Substrate Characterization and Outcome of Catheter Ablation of Ventricular Tachycardia in Patients With Nonischemic Cardiomyopathy and Isolated Epicardial Scar

Background: The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate. Methods: Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, <1.0 mV and signal abnormality). Abnormal endocardial unipolar LVA (≤8.3 mV) and endocardial bipolar split electrograms and predictors of ablation success were assessed. Results: Epicardial bipolar LVA (27.3 cm 2 [interquartile range, 15.8–50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm 2 [interquartile range, 9.4–68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63–43.12], P =0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27–3.00], P =0.002) were associated with VT recurrence. Conclusions: In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence.

Subjective identification and ablation of drivers in persistent atrial fibrillation

Background Ablation of drivers in persistent atrial fibrillation (AF) has shown controversial results. Purpose To test the efficacy of a tailored approach for persistent AF ablation which includes pulmonary vein isolation (PVI) plus “subjective” identification and ablation of drivers. Methods From May 2017 to December 2019, selected patients with persistent AF and ongoing AF at the beginning of the ablation procedure were included. Conventional high-density mapping catheters (PentaRay NAV, IntellaMap Orion or Advisor HD Grid) were used. Drivers were subjectively identified as: a) fractionated continuous (or quasi-continuous) electrograms on 1–2 adjacent bipoles, without dedicated software (Figure 1A, dashed line; PR = PentaRay NAV); and b) sites with spatiotemporal dispersion (i.e. all the cycle length comprised within the mapping catheter) plus non-continuous fractionation on single bipoles (Figure 1B, arrows; in panels A and B: paper speed 200 mm/s; ORB = 24-pole ORBITER Woven catheter, blue bipoles around tricuspid annulus and green bipoles into the coronary sinus). Ablation included PVI + focal or linear ablation targeting sites with drivers. Ablation success was defined as conversion to sinus rhythm or atrial flutter during ablation. Follow-up included visits with 24h Holter ECG at 3–6–12 months. Survival free from atrial arrhythmias lasting &gt;30 seconds was compared between patients ablated with this tailored approach, and all consecutive patients with persistent AF treated with a PVI-only strategy during the same period. Results 158 Patients received ablation: 35 with the tailored approach (61,7±10,2 years; 29% females) and 123 with only PVI (62,5±9,6 years; 25% females; 89% cryoablation). Basal characteristics were similar (Table 1). In the tailored-approach group, 14 patients (40%) presented 28 detectable sites with continuous fractionated electrograms, 26 on the left atrium and 2 on the right atrium, which was only mapped if ablation of drivers in the left atrium was not successful; 12 (43%) were located within the pulmonary vein antra. 27 patients (77%) showed 103 sites with spatiotemporal dispersion (4 [3–5] per patient). Ablation success was achieved in 17 patients (48%; conversion to sinus rhythm, n=7; conversion to atrial flutter, n=10) in the tailored-approach group and 1 patient (0,8%, sinus rhythm) in the PVI-only group. Excluding a 3-month blanking period, the tailored approach, compared to only PVI, improved one-year freedom from atrial arrhythmias (71% Vs 51%, p=0,05) and mean survival free from atrial arrhythmias (26±3 months; 95% CI 21–32 months Vs 18±2 months; 95% CI 15–22 months) (Figure 1C), at the cost of a longer median procedural time (246 [212–277] vs 108 [81–143] min, p&lt;0,001) and fluoroscopy time (51 [36–76] vs 33 [21–45] min, p&lt;0,001). Conclusion Subjective identification and ablation of drivers, added to PVI, improved freedom from atrial arrhythmias. FUNDunding Acknowledgement Type of funding sources: None. Table 1. Basal characteristics Figure 1

Evaluation of Thyroglobulin Antibody Normalization in Papillary Thyroid Cancer Patients Receiving High-Dose I-131 Therapy

Purpose: Thyroglobulin antibody (TgAb) elevation after I-131 ablation may be difficult to evaluate in cases of recurrence, especially in high-risk patients. This study aimed to evaluate factors contributing to TgAb normalization in papillary thyroid cancer patients receiving high-dose I-131 therapy. Methods: From September 2009 to June 2012, 98 papillary thyroid cancer patients treated with 150 mCi radioactive iodine (RAI) were retrospectively enrolled. Early (3 day) and Delayed (7 day) post-RAI neck counts and reduction ratios were measured and correlated with clinical and pathologic findings. Patients with normal neck ultrasound and undetectable level of serum thyroglobulin (<0.1 ng/mL) and TgAb (<10 IU/mL) were defined as having successful ablation.Results: Thirty-five patients (35.7%) had thyroiditis and 28 (28.6%) achieved ablation success. The thyroiditis group had lower neck counts in both Early and Delayed whole-body scans (WBS), and higher reduction rates than the thyroiditis-absent group. In the ablation success group, Early and Delayed neck counts were significantly higher and the reduction rate of RAI was lower than those in the ablation failure group (p < 0.05). In multivariable analysis, Delayed neck count was the only significant factor for predicting ablation failure (odds ratio = 54.37, 95% confidence interval = 1.33-14.32; p = 0.015).Conclusion: I-131 uptake in the remnant thyroid gland and thyroiditis are factors that indicate TgAb normalization and ablation success in thyroid cancer patients receiving high-dose I-131 therapy.

Catheter Ablation of Ventricular Tachycardia in LMNA Cardiomyopathy: Out of Sight but not Out of Mind

Lamin Cardiomyopathy (LC) is associated with refractory ventricular arrhythmias. Catheter ablation success rate is low due to presence of multiple circuits and intramural substrate. We present a LC case presented with electrical storm. During catheter ablation, arrhythmia was easily inducible but activation mapping, including full epicardial and endocardial mapping, failed to demonstrate the full tachycardia cycle length (70% only) suggesting intramural activation. Critical isthmus was not identified even with successful concealed entrainment on both Endo/epicardial surfaces. This case shows that even combined endocardial and epicardial catheter approach can be ineffective in identifying the full arrhythmogenic substrate in LC.

Contemporary procedure characteristics and outcomes of accessory atrioventricular pathway ablations in an integrated community-based health care system using a tiered approach

Background Since the early descriptions of large series of accessory atrioventricular pathway ablations in adults and adolescents over 20 years ago, there have been limited published reports based on more recent experiences of large referral centers. We aimed to characterize accessory pathway distribution and features in a large community-based population that influence ablation outcomes using a tiered approach to ablation. Methods Retrospective analysis of 289 patients (age 14–81) who underwent accessory ablation from 2015–2019 was performed. Pathways were categorized into anteroseptal, left freewall, posteroseptal, and right freewall locations. We analyzed patient and pathway features to identify factors associated with prolonged procedure time parameters. Results Initial ablation success rate was 94.7% with long-term success rate of 93.4% and median follow-up of 931 days. Accessory pathways were in left freewall (61.6%), posteroseptal (24.6%), right freewall (9.6%), and anteroseptal (4.3%) locations. Procedure outcome was dependent on pathway location. Acute success was highest for left freewall pathways (97.1%) with lowest case times (144 ± 68 min) and fluoroscopy times (15 ± 19 min). Longest procedure time parameters were seen with anteroseptal, left anterolateral, epicardial-coronary sinus, and right anterolateral pathway ablations. Conclusions In this community-based adult and adolescent population, majority of the accessory pathways are in the left freewall and posteroseptal region and tend to be more easily ablated. A tiered approach with initial use of standard ablation equipment before the deployment of more advance tools, such as irrigated tips and 3D mapping, is cost effective without sacrificing overall efficacy.

Comparison of Outcomes of Pediatric Catheter Ablation by Anesthesia Strategy: A Report from the NCDR ® IMPACT Registry

Background - Anesthesia strategies for pediatric ablation procedures include general anesthesia (GA) and monitored anesthesia care (MAC). The effects of anesthesia strategy on arrhythmia inducibility and procedural outcomes have not been investigated. Methods - A multicenter retrospective study was performed, utilizing data from the NCDR ® IMPACT Registry. Data from subjects 1-21 years undergoing elective first-time electrophysiology study (EPS) for evaluation of documented SVT, EAT, or PVC/VT from 4/1/16-12/31/19 were included, excluding cases with WPW, congenital heart disease, and/or cardiomyopathy. The primary outcome was a negative EPS, defined as failure to induce the clinical tachyarrhythmia. Secondary outcomes included ablation success and adverse events (AE). Results - 6621 subjects from 78 centers were evaluated: 49% male; mean age 13.3±3.8 years. GA was utilized in 5913 (89%), with MAC in 708 (11%). A negative EPS occurred in 9% of cases overall, with no difference by anesthesia strategy (9% GA vs. 10% MAC, p=0.2). In SVT and EAT, there was no significant difference in likelihood of a negative EPS by anesthesia strategy. In PVC/VT, there was a higher rate of negative EPS under GA (28% GA vs. 16% MAC, p=0.02), translating to a higher rate of non-ablation (34% GA vs. 14% MAC, p<0.001). In multivariable models, GA was associated with negative EPS in PVC/VT (OR 2.2, 95% CI 1.1-4.4, p=0.03), but not in SVT or EAT. Acute ablation success was not different between strategies (94% GA vs. 94% MAC, p=0.2). Major AE were rare, with no differences between GA and MAC. Conclusions - In this first report on pediatric ablation data in IMPACT, there were no differences between GA and MAC in SVT or EAT inducibility, acute ablation success, or major AE. GA was associated with higher rates of non-inducibility and non-ablation in PVC/VT cases. A MAC strategy should be considered for PVC/VT ablation in the pediatric population.

Impact of age on catheter ablation of premature ventricular contractions

Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation (CA) of frequent premature ventricular contractions (PVC) is increasingly performed in older patients as the population ages. Purpose The purpose of this study was to assess the impact of age on procedural characteristics, safety and efficacy on PVC ablations. Methods Consecutive patients with symptomatic PVCs undergoing CA between 2015 and 2020 were evaluated. Acute ablation success was defined as the elimination of PVCs at the end of the procedure. Sustained success was defined as an elimination of symptoms, and ≥80% reduction of PVC burden determined by Holter-ECG during long-term follow. Patients were sub-grouped based on age (&lt; 65 years vs. ≥ 65 years). Results A total of 114 patients were enrolled (median age 64 years, 71% males) and followed up for a median duration of 228 days. Baseline and procedural data were similar in both age groups. A left-sided origin of PVCs was more frequently observed in the elderly patient group compared to younger patients (83% vs. 67%, p = 0.04, Figure 1). The median procedure time was significantly shorter in elderly patients (160 min vs. 193 min, p = 0.02). The rates of both acute (86% vs. 92%, p = 0.32) and sustained success (70% vs. 71%, p = 0.90) were similar between groups. Complications rates (3.7%) did not differ between the two groups. Conclusion In a large series of patients with a variety of underlying arrhythmia substrates, similar rates of acute procedural success, complications, and ventricular arrhythmia-free-survival were observed after CA of PVCs. Older age alone should not be a reason to withhold CA of PVCs. Abstract Figure 1