Prediction of premature ventricular complex origin in left vs. right ventricular outflow tract: a novel anatomical imaging approach.

AIMS: Left ventricular (LV) outflow tract ventricular arrhythmias (OTVA) are associated with hypertension (HT), older age, and LV dysfunction, suggesting that LV overload plays a role in the aetiopathogenesis. We hypothesized that anatomical modifications of the LV outflow tract (LVOT) could predict left vs. right OTVA site of origin (SOO). METHODS AND RESULTS: Fifty-six (32 men, 53 ± 18 years old) consecutive patients referred for OTVA ablation were included. Cardiac multidetector computed tomography was performed before ablation and then imported to the CARTO system to aid the mapping and ablation procedure. Anatomical characteristics of the aortic root as well as aortopulmonary valvular planar angulation (APVPA) were analysed. The LV was the OTVA SOO (LVOT-VA) in 32 (57%) patients. These patients were more frequently male (78% vs. 22%, P = 0.001), older (57 ± 18 vs. 47 ± 18 years, P = 0.055), and more likely to have HT (59% vs. 21%, P = 0.004), compared to right OTVA patients. Aortopulmonary valvular planar angulation was higher in LVOT-VA patients (68 ± 5° vs. 55 ± 6°, respectively; P < 0.001). Absolute size of all aortic root diameters was associated with LVOT origin. However, after indexing by body surface area, only sinotubular junction diameter maintained a significant association (P = 0.049). Multivariable analysis showed that APVPA was an independent predictor of LVOT origin. Aortopulmonary valvular planar angulation ≥62° reached 94% sensitivity and 83% specificity (area under the curve 0.95) for predicting LVOT origin. CONCLUSIONS: The measurement of APVPA as a marker of chronic LV overload is useful for the prediction of left vs. right ventricular OTVA origin.

Elucidation of hidden slow conduction by double ventricular extrastimuli: a method for further arrhythmic substrate identification in ventricular tachycardia ablation procedures.

Aims: Identification of local abnormal electrograms (EGMs) during ventricular tachycardia substrate ablation (VTSA) is challenging when they are hidden within the far-field signal. This study analyses whether the response to a double ventricular extrastimulus during substrate mapping could identify slow conducting areas that are hidden during sinus rhythm. Methods and results: Consecutive patients (n = 37) undergoing VTSA were prospectively included. Bipolar EGMs with >3 deflections and duration <133 ms were considered as potential hidden slow conduction EGMs (HSC-EGM) if located within/surrounding the scar area. Whenever a potential HSC-EGM was identified, a double ventricular extrastimulus was delivered. If the local potential delayed, it was annotated as HSC-EGM. The incidence of HSC-EGM in core, border-zone, and normal-voltage regions was determined. Ablation was delivered at conducting channel entrances and HSC-EGMs. VT inducibility after VTSA obtained was compared with data from a historic control group. 2417 EGMs were analyzed. 575 (23.7%) qualified as potential HSC-EGM, and 198 of them were tagged as HSC-EGMs. Scars in patients with HSC-EGMs (n = 21, 56.7%) were smaller (35.424.7 vs 67.639.1 cm2; P = 0.006) and more heterogeneous (core/scar area ratio 0.250.2 vs 0.450.19; P = 0.02). 28.8% of HSC-EGMs were located in normal-voltage tissue; 81.3% were targeted for ablation. Patients undergoing VTSA incorporating HSC analysis needed less radiofrequency time (17.411 vs 2310.7 minutes; P = 0.016) and had a lower rate of VT inducibility after VTSA than the historic controls (24.3% vs 50%; P = 0.018). Conclusion: Ventricular tachycardia substrate ablation incorporating HSC analysis allowed further arrhythmic substrate identification (especially in normal-voltage areas) and reduced RF time and VT inducibility after VTSA.

Multielectrode vs. point-by-point mapping for ventricular tachycardia substrate ablation: a randomized study.

Aims: Ventricular tachycardia (VT) substrate ablation is based on detailed electroanatomical maps (EAM). This study analyses whether high-density multielectrode mapping (MEM) is superior to conventional point-by-point mapping (PPM) in guiding VT substrate ablation procedures. Methods and results: This was a randomized controlled study (NCT02083016). Twenty consecutive ischemic patients undergoing VT substrate ablation were randomized to either group A [n = 10; substrate mapping performed first by PPM (Navistar) and secondly by MEM (PentaRay) ablation guided by PPM] or group B [n = 10; substrate mapping performed first by MEM and second by PPM ablation guided by MEM]. Ablation was performed according to the scar-dechanneling technique. Late potential (LP) pairs were defined as a Navistar-LP and a PentaRay-LP located within a three-dimensional distance of ≤ 3 mm. Data obtained from EAM, procedure time, radiofrequency time, and post-ablation VT inducibility were compared between groups. Larger bipolar scar areas were obtained with MEM (55.7±31.7 vs. 50.5±26.6 cm2; P = 0.017). Substrate mapping time was similar with MEM (19.7±7.9 minutes) and PPM (25±9.2 minutes); P = 0.222. No differences were observed in the number of LPs identified within the scar by MEM vs. PPM (73±50 vs. 76±52 LPs per patient, respectively; P = 0.965). A total of 1104 LP pairs were analysed. Using PentaRay, far-field/LP ratio was significantly lower (0.58±0.4 vs. 1.64±1.1; P = 0.01) and radiofrequency time was shorter [median (interquartile range) 12 (7-20) vs. 22 (17-33) minutes; P = 0.023]. No differences were observed in VT inducibility after procedure. Conclusion: MEM with PentaRay catheter provided better discrimination of LPs due to a lower sensitivity for far-field signals. Ablation guided by MEM was associated with a shorter radiofrequency time.

Automatic activation mapping and origin identification of idiopathic outflow tract ventricular arrhythmias.

PURPOSE: Activation mapping is used to guide ablation of idiopathic outflow tract ventricular arrhythmias (OTVAs). Isochronal activation maps help to predict the site of origin (SOO): left vs right outflow tract (OT). We evaluate an algorithm for automatic activation mapping based on the onset of the bipolar electrogram (EGM) signal for predicting the SOO and the effective ablation site in OTVAs. METHODS: Eighteen patients undergoing ablation due to idiopathic OTVAs were studied (12 with left ventricle OT origin). Right ventricle activation maps were obtained offline with an automatic algorithm and compared with manual annotation maps obtained during the intervention. Local activation time (LAT) accuracy was assessed, as well as the performance of the 10ms earliest activation site (EAS) isochronal area in predicting the SOO. RESULTS: High correlation was observed between manual and automatic LATs (Spearman's: 0.86 and Lin's: 0.85, both p<0.01). The EAS isochronal area were closely located in both map modalities (5.55 ± 3.56mm) and at a similar distance from the effective ablation site (0.15±2.08mm difference, p=0.859). The 10ms isochronal area longitudinal/perpendicular diameter ratio measured from automatic maps showed slightly superior SOO identification (67% sensitivity, 100% specificity) compared with manual maps (67% sensitivity, 83% specificity). CONCLUSIONS: Automatic activation mapping based on the bipolar EGM onset allows fast, accurate and observer-independent identification of the SOO and characterization of the spreading of the activation wavefront in OTVAs.

Long-term benefit of first-line peri-implantable cardioverter-defibrillator implant ventricular tachycardia-substrate ablation in secondary prevention patients.

AIMS: This study assessed the benefit of peri-implantable cardioverter-defibrillator implant ventricular tachycardia (VT)-substrate ablation in patients with structural heart disease (SHD). METHODS AND RESULTS: Patients with SHD and indication for secondary prevention ICD implant were prospectively included. Patients presenting with incessant and/or slow VT or frequent (≥2) VT episodes who underwent peri-ICD VT-substrate ablation (the scar dechannelling technique) were compared with those who received ICD alone and did not meet ablation criteria. The primary endpoint was any sustained VT/ICD therapy during follow-up. Of 206 patients included (43.2% non-ischaemic), 70 were assigned to ablation and 136 received ICD implant alone. During a mean follow-up of 45.6 ± 24.7 months, the primary endpoint was more frequent in the non-ablation group (47.1 vs. 22.9%; P< 0.0001). Higher VT recurrence-free survival rate [log-rank P= 0.001; HR = 0.42 (0.24-0.73), P= 0.002] and ICD shock-free survival rate [log-rank P= 0.007; HR = 0.36 (0.17-0.78); P = 0.01] were observed in the ablation group. Higher relative risk reduction was observed in ischaemic [HR = 0.38 (0.18-0.83); P = 0.015] vs. non-ischaemic patients [HR = 0.49 (0.23-1.01); P = 0.08]. Patients with left ventricular ejection fraction (LVEF) <35% showed no differences in VT recurrence between treatment groups (log-rank P = 0.213) although VT burden during follow-up was lower in the ablation group [median (interquartile range) 1 (1-3) vs. 4 (1-10) VT episodes; P = 0.05]. CONCLUSION: First-line peri-ICD implant VT-substrate ablation was associated with decreased VT recurrence and ICD shocks during long-term follow-up in patients with SHD and indication for secondary prevention ICD implant, especially in ischaemic patients. In patients with LVEF <35%, no benefit was observed in terms of VT recurrence-free survival, although VT burden during follow-up was lower in the ablation group.

Substrate modification or ventricular tachycardia induction, mapping, and ablation as the first step? A randomized study.

BACKGROUND: The role and optimal sequence of ventricular tachycardia (VT) induction, mapping, and ablation when combined with substrate modification is unclear. OBJECTIVE: The purpose of this study was to test the benefits of starting the scar-related VT ablation procedure with substrate modification vs the standard protocol of VT induction, mapping, and ablation as the first step. METHODS: Forty-eight consecutive patients with structural heart disease and clinical VTs were randomized to simplified substrate ablation procedure with scar dechanneling as the first step (group 1, n = 24) or standard procedure with VT induction, mapping, and ablation followed by scar dechanneling (group 2, n = 24). Procedure and fluoroscopy times, the need for external cardioversion, acute results, and VT recurrence during follow-up were compared between groups. RESULTS: Thirty-seven patients had ischemic cardiomyopathy, 10 nonischemic cardiomyopathy, and 1 arrhythmogenic cardiomyopathy. Before substrate ablation, 32 VTs were induced and targeted for ablation in 23 patients of group 2. Procedure time (209 ± 70 minutes vs 262 ± 63 minutes; P = .009), fluoroscopy time (14 ± 6 minutes vs 21± 9 minutes; P = .005), and electrical cardioversion (25% vs 54%; P = .039) were lower in group 1. After substrate ablation, 16 patients (66%) of group 1 and 12 patients (50%) of group 2 were noninducible (P = .242). End-procedure success (after residual inducible VT ablation) was achieved in 87.5% and 70.8% of patients, respectively (P = .155). There were no differences in VT recurrence rate between groups during a mean follow-up of 22 ± 14 months (log rank, P = .557). CONCLUSION: VT induction and mapping before substrate ablation prolongs the procedure, radiation exposure, and the need for electrical cardioversion without improving acute results and long-term ablation outcomes.

Infarct transmurality as a criterion for first-line endo-epicardial substrate-guided ventricular tachycardia ablation in ischemic cardiomyopathy.

BACKGROUND: There is no consensus on the appropriate indications for the epicardial approach in substrate ablation of post-myocardial infarction (MI) ventricular tachycardia (VT). OBJECTIVE: The purpose of this study was to investigate whether infarct transmurality (IT) could identify patients who would benefit from a combined first-line endo-epicardial approach. METHODS: Before ablation, IT was assessed by contrast-enhanced cardiac magnetic resonance imaging (hyperenhancement ≥75% of the wall thickness in ≥1 segment), echocardiography (dyskinesia/akinesia + hyperrefringency + wall thinning), computed tomography (wall thinning), or scintigraphy (transmural necrosis). Prospectively from January 2011, an endocardial approach was used in patients with subendocardial MI (group 1) and a combined endo-epicardial approach in patients with transmural MI (group 2). Outcomes in both groups were compared with those in patients with transmural MI and only endocardial approach due to previous cardiac surgery or procedure performed before January 2011 (group 3). The primary end point was VT/ventricular fibrillation recurrence-free survival. RESULTS: Ninety patients (92.2% men; mean age 67.4 ± 9.8 years) undergoing VT substrate ablation were included: group 1, n = 34; group 2, n = 24; group 3, n = 32. During a mean follow-up duration of 22.5 ± 13.7 months, 5 patients in group 1 (14.7%), 3 patients in group 2 (12.5%), and 13 patients in group 3 (40.6%) had VT recurrences (P = .011). Time to recurrence was the shortest in group 3 (log-rank, P = .018). The endocardial approach in patients with transmural MI was associated with an increased risk of recurrence (hazard ratio 4.01; 95% confidence interval 1.41-11.3; P = .009). CONCLUSION: The endocardial approach in patients with transmural MI undergoing VT substrate ablation is associated with an increased risk of recurrence. IT may be a useful criterion for the selection of a first-line combined endo-epicardial approach.

Impact of earliest activation site location in the septal right ventricular outflow tract for identification of left vs right outflow tract origin of idiopathic ventricular arrhythmias.

BACKGROUND: The earliest activation site (EAS) location in the septal right ventricular outflow tract (RVOT) could be an additional mapping data predictor of left ventricular outflow tract (LVOT) vs RVOT origin of idiopathic ventricular arrhythmias (VAs). OBJECTIVE: The purpose of this study was to assess the impact of EAS location in predicting LVOT vs RVOT origin. METHODS: Macroscopic and histologic study was performed in 12 postmortem hearts. Electroanatomic maps (EAMs) from 37 patients with outflow tract (OT) VA with the EAS in the septal RVOT were analyzed. Pulmonary valve (PV) was defined by voltage scanning after validation of voltage thresholds by image integration. EAM measurements were correlated with those of macroscopic/histologic study. RESULTS: A cutoff value of 1.9 mV discriminated between subvalvular and supravalvular positions (90% sensitivity, 96% specificity). EAS ≥1 cm below PV excluded RVOT site of origin (SOO). According to anatomic findings (distance PV-left coronary cusp = 5 ± 3 vs PV-right coronary cusp = 11 ± 5 mm), EAS-PV distance was significantly shorter in VAs arising from left coronary cusp than from the other LVOT locations (4.2 ± 5.4 mm vs 9.2 ± 7 mm; P = .034). The 10-ms isochronal longitudinal/perpendicular diameter ratio was higher in the RVOT vs the LVOT SOO group (1.97 ± 1.2 vs 0.79 ± 0.49; P = .001). An algorithm based on EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio predicted LVOT SOO with 91% sensitivity and 100% specificity. CONCLUSION: An algorithm based on the EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio accurately predicts LVOT vs RVOT SOO in outflow tract VAs with EAS in the septal RVOT.

Ablation of frequent PVC in patients meeting criteria for primary prevention ICD implant: Safety of withholding the implant.

BACKGROUND: Premature ventricular complex (PVC) ablation has been shown to improve left ventricular ejection fraction (LVEF) and New York Heart Association functional class in patients with left ventricular dysfunction. Both are considered key variables in predicting risk of sudden cardiac death. OBJECTIVE: The objective of this study was to assess whether ablation might remove the primary prevention (PP) implantable cardioverter-defibrillator (ICD) indication in patients with frequent PVC. METHODS: Sixty-six consecutive patients with PP-ICD indication and frequent PVC [33 (50%) men; mean age 53 ± 13 years; 11 (17%) with ischemic heart disease] underwent PVC ablation. The ICD was withheld and the indication was reevaluated at 6 and 12 months. RESULTS: LVEF progressively improved from 28% ± 4% at baseline to 42% ± 12% at 12 months (P < .001). New York Heart Association functional class improved from 2 patients with NYHA functional class I (3%) at baseline to 35 (53%) at 12 months (P < .001). The brain natriuretic peptide level decreased from 246 ± 187 to 176 ± 380 pg/mL (P = .004). The PP-ICD indication was removed in 42 patients (64%) during follow-up, from 38 (92%) of them at 6 months, showing an independent association with baseline PVC burden and successful sustained ablation. In patients with successful sustained ablation, a cutoff value of 13% PVC burden had a sensitivity of 100% and a specificity of 93% (area under the curve 99%) for removing ICD indication postablation. No sudden cardiac deaths or malignant ventricular arrhythmias were observed. CONCLUSION: In patients with frequent PVC and PP-ICD indication, ablation improves LVEF and, in most cases, allows removal of the indication. Withholding the ICD and reevaluating within 6 months of ablation seems to be a safe and appropriate strategy.