Idiopathic Outflow Tract Ventricular Arrhythmias Research Articles

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.

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).

Percutaneous Epicardial Ablation of Ventricular Arrhythmias Arising from the Left Ventricular Summit.

The left ventricular summit (LVS) is the highest point of the left ventricular epicardium, and ventricular arrhythmias originating from this area accounts for 10% to 15% of idiopathic outflow tract ventricular arrhythmias. Direct epicardial ablation of outflow tract ventricular arrhythmias arising from the LVS is successful only in a minority of patients because of close proximity to the coronary artery or thick epicardial fat. Therefore, alternative strategies should be prioritized before performing epicardial approach. When performed, electrocardiogram characteristics suggestive of the site of origin to be the accessible area within the LVS needs be evaluated to avoid ineffective epicardial approach.

Usefulness of the over-the-wire microelectrodes catheter in treatment of ventricular arrhythmia arising from the left ventricular summit.

This study was aimed to investigate the efficacy of the over-the-wire (OTW) microelectrodes catheter in coronary venous system (CVS) mapping and treatment of outflow tract ventricular arrhythmia (OTVA) arising from the vicinity of the left ventricular summit (LVS). Consecutive 62 patients with idiopathic OTVA in whom the OTW microelectrodes catheter was routinely used for CVS mapping were analyzed. CVS mapping was performed for both main trunk (from great cardiac vein to anterior interventricular vein) and branches including the annular branch or septal branch. The earliest activation site (EAS) was within the CVS in 21 patients. Among them, the EAS was within the main trunk of the CVS in seven (33%) and within the branch of the CVS in 14 (67%) patients. Radiofrequency catheter ablation was started at an anatomically adjacent site to the EAS, which eliminated OTVA in 16 (76%) patients　(the endocardial LVOT in 10 and the aortic sinus of Valsalva in six patients). For the remaining five patients with unsuccessful catheter ablation at an anatomically adjacent site, targeted OTVA was eliminated by catheter ablation at the EAS within the CVS in two patients and by chemical ablation with ethanol injection in one patient, resulting in the overall success rate of 90% (19/21). The OTW microelectrodes-guided ablation of OTVA from the vicinity of the LVS was effective. In maximizing the efficacy of ablation, CVS branch mapping is important since the earliest activation was commonly recorded not in the main trunk but within the branch of the CVS.

Modern mapping and ablation of idiopathic outflow tract ventricular arrhythmias.

Outflow tract (OT) premature ventricular complexes (PVCs) are being recognized as a common and often troubling, clinical electrocardiographic finding. The OT areas consist of the Right Ventricular Outflow Tract (RVOT), the Left Ventricular Outflow Tract (LVOT), the Aortomitral Continuity (AMC), the aortic cusps and the Left Ventricular (LV) summit. By definition, all OT PVCs will exhibit an inferior QRS axis, defined as positive net forces in leads II, III and aVF. Activation mapping using the contemporary 3D mapping systems followed by pace mapping is the cornerstone strategy of every ablation procedure in these patients. In this mini review we discuss in brief all the modern mapping and ablation modalities for successful elimination of OT PVCs, along with the potential advantages and disadvantages of each ablation technique.

Catheter ablation of idiopathic outflow tract ventricular arrhythmias with low intraprocedural burden guided by pace mapping.

BackgroundThere 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).ObjectiveWe 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.MethodsOutcomes 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.ResultsSixty-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.ConclusionIn 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.

Earliest activation time is a good predictor of successful ablation of idiopathic outflow tract ventricular arrhythmias

BackgroundIn idiopathic outflow tract ventricular arrhythmias (OT‐VAs), identifying the site with the earliest activation time (EAT) using activation mapping is critical to eliminating the arrhythmogenic focus. However, the optimal EAT for predicting successful radiofrequency catheter ablation (RFCA) has not been established.HypothesisTo evaluate the association between EAT and successful RFCA in idiopathic OT‐VAs and to determine the optimal cut‐off value of EAT for successful ablation.MethodsWe retrospectively analyzed patients undergoing RFCA for idiopathic OT‐VAs at a single center from January 2015 to December 2019.ResultsAcute procedural success was achieved in 168 patients (87.0%). Among these patients, 158 patients (81.9%) were classified in the clinical success group according to the recurrence of clinical VAs during median (Q1, Q3) follow‐up (330 days [182, 808]). EAT was significantly earlier in the clinical success group compared with the recurrence (p = .006) and initial failure (p < .0001) groups. The optimal EAT cut‐off value predicting clinical success was −30 ms in the right ventricular outflow tract (RVOT) with 77.4% sensitivity and 96.4% specificity. In all cases of successful ablation in the left ventricular outflow tract (LVOT), EAT in the RVOT was not earlier than −29 ms.ConclusionsEAT in patients with successful catheter ablation was significantly earlier than that in patients with recurrence and initial failure. EAT earlier than −30 ms could be used as a key predictor of successful catheter ablation as well as an indicator of the need to shift focus from the RVOT to the LVOT.

Prevalence and prognostic value of left ventricular late gadolinium enhancement in patients with idiopathic outflow tract ventricular arrhythmias

Abstract Background Patients with idiopathic outflow tract ventricular arrhythmias (OTVAs) and structurally normal heart by ECG and echocardiogram often undergo cardiac magnetic resonance (CMR) study to evaluate for presence of concealed myocardial abnormalities with late gadolinium enhancement (LGE). However, the clinical impact of incidental LGE finding in the left ventricle (LV) in patients with idiopathic OT-VAs is unclear. Accordingly, the aim of the present study was to investigate the prevalence, characteristics and prognostic significance of isolated LV LGE in a large population of patients with OTVA undergoing CMR. Methods A total of 364 consecutive patients (43±16 years, 53% male) with OTVA and negative routine diagnostic work-up were included. All patients underwent a CMR study with LGE imaging for detection of scar/replacement fibrosis. Presence of LGE was correlated with long term major adverse cardiovascular events including sudden cardiac death (SCD), resuscitated cardiac arrest and nonfatal documented sustained ventricular tachycardia. Results Isolated LGE in the LV was identified in 15 patients (4%), typically involving the inferolateral wall (11 cases, 73%) and having a median extension of 3 (2–5)% of the LV mass. All cases showed a midmyocardial/subepicardial distribution consistent with a possible prior myocarditis. Patients with incidental finding of LV-LGE were older (55±13 years vs. 42±16 years; p&amp;lt;0.01) and were more frequently males (80% vs. 51%; p=0.03). After a median follow-up of 69 (47–98) months, none of the patients in the LV-LGE group and 1 patient (0.3%) in the non-LGE group (p=1.0) experienced the composite end-point which consisted in an episode of sustained VT with hypotension and dizziness. The patient subsequently underwent effective radiofrequency ablation of the VT from the right ventricular outflow tract. Conclusion In this large CMR study, isolated LV scar was found in 4% of patients with idiopathic OT-VAs, was small in size with distribution consistent with prior myocarditis. The LGE abnormality did not portend a negative prognosis. Funding Acknowledgement Type of funding source: None

A Simplified Two-Stepwise Electrocardiographic Algorithm to Distinguish Left from Right Ventricular Outflow Tract Tachycardia Origin

Background: There are several electrocardiographic algorithms to predict the origin of idiopathic outflow tract ventricular arrhythmias (OT-VAs). This study aimed to develop a more accurate and efficient stepwise electrocardiographic algorithm to discriminate left ventricular outflow tract (LVOT) from right ventricular outflow tract (RVOT) origin. Methods and Results: We analyzed 12-lead electrocardiographic characteristics of 173 consecutive OT-VAs patients who underwent successful radiofrequency catheter ablation in the RVOT (n = 124) or LVOT (n = 49). Based on the areas under the receiver operating characteristic curves, the combination of transitional zone (TZ) index <0 and V2S/V3R index ≤1.5 exhibited 93.5% sensitivity, 85.9% specificity, and 87.3% accuracy. A further analysis was performed in the 71 OT-VAs with a V3-lead precordial transition. The sensitivity, specificity, and accuracy of the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms were 91.7, 83.1, and 85.9%, respectively. In the prospective evaluation, the combination of TZ index and V2S/V3R index could identify the correct origin sites with 91.2% accuracy in the overall analysis, and the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms exhibited 94% accuracy in V3-lead precordial transition. Conclusions: The combination of TZ index <0 and V2S/V3R index ≤1.5 is a simple and efficient stepwise electrocardiographic algorithm for predicting LVOT origin. For the OT-VAs with a V3-lead precordial transition, the integration of V2S/V3R index ≤1.5 and R-wave deflection interval in lead V3 >80 ms would be a better choice.

The aortic cusps are the predominant successful ablation site of idiopathic outflow-tract ventricular arrhythmias

BackgroundData regarding the successful ablation site of idiopathic outflow tract (OT) ventricular arrhythmias (VAs) in the modern era of mapping and ablation are limited. Methods and resultsOver a 4-year period, a total of 309 patients underwent detailed activation mapping of OT VAs including the right ventricular outflow tract (RVOT), the left ventricular outflow tract (LVOT) and the aortic cusps (AC), and the coronary venous system. 244 cases were successfully ablated at the index procedure (78.9%). The successful ablation site was more frequently located at the LVOT/ACs (51.6%) followed by RVOT (36.2%). In particular, the ACs was the predominant successful ablation site of idiopathic OT VAs (46.7%). An epicardial site of origin was predictor of ablation failure (p < 0.05). ConclusionsThe ACs is the predominant successful ablation site of idiopathic OT VAs. Take-home messageThe aortic cusps are the predominant successful ablation site of idiopathic idiopathic outflow tract ventricular arrhythmias.

236 Modified High Precordial Lead R-Wave Deflection Interval Accurately Predicts Left and Right-Sided Idiopathic Outflow Tract Ventricular Arrhythmias

Electrocardiogram (ECG) prediction algorithms for outflow tract ventricular arrhythmias (OTVA) using standard precordial lead configuration localise OTVA with variable accuracy. We evaluated if modifying ECG precordial leads to a higher intercostal position improved the accuracy of OTVA localisation. Patients undergoing OTVA catheter ablation were prospectively enrolled. Multiple indices were measured to develop an algorithm that differentiated RVOT and LVOT with high accuracy: the modified lead R-wave deflection interval (RWDI). The accuracy of the RWDI was compared to all ECG algorithms using a standard precordial ECG position. Finally, prospective validation of the modified lead RWDI was performed. 40 patients (31 females, mean age 51±18 years) had a successful catheter ablation for OTVA (RVOT 60%, LVOT 40%). The modified lead RWDI was significantly shorter in the RVOT group compared to the LVOT group (16.7±13.4ms vs 66.8±14.4ms, p<0.0005). Using a RWDI <40ms to predict a RVOT focus, the sensitivity and specificity of the modified lead RWDI were both 100% and area under the receiver operator characteristic curve was 1. This was superior to all previously published algorithms. In the validation cohort (n=16 patients), the sensitivity and specificity of the modified lead RWDI was 88% and 75%, respectively. In 2 patients with a failed RVOT ablation, the modified lead RWDI was >40ms, indicating a LVOT focus. The modified lead RWDI is a simple, easily interpretable algorithm that can differentiate a right or left-sided origin of OTVA with high accuracy.

Mapping and Ablation of Arrhythmias from Uncommon Sites (Aortic Cusp, Pulmonary Artery, and Left Ventricular Summit).

Despite advances in our understanding of the relevant anatomy and mapping and catheter ablation techniques of idiopathic outflow tract ventricular arrhythmias, challenging sites for catheter ablation remain the aortic cusps, pulmonary artery, and notably the left ventricular summit. A systematic approach should be used to direct mapping efforts efficiently between endocardial, coronary venous, and epicardial sites. Foci at the left ventricular summit, particularly intraseptal and at the inaccessible epicardial region, remain difficult to reach and when percutaneous techniques fail, surgical ablation remains an option but with risk of late coronary artery stenosis.

Trends in Successful Ablation Sites and Outcomes of Ablation for Idiopathic Outflow Tract Ventricular Arrhythmias

This study sought to examine clinical characteristics of procedural and long-term outcomes in patients undergoing catheter ablation (CA) of outflow tract ventricular arrhythmias (OT-VAs) over 16 years. CA is an effective treatment strategy for OT-VAs. Patients undergoing CA for OT-VAs from 1999 to 2015 were divided into 3 periods: 1999 to 2004 (early), 2005 to 2010 (middle), and 2011 to 2015 (recent). Successful ablation site (right ventricular OT, aortic cusps/left ventricular OT, or coronary venous system/epicardium), VA morphology (right bundle branch block or left bundle branch block), and acute and clinical success rates were assessed. Six hundred eighty-two patients (336 female) were included (early: n=97; middle: n=204; recent: n=381). Over time there was increase in use of irrigated ablation catheters and electroanatomic mapping, and more VAs were ablated from the aortic cusp/left ventricular OT or coronary venous system/epicardium (14% vs. 45% vs. 56%; p<0.0001). Acute procedural success was achieved in 585 patients (86%) and was similar between groups (82% vs. 84% vs. 88%; p=0.27). Clinical success was also similar between groups (86% vs. 87% vs. 88%; p=0.94), but more patients in earlier periods required repeat ablation (18% vs. 17% vs. 9%; p=0.02). Overall complication rate was 2% (similar between groups). Over a 16-year period there was an increase in patients undergoing CA for OT-VTs, with more ablations performed at non-right ventricular outflow tract locations using electroanatomic mapping and irrigated-tip catheters. Over time, single procedure success has improved and complications have remained limited.

Electrocardiographic features, mapping and ablation of idiopathic outflow tract ventricular arrhythmias.

Idiopathic outflow tract ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. These arrhythmias have focal origin and display characteristic electrocardiographic features. The purpose of this article is to review the state of the art of diagnosis and treatment of idiopathic outflow tract ventricular arrhythmias. We systematically reviewed scientific literature about idiopathic outflow tract ventricular arrhythmias selecting the most relevant papers on this topic. The right ventricle outflow tract is the most common site of origin for outflow tract ventricular arrhythmias, but also left ventricle outflow tract can harbour these arrhythmias. Outflow tract ventricular arrhythmias are generally benign and may require treatment if they are symptomatic, incessant or give rise to cardiomyopathy. Radiofrequency catheter ablation is an effective and safe therapeutic strategy. A successful procedure requires a thorough preoperative analysis of the 12-lead electrocardiogram of the spontaneous arrhythmia combined with a detailed electroanatomical mapping and intracardiac echocardiography. Idiopathic outflow tract arrhythmias are frequent in daily clinical practice and can be successfully eliminated through discrete radiofrequency catheter ablation with low rates of complications.

P3750Efficiency of electrocardiographic algorithms in management of idiopathic outflow tract ventricular arrhythmias in children

Abstract Introduction Ablation of idiopathic ventricular arrhythmias (IVA) originating in left ventricle outflow tract (LVOT) are more challenging as compared to right ventricle outflow tract (RVOT). In recent years, several ECG algorithms predicting the site of origin (SOO) of arrhythmia for adult population have been published. There is a sparse information on their diagnostic performance in children. Purpose The aim of this study was to validate two algorithms: 1) Novel TZ index, 2) V2S/V3R and their combined application in children for predicting the appropriate SOO of IVA. Methods Two groups of children without structural heart disease, thorax anomalies and normal QRS complexes during sinus rhythm were included in the study: 1) patients with IVA with inferior axis who underwent successful RFCA using the 3D-electroanatomical system, 2) patients with paced or mechanically-induced QRS complexes from LVOT or RVOT during other procedures. ECGs were analyzed in a specially developed software for analyzing the amplitude of the QRS complex waves. Semi-automated measurements of amplitudes of QRS complexes and calculations were carried out for 2 published algorithms: 1) Novel TZ index, 2) V2S/V3R. The results of their separate and combined use were compared with SOO of acute successful RFCA and mapping or spot of pacing. Results 108 PVC morphologies (68 from the RVOT and 40 from LVOT) from 74 pediatric patients (age: 14.0±2.9, 39 female) were included into the study. The algorithm V2S/V3R predicted left-sided SOO with a sensitivity and specificity of 94%. Novel TZ-index showed sensitivity of 89% and specificity of 84%. Combined use of Novel TZ-index+V2S/V3R showed high sensitivity (92%) and very height specificity (97%) of the LVOT SOO prediction Conclusion Both algorithms allowed accurate, simple and precise identification of SOO of RVOT/LVOT IVA in children. The combined use of those algorithms may facilitate additional pharmacologic treatment, omitting RVOT mapping with direct mapping LVOT, performance of the procedure by experienced operator.

Clinical efficacy of open-irrigated electrode cooled with half-normal saline for initially failed radiofrequency ablation of idiopathic outflow tract ventricular arrhythmias.

Acute failure of radiofrequency ablation (RFA) of ventricular arrhythmias (VAs) occur in 10%-20% of patients and is partly attributed to inadequate lesion depth acquired with standard ablation protocols. Half-normal saline (HNS)-irrigation is a promising strategy to improve the success rate of VA ablation. This study investigated the efficacy of HNS-irrigated ablation after a failed standard plain normal saline solution (PNSS)-irrigated ablation on idiopathic outflow tract ventricular arrhythmia (OT-VA). This is a prospective observational study of consecutive patients undergoing RFA of idiopathic OT-VA comparing the efficacy of additional HNS-irrigated ablation for failed standard PNSS-irrigated ablation. Acute failure was defined as persistence of spontaneous VA or persistent inducibility of the clinical VA. Out of 160 OT-VA cases (51 ± 15-year-old, 62 males), 31 underwent HNS irrigation after a failed standard PNSS-irrigated ablation. The HNS group had a significantly longer procedure time (60.06 ± 43.83 vs 37.51 ± 33.40 minutes; P = .013) and higher radiation exposure (31.45 ± 20.24 vs 17.22 ± 15.25 minutes; P = .001) than the PNSS group but provided an additional acute success in 21 of 31 (67.7%) patients. Over a follow-up duration of 7.8 ± 4.6 months, 24 recurrences were identified, including 8 (25.8%) in the HNS and 16 (12.4%) in the PNSS group, with lower freedom from recurrence in the HNS group (log rank P = .009). No major complication was observed. HNS-irrigated ablation after failed standard PNSS-irrigated ablation is safe and additionally improves acute ablation success by 67.7% for idiopathic OT-VA but with a higher rate of recurrence on follow-up. Whether the application of HNS as initial irrigant could result in better outcome requires further investigation.

Idiopathic Outflow Tract Ventricular Arrhythmia Ablation: Pearls and Pitfalls.

Idiopathic outflow tract ventricular arrhythmias (VAs) occur typically in patients without structural heart disease. They are often symptomatic and can sometimes lead to left ventricular systolic dysfunction. Both activation and pace mapping are utilised for successful ablation of these arrhythmias. Pace mapping is particularly helpful when the VA is infrequent and/or cannot be elucidated during the ablation procedure. VAs originating from different sites in the outflow tract region have distinct QRS patterns on the 12-lead ECG and careful analysis of the latter can help predict the site of origin of these arrhythmias. Successful ablation of these VAs requires understanding of the detailed anatomy of the OT region, which can be accomplished through electroanatomic mapping tools and intracardiac echocardiography.

QRS morphology shift following catheter ablation of idiopathic outflow tract ventricular arrhythmias: Prevalence, mapping features, and ablation outcomes.

In patients with monomorphic idiopathic outflow tract ventricular arrhythmias (OT-VAs), catheter ablation (CA) at the earliest activation site can result in a shift in QRS morphology indicating a change in the activation patterns. This study aimed to investigate the prevalence, mapping features, and ablation outcomes of OT-VAs displaying a QRS morphology shift following CA. We retrospectively analyzed 446 patients with monomorphic OT-VAs. A QRS morphology shift following CA was observed in 17 (4%) patients. Initially, the earliest activation site was within the right ventricular outflow tract (RVOT) in one (6%) patient, the left ventricular outflow tract (LVOT) in 10 (59%) patients (left coronary cusp/right coronary cusp junction in seven patients and LVOT endocardium in three patients), and within the distal coronary venous system in six (35%) patients. The VA was suppressed in all 17 patients, but VA recurrence with a different QRS morphology was observed after a waiting period. The recurrent VA was remapped in all patients and was eliminated targeting the new earliest site in 15 (88%) cases. In 11 of 15 successful cases, the ablation site for the recurrent VA shifted to an anatomical structure distinct from but adjacent to the initial site. In the remaining four patients, the recurrent VA was eliminated within the same anatomical structure. In patients with idiopathic OT-VAs, a QRS morphology shift following CA can be observed in 4% of the cases. In these cases, detailed remapping is necessary since the successful ablation site for the VAs with altered QRS morphology shifts to different anatomical structures in most patients.

GW29-e1352 Unipolar electrogram based quantitative criteria improves specificity for predicting arrhythmogenic site in focal idiopathic outflow tract ventricular arrhythmia mapping and ablation

GW29-e1352 Unipolar electrogram based quantitative criteria improves specificity for predicting arrhythmogenic site in focal idiopathic outflow tract ventricular arrhythmia mapping and ablation

Predictive value of unipolar and bipolar electrograms in idiopathic outflow tract ventricular arrhythmia mapping and ablation.

Radiofrequency catheter ablation is an effective therapy for focal idiopathic outflow tract ventricular arrhythmia (OTVA). However, visual inspection of the unipolar electrogram (EGM) QS morphology is subjective with a poor specificity for predicting successful ablation sites. This study aims to evaluate the predictive value of unipolar and bipolar EGMs in OTVA mapping and ablation. Twenty-two patients scheduled for idiopathic OTVA ablation were prospectively enrolled. During the procedure, unipolar and bipolar EGMs were recorded simultaneously and visually inspected by the operator to identify their values for predicting arrhythmogenic sites. Quantitative features of the unipolar EGM including the ratio of amplitude of the first positive peak versus the nadir (R-ratio), the maximum descending slope (MaxSlope), and the time interval between the initial deflection point to the MaxSlope (D-Max) were calculated for each target site in offline analysis. EGMs from 100 sites were collected in 20 patients and analyzed. The bipolar reverse polarity characteristic was not as practical for identifying successful ablation site as the unipolar QS characteristic. Successful ablation sites demonstrated smaller R-ratio and shorter D-Max than unsuccessful sites, but no significant difference in MaxSlope. A unipolar EGM-derived quantitative criterion provided significantly better specificity (0.70) than visual inspection (0.37) without compromising on the sensitivity (0.83vs. 0.89). The bipolar reverse polarity characteristic was not a practical method for identifying target in idiopathic OTVA ablation. The unipolar EGM-derived quantitative criteria have better predictive performance than visual inspection of the QS characteristic and are likely to reduce unnecessary ablation sites.