an irrigation flow rate at 17 mL/h aiming at AI values of 550 at anterior ablation sites and 400 at the posterior wall and the LA roof. Ablation settings in the 50 W AI group used an irrigation flow rate at 20 mL/h aiming at AI values of 550 at anterior ablation sites and 400 at posterior sites and the LA roof. In the 90 W/4 s group, ablation was conducted in a temperature-controlled mode targeting a temperature of 55°C with a cut-off limit of 60°C, maximum of 90 W, and an irrigation flow rate of 8 mL/h, increasing to 15 mL/h if measured temperature reached a certain threshold. Power settings of 90 W over 4 s were used for creation of the complete circumferential lesions along the anterior and posterior pulmonary vein (PV) ostium; a touch-up ablation using 50 W temperature-controlled ablation was allowed on operators’ discretion.

A contact force >10 g and an inter-lesion distance <6 mm between ablation localizations were aimed for in all ablation lesions. A procedural endpoint was PVI with proof of entrance and exit block in all PVs. No oesophageal temperature monitoring was used.

Post-procedural care

Femoral access sites were closed by a figure-of-eight suture and manual compression. Pericardial effusion was excluded by transthoracic echocardiography (TTE) directly after the procedure. Patients received proton pump inhibitors for 4 weeks. Anti-arrhythmic drug therapy was prescribed on an individual basis for each patient. All patients stayed at least one night in hospital post-ablation.

Workflow analysis of peri-procedural care and intra-procedural measurements

Using a specific computer programme (Pace Insights, Biosense Webster), peri- and intra-procedural steps were documented starting when the patient entered the EP laboratory. Six procedural steps (pre-procedural preparation, vascular access and transseptal puncture, LA mapping, ablation, validation of PVI and vascular closure, and post-procedural preparation) were subjected to laboratory cycle analysis. Total procedure time and skin-to-skin times from vascular access to closure were assessed. Further analysis included the number and duration of radiofrequency (RF) applications.

Clinical follow-up

All patients underwent medical history assessment, clinical investigation, electrocardiogram (ECG), and Holter ECG (24–72 h) at our outpatient clinic or at ambulatory cardiologists 3 months after the ablation procedure. Further follow-up including clinical investigation, TTE, ECG, and Holter ECG (24–72 h) was recommended after 6 and 12 months and every 6–12 months afterwards.

Statistics

Continuous variables were expressed as mean ± standard deviation for normal distributions or as median/inter-quartile range for non-normal distributions or categorical data. Categorical variables were displayed as counts (%). Differences among the study groups were investigated via Student’s t-test, analysis of variance, χ² test, or Fisher’s exact test, as appropriate. Arrhythmia-free survival outside a blanking period of 90 days was assessed via creation of Kaplan–Meier curves. All analyses were performed using SPPS, version 25 (IBM Cooperation, Armonk, NY, USA).

Results

Baseline data and procedural data

The study cohort consisted of 307 patients (99 females) with 102 patients underwent conventional ablation using 30/35 W AI-guided ablation (30/35 W AI group), 102 patients underwent 50 W AI-guided ablation (50 W AI group), and 103 patients underwent 90 W/4 s ablation (90 W/4 s group). Patients’ baseline characteristics were not different among the study groups. The baseline parameters are depicted in Table 1.

Table 1.

Patients’ cohort baseline data

Parameter	35/30 W AI	50 W AI	90 W/4 s	P-value
Patients, n	102	102	103
Female, n (%)	35 (34.3)	32 (31.4)	32 (31.1)	0.86
Age (years)	67.7 ± 11.4	65.4 ± 11.2	66.9 ± 10.4	0.32
BMI (kg/m2)	28.1 ± 5.9	29.7 ± 6.8	28.9 ± 3.4	0.12
LA diameter (mm)	45.6 ± 3.3	46.1 ± 3.1	45.5 ± 4.2	0.44
LVEF (%)	51.1 ± 9.7	50.9 ± 10.2	52.1 ± 7.7	0.61
Paroxysmal AF, n (%)	37 (36.3)	35 (34.3)	34 (33.0)	0.89
Persistent AF, n (%)	67 (65.7)	70 (68.6)	69 (67.0)	0.90
Arterial hypertension, n (%)	70 (68.6)	65 (63.7)	67 (65.0)	0.76
Diabetes mellitus, n (%)	22 (21.6)	26 (25.5)	18 (17.5)	0.38
Structural heart disease, n (%)	12 (11.8)	12 (11.7)	13 (12.6)	0.98
ICM, n (%)	7 (6.8)	4 (3.9)	7 (6.8)	Nd
DCM, n (%)	5 (4.9)	5 (4.9)	4 (3.8)	Nd
HCM, n (%)	0 (0.0)	2 (2.0)	2 (1.9)	Nd
Non-compaction Cardiomyopathy, n (%)	0 (0.0)	1 (1.0)	0 (0.0)	Nd
Stroke, n (%)	7 (6.8)	10 (9.8)	8 (7.8)	0.73
CHA2DS2-VASc score, median (IQR)	2 (2; 4)	3 (2; 4)	2 (1; 3)	0.92
Anticoagulation, n (%)	87 (85.3)	89 (87.3)	85 (82.5)	0.63
DOAC, n (%)	82 (80.4)	83 (81.4)	82 (79.6)	0.95
Vitamin K antagonist, n (%)	5 (4.9)	6 (5.9)	3 (2.9)	Nd
Anti-arrhythmic drug therapy, n (%)	35 (34.3)	37 (36.3)	32 (31.1)	0.73
Class I, n (%)	9 (8.8)	8 (7.8)	11 (10.7)	0.77
Class III, n (%)	26 (25.5)	29 (28.4)	21 (20.4)	0.40

Data are presented as n (%) or mean ± standard deviation.

AF, atrial fibrillation; AI, ablation index; BMI, body mass index; DCM, dilative cardiomyopathy; DOAC, direct oral anticoagulant; HCM, hypertrophic cardiomyopathy; ICM, ischaemic cardiomyopathy; IQR, inter-quartile range; LA, left atrium; LVEF, left ventricular ejection fraction.

Pulmonary vein isolation was performed in all patients with additional CTI ablation in 16 patients (5.2%). Left atrial electroanatomical mapping revealed presence of limited LA low-voltage areas in 12 patients (3.9%), and no additional ablation beyond PVI was performed in all patients. Procedural parameters are shown in Table 2 and Figure 3. The mean procedure duration was significantly different among the study groups with 105.3 ± 22.7 min in the 30/35 W AI group, 81.4 ± 21.3 min in the 50 W AI group, and 69.5 ± 12.2 min in the 90 W/4 s group (P < 0.001; Table 2). Fluoroscopy times, RF times, and the median duration of ablation applications were significantly different among the study groups with the lowest numbers in the 90 W/4 s group except for the numbers of RF applications (Table 2, Figure 3A and B). Irrigation volumes significantly differed among the study groups with 307 ± 28, 342 ± 32, and 47 ± 12 mL for 30/35 W AI, 50 W AI, and 90 W/4 s cohorts, respectively (P < 0.001). Pulmonary vein isolation of all veins was successfully performed in 100% of patients (Table 2). First-pass isolation of all PVs was achieved in 72 (70.6%), 70 (68.6%), and 68 (66.0%) patients, respectively (P = 0.78; Figure 3C).

Table 2.

Procedural data

Parameter	35/30 W AI	50 W AI	90 W/4 s	P-value
Procedural duration (min)	105.3 ± 22.7	81.4 ± 21.3	69.5 ± 12.2	<0.001
Fluoroscopy time (s)	445.5 ± 219.0	361.8 ± 151.1	293.2 ± 127.1	<0.001
Fluoroscopy dosage (γGym2)	407.2 ± 234.5	386.5 ± 228.9	355.2 ± 135.2	0.19
Duration per RF application (s)	24.7 ± 6.7	17.3 ± 3.0	4.0 ± 0.0	<0.001
Irrigation volume (mL)	307 ± 28	342 ± 32	47 ± 12	<0.001
Acute success (PVI)	100 (0.0)	100 (0.0)	100 (0.0)	1.0
CTI ablation	4 (3.9)	6 (5.9)	6 (5.8)	0.87
Peri-procedural complications, n (%)	2 (2.0)	1 (1.0)	2 (2.0)	0.87
False aneurysm at puncture site, n (%)	1 (1.0)	1 (1.0)	1 (1.0)	1.0
Bleeding without transfusion, n (%)	1 (1.0)	0 (0.0)	1 (1.0)	0.87

Data are presented as n (%) or mean ± standard deviation.

AI, ablation index; CTI, cavotricuspid isthmus; PVI, pulmonary vein isolation; RF, radiofrequency.

Figure 3.

Ablation parameters. AI, ablation index; LPV, left pulmonary vein; RF, radiofrequency; RPV, right pulmonary vein.

Workflow analysis

The results of the laboratory interval analysis are shown in Table 3 and Figure 4. The total procedure duration of 132.8 ± 42.1, 107.4 ± 25.7, and 95.2 ± 14.0 min was recorded for 30/35 W AI, 50 W AI, and 90 W/4 s study groups, respectively (P < 0.001 for differences among the study groups). The ‘skin-to-skin’ time was 105.3 ± 22.7, 81.4 ± 21.3, and 69.5 ± 12.2 min for the 30/35 W AI-guided, 50 W AI-guided, and 90 W/4 s study groups, respectively (P < 0.001 for differences among the study groups). There was no significant difference among times for pre-procedural preparation vascular access and post-procedural preparation (Table 3). Three procedural steps showed significant differences among the study groups: mapping times were 19.3 ± 5.7, 15.2 ± 5.2, and 13.1 ± 6.9 (P < 0.001); ablation times were 51.1 ± 14.1, 34.2 ± 11.8, and 25.4 ± 8.9 min (P < 0.001); and validation and vascular closure times were 4.7 ± 2.4, 3.5 ± 1.8, and 3.3 ± 2.1 min (P < 0.001).

Table 3.

Laboratory cycle analysis

Parameter	Pre-procedural (min)	Vascular access + TSP (min)	Mapping (min)	Ablation (min)	Validation + vascular closure (min)	Post-procedural (min)	Skin-to-skin (min)	Total duration (min)
30/35 W AI	20.7 ± 7.1	30.2 ± 10.7	19.3 ± 5.7	51.1 ± 14.1	4.7 ± 2.4	6.8 ± 3.0	105.3 ± 22.7	132.8 ± 42.1
50 W AI	19.1 ± 6.6	28.5 ± 12.7	15.2 ± 5.2	34.2 ± 11.8	3.5 ± 1.8	6.9 ± 2.1	81.4 ± 21.3	107.4 ± 25.7
90 W/4 s	19.0 ± 5.9	27.7 ± 10.2	13.1 ± 6.9	25.4 ± 8.9	3.3 ± 2.1	6.7 ± 1.7	69.5 ± 12.2	95.2 ± 14.0
P-value	0.11	0.27	<0.001	<0.001	<0.001	0.83	<0.001	<0.001

Data are presented as mean ± standard deviation.

AI, ablation index; TSP, transseptal puncture. P values < 0.05 are displayed in italic letters.

Figure 4.

Laboratory and procedural timing analysis. AI, ablation index; TSP, transseptal puncture.

Procedural safety

Five major complications (1.6%, three false aneurysms and two venous access site bleedings with prolonged hospital stay but without blood transfusion) occurred with no difference in the frequency of occurrence among the study groups. No patient complained of dysphagia during the hospital stay, and there was no detection of an atrio-oesophageal fistula during the study period. No documentation or symptoms suggestive of PV stenosis occurred during the follow-up period.

Arrhythmia-free survival

The mean follow-up duration was 576 ± 262, 498 ± 216, and 477 ± 179 days for 30/35 W AI, 50 W AI, and 90 W/4 s groups, respectively. Arrhythmia recurrence was documented in 30 (29.4%, 30/35 W AI), 26 (25.5%, 50 W AI), and 26 patients (25.2%, 90 W/4 s; P = 0.75). Kaplan–Meier estimation of arrhythmia-free survival was 81.6 ± 3.9% (30/35 W AI), 79.3 ± 4.1% (50 W AI), and 80.4 ± 4.0% (90 W/4 s) after 12 months (log-rank P = 0.96; Figure 5). Repeat ablation was performed in 27 patients (12, 9, and 6 patients in 30/35 W AI, 50 W AI, and 90W/4 s groups, respectively). Recovery of electrical conduction to at least one PV was noted in 16 patients (8, 5, and 3 patients in 30/35 W AI, 50 W AI, and 90 W/4 s groups, respectively) without significant differences among the study groups (P = 0.78).

Figure 5.

Estimated arrhythmia-free survival after AF ablation. AI, ablation index; AF, atrial fibrillation.

Discussion

This is a single-centre study evaluating the effects on procedural efficacy, safety, and EP laboratory efficacy of various EP laboratory settings employing contemporary energy settings, contact force sensing catheters, and high-resolution mapping catheters. We discovered that using contemporary mapping catheters and energy settings combining shorter ablation duration with the higher energy application leads to considerably higher laboratory efficacy with equivalent procedure efficacy and safety.

High-power short-duration ablation

The concept of using higher power and shorter ablation duration derives from biophysical analysis of ablation lesions, which found that shorter ablations with high energy led to more shallow and broad lesions with a high proportion of resistivity instead of conductive heating.^7,8 In theory, HPSD ablation leads to effective applications targeting the myocardium without generating collateral damage.⁹ Ablation times should decrease due to shortened application durations as a side effect. The concept has been evaluated in several non-randomized^{3–5,10–14} and smaller randomized studies.¹⁵ Most studies found a high procedural efficacy without compromising procedural safety due to the occurrence of acute peri-procedural complications or mid-term events like atrio-oesophageal fistulas. A recent report found a higher incidence of PV stenosis when higher energy settings were utilized.¹⁶ This report may serve as a warning until new ablation protocols may be utilized before systematic assessment was performed. Kottmaier et al.¹⁰ investigated a 70 W 7/5 s protocol in 100 patients and found shorter procedure and ablation times without differences in the occurrence of peri-procedural complications. In this study, the mean ablation duration of 12 min was recorded for HPSD ablation. Chen et al.¹¹ investigated a 50 W AI-guided protocol, which resulted in the mean procedure duration of 55 min and the mean ablation duration of 11 min. The Fast and Furious-AF study investigated a 90 W/4 s protocol and had comparable results with 55 min procedure time and a mean of 5.6 min of ablation when compared with 105 and 26 min of procedure and ablation times, respectively, in a control group with 30/35 W guided by AI.⁴ Our findings are in line with previous studies, which investigated different protocols of HPSD ablation. We show for the first time the impact of three different energy settings, which were implemented in a comparable workflow, on arrhythmia-free survival. Our study did not find a significant difference in outcomes between patients treated with different energy settings.

A 12 month follow-up of the Fast and Furious-AF study found estimated arrhythmia-free survival in 78% of patients in a cohort with about 50% of patients suffering from persistent AF.¹⁷ Chen et al.¹⁸ reported on arrhythmia-free survival after 15 months in 85% (89% for paroxysmal and 80% for persistent AF). Kottmaier et al.¹⁰ reported on 83 and 65% of patients with paroxysmal AF treated with HPSD and conventional ablation after 1 year follow-up, respectively. Another study that investigated ablation with 40 and 35 W found arrhythmia-free survival in 87–90% of patients after 12 months.¹⁹

First-pass isolation rates vastly differ among available studies and are reported to be from 49 to 99% using different energy settings and ablation catheter technologies.^{4,10,11,14,20–23} In a study by Bortone et al., very HPSD utilizing 90 W ablation resulted in only 49% of patients with first-pass isolation.²¹ Studies using 40, 45, or 50 W under guidance of quality indices resulted in very high rates of first-pass isolation, which were 85–99%.^11,19,20 In our study, we found first-pass isolation in 66–70% of patients, which is relatively low when compared with most studies. Reasons for these disparities among studies are unknown and may be found in different ablation techniques with respect to lesion localization and size as well as with applied inter-lesion distance and contact force during ablation. Additionally, there is no clear definition of first-pass isolation, e.g. if life verification of isolation is needed or if ablation along the carina is allowed.

High-resolution intra-cardiac mapping

Intra-cardiac mapping during catheter ablation is usually performed utilizing specialized multi-polar diagnostic catheters. Besides traditional circular mapping catheters, which are widely adopted for PVI, novel catheters enable a higher mapping resolution and may allow for faster mapping due to optimized shape and function.^22–24 There is no systematic assessment of the impact of modern multi-electrode catheters on ablation outcomes yet. We found a decrease in mapping times previous to and after ablation steps when utilizing the pentaspline catheter without the increase in peri-procedural complications. Chen et al.¹¹ and Tilz et al.⁴ performed HPSD ablation without high-density FAM mapping. Importantly, patients investigated by Chen et al.¹¹ and Tilz et al.⁴ underwent PVI only without systematic assessment of low-voltage zones, which is in contrast to the approach used in our study.⁴ In our study, detailed remapping of the LA was performed in all patients to assess for low-voltage areas. Additionally, additional RA mapping was performed in most patients who underwent procedures with sheath visualization.

Evolution of an institutional workflow for atrial fibrillation ablation

We systematically assessed the incorporation of two important steps into our institutional AF ablation workflow. The first step was utilization of modern energy settings applying two different HPSD protocols with two different ablation catheters. Additionally, the traditional circular mapping catheter was replaced by a modern pentaspline multi-polar mapping catheter when higher energy settings were used. We found a significant decrease in total durations in which patients were present in the EP laboratory as well as a decrease in ‘skin-to-skin’ times when these changes were applied. Our systematic analysis revealed that two main drivers of procedure time shortening were decreased mapping times (mapping pre- and post-ablation) and shortened ablation times. This decrease in procedure times was accompanied by a significant decrease in radiation dosage and fluoroscopy times.

All above-mentioned studies found shortened procedure durations when implementing high energy ablation settings. Nevertheless, if shortened procedure duration was an effect of these changes in ablation workflows, the parallel impact of other factors such as an increase in overall operator experience or improvement in working processes was not systematically assessed in all studies. We show for the first time a systematic analysis of EP laboratory time intervals which assessed the effects of implementation of modern mapping catheters and HPSD ablation settings. Systematic assessment of laboratory time intervals can serve as an important tool for optimization of procedural workflows. A previous study by Berte et al.²⁵ showed that standardization of the workflow and analysis via a laboratory optimization tool may help to reduce procedure times and ablation times and increase procedure efficacy. In the light of high numbers of performed AF ablations annually worldwide and of economic constraints in the healthcare system, a highly effective and timely procedure is an important element in routine workflows of interventional procedures today.²⁶ Our study identified a reduction in the ablation time as a key parameter when a procedure duration reduction needs to be achieved. Nevertheless, improved efficacy comes to a higher cost of materials at the current timepoint at which advanced technologies need further adoption to the market.

Limitations

This is a prospective, non-randomized study with its typical limitations. Although there was no difference among patients’ baseline characteristics, a potential bias between the study groups cannot be excluded due to the non-randomized fashion of the study. Although all operators were experienced in catheter ablation before the start of the study period, effects of a learning curve cannot be excluded completely. A general unspecific increase in procedural efficacy alongside shorter procedure times unrelated to the technology may present a potential study bias. The patient number is too small to investigate the occurrence of atrio-oesophageal fistula. Additionally, no endoscopy was routinely performed after ablation procedures in patients undergoing HPSD ablation and silent oesophageal injury might be overseen. There were no routine investigations on silent cerebral embolisms in our study, and this complication may therefore be underreported.

Conclusions

The implementation of high-density multi-polar mapping catheters and HPSD ablation energy settings results in significant procedure shortening without affecting procedural efficacy and safety. Procedure duration shortening is a result of reduction in mapping and ablation time intervals.

Funding

None declared.

Data availability

Data are not shared openly but are available on reasonable request from the authors.