Outflow Tract Ventricular Arrhythmias Research Articles

Right ventricular outflow tract arrhythmias in patients with obstructive sleep apnea- electrophysiological insights

Abstract Background Obstructive sleep apnea (OSA) was associated with atrial fibrillation and heart failure. Furthermore, the arrhythmic sudden death during sleep in patients with OSA raises serious concerns. Non-ischemic ventricular arrhythmias arise frequently from the right ventricular outflow tract (RVOT). The involvement of obstructive sleep apnea in the genesis of arrhythmia (premature ventricular contraction or tachycardia) originating specifically in the RVOT is not yet coherently established. Purpose This study aims to demonstrate the possible relationship between untreated obstructive sleep apnea and the occurrence of RVOT arrhythmia and to follow the electrophysiological features and outcomes after radiofrequency catheter ablation (RFA) in patients carrying this double burden. Methods One-hundred-twelve (112) consecutive asymptomatic and symptomatic patients admitted with RVOT arrhythmia ((PVCs and VTs) underwent a sleep study (polysomnography). Apnea was set out as the cessation of breathing and hypopnea was defined as shallow, slow, and restricted breathing occurring in episodes of ten seconds or more. The patients had normal left and right ventricle ejection fractions and no structural cardiovascular disease or other known extracardiac arrhythmia predisposing conditions. No significantly elevated systolic pressure in the pulmonary artery was assessed at echocardiography. Every patient was investigated by electrophysiologic study (EPS) and RFA of the clinical ventricular arrhythmia was immediately performed. Practicing and former professional athletes were excluded. Results Seventy-eight (69 %) of the included patients had an apnea-hypopnea index > 10/h. The included patients had the following characteristics: mean age 52 ± 8 years, 62% males, 81% had a BMI >30kg/m². The cardiac electrophysiologic study did not induce sustained VTs. The distribution of the PVCs and non-sustained VTs evidenced a predilection for the superior, septal and anterior (68%) and also superior and anterolateral aspects of the RVOT (23%). Radiofrequency catheter ablation (RFA) guided by activation mapping, precocity (the site of earliest activation > 30 ms before the setting of the QRS complex) and pace-mapping were performed in all patients. Immediate success was obtained in 98 patients (88%). After a mean follow-up of 24± 6 months, 28 patients (28%) from the success arm had a recurrence of the PVCs or the non-sustained VTs, 22 patients (22%) with and 6 patients (6%) without sleep apnea. Conclusions RVOT arrhythmia genesis and relapse after successful RFA seem highly associated with sleep apnea. Furthermore, patients with sleep apnea are more prone to have recurrent arrhythmias after radiofrequency catheter ablation in the absence of appropriate control of OSA.

Safety and efficacy of ultra-long intermediate-power ablation for outflow tract ventricular arrhythmia arising from the left ventricular summit

Abstract Background Radiofrequency ablation (RFA) has been effective in managing premature ventricular contractions (PVCs). Despite improvement in ablation techniques, recurrence remains high for LV summit PVCs. Epicardial ablation here is often precluded due to fat and proximity to coronaries, thus, aggressive but safe endocardial options are needed. Purpose To evaluate the safety and effectiveness of ultra-long ablation (>240 seconds) duration for refractory LV summit PVCs. Methods Patients with deep intramural LV summit PVCs were identified by lack of PVC elimination or late (>60 s suppression) and recurrence post-lesion under the left aortic sinus of Valsalva. We included patients who received the longest RFA of at least 240 seconds (maximum 15 minutes). RFA power was titrated slowly from 20 to 35W, carefully ensuring that the impedance drop did not exceed 12 ohms. Acute procedure success was defined as clinical PVC suppression for ≥60 minutes after the last lesion. Short-term success was defined as symptom improvement, ejection fraction (EF) recovery, and drop in PVC burden at 3 months. Results Twenty patients (59.5 ± 16.4 years, 55% male) were included. Baseline features are shown in Table 1. All RFA were delivered endocardially. No steam pops were noted. PVC burden was significantly lower at 3-month follow-up (P< 0.01), Figure 1A. Most patients had a normal ejection fraction (EF) at baseline; thus, no significant difference change in EF was observed (Figure 1B). One complication was recorded, which was tamponade likely caused by coronary sinus dissection requiring pericardiocentesis. Acute success was achieved in 95.0% of the cases, and all cases followed at 3 months (18/18) achieved short-term success. Conclusion Ultra-long duration RFA with lesions ≥ 240 seconds at 35W per lesion for LV summit PVCs appeared to be safe and effective in achieving acute and short-term success. The lack of acute suppression should not discourage operators, as there seems to be delayed suppression in some cases. Careful monitoring of biophysics is paramount when attempting this technique.

Can the QRS morphology of outflow tract ventricular arrhythmia change when right bundle branch block emerges during sinus rhythm?

QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. Twenty-four patients (age 59±17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right-left cusp junction in two, and great cardiac vein in two. QRS-morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. There are some cases of OT-VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT-VA ablation, it does not necessarily mean that the origin or exit of the VA has changed.

A 3-Dimensional Ablation At Patient With Tachycardia Right Ventricular Outflow Track (RVOT) Origin: First Experienced in Saiful Anwar General Hospital Malang

Background: Premature ventricular complexes (PVCs) occur commonly in general population. It can occur in patient without structural heart disease as well as those with any form of cardiac disease. Commonly PVCs are asymptomatic, but in patients with frequent PVCs causing palpitations, syncope or dizziness, easily to fatigue, or shortness of breath. PVCs has been connected with a more than two-fold higher risk of cardiovascular events including stroke, mortality and also associated with arrhythmias or cardiomyopathy. Medications can be used to suppress PVCs but when drug therapy is ineffective, PVC ablation is reasonable to eliminate symptoms and treat or prevent PVC-induced cardiomyopathy. Case Presentation: A hypertension and menopause, 57-year-old woman, frequently complained about palpitation with shortness of breath, dizziness and sometimes near syncope since 2017, occurring both at rest and with mild activities. After serial examinations, found Frequent PVC (39%) with RVOT-Origin and reduced ejection fraction (EF 48%), then conclude with Suspect Tachycardia Induced cardiomyopathies. She performs cardiac electrophysiological study and continue with 3-Dimentional Ablation with Radiofrequency (RFA) at RVOT in Saiful Anwar Hospital, that is The First 3-Dimension Ablation in East Java. 1 year follow up shows no recurrency and successful to improve quality of life of the patient Discussion: According to guideline, catheter ablation is class I recommendation for patients with symptomatic outflow tract ventricular arrhythmias if medications are ineffective, not tolerated, or patient’s choose Conclusion: Three-Dimensional Ablation at patient with Right Ventricular Outflow Track Tachycardia, can successfully eliminate PVCs with no recurrency in 1 year follow-up.

Unfolding the transition ratio: insight into the diagnostic criteria for the diagnosis of the origin of outflow tract ventricular arrhythmias

Abstract Background algorithms for the diagnosis of the site of origin of ventricular outflow tract arrhythmias (OTVA) share the rationale that more posterior structures (LVOT) produce a greater vector approaching the precordial leads than anterior structures (RVOT), i.e. R waves in V1-V3 of greater amplitude and duration, a transition generally earlier than the QRS in sinus rhythm (SR), and vice-versa. Methods in a retrospective cohort of 45 patients (53.3% LVOT, 46.7% RVOT) with OTVA (left bundle branch block morphology, transition in lead V3, absence of conduction aberrancy in SR, who underwent successful catheter ablation were retrospectively analyzed, comparing the diagnostic yield of the main literature criteria. a) The V2 transition ratio, (TR) calculated with the formula [(R\R+S)PVC : (R\R+S)SR] (LVOT if > 0.6) [1]. b) The V1-V2 S-Rd, calculated as [(V1S + V2S) – (V1R + V2R)] (LVOT if < 1.625) [2]. c) The V2S\V3R amplitude ratio (LVOT if < 1.5) [3]. d) The transition zone index (TZI), obtained by subtracting the transition zone of the PVC with that of the SR (LVOT if < 0) [4]. We extended the use of these criteria to the precordial leads V1 to V3; for TR the equation was applied to amplitude as well as duration measurements. Results Comparison of PVC QRS morphology with that of SR. 1. The diagnostic accuracy of the TR showed incremental values moving from lead V1 to V3, both using amplitude and duration measurements; compared to the modest accuracy of the V2 TR (AUC 0.630, 0.727), the V3 TR (LVOT if > 1) showed an accuracy of 85.3% (AUC 0.804, 0.855). 2. Simplifying the complex TR equation, comparing R or S waves of the PVC with those of the SR, we again found incremental values of accuracy moving from lead V1 to V3, with better results for the SVT\SSR compared to the RVT\RRS; the V3 SVT\SRS) (LVOT if < 1) showed an accuracy of 86.6% (AUC 0.917). 3. The TZI showed in our series a lower diagnostic yield compared to that of the literature (AUC 0.748, accuracy 73.3%) Comparison of PVC QRS morphology between two contiguous leads: 4. Compared to the V1-V2 S-Rd (AUC 0.830), the V2-V3 S-Rd (AUC 0.855), calculated as [(V2S + V3S) – (V2R + V3R)] showed greater accuracy (82.2%). 5. Similarly, compared to the V1S\V2R amplitude ratio (AUC 0.774), the V2S\V3R (AUC 0.930) showed the greatest accuracy (88.8%, with a more balanced sensitivity and specificity moving the cut-off for the diagnosis of origin from LVOT to < 2), resulting the criterion with the highest diagnostic yield. Conclusions variables that compare the morphology of the QRS of the PVC of two contiguous leads have greater accuracy than those that compare the morphology of the QRS of the PVC with that of the SR, with greater diagnostic yield when applied from lead V1 to V3; the V2S\V3R ratio represents the best criterion, with high sensitivity, like the V3 transition ratio; the simple ratio (SVT\SSR) can virtually replace the more complex TR, with similar accuracy but high specificity.

Activation pattern of the coronary sinus facilitates the differentiation for ventricular outflow tract arrhythmias.

The accuracy of surface ECG algorithms for predicting the origin of outflow tract ventricular arrhythmias (OT-VAs) might be questioned. Intracardiac electrograms recorded at anatomic landmarks could provide new predictive insights. We aim to evaluate the efficacy of a novel criterion utilizing the activation pattern of the coronary sinus (CS) in localizing OT-VAs, including VAs originating from the right ventricular outflow tract (RVOT), endocardial left ventricular outflow tract (Endo-LVOT), and epicardial left ventricular outflow tract (Epi-LVOT). We measured the ventricular activation time of the mitral annulus (MA) from the onset of the earliest QRS complex of VAs to the initial deflection over the isoelectric line at local signals, namely the QRS-MA interval. The activation at 3 and 12 o'clock of the MA was recorded as the QRS-MA3 and QRS-MA12 intervals, respectively. Their predictive values were compared to previous ECG algorithms. A total of 68 patients with OT-VAs were enrolled (51 for development and 17 for validation). From early to late, the ventricular activation sequences at MA12 were as follows: Epi-LVOT, Endo-LVOT, and RVOT. In LBBB morphology OT-VAs, the QRS-MA12 interval was significantly earlier for LVOT origins than RVOT origins. In the combined cohort of development and validation cohort, a cut-off value of ≤10 ms predicted the LVOT origin with a sensitivity of 100% and specificity of 78%. The QRS-MA12 interval ≤ -24 ms additionally predicted epicardial LVOT sites of origin. The QRS-MA interval could accurately differentiate the OT-VAs localization.

Right ventricular scalloping index as cardiac magnetic resonance-derived marker for diagnosis of arrhythmogenic right ventricular cardiomyopathy.

The cardiac magnetic resonance (CMR) evaluation of right ventricular (RV) morphologic abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is subjective. Here, we aimed to use a quantitative index, the right ventricular scalloping index (RVSI), to standardize the measurement of RV free wall scalloping and aid in the imaging diagnosis. We retrospectively included 15 patients with definite ARVC and 45 age- and sex-matched patients with idiopathic right ventricular outflow tract ventricular arrhythmia (RVOT-VA) as controls. The RVSI was measured from cine images on four-chamber view to evaluate its ability to distinguish between ARVC and RVOT-VA patients. Other cardiac functional parameters including strain analysis were also performed. The RVSI was significantly higher in the ARVC than RVOT-VA group (1.56 ± 0.23 vs 1.30 ± 0.08, p < 0.001). The diagnostic performance of the RVSI was superior to the RV global longitudinal, circumferential, and radial strains, RV ejection fraction, and RV end-diastolic volume index. The RVSI demonstrated high intraobserver and interobserver reliability (intraclass correlation coefficient, 0.94 and 0.96, respectively). RVSI was a strong discriminator between ARVC and RVOT-VA patients (area under curve [AUC], 0.91; 95% CI, 0.82-0.99). A cutoff value of RVSI ≥1.49 provided an accuracy of 90.0%, specificity of 97.8%, sensitivity of 66.7%, positive predictive value (PPV) of 90.9%, and a negative predictive value (NPV) of 89.8%. In a multivariable analysis, a family history of ARVC or sudden cardiac death (odds ratio, 38.71; 95% CI, 1.48-1011.05; p = 0.028) and an RVSI ≥1.49 (odds ratio, 64.72; 95% CI, 4.58-914.63; p = 0.002) remained predictive of definite ARVC. RVSI is a quantitative method with good performance for the diagnosis of definite ARVC.

Automatic and interpretable prediction of the site of origin in outflow tract ventricular arrhythmias: machine learning integrating electrocardiograms and clinical data.

The treatment of outflow tract ventricular arrhythmias (OTVA) through radiofrequency ablation requires the precise identification of the site of origin (SOO). Pinpointing the SOO enhances the likelihood of a successful procedure, reducing intervention times and recurrence rates. Current clinical methods to identify the SOO are based on qualitative analysis of pre-operative electrocardiograms (ECG), heavily relying on physician's expertise. Although computational models and machine learning (ML) approaches have been proposed to assist OTVA procedures, they either consume substantial time, lack interpretability or do not use clinical information. Here, we propose an alternative strategy for automatically predicting the ventricular origin of OTVA patients using ML. Our objective was to classify ventricular (left/right) origin in the outflow tracts (LVOT and RVOT, respectively), integrating ECG and clinical data from each patient. Extending beyond differentiating ventricle origin, we explored specific SOO characterization. Utilizing four databases, we also trained supervised learning models on the QRS complexes of the ECGs, clinical data, and their combinations. The best model achieved an accuracy of 89%, highlighting the significance of precordial leads V1-V4, especially in the R/S transition and initiation of the QRS complex in V2. Unsupervised analysis revealed that some origins tended to group closer than others, e.g., right coronary cusp (RCC) with a less sparse group than the aortic cusp origins, suggesting identifiable patterns for specific SOOs.

Differentiating Origins of Outflow Tract Ventricular Arrhythmias: The Correction of Transitional Zone Index Is Not Superior to the Original One

Introduction: Our team once proposed a correction of transitional zone index (CTZI) based on the transitional zone index (TZI) in view of achieving a more precise prediction of outflow tract ventricular arrhythmia (OTVA). The predictive accuracy of these two electrocardiogram (ECG) algorithms has not been validated and compared. The purpose of this study was to compare the predictive accuracy of TZI and CTZI in a much larger population with idiopathic OTVA. Methods: The predictive accuracy of TZI and CTZI was compared in 695 individuals with idiopathic premature ventricular complex or ventricular tachycardia which exhibited a left bundle branch block pattern and inferior axis QRS morphology. Receiver operating characteristic curve analysis, decision curve analysis, and calibration curve were used to compare the predictive accuracy of TZI and CTZI. Results: TZI and CTZI manifested the similar area under the curve. While a TZI of <0 predicted a left ventricular outflow tract (LVOT) origin with a high specificity of 88.2% but a low sensitivity of 67.1%, a CTZI of <0 yielded a high sensitivity of 84.3% but a low specificity of 59.5% in the overall analysis. Similar results were yielded in the sub-analysis of participants with a precordial transition occurring at lead V3. In the sub-analysis of participants with a TZI = 0, CTZI demonstrated a bit higher but not satisfactory predictive accuracy than TZI. Conclusion: Based on the scientific spirit of self-criticism and seeking truth from facts, our team disproves the correction of TZI proposed previously.

Experience of left ventricular outflow tract arrhythmia ablation in paediatric patients using limited fluoroscopy and three-dimensional mapping technique.

The left ventricular outflow tract is an important source of ventricular arrhythmias. Up to one-third of all idiopathic ventricular arrhythmias in patients with structurally normal hearts may arise from this region. We would like to share the results of our left ventricular outflow tract ablation using three-dimensional mapping and limited fluoroscopy. This is a single-centre retrospective cohort study. Forty-six consecutive patients who underwent left ventricular outflow tract ablation procedures between January 2015 and June 2023 were included in the study. The EnSite Precision System (Abbott, St. Paul, MN, USA) was used to facilitate mapping and to reduce or eliminate the need for fluoroscopy. The study group comprised 29 males and 17 females, with a mean age of 13.4 ± 4.5 years. The most common location for arrhythmias was the left coronary cusp (n : 21). Other locations, in sequence, included the junction of the right and left coronary commissure (n : 10), right coronary cusp (n : 10), left ventricular outflow tract endocardium (n:4), aorto-mitral junction (n : 1), and great cardiac vein (n : 1). Nine of these patients had previously undergone unsuccessful right ventricular outflow tract ablation at another centre. Cryoablation was performed in three patients, irrigated radiofrequency ablation in three patients, and conventional radiofrequency ablation in the remaining patients. The acute success rate was 100%, and no recurrences were observed. The mean follow-up period was 49.6 ± 24.4 months. All patients were asymptomatic and were being followed without antiarrhythmic medication. Although left ventricular outflow tract ablations pose a risk for coronary artery and heart valve complications, they can be performed successfully and safely with the guidance of three-dimensional mapping.

A valuable electrophysiological insight to distinguish right from left outflow tract ventricular arrhythmia -local activation time in the anterior intraventricular vein and distal great cardiac vein-

Abstract Background Although several ECG criteria have been helpful to differentiate right from left outflow tract ventricular arrhythmias (OTVAs), discriminating OTVA origins especially with left bundle branch block (LBBB) is still considered challenging. Objective The aim of this study was to investigate the local activation time (LAT) in the anterior intraventricular vein (AIV) and distal great cardiac vein (d-GCV), and to identify an electrophysiological method of distinguishing right from left OTVAs. Methods We measured the LAT relative to the QRS onset of OTVAs in the AIV and d-GCV using a microelectrode with a lumen catheter in patients undergoing successful OT-VA ablation between January 2017 and July 2022 in our institution. The ECG parameters such as the V2 transition-ratio and V2S/V3R index to distinguish right-OT-VAs from left-OT-VAs with LBBB were also investigated. Results Local potentials at the AIV and/or d-GCV OTVA sites in 76 consecutive patients (mean age: 56.5±16.2 year-old, right-OTVAs:40, left-OTVAs:36) were analyzed. The LAT of the AIV/d-GCV was significantly shorter for right-OTVAs than left-OTVAs (d-GCV -26.7±26.8 vs. -2.7±21.4 msec, p&amp;lt;0.001, AIV -9.9±23.2 vs. 16.9±18.2 msec, p&amp;lt;0.001), and associated with the identification of right-OTVAs and left-OTVAs (AUC: d-GCV: 0.76 [95%CI 0.65-0.86], AIV: 0.81 [0.70-0.92]). Defining a LAT &amp;lt;0ms in the AIV (sensitivity: 0.74, specificity: 0.75), &amp;lt;-24ms in the d-GCV (sensitivity: 0.83, specificity: 0.60) as cutoff values respectively, the overall odds ratio (OR) increased more for right-OTVAs than left-OTVAs (OR; AIV: 6.7 [1.9-23.4], p=0.002, d-GCV: 7.5 [2.5-22.1], p&amp;lt;0.001). In the multivariate analysis, a LAT&amp;lt;-24ms in the d-GCV was revealed as an independent predictor certifying right-OTVA origins (OR 14.4 (2.1-95.1), p=0.006), which was superior to the V2 transition-ratio and V2S/V3R index. Conclusion The AIV/d-GCV activation time could outperform other previous ECG criteria to discriminate right-sided from left-OTVA ventricular arrhythmias with LBBB.

Clinical and prognostic significance of left ventricular dysfunction predictors in patients with ventricular ectopy and without structural heart disease

Aim. To determine the predictors of left ventricular dysfunction in patients with ventricular ectopic beats without structural heart disease.Material and Methods. We modeled ventricular ectopy in rats through early afterdepolarization (aconitine-induced arrhythmia) and delayed afterdepolarization (adrenaline arrhythmia). In addition, we modeled ventricular ectopy in rabbits and cats by delayed afterdepolarization (barium chloride-induced and strophanthin arrhythmias, respectively) and also modeled ventricular ectopy in dogs by re-entry hydrogen peroxide-induced arrhythmia. In addition to conventional electrocardiography parameters, we analyzed pre-ectopic interval, its variability, and the internal deviation index. Further, the study included 514 patients aged 16 to 34 years (mean 21.2 ± 0.2 years), and the number of premature ventricular contractions (PVCs) per day of observation ranged from 6,157 to 37,254 (mean 19,706 ± 656 PVCs). We registered the same parameters as in experimental arrhythmias but calculated them separately for mono- and polymorphic, left and right ventricular out-flow tract arrhythmias. The duration of follow-up of patients was up to 10 years. The endpoint was the detection or absence of cardiovascular and/or extracardiac pathology.Results. We recorded polymorphic PVCs and early monomorphic PVCs when modeling ventricular arrhythmias by the mechanism of delayed post-depolarization and early post-depolarization, respectively. Both early and late monomorphic PVCs were documented when inducing ventricular arrhythmias by re-entry. When modeling hydrogen peroxide-induced and strophanthin arrhythmias, we observed significantly higher values of PVC-QRS complex and ventricular arrhythmia internal deviation index in comparison with aconitine-induced arrhythmia. Favourable outcome was registered in 50.97% of patients, whilst coronary artery disease, arterial hypertension, and mitral valve prolapse were documented in 7.98%, 16.73% and 2.92% patients. The rest of the patients had gastrointestinal diseases. In patients with favourable outcome, the signs of monomorphic PVCs correlated with those revealed during the modeling of ventricular ectopy by early afterdepolarization (r = 0.92), whereas those signs of polymorphic PVCs correlated with those observed at barium chloride-induced delayed afterdepolarization (r = 0.94). In patients with CAD, signs of PVCs correlated with those registered during re-entry hydrogen peroxide-induced arrhythmia (r = 0.93), Finally, in patients with arterial hypertension and mitral valve prolapse signs of PVCs correlated with those documented at strophanthin-(r = 0.92) and adrenaline-induced delayed afterdepolarization (r = 0.89). In these patients, the values for both monomorphic and polymorphic PVCs, ventricular arrhythmia internal deviation index, duration of PVC-QRS complex and PVC-QRS/QRSaverage did not exceed 0.42 units, 149 ms and 1,44 units, respectively. The development of coronary artery disease and arterial hypertension well correlated with an increase in ventricular arrhythmia internal deviation index ≥ 0.56 units and QRS complex duration ≥ 157 ms. Mitral valve prolapse was associated with the duration of the QRS complex ≥ 159 ms of polymorphic PVCs.Conclusion. In patients with ventricular ectopy but without structural heart disease, an increase in the values of ventricular arrhythmia internal deviation index and the duration of PVC-QRS complex was ≥ 0.48 units and 149 ms, respectively, associated with the development of cardiovascular pathology. Development of coronary artery disease and hypertension correlated with ventricular arrhythmia internal deviation index ≥ 0.56 units, and QRS complex duration ≥ 157 ms in monomorphic and polymorphic PVCs, whereas development of mitral valve prolapse correlated QRS complex duration ≥ 159 ms in polymorphic PVCs.

A novel ECG algorithm to differentiate between ventricular arrhythmia from right versus left ventricular outflow tract.

The aim of this study was to evaluate the accuracy of the diagnostic criteria for determining the origin of outflow tract ventricular arrhythmia (OTVA) and develop an ECG algorithm to predict its origin. We analyzed the ECGs of 100 patients with OTVA who underwent successful ablation. The QRS complex was measured during sinus rhythm and ventricular arrhythmia. After the ECG algorithm was developed, it was validated in an additional 100 patients from two different hospitals. In this retrospective study, among the parameters without restrictions in the transition lead, the V2S/V3R index (AUC = 0.96) was significantly better in predicting ventricular arrhythmia originating from the right ventricular outflow tract (RVOT). Further, the larger initial r wave surface area (ISA) in V1 and V2 (AUC = 0.06) was significantly better in predicting ventricular arrhythmias originating from the left ventricular outflow tract (LVOT). Among the parameters with the transition lead in V3, the V2S/V3R index (AUC = 0.82) was significantly better in predicting VAs originating from the RVOT. On the contrary, the V3 R-wave deflection interval (AUC = 0.19) was significantly better in predicting ventricular arrhythmias originating from the LVOT. The algorithm combining the V2S/V3R index and the larger ISA in V1 and V2 could predict OTVA origin with an accuracy of 95.00%, a sensitivity of 87.18%, a specificity of 100.00%, a positive predictive value (PPV) of 100.00%, and a negative predictive value (NPV) of 92.42%. In the validation study, the algorithm exhibited excellent accuracy (95.00%) and AUC (AUC = 0.95), with a sensitivity of 94.12%, a specificity of 95.45%, a PPV of 91.43%, and an NPV of 96.92%. Our developed algorithm can reliably predict OTVA origin without restrictions in the transition lead.

Validation of a clinical model for predicting left versus right ventricular outflow tract origin of idiopathic ventricular arrhythmias.

Prediction of the chamber of origin in patients with outflow tract ventricular arrhythmias (OTVA) remains challenging. A clinical risk score based on age, sex and presence of hypertension was associated with a left ventricular outflow tract (LVOT) origin. We aimed to validate this clinical score to predict an LVOT origin in patients with OTVA. In a two-center observational cohort study, unselected patients undergoing catheter ablation (CA) for OTVA were enrolled. All procedures were performed using an electroanatomical mapping system. Successful ablation was defined as a ≥80% reduction of the initial overall PVC burden after 3 months of follow-up. Patients with unsuccessful ablation were excluded from this analysis. We included 187 consecutive patients with successful CA of idiopathic OTVA. Mean age was 52±15 years, 102 patients (55%) were female, and 74 (40%) suffered from hypertension. A LVOT origin was found in 64 patients (34%). A score incorporating age, sex and presence of hypertension reached 73% sensitivity and 67% specificity for a low (0-1) and high (2-3) score, to predict an LVOT origin. The combination of one ECG algorithm (V2 S/V3 R-index) with the clinical score resulted in a sensitivity and specificity of 81% and 70% for PVCs with R/S transition at V3 . The published clinical score yielded a lower sensitivity and specificity in our cohort. However, for PVCs with R/S transition at V3, the combination with an existing ECG algorithm can improve the predictability of LVOT origin.

Value of Electrocardiogram Algorithms Predicting Right Ventricular Outflow Tract Origin in the Era of Catheter Mapping

Background: The 12-lead electrocardiogram (ECG) is an extremely useful tool for analyzing cardiac arrhythmias and numerous ECG algorithms have been developed to predict the origin of right ventricular outflow tract (RVOT) arrhythmias. Aim: To determine if using complex, time-consuming analysis, and difficult-to-memorize ECG algorithms is feasible and preferable before the ablation procedure when compared with the use of multipolar mapping catheter use during the ablation procedure. Methods: 47 consecutive patients admitted for radiofrequency catheter ablation of idiopathic PVC were included prospectively in this study. Of the algorithms selected for comparison, three have a memorable design and easy applicability (Dixit, Joshi, Pytkowski) and the fourth has a complex, detailed design and is more difficult to memorize (Zhang). Results: The greatest accuracy was observed for the algorithms proposed by Dixit and Pytkowski – 92. 3%. However, when the algorithms were compared for their accuracy, specificity, and sensitivity, no significant differences were found (p=0. 96). Conclusions: 3-D guided mapping using a conventional ablation catheter in a narrower, precise area of interest in the RVOT, based on ECG algorithms is not inferior compared to the multielectrode catheter mapping in the whole RVOT, in terms of mapping time, total procedural time, and radiofrequency application time.

Commentary: A novel and effective ECG method to differentiate right from left ventricular outflow tract arrhythmias: angle-corrected V2S.

Commentary: A novel and effective ECG method to differentiate right from left ventricular outflow tract arrhythmias: angle-corrected V2S.

Anatomy of the Ventricular Outflow Tracts: An Electrophysiology Perspective.

Outflow tract ventricular arrhythmias are the most common type of idiopathic ventricular arrhythmia. A systematic understanding of the outflow tract anatomy improves procedural efficacy and enables electrophysiologists to anticipate and prevent complications. This review emphasizes the three-dimensional spatial relationships between the ventricular outflow tracts using seven anatomical principles. In turn, each principle is elaborated on from a clinical perspective relevant for the practicing electrophysiologist. The developmental anatomy of the outflow tracts is also discussed and reinforced with a clinical case.

Half versus normal saline irrigation during catheter ablation of outflow tract ventricular arrhythmias (HALF): a multi-center, parallel, open-label, randomized controlled study.

Animal studies demonstrated that deeper lesions could be achieved during radio-frequency catheter ablation (RFCA) by using half saline (HS) compared to normal saline (NS) as irrigation. This study sought to compare the efficiency and safety of HS and NS for irrigation during RFCA of idiopathic outflow tract ventricular arrhythmia (OT-VA). In this multicenter, randomized controlled study, 167 patients undergoing RFCA of OT-VA were randomized 1:1 to receive HS- or NS-irrigated ablation. Acute success was defined as the absence of induced targeted premature ventricular contraction (PVC) at the end of the procedure. The 6-month success was defined as a ≥ 80% reduction of pre-procedural PVC burden. There were no differences of baseline characteristics between the HS and NS group. Patients in HS group had shorter total ablation time (259.5 ± 155.5 S vs. 355.6 ± 230.7 S, P = 0.04) than that in NS group. The acute and 6-month success rates were similar between the HS and NS group (92.8 vs. 91.7%, P = 0.79; 90.9 vs. 92.1%, P = 0.79, respectively). No significant difference was observed in the incidence of steam pops between the HS and NS group (2.4 vs. 1.2%, P = 0.62). The ablation using HS irrigation achieved similar success rate and safety compared to that using NS irrigation but was associated with a shorter total ablation time. Chinese Clinical Trial Registry (ChiCTR2200059205).

PO-04-222 OUTFLOW TRACT VERSUS NON-OUTFLOW TRACT VENTRICULAR ARRHYTHMIAS IN ATHLETES: MYOCARDIAL SUBSTRATE AND LONG-TERM CLINICAL OUTCOMES

Outflow tract ventricular arrhythmias (OT-VA) are common in healthy subjects without structural heart disease (SHD), and are generally considered benign. However, athlete-specific data on the clinical meaning of different ventricular arrhythmia (VA) morphologies are scarce. To assess the prevalence of SHD as well as long-term clinical and sports medicine outcomes in a cohort of athletes with OT-VA undergoing a comprehensive diagnostic assessment, by comparing them with athletes with non-outflow tract VAs (nOT-VA). We conducted a multi-center, observational, retrospective study enrolling athletes who were referred because of complex VAs (>500 PVCs/24 h, exercise-induced VAs, nonsustained or sustained ventricular tachycardia). Athletes were categorized into two groups: OT-VA, in case of monomorphic ventricular arrhythmias of left bundle branch block and inferior axis morphology; nOT-VA, in case of polymorphic VAs or monomorphic VAs of right bundle branch block or left bundle branch block and superior/intermediate axis. The two co-primary outcomes were survival free from all-cause death or sustained VAs and sports practice at last follow-up. 175 athletes with complex ventricular arrhythmias (OT-VA,n=82; nOT-VA,n=93) were included in the present analysis; clinical characteristics are resumed in the Table. Remarkably, the prevalence of signs of SHD was higher in nOT-VA compared to OT-VA (Table). A final diagnosis of idiopathic VA was more common in OT-VA compared to nOT-VA and, accordingly, catheter ablation was more commonly performed in the former group. Over a median follow-up of 61(43-85) months, there were 2 cardiac arrests and 1 appropriate ICD shock, all occurring in athletes in the nOT-VA group with in vivo evidence of SHD and polymorphic VAs, for an overall prevalence of a primary outcome event of 0 and 3% in the OT-VA and the nOT-VA groups, respectively (p=0.25). At last follow-up, 31 athletes (18%) practiced competitive sports (OT-VA vs. nOT-VA,p=0.23), while 92 (53%) were leisure-time athletes (OT-VA vs. nOT-VA,p=0.91). Our data confirm that the prevalence of an underlying SHD substrate is lower in athletes with OT-VA than in athletes with nOT-VA, and that all major adverse cardiac events occurred in athletes with polymorphic VAs. Nevertheless, a comprehensive workup with liberal use of cardiac magnetic resonance allowed the identification of SHD in a substantial minority of athletes with OT-VA, with clear implications for sports eligibility assessment.

PO-04-169 DELAYED EFFECT OF CATHETER ABLATION FOR INTRAMURAL OUTFLOW TRACT VENTRICULAR ARRHYTHMIAS

Despite sequentially bilateral outflow tract catheter ablation, intramural septal outflow tract ventricular arrhythmia (OT-VA) can be clinically challenging. The outcome of intramural septal OT-VA without complete elimination after sequentially bilateral ablation remains unknown. We aimed to investigate the outcome of intramural septal OT-VA without complete elimination after sequentially bilateral catheter ablation. During 2008 to 2020, patients with intramural OT-VA undergoing sequentially bilateral ablation were recruited. ECG and electrophysiological parameters were analyzed. The intramural OT-VA was defined by one of the following: 1. Difference of activation time between right and left ventricular outflow tract < 20 ms; 2. Pacemapping at the earliest activation site could not yield 12/12 matched morphology; 3. Catheter ablation at the earliest activation site could not completely eliminate the ventricular arrhythmia. Partial success was defined by a > 80% reduction in ventricular arrhythmia burden immediately after ablation. Delayed resolution was defined by a ventricular arrhythmia burden persistently < 2% of total daily beats during follow-up. In total, 124 patients (76 men, age: 53.5 ± 14) with intramural OT-VA undergoing sequentially bilateral ablation were studied. Acute success, partial success, and failure were found in 85 (68.5%), 26 (21.0%), and 13 (10.5%) patients respectively. For the patients with partial success, after a median follow-up period of 17.4 months (25%-75%, interquartile range: 2.8-53.2), recurrence and delayed resolution were observed in 21 and 5 (19.2 %) patients, respectively. The delayed effect was observed within 3.0 (25%-75%, interquartile range: 1.9-10.6) months after ablation (Figure). Of 5 patients with delayed resolution, the ventricular arrhythmias were characterized by left bundle branch block morphology and dominantly precordial R/S transition at V3, and the activation time of ventricular arrhythmias at right ventricular outflow tract was earlier than those at left ventricular outflow tract. Despite partial success could be achieved immediately after bilateral ablation of intramural OT-VA, the recurrence rate was still high. Delayed resolution of intramural OT-VA could only be observed in 19.2% of patients and the majority of ventricular arrhythmia resolution was observed within 3 months after catheter ablation.