Spatial resolution of pace mapping of idiopathic ventricular tachycardia/ectopy originating in the right ventricular outflow tract

doi:10.1016/j.hrthm.2007.11.011

Heart Rhythm

Volume 5, Issue 3, March 2008, Pages 339-344

https://doi.org/10.1016/j.hrthm.2007.11.011 Get rights and content

Background

Pace mapping has been used to identify the site of origin of focal ventricular arrhythmias. The spatial resolution of pace mapping has not been adequately quantified using currently available three-dimensional mapping systems.

Objective

The purpose of this study was to determine the spatial resolution of pace mapping in patients with idiopathic ventricular tachycardia or premature ventricular contractions originating in the right ventricular outflow tract.

Methods

In 16 patients with idiopathic ventricular tachycardia/ectopy from the right ventricular outflow tract, comparisons and classifications of pace maps were performed by two observers (good pace map: match >10/12 leads; inadequate pace map: match ≤10/12 leads) and a customized MATLAB 6.0 program (assessing correlation coefficient and normalized root mean square of the difference (nRMSd) between test and template signals). With an electroanatomic mapping system, the correlation coefficient of each pace map was correlated with the distance between the pacing site and the effective ablation site. The endocardial area within the 10-ms activation isochrone was measured.

Results

The ablation procedure was effective in all patients. Sites with good pace maps had a higher correlation coefficient and lower nRMSd than sites with inadequate pace maps (correlation coefficient: 0.96 ± 0.03 vs 0.76 ± 0.18, P <.0001; nRMSd: 0.41 ± 0.16 vs 0.89 ± 0.39, P <.0001). Using receiver operating characteristic curves, appropriate cutoff values were >0.94 for correlation coefficient (sensitivity 81%, specificity 89%) and ≤0.54 for nRMSd (sensitivity 76%, specificity 80%). Good pace maps were located a mean of 7.3 ± 5.0 mm from the effective ablation site and had a mean activation time of −24 ± 7 ms. However, in 3 (18%) of 16 patients, the best pace map was inadequate at the effective ablation site, with an endocardial activation time at these sites of −25 ± 12 ms. Pace maps with correlation coefficient ≥0.94 were confined to an area of 1.8 ± 0.6 cm². The 10-ms isochrone measured 1.2 ± 0.7 cm².

Conclusion

The spatial resolution of a good pace map for targeting ventricular tachycardia/ectopy is 1.8 cm² in the right ventricular outflow tract and therefore is inferior to the spatial resolution of activation mapping as assessed by isochronal activation. In approximately 20% of patients, pace mapping is unreliable in identifying the site of origin, possibly due a deeper site of origin and preferential conduction via fibers connecting the focus to the endocardial surface.

Section snippets

Patient characteristics

The study consisted of 16 consecutive patients (10 men and 6 women; mean age 49 ± 11 years) referred for ablation of idiopathic PVCs (n = 13) or idiopathic VT (n = 3) found to be originating in the right ventricular outflow tract. All patients had normal left and right ventricular function as assessed by echocardiography. None of the patients had evidence of right ventricular dysplasia. The patients had been symptomatic with palpitations for 7 ± 12 years and had not responded to therapy with 2

Endocardial activation mapping

Activation mapping was performed at a mean of 54 ± 23 points per patient. Effective sites had a mean activation time of −24 ± 7 ms relative to the earliest onset of the QRS complex. During ablation of the targeted arrhythmia, 8 ± 7 radiofrequency lesions per patient were delivered. All patients underwent successful ablation of the targeted PVCs or VT. The mean area of the first 10-ms isochrone was 1.2 ± 0.7 cm² (range 0.4–3.5 cm²), with a mean circumference of 4.3 ± 1.4 cm (range 2.5–7.2 cm).

Discussion

The spatial resolution of a good pace map with a correlation coefficient ≥0.94 is 1.8 ± 0.6 cm². This is inferior to the spatial resolution of activation mapping, as indicated by the 10-ms isochrone that measured 1.2 ± 0.7 cm². In approximately 20% of patients, the accuracy of pace maps for identifying the site of origin was insufficient.

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Cited by (116)

Catheter Ablation of Ventricular Fibrillation
2022, Cardiac Electrophysiology Clinics
Ablation of multifocal premature ventricular contractions using automated pace-mapping software
2022, Revista Portuguesa de Cardiologia
Ablation of multifocal premature ventricular complexes (PVCs) is challenging. Activation mapping can be performed for the predominant morphology, but may be useless for other less prevalent ones. We aimed to describe the efficacy of an automated pace-mapping software-based ablation strategy for ablating the site of origin of multiple PVC locations.
Consecutive patients referred for ablation of multifocal PVCs were prospectively enrolled. Spontaneous PVC templates were recorded and a detailed pace-mapping map was generated to spot the site of origin of PVCs.
A total of 47 PVCs were targeted in 21 patients (five and 16 patients with three or two PVCs morphologies each, respectively). Detailed pace-mapping comprising 73.5±41.6 different pacing locations was performed (best matching 97.2% [IQR 95.9-98.3%] similar to the clinical PVC). Activation points were acquired if possible, although ablation was only based on pace-mapping in 13 (27.6%) foci. Complete acute procedural success was obtained in 14 (66.7%) patients, while one PVC morphology was deliberately not ablated in five patients (23.8%). After 12.3±9.4 months of follow-up, PVC burden decreased from 24.4±10.4% to 5.6±5.0% (p<0.001). Interestingly, patients with acute procedural failures or with some PVCs deliberately not targeted during the procedure also experienced a significant decrease in PVC burden (30.0±8.9% to 11.9±3.5%, p=0.002).
Quantitative morphology-matching software can be used to obtain a detailed map identifying the site of origin of each single PVC, and successful ablation can be performed at these sites, even if activation points cannot be obtained due to the paucity of ectopic beats.
A ablação de extrassístoles ventriculares (ESV) multifocais constitui um desafio. O mapeamento de ativação pode ser realizado para a morfologia predominante, podendo, no entanto, ser inútil nas morfologias menos predominantes. Pretendemos descrever a eficácia de uma estratégia de ablação baseada num software automático de pace-mapping para ablação do local de origem de múltiplas localizações de ESV.
Doentes consecutivos indicados para ablação das ESV multifocais foram incluídos prospetivamente. Foram gravados templates espontâneos de ESV e foi gerado um mapa detalhado de pace-mapping para detetar o local de origem das ESV.
Quarenta e sete ESV foram estudadas em 21 doentes (5 e 16 doentes com três morfologias e com duas morfologias de ESV, respetivamente). Foi concebido um mapa detalhado de pace-mapping compreendendo 73,5 ± 41,6 locais diferentes de pacing [melhor combinação 97,2% (IQR 95,9%-98,3%) semelhante à ESV clínica). Foram captados pontos de ativação, embora a ablação se tenha baseado apenas no pace-mapping em 13 focos (27,6%). Verificou-se um sucesso agudo completo do procedimento em 14 doentes (66,7%), embora uma morfologia de ESV não tenha sido deliberadamente intervencionada em 5 doentes (23,8%). Após 12,3±9,4 meses de seguimento, a carga de ESV diminuiu de 24,4±10,4% para 5,6±5,0% (p<0,001). Os doentes com insucesso agudo do procedimento ou com algumas ESV deliberadamente não intervencionadas durante o mesmo também sofreram uma diminuição significativa da carga de ESV (30,0±8,9% a 11,9±3,5%, p=0,002).
Um software quantitativo adequado à morfologia de ESV para obter um mapa detalhado com o seu local de origem pode ser utilizado, sendo a ablação bem-sucedida nestes locais, mesmo que não seja possível obter pontos de ativação devido à escassez de batimentos ectópicos.
Impact of a predefined pacemapping protocol use for ablation of infrequent premature ventricular complexes: A prospective, multicenter study
2021, Heart Rhythm
Pacemapping (PM) is a useful maneuver for aiding premature ventricular complex (PVC) ablation. Its standalone clinical value is still to be defined.
The purpose of this study was to analyze the efficacy of a predefined PM protocol for low-burden PVC ablation, regardless of their site of origin (SOO) and the presence of structural heart disease.
This was a prospective, nonrandomized, multicenter study. The PM protocol was performed when <1 PVC/min was found. The “target area” was delimited by the 3 best matching points >94% correlation, and 3 radiofreqency (RF) applications were delivered.
Of 185 patients, 105 (57%) underwent activation mapping, 60 (32%) were PM-guided, and 20 (11%) were canceled due to absence of PVCs. Baseline QRS, PVC burden, and outflow tract origin were independent predictors of PM-guided ablation. A higher proportion of right ventricular outflow tract SOO in the PM group (52% vs 40%; P = .03) was observed. Mean target area was 0.6 ± 0.9 cm². Mean 10-ms isochronal area in local activation time (LAT)-guided procedures was higher (1.7 ± 2.3 cm²; P <.001). Mean number of PM matching points acquired was 39 ± 21 (range 6–98). Mean mapping and RF times were similar in both groups. However, significantly shorter procedural (53 ± 24 vs 61 ± 26 minutes; P = .04) as well as RF times (111 ± 51 vs 149 ± 149 seconds; P = .05) were needed in the PM group using the proposed protocol. Global clinical success reached 87% for the PM group and 90% (P = .58) the for LAT mapping group.
When LAT mapping is precluded, application of a PM-guided ablation protocol directed to >94% matching correlation target area is a more efficient alternative with comparable clinical results.
Catheter ablation of idiopathic outflow tract ventricular arrhythmias with low intraprocedural burden guided by pace mapping
2021, Heart Rhythm O2
Citation Excerpt :
However, these differences could also be accounted for by the higher use of CF-sensing catheters in the PM group, with higher CF known to correlate with larger ablation lesions,13 and hence potentially the need for less ablation. PM has been shown to have a lower spatial resolution compared to activation mapping (pace map ≥0.94 correlation coefficient area: 1.8 ± 0.6 cm2 vs 10 ms isochronal activation area: 1.2 ± 0.7 cm2).3 The relatively high-density nature of our PM approach is important to define an area with high pace map correlation, which is bordered by progressively lower pace map sites.
There are limited data comparing ablation outcomes in patients with low intraprocedural burden of ventricular arrhythmias (VA) undergoing a pace mapping (PM)–guided strategy vs those with high burden guided by standard activation mapping strategy (non-PM).
We sought to determine if catheter ablation–guided by PM of low-intraprocedural-burden idiopathic outflow tract VA would be noninferior compared to non-PM-guided ablation.
Outcomes of catheter ablation of idiopathic outflow tract VA in 22 patients with a low burden of intraprocedural VA using PM-guided ablation were compared to 44 patients with a high burden of intraprocedural VA undergoing ablation using standard techniques.
Sixty-six patients were included (age 46.5 ± 14.8 years; 68% female, left ventricular ejection fraction 59% ± 5%). Within the PM group, 24-hour preprocedure premature ventricular complex (PVC) burden was 9.5% (interquartile range [IQR] 4%–13.8%), number of pace maps 33.6 ± 18.5, surface area of ≥95% pace map correlation 1.9 ± 1.2 cm², with best pace map correlation 96% (IQR 92%–97%). Within the non-PM group, 24-hour preprocedure PVC burden was 13.5% (IQR 6.6%–30%), earliest activation time -33.7 ± 9.9 ms. Procedural duration, general anesthesia administration, fluoroscopy dose, and complications were all comparable. Following final procedure, 24-hour VA burden (PM 0% [IQR 0–2.4%] vs non-PM 0% [IQR 0–4.2%], P = .98), along with VA-free survival at 6-month follow-up (PM 77% vs non-PM 71%, P = .77), were both comparable.
In patients with low intraprocedural burden of outflow tract VA, PM-guided catheter ablation can accurately identify the VA site of origin, leading to outcomes comparable to those achieved with standard ablation techniques.
Prospective Multicenter Assessment of a New Intraprocedural Automated System for Localizing Idiopathic Ventricular Arrhythmia Origins
2021, JACC: Clinical Electrophysiology
The objective of this study was to present a new system, the Automatic Arrhythmia Origin Localization (AAOL) system, which used incomplete electroanatomic mapping (EAM) for localization of idiopathic ventricular arrhythmia (IVA) origin on the patient-specific geometry of left ventricular, right ventricular, and neighboring vessels. The study assessed the accuracy of the system in localizing IVA source sites on cardiac structures where pace mapping is challenging.
An intraprocedural automated site of origin localization system was previously developed to identify the origin of early left ventricular activation by using 12-lead electrocardiograms (ECGs). However, it has limitations, as it could not identify the site of origin in the right ventricle and relied on acquiring a complete EAM.
Twenty patients undergoing IVA catheter ablation had a 12-lead ECG recorded during clinical arrhythmia and during pacing at various locations identified on EAM geometries. The new system combined 3-lead (III, V₂, and V₆) 120-ms QRS integrals and patient-specific EAM geometry with pace mapping to predict the site of earliest ventricular activation. The predicted site was projected onto EAM geometry.
Twenty-three IVA origin sites were clinically identified by activation mapping and/or pace mapping (8, right ventricle; 15, left ventricle, including 8 from the posteromedial papillary muscle, 2 from the aortic root, and 1 from the distal coronary sinus). The new system achieved a mean localization accuracy of 3.6 mm for the 23 mapped IVAs.
The new intraprocedural AAOL system achieved accurate localization of IVA origin in ventricles and neighboring vessels, which could facilitate ablation procedures for patients with IVAs.
Modified Precordial Lead R-Wave Deflection Interval Predicts Left- and Right-Sided Idiopathic Outflow Tract Ventricular Arrhythmias
2020, JACC: Clinical Electrophysiology
This study evaluated if modifying electrocardiographic (ECG) precordial leads to a higher intercostal position improved the accuracy of outflow tract ventricular arrhythmia (OTVA) localization.
Precordial ECG prediction algorithms that use a standard lead configuration localize OTVA with variable accuracy.
Patients who underwent OTVA ablation were prospectively enrolled to have a standard and modified (high) precordial ECG. R- and S-wave amplitudes and intervals were measured to develop an algorithm that differentiated the right ventricular outflow tract (RVOT) and the left ventricular outflow tract (LVOT) with high accuracy—the modified lead R-wave deflection interval (RWDI). This interval was defined from the earliest QRS onset (using all modified leads) to the lead with longest R-wave deflection. The RWDI was compared with all other ECG algorithms.
A total of 50 patients (38 women; mean age 51 ± 17 years) had successful catheter ablation for OTVA (RVOT 60%, LVOT 40%). The modified lead RWDI was significantly shorter in the RVOT group (18.5 ms, interquartile range 25th to 75th percentile [IQR₂₅₋₇₅]: 0 to 29.5 ms) compared with the LVOT group (67.5 ms, IQR₂₅₋₇₅: 56.5 to 77 ms; p < 0.05). Using a RWDI ≤40 ms to predict an RVOT focus, the sensitivity and specificity of the modified lead RWDI were 100% and 95%, respectively; the area under the receiver-operating characteristic curve was 0.96. This was superior to all previously developed algorithms. In a computed tomography analysis (n = 50), the modified leads were significantly closer to the outflow tracts compared with the standard precordial leads.
The modified lead RWDI is a simple, easily interpretable algorithm that can potentially differentiate a right- or left-sided origin of OTVA with high accuracy.

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: Drs. Morady and Oral served as consultants to Biosense Webster.

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Original-clinicalSpatial resolution of pace mapping of idiopathic ventricular tachycardia/ectopy originating in the right ventricular outflow tract

Background

Objective

Methods

Results

Conclusion

Section snippets

Patient characteristics

Endocardial activation mapping

Discussion

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

Am J Cardiol

Original-clinical
Spatial resolution of pace mapping of idiopathic ventricular tachycardia/ectopy originating in the right ventricular outflow tract