Outflow Tract Premature Ventricular Contractions Research Articles

Accuracy of pace-mapping using an automated template matching module for site of origin identification of idiopathic outflow tract premature ventricular contractions

Abstract Background Activation mapping (AM) is the preferred approach to identify the premature ventricular complexes (PVC) site of origin (SOO) but it is limited when PVCs are infrequent. Pace-mapping (PM) is often used in combination with AM. Yet, relying on PM as sole guide for ablation requires a high accuracy for detecting the PVC SOO. Limited data exists on the accuracy of automated PM using PASO™ for identifying the SOO of idiopathic PVCs, particularly in the left ventricular outflow tract (LVOT). In two cohorts with both idiopathic and non-idiopathic PVCs, a PASO™ >94% was associated with ablation success. Purpose This study evaluated the accuracy of PM using the automated digital pace-matching module integrated in the CARTO mapping system for identifying the SOO of idiopathic outflow-tract PVCs. It also compared its accuracy in the LVOT versus the right ventricular outflow tract (RVOT). Methods Consecutive patients undergoing successful ablation of idiopathic outflow-tract PVCs were prospectively included. AM and PM were performed with a 3.5mm tip catheter. PM was conducted at 2mA, 5mA, or 10mA output, selecting the lowest output that captured at each site. Ablation was performed at the site of earliest bipolar local activation time. The PVC SOO was defined as the site of acute ablation success. The distance between the best PM (BPM) and the SOO and the areas defined by PM ≥98%, ≥96%, and ≥94% were measured. Long-term success was defined by a ≥80% reduction in PVC burden at 3-month follow-up. Results In total, 27 patients were included; 18 had PVCs from the RVOT and 9 from the LVOT. All procedures were acutely successful after a median of 2 (IQR 1-3) radiofrequency applications (RFA) in the RVOT and one (IQR 1-2) RFA in the LVOT. In the RVOT, the median BPM was 98.1% (98.0-98.6), the median distance from the BPM to the SOO was 3.5 mm (IQR 0–8.5mm) and the areas of PM ≥98%, ≥96%, ≥94% were 1.2cm2 (0.5 – 1.8), 3.4cm2 (1.5-4.7) and 7.1cm2 (4.9-11.1). In the LVOT, the median BPM was 95.5% (IQR 94.9 – 97.8%) and the median distance from the BPM to the SOO was 8 mm (IQR 2–15mm). Only 3/9 patients with LVOT PVCs had a BPM ≥96% (1/9 ≥98%) and in all 3, the PVC SOO was coincident with the BPM site. From the remaining 6 patients, 5 had a BPM ≥94% but only in 2/5 the PVC SOO was within the area defined by the BPM site. In 26/27 (96%) patients, no PVC recurrence was documented after 3 months (median burden 0% [IQR 0-0]). Conclusions The accuracy of using the best pace-match provided by PASO™ for identifying the PVC SOO in the RVOT is high, making it a suitable target for limited ablation when activation mapping is not possible because of insufficient PVCs. In the LVOT, the best pace-match is frequently lower than in the RVOT and it misses the PVC SOO in almost half of the patients. The previously suggested PM >94% cut-off seems to be insufficient to identify the PVC SOO in both the RVOT and LVOT.TablePacemap

Wall shear stress in outflow tract premature ventricular contraction location assessed through 4D-flow MRI.

Wall shear stress in outflow tract premature ventricular contraction location assessed through 4D-flow MRI.

Use of Ripple mapping to enhance localization and ablation of outflow tract premature ventricular contractions.

Accurate localization of septal outflow tract premature ventricular contractions (PVCs) is often difficult due to frequent mid-myocardial or protected origin. Compared with traditional activation mapping, CARTO Ripple mapping provides visualization of all captured electrogram data without assignment of a specific local activation time and thus may enhance PVC localization. Electroanatomic maps for consecutive catheter ablation procedures for septal outflow tract PVCs (July 2018-December 2020) were analyzed. For each PVC, we identified the earliest local activation point (EA), defined by the point of maximal -dV/dt in a simultaneously recorded unipolar electrogram, and the earliest Ripple signal (ERS), defined as the earliest point at which three grouped simultaneous Ripple bars appeared in late diastole. Immediate success was defined as full suppression of the clinical PVC. Fifty-seven unique PVCs in 55 procedures were included. When ERS and EA were in the same chamber (RV, LV, or CS), the odds ratio for the successful procedure was 13.1 (95% confidence interval [CI] 2.2-79.9, p = .005). Discordance between sites was associated with a higher likelihood of needing multi-site ablation (odds ratio [OR] 7.9 [1.4-4.6; p = .020]). Median EA-ERS distance in successful versus unsuccessful cases was 4.6 mm (interquartile range 2.9-8.5) versus 12.5 mm (7.8-18.5); (p = .020). Greater EA-ERS concordance was associated with higher odds of single-site PVC suppression and successful septal outflow tract PVC ablation. Visualization of complex signals via automated Ripple mapping may offer rapid localization information complementary to local activation mapping for PVCs of mid-myocardial origin.

The V1 transition ratio: electrocardiographic criterion for predicting the success of ablation for outflow tract premature ventricular contractions

Abstract Funding Acknowledgements Type of funding sources: None. Background Several electrocardiographic (ECG) criteria have been proposed for distinguishing left from right ventricular outflow tract premature ventricular contractions (OTPVCs) origins. However, electrocardiographic criteria predicting successful catheter ablation (CA) for OTPVCs are still unknown regardless of right and left ventricular origins. Methods We enrolled 63 patients who underwent CA for OTPVCs from September 2020 to August 2022, except patients with bundle branch block and axis deviation in 12-lead ECG. Radiofrequency catheter ablation (RFCA) was performed using 3D-mapping system and irrigation catheter. Electrocardiographic parameters of successful and unsuccessful patients were retrospectively analyzed. The transition ratios were calculated by the percentage R-wave during PVC (R/R+S) PVC divided by the percentage R-wave in sinus rhythm (R/R+S) SR . Success of CA for OTPVCs was defined as absence of targeted PVCs during all follow up visits and PVC burden <5% on follow-up period. Results 54 patients (85.7%) were success and 9 patients (14.3%) were unsuccess. Age, sex, Ejection Fraction (EF) and the burden of PVCs before CA were similar between 2 group. (Age: 50±15 vs 54±12 years, p=0.51, male: 46.3 vs 53.7%, p=0.73, EF: 66(58-73) vs 69(59-74), p=0.52, burden of PVCs: 22(17-29) vs 15(13-33)%, p=0.45). V1 transition ratio of unsuccessful group was significantly higher than successful group. (0.70(0.32-1.49) vs 1.55(1.09-9.37), p=0.013) V2 and V3 transition ratios were not significantly different between the two groups. The best cutoff values of V1 transition ratio were 1.0 (AUC 0.78, 95%CI: 0.61-0.94, sensitivity 0.70, specificity 0.88). Conclusion V1 transition ratio>1.0 is more likely to be associated with a higher rate of RFCA failure of OTPVCs.

Similarly high success and low complication rates of catheter ablation for idiopathic premature ventricular contractions from the left and right ventricular outflow tract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation is the first line treatment for idiopathic premature ventricular contractions (PVCs) from the right ventricular outflow tract (RVOT) but not from the left ventricular outflow tract (LVOT), due to presumed lower success and higher complication rates in the LVOT. In this observational single center study we analyzed success rates and complication rates in patients undergoing catheter ablation for idiopathic PVCs with an inferior axis. Methods Patients undergoing catheter ablation for idiopathic PVCs with an inferior axis at Hannover Heart Rhythm Center between 2012 and 2020 were included. Patients were excluded if no activation mapping could be performed because of low PVC activity. Ablation success was defined as complete suppression of the index PVC at the end of the procedure. Results 108 patients (53% male, age 53 ± 17 years) with predominantly symptomatic (94%) PVCs with one (72%), two (20%) or more (8%) morphologies and a PVC count of 22063 ± 14426 /24h were included. 47 PVCs (44%) were located in the RVOT (21 anterior RVOT and 26 septal RVOT) and 39 PVCs (36%) in the LVOT (11 lateral LVOT, 5 septal LVOT, 8 RCC, 2 ACC, 13 LCC). 14 PVCs (13%) had the origin close to the CS/LV summit and 8 PVCs (7%) in the parahisian region. Overall success rate was 82%. Success rates for RVOT and LVOT origin were 98% (46/47 cases) and 97% (38/39 cases) respectively. No significant differences in procedure time (145 ± 68 vs. 158 ± 72 min), ablation time (441 ± 328 vs. 462 ± 307 sec), fluoroscopy time (496 ± 521 vs. 519 ± 473 sec) or minor complications (5 vs. 8) were observed for outflow tract PVCs, and no major complications occurred in this group. However, 3 major complications and significantly lower success rates were observed for non-outflow tract PVCs (0/8 for parahisian origin, 4/14 (29%) for CS/LV summit origin). 2 patients with a parahisian focus experienced higher degree AV block and 1 patient with an LV summit focus had a pericardial tamponade. Conclusion Catheter ablation of PVCs with LVOT origin can be performed with similarly high success and low complication rates compared to PVCs with RVOT origin, and therefore could be considered as first-line therapy like RVOT PVCs. On the other hand, identification of PVCs with a parahisian or CS/LV summit focus should be aspired before an ablation procedure, as these localizations are associated with poorer ablation outcome and higher complication rates.

Wall-Shear Stress in Outflow Tract Premature Ventricular Contraction Location: Opening Doors with 4D-Flow MRI

Wall-Shear Stress in Outflow Tract Premature Ventricular Contraction Location: Opening Doors with 4D-Flow MRI

A simplified approach to radiofrequency catheter ablation of idiopathic ventricular outflow tract premature ventricular contractions.

Frequently, low voltage areas (LVAs) and diastolic potentials (DPs) are present at ablation sites in sinus rhythm in patients with idiopathic premature ventricular contractions (PVCs). Validate these findings as substrates for PVCs and evaluate the feasibility of a simplified substrate approach based on LVAs and DPs for ablation of idiopathic outflow tract PVCs, in patients with a low PVC burden during the procedure. Prospective single-arm clinical trial at two centers with comparison with a historical group, matched to age and gender. The study group consisted of consecutive patients referred for ablation of frequent idiopathic PVCs with inferior axis, that presented with less than twoPVCs/min in first 5 min of the procedure. The ablation was based on fast mapping of the right ventricular outflow tractin sinus rhythm looking for LVAs and DPs, defined as isolated small amplitude potentials occurring after the T wave of the surface echocardiogram. The area with LVAs and DPs was tagged, and a simplified activation mapping of the PVCs was done in that area. The procedure time, success rate, and recurrence rate were compared with the historical group in whom ablation was performed based on activation and pace mapping only. A validation group without PVCs was also studied to assess the prevalence of LVAs and DPs in the general population. The study (n = 38), historical (n = 38), and validation (n = 38) groups did not differ in relation to age or gender. Prevalence of LVAs and DPs was significantly higher in the study group in comparison with the validation group, respectively, 71% versus 11%, p < 0.0001 and 87% versus 8%, p < 0.0001. Procedure time was significantly lower in the study group when comparing to the historical group, 130 (100-164) versus 183 (160-203) min, p < 0.0001 and the success rate was significantly higher, 90% versus 64%, p = 0.013. The recurrence rate in patients with a successful ablation was not significantly different between both groups, Log-rank = 0.125. The prevalence of LVAs and DPs was significantly higher in the study group than in the validation group. The proposed approach proved to be feasible, faster, and more efficient than the historical approach.

Limitations of Unipolar Signals in Guiding Successful Outflow Tract Premature Ventricular Contraction Ablation.

Unipolar electrograms (UniEGMs) are commonly used to annotate earliest local activation of focal arrhythmias. However, their utility in guiding premature ventricular contractions (PVCs) ablation may be limited when the PVC source is less superficial. The authors sought to compare bipolar electrograms (BiEGMs) vs UniEGMs in guiding successful ablation of right ventricular outflow tract (RVOT) vs intramural outflow tract (OT) PVCs. The authors hypothesized that: 1) earliest bipolar local activation time (LATBi) would better guide mapping and ablation, vs UniEGM dV/dt (LATUni) or QS morphology; and 2) LAT differences using bipolar vs unipolar EGMs (ΔLATBi-Uni) would be greater for intramural OT than RVOT PVCs. Consecutive patients undergoing successful PVC ablation 2017 to2020 requiring only RVOT or RVOT+left ventricular OT (RVOT+LVOT) ablation were retrospectively analyzed. BiEGMs and UniEGMs at successful ablation sites were compared. Of 70 patients, 50 required RVOT-only, and 20 required RVOT+LVOT ablation for acute and long-term PVC suppression. Mean ΔLATBi-Uni was lower for RVOT vs RVOT+LVOT groups (9.3 ± 6.4ms vs 17.4 ± 9.9ms; P< 0.01). QS UniEGM was seen in 78% of RVOT, compared with 53% of RVOT+LVOT patients (P< 0.016). RVOT+LVOT sites most frequently included the posteroseptal RVOT and adjacent LVOT (73%), and 43% lacked a QS unipolar EGM. ΔLATBi-Uni≥15ms best distinguished sites in which RVOT-only vs RVOT+LVOT ablation achieved acute PVC suppression (area under the curve: 0.77). Earliest BiEGM activation guides successful ablation of OT PVCs better than UniEGM-guided analysis, especially when an intramural PVC source is present.

The value of QRS onset of the outflow tract PVC in V1 and V2 leads recorded in fourth, third, and second intercostal spaces to differentiate main origins of premature ventricular contraction-Aprospective cohort study.

BackgroundElectrocardiography (ECG) is now proposed as a simple and cost‐effective tool to determine the location of arrhythmias before ablation. We aimed to examine the value of the QRS onset of outflow tract PVC in V1 and V2 leads recorded in fourth, third, and second intercostal spaces to differentiate two main origins for premature ventricular contraction (PVC) including right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT).MethodsIn this prospective cohort study, a total of 58 patients were studied, from whom a surface ECG was obtained using V1 and V2 leads in the fourth, third, and second intercostal spaces. ECG and Electrophysiology studie (EPS) data were then recorded and compared to determine the sensitivity and specificity of QRS onset in locating arrhythmias. The reciever operating characterictic (ROC) curve analysis was applied to test diagnostic performance.ResultsBased on the time of PVC initiation in each of the V1 and V2 leads in the fourth intercostal space, if PVC is recorded earlier in the V1 lead, its source in 95.8% of the patients is RVOT and if PVC preceded the V2 lead, 70.59% of the patients had PVC from LVOT. Comparing of QRS onset in V1 and V2 leadsrecorded from third% and and second intercostal spaces had considerable sensitivity and specificity to determine the origin of the outflow tract PVC (81.82 and 94.12%, respectively)ConclusionSimultaneous recording of outflow tract PVCs from second third and fourth intercostal spaces and comparing their onset can determine the left and right outflow tract PVCs with high sensitivity and specificity.

CE-520-03 USE OF RIPPLE MAPPING TO ENHANCE LOCALIZATION AND ABLATION OF OUTFLOW TRACT PREMATURE VENTRICULAR CONTRACTIONS

Mapping outflow tract (OT) premature ventricular contractions (PVCs) can be difficult given a frequent mid-myocardial origin. Compared to local activation time mapping, Carto® Ripple Mapping provides visualization of both far field and near field signals independent of local annotation that may enhance PVC localization.

Abstract 14421: Limitations of Using Unipolar Signals to Guide Outflow Tract Premature Ventricular Contraction Ablation

Introduction: Unipolar electrogram (EGM) signals are universally used to annotate earliest activation and guide ablation (Abl) of focal arrhythmias. However, their utility in mapping PVCs is limited given 3-dimensionality of wave front propagation, especially when the source is intramural. Hypothesis: 1) earliest onset of bipolar activation would better guide mapping and Abl in these cases, versus maximum unipolar dV/dt or QS morphology; and 2) differences would be greater for intramural outflow tract (OT) PVCs versus those eliminated with RVOT Abl only. Methods: Consecutive patients undergoing successful RVOT or RVOT+LVOT PVC Abl at our center from 2017-2020 were retrospectively analyzed. Bipolar and Unipolar EGMs at successful Abl sites were compared. Results: Of 71 patients, 41 had only RVOT and 30 had RVOT + LVOT Abl. All had acute and long-term PVC suppression over mean 22.6 ± 11.6 month follow-up. Mean EGM difference was 7.6 ± 4.7 ms in the RVOT group vs 18.9 ± 10.5 ms in RVOT+LVOT group (p&lt;0.01). QS unipolar EGM was seen in 95% of RVOT patients, 88% of which were at the anterior RVOT/crux, vs 40% of RVOT+LVOT patients (p&lt;0.016). Activation was equally earliest from the posteroseptal RVOT and adjacent LVOT site in 73%, and most of these sites did not have a QS unipolar EGM (Figure). Conclusions: Bipolar EGM activation timing guided successful ablation of OT PVCs better than unipolar EGM analysis. A QS unipolar EGM did not reliably predict best ablation sites, especially for intramural PVCs.

The QRS-right ventricular apex interval as acut-off value to differentiate the origin of outflow tract premature ventricular complexes.

Many electrocardiography (ECG) criteria have been proposed for the localization of outflow tract premature ventricular contractions (PVCs); however, in some cases, it is difficult to accurately localize the origin of PVCs using the surface ECG. The authors aimed to study the QRS-right ventricular apex (RVA) interval measured during electrophysiological study and its role in the differentiation between different sites of origin of outflow tract PVCs. The study included 90patients (81females, mean age 37.20 ± 7.87) referred for outflow tract PVC ablation. The authors measured the interval from the onset of the earliest QRS complex of the PVCs to the distal RVA intracardiac signal (the QRS-RVA interval) during the electrophysiological study and correlated this interval with the origin of outflow tract PVCs as identified by successful ablation during the procedure. The QRS-RVA interval was significantly longer in PVCs originating from the left ventricular outflow tract (LVOT) compared to the right ventricular outflow tract (RVOT) (67.33 ± 7.56 for LVOT PVCs vs. 37.11 ± 4.34 for RVOT PVCs, p < 0.001). Receiver operating characteristic (ROC) analysis showed that aQRS-RVA interval ≥ 48 ms predicted an LVOT origin of PVCs. Ashorter interval was noted in PVCs originating from the RVOT free wall rather than the septal RVOT wall, and ashorter interval was also noted in LVOT PVCs originating from the right coronary cusp as compared to other LVOT PVCs, although these differences did not reach statistical significance. Measuring the QRS-RVA interval is asimple and accurate method for differentiating the origin of outflow tract PVCs during an electrophysiological study. AQRS-RVA interval ≥ 48 ms predicts an LVOT origin of PVCs rather than an RVOT origin.

Mapping strategies for premature ventricular contractions-activation, voltage, and/or pace map.

Ahigh premature ventricular contraction (PVC) burden is associated with an increase in cardiovascular mortality and may become clinically apparent through palpitations, reduced physical capacity or PVC-induced cardiomyopathy. Catheter ablation has been shown to be amore effective tool to treat patients with ahigh PVC burden than medical therapy alone. Current recommendations list catheter ablation as aclassI option in patients with symptomatic idiopathic outflow tract PVCs as well as in patients with suspected PVC-induced cardiomyopathy. Careful planning is necessary to maximize efficiency and outcome of the ablation procedure. Prediction of the most likely PVC origin by studying the 12-lead electrocardiogram (ECG) is important. Ahigh burden of spontaneous PVCs is associated with abetter outcome during and after the procedure; pharmacological provocation can be performed. Developments in high density mapping systems have greatly advanced accuracy and efficiency of arrhythmia mapping in recent years. Different systems are now available that allow the simultaneous use and integration of different mapping information in an automated manner. Voltage mapping, activation mapping and pace mapping are used in clinical practice today. Activation mapping is used to visualize the area of earliest activation. While it is avery accurate tool, it relies on ahigh burden of spontaneous PVCs. Pace mapping aims to find the target area by means of stimulation and comparison of paced QRS complexes with the clinical PVC. Today, mostly acombination of both methods is used to maximize procedure outcome and efficiency. While voltage mapping plays aprimary role in the mapping of substrate-based sustained arrhythmias in patients with underlying structural heart disease, activation and pace mapping are the methods of choice for PVC mapping.

Impact of contact force sensing technology on outcome of catheter ablation of idiopathic pre-mature ventricular contractions originating from the outflow tracts.

Catheter ablation of frequent idiopathic pre-mature ventricular contractions (PVC) is increasingly performed. While potential benefits of contact force (CF)-sensing technology for atrial fibrillation ablation have been assessed in several studies, the impact of CF-sensing on ventricular arrhythmia ablation remains unknown. This study aimed to compare outcomes of idiopathic outflow tract PVC ablation when using standard ablation catheters as opposed to CF-sensing catheters. In a retrospective multi-centre study, unselected patients undergoing catheter ablation of idiopathic outflow tract PVCs between 2013 and 2016 were enrolled. All procedures were performed using irrigated-tip ablation catheters and a 3D electro-anatomical mapping system. Sustained ablation success was defined as a ≥80% reduction of pre-procedural PVC burden determined by 24 h Holter ECG during follow-up. Overall, 218 patients were enrolled (median age 52 years, 51% males). Baseline and procedural data were similar in the standard ablation (24%) and the CF-sensing group (76%). Overall, the median PVC burden decreased from 21% (IQR 10-30%) before ablation to 0.2% (IQR 0-3.0%) after a median follow-up of 2.3 months (IQR 1.4-3.9 months). The rates of both acute (91% vs. 91%, P = 0.94) and sustained success (79% vs. 74%, P = 0.44) were similar in the standard ablation and the CF-sensing groups. No differences were observed in subgroups according to arrhythmia origin from the RVOT (65%) or LVOT (35%). Complications were rare (1.8%) and evenly distributed between the two groups. The use of CF-sensing technology is not associated with increased success rate nor decreased complication rate in idiopathic outflow tract PVC ablation.

Substrate guided ablation of idiopathic right ventricular outflow tract premature ventricular contractions in patients with low arrhythmia burden during the procedure

Abstract Background Ablation of premature ventricular contractions (PVCs) is currently based on activation mapping. This strategy is impaired by the absence or paucity of PVCs on the day of the procedure. Frequently, isolated diastolic potentials (DP) are present at the successful ablation site in sinus rhythm (SR), although their meaning is still a matter of debate. Objective Evaluate the feasibility and results of a substrate-based approach for ablation of idiopathic right ventricular outflow tract (RVOT) PVCs, in patients that present with a low PVC burden during the procedure. Methods We included 12 consecutive patients referred for ablation of frequent (&amp;gt;10000/24 hours) idiopathic PVCs from the RVOT that present with less than 2 PVCs/min in the beginning of the procedure. The ablation was based on fast mapping of the RVOT in SR looking for DPs, defined as isolated small amplitude potentials occurring after the T wave of the surface ECG in SR (Figure). The area with DPs was marked and a reduced activation mapping of the PVCs was done in that area. We evaluated the procedure time, mapping, fluoroscopy and radiofrequency (RF) application times. The number of points used for the maps, the area of DPs, local activation time and success rate. Values are presented as median (Q1-Q3). Electroanatomical mapping of the RVOT in SR was also performed in a control group of 10 subjects that underwent ablation of supraventricular arrhythmias, to evaluate the prevalence of DPs in subjects without PVCs. Results The number of PVCs during the procedure was 1 (0.1–1.6)/min. Both groups did not differ in relation to age or gender. Median age 45 (34–65) years, 6 males in the PVC group and 40 (33–65) years, 6 males in the control group, p=0.821 and p=0.231 respectively. The number of points sampled per RVOT map in SR was 400 (193–500) in the PVC group and 330 (277–425) in the control group, p=0.539. All patients in the study group had DPs in the RVOT. None of the control group subjects had DPs in the RVOT. Ablation data is presented in the Table. The acute success rate was 100%. After a median follow-up time of 4 (3–6) months one patient had recurrence. Conclusion In these group of patients with very low PVC burden during the procedure, this approach partially based on substrate mapping, made ablation of the PVCs feasible, in a fast and efficient way. Funding Acknowledgement Type of funding source: None

Prospective use of ablation index for the ablation of right ventricle outflow tract premature ventricular contractions: a proof of concept study.

Radiofrequency catheter ablation (RFCA) represents an effective option for idiopathic premature ventricular contractions (PVCs) treatment. Ablation Index (AI) is a novel ablation marker incorporating RF power, contact force, and time of delivery into a single weighted formula. Data regarding AI-guided PVCs RFCA are currently lacking. Aim of the study was to compare AI-guided and standard RFCA outcomes in patients with PVCs originating from the right ventricle outflow tract (RVOT). Consecutive patients undergoing AI-guided RFCA of RVOT idiopathic PVCs were prospectively enrolled. Radiofrequency catheter ablation was performed following per-protocol target cut-offs of AI, depending on targeted area (RVOT free wall AI cut-off: 590; RVOT septum AI cut-off: 610). A multi-centre cohort of propensity-matched (age, sex, ejection fraction, and PVC site) patients undergoing standard PVCs RFCA was used as a comparator. Sixty AI-guided patients (44.2 ± 18.0 years old, 58% male, left ventricular ejection fraction 56.2 ± 3.8%) were enrolled; 34 (57%) were ablated in RVOT septum and 26 (43%) patients in the RVOT free wall area. Propensity match with 60 non-AI-guided patients was performed. Acute outcomes and complications resulted comparable. At 6 months, arrhythmic recurrence was more common in non-AI-guided patients whether in general (28% vs. 7% P = 0.003) or by ablated area (RVOT free wall: 27% vs. 4%, P = 0.06; RVOT septum 29% vs. 9% P = 0.05). Ablation Index guidance was associated with improved survival from arrhythmic recurrence [overall odds ratio 6.61 (1.95-22.35), P = 0.001; RVOT septum 5.99 (1.21-29.65), P = 0.028; RVOT free wall 11.86 (1.12-124.78), P = 0.039]. Ablation Index-guidance in idiopathic PVCs ablation was associated with better arrhythmic outcomes at 6 months of follow-up.

A case of outflow tract premature ventricular contractions with very distant exit sites suspected to have a single origin

Outflow tract premature ventricular contractions sometimes demonstrate multiple exit sites in the right and left outflow tracts with preferential pathways. Here we present a case of outflow tract premature ventricular contractions, which were eliminated by ablation from the right ventricular outflow tract accompanied by additional ablation from the very distant endocardial left ventricular outflow tract. The findings during the ablation indicated there was a single origin with multiple exit sites rather than multiple origins for each QRS morphology. This case illustrates that the preferential pathways can demonstrate very distant multiple exit sites.

High-Dose Dobutamine for Inducibility of Atrial Arrhythmias During Atrial Fibrillation Ablation.

This study sought to compare the effect of high-dose dobutamine (DBT) with that of high-dose isoproterenol (IPN) in eliciting triggers during atrial fibrillation (AF) ablation. High-dose IPN is commonly used to elicit triggers during AF ablation. However, it is not available worldwide and, in the United States, its cost per dose has significantly increased. DBT is a similarly nonselective β-agonist and, as such, is a potential alternative. This was a prospective, randomized 2×2 crossover study of patients undergoing AF ablation. Patients were assigned to receive IPN (20 to 30μg/min for 10min) followed by DBT (40 to 50μg/kg/min for 10min) or vice versa in a 1:1 fashion. The type, number, and location of triggers as well as heart rate, blood pressure, and side effects were noted. Fifty patients were included in the study. Both drugs caused a significant increase in heart rate, with a consistently lower peak for DBT. Blood pressure significantly increased with DBT, while there was a significant reduction with IPN, despite phenylephrine support. Atrial arrhythmias induced during DBT were comparable to that induced during IPN. In patients with IPN-inducible outflow tract premature ventricular contractions, a similar effect was noted with DBT. No major complications occurred during either drug challenge. High-dose DBT is safe and comparable to high-dose IPN in respect of eliciting AF triggers, withtheadvantage to maintain systemic pressure without the need of additional vasopressor support. This studysupports the use of high-dose DBT in electrophysiology laboratories in which IPN is not readily available andfor those patients in whom hypotension is a concern.

Electrocardiographic localization of ventricular arrhythmias successfully ablated from the distal great cardiac vein.

Idiopathic ventricular arrhythmias (IVAs) from the left ventricular (LV) summit may be successfully ablated from the distal great cardiac vein (dGCV). Using a 12-lead electrocardiogram (ECG) to localize IVAs that can be ablated from the dGCV is valuable for ablation planning. To determine if a "w" wave, a notch in the Q wave in lead I, and other ECG features can identify IVAs that can be successfully ablated from the dGCV. We reviewed outflow tract premature ventricular contraction (PVC) ablations performed at two centers between September 2010 and June 2018. Successful PVC ablations, in which the PVCs were mapped from the right ventricular outflow tract, coronary cusps, commissures, endocardial LV, and the coronary venous system including the dGCV were included. ECG characteristics were compared between patients with successful ablations in the dGCV and non-dGCV sites. Of the 120 patients (age 56.8 ± 13.8 years, 45% female) that met the inclusion criteria, the dGCV was the successful ablation site in 18 patients (15%). Multivariate analysis with binary logistic regression showed that a "w" in lead I in combination with an early precordial pattern break and a maximum deflection index (MDI) ≥ 0.5 had sensitivity and specificity for a successful ablation in the dGCV of 94.4% and 96.1%, respectively. Combining a "w" wave in lead I with an early precordial pattern break and an MDI ≥ 0.5 is highly sensitive and specific for identifying the dGCV as a successful ablation site for PVCs.

Concealed structural heart disease discovered at cardiac magnetic resonance in patients with ventricular extrasystoles from ventricular outflow tract and apparently normal hearts.

Outflow tract (OT) premature ventricular contractions (PVCs) are commonly found in clinical practice; in most cases, PVCs are benign and observed in structurally normal hearts, not requiring any therapeutic intervention. In this study, we therefore sought to evaluate with cardiac magnetic resonance (CMR) patients with PVC and apparently normal heart at echocardiographic examination, in order to identify possible substrates linked with higher prevalence of arrhythmias or structural heart disease. Thirty-three consecutive patients with frequent PVCs originating from the ventricular OT (right and left) were enrolled in the study and assessed by echocardiography and CMR. All patients had normal baseline electrocardiogram. CMR showed structural changes in 5 patients out of 33; in 3 cases, areas of fibrosis limited in one case to the middle basal segments of the interventricular septum and in two patients to the middle basal segments of the inferior-lateral wall were found. In 2 other cases, however, late gadolinium enhancement showed significant anomalies characterized in one patient by extensive areas of subepicardial fibrosis of the left ventricle, suitable with arrhythmogenic left dominant dysplasia; in another patient, a marked trabeculation of left ventricular medium apical segments suitable with non-compaction myocardium was present. CMR may identify cases of structural heart disease in subjects with OT PVCs and apparently normal electrocardiogram and echocardiogram examinations. A preliminary screening with CMR may be considered before any further invasive electrophysiology assessment and therapeutic planning.