Impact of artificial intelligence arrhythmia mapping on time to first ablation, procedure duration, and fluoroscopy use.

INTRODUCTION: Artificial intelligence (AI) ECG arrhythmia mapping provides arrhythmia source localization using 12-lead ECG data; whether this information impacts procedural efficiency is unknown. We performed a retrospective, case-control study to evaluate the hypothesis that AI ECG mapping may reduce time to ablation, procedural duration, and fluoroscopy. MATERIALS AND METHODS: Cases in which system output was used were retrospectively enrolled according to IRB-approved protocols at each site. Matched control cases were enrolled in reverse chronological order beginning on the last day for which the technology was unavailable. Controls were matched based upon physician, institution, arrhythmia, and a predetermined complexity rating. Procedural metrics, fluoroscopy data, and clinical outcomes were assessed from time-stamped medical records. RESULTS: The study group consisted of 28 patients (age 65 ± 11 years, 46% female, left atrial dimension 4.1 ± 0.9 cm, LVEF 50 ± 18%) and was similar to 28 controls. The most common arrhythmia types were atrial fibrillation (n = 10), premature ventricular complexes (n = 8), and ventricular tachycardia (n = 6). Use of the system was associated with a 19.0% reduction in time to ablation (133 ± 48 vs. 165 ± 49 min, p = 0.02), a 22.6% reduction in procedure duration (233 ± 51 vs. 301 ± 83 min, p < 0.001), and a 43.7% reduction in fluoroscopy (18.7 ± 13.3 vs. 33.2 ± 18.0 min, p < 0.001) versus controls. At 6 months follow-up, arrhythmia-free survival was 73.5% in the study group and 63.3% in the control group (p = 0.56). CONCLUSION: Use of forward-solution AI ECG mapping is associated with reductions in time to first ablation, procedure duration, and fluoroscopy without an adverse impact on procedure outcomes or complications.

Comparison of dual-bolus versus dual-sequence techniques for determining myocardial blood flow and myocardial perfusion reserve by cardiac magnetic resonance stress perfusion: From the Automated Quantitative analysis of myocardial perfusion cardiac Magnetic Resonance Consortium.

BACKGROUND: Quantitative stress cardiac magnetic resonance (CMR) can be performed using the dual-sequence (DS) technique or dual-bolus (DB) method. It is unknown if DS and DB produce similar results for myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). The study objective is to investigate if there are any differences between DB- and DS-derived MBF and MPR. METHODS: Retrospective observational study with 168 patients who underwent stress CMR. DB and DS methods were simultaneously performed on each patient on the same day. Global and segmental stress MBF and rest MBF values were collected. RESULTS: Using Bland-Altman analysis, segmental and global stress MBF values were higher in DB than DS (0.22 ± 0.60 mL/g/min, p < 0.001 and 0.20 ± 0.48 mL/g/min, p = 0.005, respectively) with strong correlation (r = 0.81, p < 0.001 for segmental and r = 0.82, p < 0.001 for global). In rest MBF, segmental and global DB values were higher than by DS (0.15 ± 0.51 mL/g/min, p < 0.001 and 0.14 ± 0.36 mL/g/min, p = 0.011, respectively) with strong correlation (r = 0.81, p < 0.001 and r = 0.77, p < 0.001). Mean difference between MPR by DB and DS was -0.02 ± 0.68 mL/g/min (p = 0.758) for segmental values and -0.01 ± 0.49 mL/g/min (p = 0.773) for global values. MPR values correlated strongly as well in both segmental and global, both (r = 0.74, p < 0.001) and (r = 0.75, p < 0.001), respectively. CONCLUSION: There is a very good correlation between DB- and DS-derived MBF and MPR values. However, there are significant differences between DB- and DS-derived global stress and rest MBF. While MPR values did not show statistically significant differences between DB and DS methods.

Prognostic Utility of Left Atrial Strain From MRI Feature Tracking in Ischemic and Nonischemic Dilated Cardiomyopathy: A Multicenter Study.

BACKGROUND. MRI-based prognostic evaluation in patients with dilated cardiomyopathy (DCM) has historically used markers of late gadolinium enhancement (LGE) and feature tracking (FT)-derived left ventricular global longitudinal strain (LVGLS). Early data indicate that FT-derived left atrial strain (LAS) parameters, including reservoir, conduit, and booster, may also have prognostic roles in such patients. OBJECTIVE. The purpose of our study was to evaluate the prognostic utility of LAS parameters, derived from MRI FT, in patients with ischemic or nonischemic DCM, including in comparison with the traditional parameters of LGE and LVGLS. METHODS. This retrospective study included 811 patients with ischemic or nonischemic DCM (median age, 60 years; 640 men, 171 women) who underwent cardiac MRI at any of five centers. FT-derived LAS parameters and LVGLS were measured using two- and four-chamber cine images. LGE percentage was quantified. Patients were assessed for a composite outcome of all-cause mortality or heart failure hospitalization. Multivariable Cox regression analyses including demographic characteristics, cardiovascular risk factors, medications used, and a wide range of cardiac MRI parameters were performed. Kaplan-Meier analyses with log-rank tests were also performed. RESULTS. A total of 419 patients experienced the composite outcome. Patients who did, versus those who did not, experience the composite outcome had larger LVGLS (-6.7% vs -8.3%, respectively; p < .001) as well as a smaller LAS reservoir (13.3% vs 19.3%, p < .001), LAS conduit (4.7% vs 8.0%, p < .001), and LAS booster (8.1% vs 10.3%, p < .001) but no significant difference in LGE (10.1% vs 11.3%, p = .51). In multivariable Cox regression analyses, significant independent predictors of the composite outcome included LAS reservoir (HR = 0.96, p < .001) and LAS conduit (HR = 0.91, p < .001). LAS booster and LGE were not significant independent predictors in the models. LVGLS was a significant independent predictor only in a model that initially included LAS booster but not the other LAS parameters. In Kaplan-Meier analysis, all three LAS parameters were significantly associated with the composite outcome (p < .001). CONCLUSION. In this multicenter study, LAS reservoir and LAS conduit were significant independent prognostic markers in patients with ischemic or nonischemic DCM, showing greater prognostic utility than the currently applied markers of LVGLS and LGE. CLINICAL IMPACT. FT-derived LAS analysis provides incremental prognostic information in patients with DCM.

Patient selection, ventricular tachycardia substrate delineation and data transfer for stereotactic arrhythmia radioablation. A Clinical Consensus Statement of the European Heart Rhythm Association (EHRA) of the ESC and the Heart Rhythm Society (HRS).

Stereotactic arrythmia radioablation (STAR) is a novel, non-invasive and promising treatment option for ventricular arrythmias (VA). It has been applied in highly selected patients mainly as bail-out procedure, when (multiple) catheter-ablations, together with anti-arrhythmic drugs, were unable to control the VAs. Despite the increasing clinical use there is still limited knowledge of the acute and long-term response of normal and diseased myocardium to STAR. Acute toxicity appeared to be reasonably low but potential late adverse effects may be underreported. Among published studies, the provided methodological information is often limited, and patient selection, target volume definition, methods for determination and transfer of target volume, and techniques for treatment planning and execution differ across studies, hampering pooling of data and comparison across studies. In addition, STAR requires close and new collaboration between clinical electrophysiologists and radiation oncologists, which is facilitated by shared knowledge in each collaborator's area of expertise and a common language. This clinical consensus statement provides uniform definition of cardiac target volumes. It aims to provide advice in patient selection for STAR including etiology specific aspects, and advice in optimal cardiac target volume identification based on available evidence. Safety concerns and the advice for acute and long-term monitoring including the importance of standardized reporting and follow-up are covered by this document. Areas of uncertainty are listed, which require high-quality, reliable pre-clinical and clinical evidence before expansion of STAR beyond clinical scenarios in which proven therapies are ineffective or unavailable.

Computed tomography predictors of increased transvenous lead extraction difficulty.

BACKGROUND: The ability of computed tomography (CT) characteristics to predict the difficulty of transvenous lead extraction (TLE) is an evolving subject. OBJECTIVE: To identify CT characteristics associated with increased TLE difficulty. METHODS: All consecutive patients undergoing TLE at the University of California San Diego from January 2018 to February 2022 were analyzed, utilizing the UC San Diego Lead Extraction Registry. Patients underwent cardiac-gated chest CT scans with intravenous contrast; all scans were reviewed by a single radiologist. Lead extraction was performed per standard institutional protocol with the initial use of a laser sheath and crossover to a mechanical sheath as needed. Multivariable linear and logistic regression analyses were performed to identify predictors of individual lead-removal fluoroscopy time and mechanical sheath use, as markers of extraction difficulty. RESULTS: A total of 343 patients were analyzed. The mean age of the study population was 63.8 ± 15.4 years; 71% were male. The mean lead dwell-in duration was 8.6 ± 5.7 years. In multivariable linear regression analysis, venous occlusion detected on CT was independently associated with higher individual lead-removal fluoroscopy time (p = 0.004), when adjusting for clinical characteristics such as lead dwell time. In multivariable logistic regression analysis, calcification and venous occlusion were independently associated with a higher need for mechanical sheath use during TLE (odds ratio:5.08, p < 0.001, 95% CI: 2.54-10.46) and (odds ratio:3.72, p < 0.001, 95% CI: 1.89-7.35), respectively. CONCLUSION: In patients undergoing TLE, venous occlusion identified by chest CT is associated with increased fluoroscopy time. Patients with lead-associated calcification or venous occlusion detected by chest CT are each five and three times more likely to require crossover from laser to a mechanical sheath.

Implantable loop recorder as a strategy following cardiovascular implantable electronic device extraction without reimplantation.

BACKGROUND: Limited data exists for outcomes in patients undergoing cardiovascular implantable electronic device (CIED) transvenous lead extraction (TLE) without clear indications for device reimplantation. The implantable loop recorder (ILR) may be an effective strategy for continuous monitoring in select individuals. OBJECTIVE: This retrospective analysis aims to investigate patients who have undergone ILR implant following TLE without CIED reimplantation. METHODS: Clinical data from consecutive patients who have undergone TLE with ILR implant and without CIED reimplantation from October 2016 to May 2020 at a single center were collected. RESULTS: Among 380 patients undergoing TLE, 28 (7.7%) underwent ILR placement without CIED reimplantation. TLE indications were systemic infection (n = 13, 46.4%), pain at the site (n = 8, 28.6%), device/lead malfunction (n = 4, 14.2%), and other. Devices extracted included: dual-chamber and single-chamber pacemaker (n = 14, 50%; n = 4, 14.2%), dual-chamber implantable cardiac defibrillator (n = 10; 35.7%), and cardiac-resynchronization therapy with defibrillator (n = 1, 3.5%). Reasons for no reimplantation included no longer meeting CIED criteria (n = 14, 50%), patient preference (n = 9, 32.1%), and no clear or inappropriate indication for initial CIED implantation (n = 5, 18%). During an average of 12.3 ± 13.1 months of follow-up, there were no lethal arrhythmias, and four (13.3%) patients underwent permanent pacemaker reimplantation due to symptomatic sinus bradycardia and atrioventricular block with syncope as discovered on ILR. Three patients died due to unknown causes (n = 1), noncardiac (n = 1), and acute coronary syndrome (n = 1). CONCLUSIONS: In patients undergoing TLE without reimplantation, an ILR may be an effective monitoring strategy in patients at low risk for cardiac arrhythmia.

'They deserve a treat': the nature and antecedents of parental licensing surrounding children's physical activity.

OBJECTIVE: Little is known about parents' compensatory health beliefs (CHB) surrounding their children's engagement in physical activity (PA). Our aim was to provide evidence regarding the nature of, and factors underpinning, parents' PA-related compensatory beliefs for their children. DESIGN: A qualitative descriptive approach and thematic content analysis were employed. SETTING: Parents were recruited from community sport and PA programmes. PARTICIPANTS: Eighteen parents aged 32-52 years (mean age = 40·8 (sd 5·4) years; six males; twelve females). RESULTS: Analyses indicated that parents compensate through 'passive' or 'active' means. Among parents who compensated, most described their provision of 'treat' foods/drinks and a minority described allowing extended sedentary time to their children. Parents' reasons underpinning these beliefs related to their child's general physical/health status and psychological characteristics, and their own motivation and mood state. CONCLUSIONS: These findings provide the first evidence of unhealthy dietary and sedentary behaviour CHB that parents may hold regarding their children's involvement in PA.

Clinical factors associated with baseline history of atrial fibrillation and subsequent clinical outcomes following initial implantable cardioverter-defibrillator placement.

BACKGROUND: Atrial fibrillation (AF) is frequently present in patients with heart failure (HF) and an implantable cardioverter-defibrillator (ICD). This study aims to identify clinical factors associated with a baseline history of AF in ICD recipients, and compares subsequent clinical outcomes in those with and without a baseline history of AF. METHODS: We studied 566 consecutive first-time ICD recipients at an academic center between 2011 and 2018. Logistic regression multivariable analyses were used to identify clinical factors associated with a baseline history of AF at the time of ICD implant. Cox-proportional hazard regression models were constructed for multivariate analysis to examine associations between a baseline history of AF with subsequent clinical outcomes, including ICD therapies, HF readmission, and all-cause mortality. RESULTS: Of all patients, 201 (36%) had a baseline history of AF at the time of ICD implant. In multivariate analyses, clinical factors associated with a baseline history of AF included hypertension, valvular heart disease, body weight, PR interval, and serum creatinine level. After multivariate adjustment for potential confounders, a baseline history of AF was associated with an increased risk of anti-tachycardia pacing (HR = 1.84, 95% CI = 1.19-2.85, P = .006), appropriate ICD shocks (HR = 1.80, 95% CI = 1.05-3.09, P = .032), and inappropriate ICD shocks (HR = 3.72, 95% CI = 1.7-7.77, P = .0001), but not other adverse outcomes. CONCLUSION: Among first-time ICD recipients, specific clinical characteristics were associated with a baseline history of AF at the time of ICD implant. After adjustment for potential confounders, a baseline history of AF was associated with a higher risk of all ICD therapies in follow-up.

Outcomes of repeated transvenous lead extraction.

INTRODUCTION: The outcomes of repeated cardiovascular implantable electronic device (CIED) lead extraction have not been well studied. We sought to determine the indications, outcomes, and safety of repeated lead extraction procedures. METHODS: This retrospective study was conducted using data from two medical centers, including 38 patients who had undergone two or more lead extraction procedures compared to 439 patients who had a single procedure. The electronic medical records and procedural databases were reviewed to determine the indications, procedural characteristics, and outcomes. The outcomes of the first procedure were compared to the outcomes of subsequent procedures. RESULTS: The 5-year cumulative probability of a repeated extraction procedure was 11% (95% confidence interval, 7%-15%). In 439 patients who underwent single lead extractions, 72% had device and lead related infections as the procedure indication compared to 39% for 38 patients who underwent repeated extraction (P < 0.001). The mean duration from device reimplant to repeated extraction procedures was 63 ± 48 months. Ninety-eight percent of the leads were removed completely in repeated procedures, similar to the 95% success rate of the first procedure (P = 0.51). There was no significant difference in major complication rate in the first or repeated extractions (2.6% vs 5.2%, P = 0.79). CONCLUSIONS: Repeated transvenous lead extraction is not uncommon. It had a high success rate comparable to that of the initial procedure and was not associated with an increased incidence of adverse events.

Rotors exhibit greater surface ECG variation during ventricular fibrillation than focal sources due to wavebreak, secondary rotors, and meander.

INTRODUCTION: Ventricular fibrillation is a common life-threatening arrhythmia. The ECG of VF appears chaotic but may allow identification of sustaining mechanisms to guide therapy. HYPOTHESIS: We hypothesized that rotors and focal sources manifest distinct features on the ECG, and computational modeling may identify mechanisms of such features. METHODS: VF induction was attempted in 31 patients referred for ventricular arrhythmia ablation. Simultaneous surface ECG and intracardiac electrograms were recorded using biventricular basket catheters. Endocardial phase maps were used to mechanistically classify each VF cycle as rotor or focally driven. ECGs were analyzed from patients demonstrating both mechanisms in the primary analysis and from all patients with induced VF in the secondary analysis. The ECG voltage variation during each mechanism was compared. Biventricular computer simulations of VF driven by focal sources or rotors were created and resulting ECGs of each VF mechanism were compared. RESULTS: Rotor-based VF exhibited greater voltage variation than focal source-based VF in both the primary analysis (n = 8, 110 ± 24% vs. 55 ± 32%, P = 0.02) and the secondary analysis (n = 18, 103 ± 30% vs. 67 ± 34%, P = 0.009). Computational VF simulations also revealed greater voltage variation in rotors compared to focal sources (110 ± 19% vs. 33 ± 16%, P = 0.001), and demonstrated that this variation was due to wavebreak, secondary rotor initiation, and rotor meander. CONCLUSION: Clinical and computational studies reveal that quantitative criteria of ECG voltage variation differ significantly between VF-sustaining rotors and focal sources, and provide insight into the mechanisms of such variation. Future studies should prospectively evaluate if these criteria can separate clinical VF mechanisms and guide therapy.

Modifying Ventricular Fibrillation by Targeted Rotor Substrate Ablation: Proof-of-Concept from Experimental Studies to Clinical VF.

INTRODUCTION: Recent work has suggested a role for organized sources in sustaining ventricular fibrillation (VF). We assessed whether ablation of rotor substrate could modulate VF inducibility in canines, and used this proof-of-concept as a foundation to suppress antiarrhythmic drug-refractory clinical VF in a patient with structural heart disease. METHODS AND RESULTS: In 9 dogs, we introduced 64-electrode basket catheters into one or both ventricles, used rapid pacing at a recorded induction threshold to initiate VF, and then defibrillated after 18±8 seconds. Endocardial rotor sites were identified from basket recordings using phase mapping, and ablation was performed at nonrotor (sham) locations (7 ± 2 minutes) and then at rotor sites (8 ± 2 minutes, P = 0.10 vs. sham); the induction threshold was remeasured after each. Sham ablation did not alter canine VF induction threshold (preablation 150 ± 16 milliseconds, postablation 144 ± 16 milliseconds, P = 0.54). However, rotor site ablation rendered VF noninducible in 6/9 animals (P = 0.041), and increased VF induction threshold in the remaining 3. Clinical proof-of-concept was performed in a patient with repetitive ICD shocks due to VF refractory to antiarrhythmic drugs. Following biventricular basket insertion, VF was induced and then defibrillated. Mapping identified 4 rotors localized at borderzone tissue, and rotor site ablation (6.3 ± 1.5 minutes/site) rendered VF noninducible. The VF burden fell from 7 ICD shocks in 8 months preablation to zero ICD therapies at 1 year, without antiarrhythmic medications. CONCLUSIONS: Targeted rotor substrate ablation suppressed VF in an experimental model and a patient with refractory VF. Further studies are warranted on the efficacy of VF source modulation.

Motion correction of wide-detector 4DCT images for cardiac resynchronization therapy planning.

BACKGROUND: Lead placement at the latest mechanically activated left ventricle (LV) segments is strongly correlated with response to cardiac resynchronization therapy (CRT). We demonstrate the feasibility of a cardiac 4DCT motion correction algorithm (ResyncCT) in estimating LV mechanical activation for guiding lead placement in CRT. METHODS: Subjects with full cardiac cycle 4DCT images acquired using a wide-detector CT scanner for CRT planning/upgrade were included. 4DCT images exhibited motion artifact-induced false-dyssynchrony, hindering LV mechanical activation time estimation. Motion-corrupted images were processed with ResyncCT to yield motion-corrected images. Time to onset of shortening (TOS) was estimated in each of 72 endocardial segments. A false-dyssynchrony index (FDI) was used to quantify the extent of motion artifacts in the uncorrected and the ResyncCT images. After motion correction, the change in classification of LV free-wall segments as optimal target sites for lead placement was investigated. RESULTS: Twenty subjects (70.7 â€‹± â€‹13.9 years, 6 female) were analyzed. Motion artifacts in the ResyncCT-processed images were significantly reduced (FDI: 28.9 â€‹± â€‹9.3 â€‹% vs 47.0 â€‹± â€‹6.0 â€‹%, p â€‹< â€‹0.001). In 10 (50 â€‹%) subjects, ResyncCT motion correction yielded statistically different TOS estimates (p â€‹< â€‹0.05). Additionally, 43 â€‹% of LV free-wall segments were reclassified as optimal target sites for lead placement after motion correction. CONCLUSIONS: ResyncCT significantly reduced motion artifacts in wide-detector cardiac 4DCT images, yielded statistically different time to onset of shortening estimates, and changed the location of optimal target sites for lead placement. These results highlight the potential utility of ResyncCT motion correction in CRT planning when using wide-detector 4DCT imaging.

Inflammatory biomarkers as predictors of systemic vs isolated pocket infection in patients undergoing transvenous lead extraction.

Background: Cardiovascular implantable electronic device (CIED) infections are a common indication for device extraction. Early diagnosis and complete system removal are crucial to reduce morbidity and mortality. The lack of clear infectious symptoms makes the diagnosis of pocket infections challenging and may delay referral for extraction. Objective: We aimed to determine if inflammatory biomarkers can help diagnose CIED isolated pocket infection. Methods: We performed a retrospective analysis of all patients undergoing transvenous lead extraction for CIED infection at the University of California San Diego from 2012 to 2022 (N = 156). Patients were classified as systemic infection (n = 88) or isolated pocket infection (n = 68). Prospectively collected preoperative procalcitonin (PCT), C-reactive protein, and white blood cell count were compared between groups. Results: Pairwise comparisons revealed that the systemic infection group had a higher PCT than the control group (P < .001) and the pocket infection group (P = .009). However, there was no significant difference in PCT value between control subjects and isolated pocket infection subjects. Higher white blood cell count was only associated with systemic infection when compared with our control group (P = .018). Conclusion: In patients diagnosed with CIED infections requiring extraction, inflammatory biomarkers were not elevated in isolated pocket infection. Inflammatory markers are not predictive of the diagnosis of pocket infections, which ultimately requires a high level of clinical suspicion.

Pulsed field ablation versus thermal energy ablation for atrial fibrillation: a systematic review and meta-analysis of procedural efficiency, safety, and efficacy.

BACKGROUND: Pulsed field ablation (PFA) induces cell death through electroporation using ultrarapid electrical pulses. We sought to compare the procedural efficiency characteristics, safety, and efficacy of ablation of atrial fibrillation (AF) using PFA compared with thermal energy ablation. METHODS: We performed an extensive literature search and systematic review of studies that compared ablation of AF with PFA versus thermal energy sources. Risk ratio (RR) 95% confidence intervals (CI) were measured for dichotomous variables and mean difference (MD) 95% CI were measured for continuous variables, where RR < 1 and MD < 0 favor the PFA group. RESULTS: We included 6 comparative studies for a total of 1012 patients who underwent ablation of AF: 43.6% with PFA (n = 441) and 56.4% (n = 571) with thermal energy sources. There were significantly shorter procedures times with PFA despite a protocolized 20-min dwell time (MD - 21.95, 95% CI - 33.77, - 10.14, p = 0.0003), but with significantly longer fluroscopy time (MD 5.71, 95% CI 1.13, 10.30, p = 0.01). There were no statistically significant differences in periprocedural complications (RR 1.20, 95% CI 0.59-2.44) or recurrence of atrial tachyarrhythmias (RR 0.64, 95% CI 0.31, 1.34) between the PFA and thermal ablation cohorts. CONCLUSIONS: Based on the results of this meta-analysis, PFA was associated with shorter procedural times and longer fluoroscopy times, but no difference in periprocedural complications or rates of recurrent AF when compared to ablation with thermal energy sources. However, larger randomized control trials are needed.

Catheter Ablation versus Advanced Therapy for Patients with Severe Heart Failure and Ventricular Electrical Storm.

BACKGROUND: Current data on outcomes of an initial strategy of catheter ablation versus advanced therapy in patients with severe HF and ES are limited. OBJECTIVE: To evaluate the outcomes of ventricular tachycardia (VT) ablation versus left ventricular assist device (LVAD) or heart transplantation (HT) in patients with severe heart failure (HF) and ventricular electric storm (ES). METHODS: Patients with severe HF and ES who underwent VT ablation, LVAD, or HT between 2012 and 2022 at our medical center were reviewed. Severe HF was defined as ejection fraction ≤ 35% or presence of severe restrictive, valvular or genetic cardiomyopathy. We assessed in-hospital adverse events and one-year outcomes between the two groups. RESULTS: Of 73 patients, 43 underwent VT ablation and 30 received advanced therapy (21 HT and 9 LVAD). One-year survival was similar (76.7% vs 86.7%, log-rank p = 0.308). However, 10 patients (23.3%) in the ablation group underwent HT during follow up. After multivariable analysis, UNOS status 1 or 2 by VT criteria (HR 5.52, 95% CI: 1.27-24.12; p = 0.023) and early VT recurrence (HR 5.67, 95% CI: 1.68-19.09; p = 0.005) were associated with HT or mortality in patients who underwent VT ablation. CONCLUSION: Patients with severe HF and ES who underwent VT ablation had similar overall survival as patients who directly proceeded with advanced therapy, although rates of HT were high during follow up. Predictors of HT or mortality after catheter ablation include UNOS status 1 or 2 by VT criteria and early VT recurrence.

Characterizing cardiac contractile motion for noninvasive radioablation of ventricular tachycardia.

Background: Respiratory motion management strategies are used to minimize the effects of breathing on the precision of stereotactic ablative radiotherapy for ventricular tachycardia, but the extent of cardiac contractile motion of the human heart has not been systematically explored. Objective: We aim to assess the magnitude of cardiac contractile motion between different directions and locations in the heart. Methods: Patients with intracardiac leads or valves who underwent 4-dimensional cardiac computed tomography (CT) prior to a catheter ablation procedure for atrial or ventricular arrhythmias at 2 medical centers were studied retrospectively. The displacement of transvenous right atrial appendage, right ventricular (RV) implantable cardioverter-defibrillator, coronary sinus lead tips, and prosthetic cardiac devices across the cardiac cycle were measured in orthogonal 3-dimensional views on a maximal-intensity projection CT reconstruction. Results: A total of 31 preablation cardiac 4-dimensional cardiac CT scans were analyzed. The LV lead tip had significantly greater motion compared with the RV lead in the anterior-posterior direction (6.0 ± 2.2 mm vs 3.8 ± 1.7 mm; P = .01) and superior-inferior direction (4.4 ± 2.9 mm vs 3.5 ± 2.0 mm; P = .049). The prosthetic aortic valves had the least movement of all fiducials, specifically compared with the RV lead tip in the left-right direction (3.2 ± 1.2 mm vs 6.1 ± 3.8 mm, P = .04) and the LV lead tip in the anterior-posterior direction (3.8 ± 1.7 mm vs 6.0 ± 2.2 mm, P = .03). Conclusion: The degree of cardiac contractile motion varies significantly (1 mm to 15.2 mm) across different locations in the heart. The effect of contractile motion on the precision of radiotherapy should be assessed on a patient-specific basis.

Successful Noninvasive 12-Lead ECG Mapping-Guided Radiotherapy of Inaccessible Ventricular Tachycardia Substrate Due to Mechanical Valves.

In patients presenting with refractory ventricular tachycardia (VT) and aortic and mitral mechanical prosthetic valves, traditional catheter ablation is challenging. We describe a case in which a novel noninvasive computational electrocardiogram mapping algorithm localized VT sources originating from substrate near the mechanical valves, in which stereotactic ablative radiotherapy eliminated VT in 1.5-year follow-up. (Level of Difficulty: Advanced.).