Rate-Dependent Pacemap Matching in Scar-Related Ventricular Tachycardia: Impact of "TR Fusion" Phenomenon.

BACKGROUND: The impact of varying rates of pacemapping (PM) rates on QRS morphology and PM score matching in patients with scar-related ventricular tachycardia (VT) has not been systematically assessed. OBJECTIVES: In this study, we sought to assess the variability in PM score matching at different pacing rates. METHODS: During substrate mapping for VT ablation, PM was performed at cycle lengths (CLs) of 600 ms, 500 ms, 400 ms, 300 ms, and VT CL. PM scores were compared for the entire QRS, the first half (H1) of QRS, and the second half (H2) of QRS to examine the influence of the preceding T wave superimposed into the onset of paced QRS complex (TR fusion). RESULTS: A total of 269 PMs in 40 patients undergoing scar-related VT ablation were systematically analyzed. The PM score improved at rates closer to VT with a median difference of 6% (Q1-Q3: 4%-10%; range: 0-33%) between the lowest and the highest PM scores at a given site. Greater slurring of the QRS onset was observed at faster-paced CL, corresponding to a superimposition of the preceding T wave into QRS onset, with significant differences in H1 but not H2 of the QRS complex. At faster PM rates, 32% of overall sites developed pseudo delta wave and 69% of endocardial pacing sites fulfilled epicardial criteria. CONCLUSIONS: The rate of pacemapping can significantly alter morphologic score matching, with the most optimal match observed closest to VT CL. The onset of QRS complex morphology is influenced by superimposition of the preceding T wave at faster rates, resulting in an underrecognized TR fusion phenomenon that may confound epicardial electrocardiographic criteria predicated upon the initial QRS slope and vector.

MRI in Patients with Cardiovascular Implantable Electronic Devices and Fractured or Abandoned Leads.

Purpose To examine the clinical effect of lead length and lead orientation in patients with cardiac implantable electronic devices (CIEDs) and lead fragments or abandoned leads undergoing 1.5-T MRI. Materials and Methods This Health Insurance Portability and Accountability Act-compliant retrospective study included patients with CIEDs and abandoned leads or lead fragments undergoing 1.5-T MRI from March 2014 through July 2020. CIED settings before and after MRI were reviewed, with clinically significant variations defined as a composite of the change in capture threshold of at least 50%, in sensing of at least 40%, or in lead impedance of at least 30% between before MRI and after MRI interrogation. Adverse clinical events were assessed at MRI and up to 30 days after. Univariable and multivariable analysis was performed. Results Eighty patients with 126 abandoned CIED leads or lead fragments underwent 107 1.5-T MRI examinations. Sixty-seven patients (median age, 74 years; IQR, 66-78 years; 44 male patients, 23 female patients) had abandoned leads, and 13 (median age, 66 years; IQR, 52-74 years; nine male patients, four female patients) had lead fragments. There were no reported deaths, clinically significant arrhythmias, or adverse clinical events within 30 days of MRI. Three patients with abandoned leads had a significant change in the composite of capture threshold, sensing, or lead impedance. In a multivariable generalized estimating equation analysis, lead orientation, lead length, MRI type, and MRI duration were not associated with a significant change in the composite outcome. Conclusion Use of 1.5-T MRI in patients with abandoned CIED leads or lead fragments of varying length and orientation was not associated with adverse clinical events. Keywords: Cardiac Assist Devices, MRI, Cardiac Implantable Electronic Device Supplemental material is available for this article. © RSNA, 2024.

Initial clinical experience of atrial fibrillation ablation guided by a cryoballoon-compatible, magnetic-based circular catheter.

INTRODUCTION: The circular catheter compatible with current cryoballoon system for atrial fibrillation (AF) ablation is exclusively sensed by impedance-based electro-anatomical mapping (EAM) system, limiting the accuracy of maps. We aim to investigate the feasibility and safety of a magnetic-based circular mapping catheter for AF ablation with cryoballoon. METHODS: Nineteen consecutive patients who underwent pulmonary vein isolation (PVI) with cryoballoon for paroxysmal or persistent AF were included. EAMs of left atrium (LA) created by the LASSOSTAR™NAV catheter (Lassostar map) before and after PVI were compared to that generated by a high-density mapping catheter (Pentaray map) from different aspects including structural similarity, PV angle, LA posterior wall (LAPW) and low voltage areas (LVAs), and the amplitude of far field electrograms (FFEs) recorded by catheters. RESULTS: All patients had successful PVI without major complications. With similar mapping time and density, the LA volume calculated from the Pentaray map and Lassostar map were comparable. There were no significant differences in PV angle of all PVs and PW area (16.8 ± 3.2 vs. 17.1 ± 2.8, p = .516) between Pentaray map and Lassostar map. High structural similarity score was observed between two maps (0.783 in RAO/LAO view and 0.791 in PA view). Lassostar map detected lesser but not statistically significant extension of LVA (13.9% vs. 18.3%, p = .07). Amplitude of FFE was larger at the right superior PV on Lassostar map (0.21 ± 0.16 vs. 0.14 ± 0.11 mV, p = .041) compared to that on the Pentaray map. CONCLUSION: In our initial experience, PVI with cryoballoon and magnetic-based circular LASSOSTAR™NAV catheter was safe and effective based on the accurate LA geometry it created.

Incidence of cryoballoon expansion dislodgement during pulmonary vein isolation-An underappreciated frequent cause of incomplete isolation.

BACKGROUND: Cryoballoon ablation for atrial fibrillation (AF) requires adequate contact between the pulmonary vein (PV) antrum and cryoballoon. The surge of intraballoon pressure during the initial phase of ablation may change the balloon's shape and compliance, resulting in balloon dislodgement and loss of PV occlusion. Without continuous monitoring, this phenomenon is often undetected but can be associated with incomplete PV isolation (PVI). METHODS: Primary cryoablation of AF was performed in 15 patients. PV occlusion status pre- and post-freezing were analyzed with intracardiac echocardiography (ICE) and dielectric imaging-based occlusion tool (DIOT) to calculate the incidence of expansion dislodgement of cryoballoon. RESULTS: A total of 105 cryoablation applications were performed on 57 veins, including three common ostiums of left pulmonary veins. In the evaluation of PV occlusion, both modalities reported consistent results in 86.7% of the assessments. Despite complete PV occlusion before ablation, peri-balloon leak after initiation of freezing was detected by ICE in 5/22 (22.7%) applications and by DIOT in 8/25 (32%) applications. CONCLUSION: Incidence of expansion dislodgement of the cryoballoon was detected in one-fourth to one-third of cryoablation applications depending on the imaging modality used, which was clinically frequent and significant.

Vasovagal Responses to Human Monomorphic Ventricular Tachycardia: Hemodynamic Implications From Sinus Rate Analysis.

BACKGROUND: Factors determining hemodynamic stability during human ventricular tachycardia (VT) are incompletely understood. OBJECTIVES: The purposes of this study were to characterize sinus rate (SR) responses during monomorphic VT in association with hemodynamic stability and to prospectively assess the effects of vagolytic therapy on VT tolerance. METHODS: This is a retrospective analysis of patients undergoing scar-related VT ablation. Vasovagal responses were evaluated by analyzing sinus cycle length before VT induction and during VT. SR responses were classified into 3 groups: increasing (≥5 beats/min, sympathetic), decreasing (≥5 beats/min, vagal), and unchanged, with the latter 2 categorized as inappropriate SR. In a prospective cohort (n = 30) that exhibited a failure to increase SR, atropine was administered to improve hemodynamic tolerance to VT. RESULTS: In 150 patients, 261 VT episodes were analyzed (29% untolerated, 71% tolerated) with median VT duration 1.6 minutes. A total of 52% of VT episodes were associated with a sympathetic response, 31% had unchanged SR, and 17% of VTs exhibited a vagal response. A significantly higher prevalence of inappropriate SR responses was observed during untolerated VT (sustained VT requiring cardioversion within 150 seconds) compared with tolerated VT (84% vs 34%; P < 0.001). Untolerated VT was significantly different between groups: 9% (sympathetic), 82% (vagal), and 32% (unchanged) (P < 0.001). Atropine administration improved hemodynamic tolerance to VT in 70%. CONCLUSIONS: Nearly one-half of VT episodes are associated with failure to augment SR, indicative of an under-recognized pathophysiological vasovagal response to VT. Inappropriate SR responses were more predictive of hemodynamic instability than VT rate and ejection fraction. Vagolytic therapy may be a novel method to augment blood pressure during VT.

Identification of Human Ventricular Tachycardia Demarcated by Fixed Lines of Conduction Block in a 3-Dimensional Hyperboloid Circuit.

BACKGROUND: The circuit boundaries for reentrant ventricular tachycardia (VT) have been historically conceptualized within a 2-dimensional (2D) construct, with their fixed or functional nature unresolved. This study aimed to examine the correlation between localized lines of conduction block (LOB) evident during baseline rhythm with lateral isthmus boundaries that 3-dimensionally constrain the VT isthmus as a hyperboloid structure. METHODS: A total of 175 VT activation maps were correlated with isochronal late activation maps during baseline rhythm in 106 patients who underwent catheter ablation for scar-related VT from 3 centers (42% nonischemic cardiomyopathy). An overt LOB was defined by a deceleration zone with split potentials (≥20 ms isoelectric segment) during baseline rhythm. A novel application of pacing within deceleration zone (≥600 ms) was implemented to unmask a concealed LOB not evident during baseline rhythm. LOB identified during baseline rhythm or pacing were correlated with isthmus boundaries during VT. RESULTS: Among 202 deceleration zones analyzed during baseline rhythm, an overt LOB was evident in 47%. When differential pacing was performed in 38 deceleration zones without overt LOB, an underlying concealed LOB was exposed in 84%. In 152 VT activation maps (2D=53, 3-dimensional [3D]=99), 69% of lateral boundaries colocalized with an LOB in 2D activation patterns, and the depth boundary during 3D VT colocalized with an LOB in 79%. In VT circuits with isthmus regions that colocalized with a U-shaped LOB (n=28), the boundary invariably served as both lateral boundaries in 2D and 3D. Overall, 74% of isthmus boundaries were identifiable as fixed LOB during baseline rhythm or differential pacing. CONCLUSIONS: The majority of VT circuit boundaries can be identified as fixed LOB from intrinsic or paced activation during sinus rhythm. Analysis of activation while pacing within the scar substrate is a novel technique that may unmask concealed LOB, previously interpreted to be functional in nature. An LOB from the perspective of a myocardial surface is frequently associated with intramural conduction, supporting the existence of a 3D hyperboloid VT circuit structure. Catheter ablation may be simplified to targeting both sides around an identified LOB during sinus rhythm.

Design and characteristics of the prophylactic intra-operative ventricular arrhythmia ablation in high-risk LVAD candidates (PIVATAL) trial.

BACKGROUND: The use of a Left Ventricular Assist Device (LVAD) in patients with advanced heart failure refractory to optimal medical management has progressed steadily over the past two decades. Data have demonstrated reduced LVAD efficacy, worse clinical outcome, and higher mortality for patients who experience significant ventricular tachyarrhythmia (VTA). We hypothesize that a novel prophylactic intra-operative VTA ablation protocol at the time of LVAD implantation may reduce the recurrent VTA and adverse events postimplant. METHODS: We designed a prospective, multicenter, open-label, randomized-controlled clinical trial enrolling 100 patients who are LVAD candidates with a history of VTA in the previous 5 years. Enrolled patients will be randomized in a 1:1 fashion to intra-operative VTA ablation (n = 50) versus conventional medical management (n = 50) with LVAD implant. Arrhythmia outcomes data will be captured by an implantable cardioverter defibrillator (ICD) to monitor VTA events, with a uniform ICD programming protocol. Patients will be followed prospectively over a mean of 18 months (with a minimum of 9 months) after LVAD implantation to evaluate recurrent VTA, adverse events, and procedural outcomes. Secondary endpoints include right heart function/hemodynamics, healthcare utilization, and quality of life. CONCLUSION: The primary aim of this first-ever randomized trial is to assess the efficacy of intra-operative ablation during LVAD surgery in reducing VTA recurrence and improving clinical outcomes for patients with a history of VTA.

Early feasibility studies in the United States: Focus on electrophysiology.

The care of patients with heart rhythm disorders is often dependent on technologies developed to address their unique clinical needs. Although much innovation occurs in the United States, recent decades have seen a significant proportion of early clinical studies performed outside the United States, driven largely by costly and time-inefficient processes seemingly inherent to the United States research ecosystem. As a result, the goals of early patient access to novel devices to address unmet needs and efficient technology development in the United States remain incompletely realized. This review will introduce key aspects of this discussion, organized by the Medical Device Innovation Consortium, in an effort to broaden awareness and encourage engagement by stakeholders in an effort to address central issues and therefore further a growing effort to shift Early Feasibility Studies to the United States for the benefit of all involved.

Telemedicine in cardiac procedures: considerations for a remote future.

PURPOSE OF REVIEW: Present a review of relevant literature and suggest a framework for discussion of the considerations affecting the evolution and adoption of Telerobotic Support and Telerobotic Collaboration in the practice of cardiac procedural medicine. RECENT FINDINGS: Recent medical practice has undergone remarkable transformation in the adoption of telemedicine. This evolution has been accelerated by the COVID-19 (SARS-CoV-2) pandemic and has largely been focused on outpatient medicine. Clinical studies and opinion articles have highlighted benefits including reduced costs, increased patient engagement, and saved time, while also raising concerns regarding privacy, care quality and data security. Early and current efforts implementing remote procedural medicine have not only demonstrated technical success but also highlighted the many issues that must be resolved before acceptance as a major aspect of everyday patient care. SUMMARY: It is inevitable that remote technologies will play an increasing role in procedural medicine as they have in outpatient clinical medicine. Thoughtful participation by physicians in the evolution of these technologies and their modes of use will be necessary to maximize the benefits to our patients and healthcare systems.

Catheter ablation of ventricular tachycardia in patients with prior cardiac surgery: An analysis from the International VT Ablation Center Collaborative Group.

INTRODUCTION: Patients with prior cardiac surgery may represent a subgroup of patients with ventricular tachycardia (VT) that may be more difficult to control with catheter ablation. METHODS: We evaluated 1901 patients with ischemic and nonischemic cardiomyopathy who underwent VT ablation at 12 centers. Clinical characteristics and VT radiofrequency ablation procedural outcomes were assessed and compared between those with and without prior cardiac surgery. Kaplan-Meier analysis was used to estimate freedom from recurrent VT and survival. RESULTS: There were 578 subjects (30.4%) with prior cardiac surgery identified in the cohort. Those with prior cardiac surgery were older (66.4 ± 11.0 years vs. 60.5 ± 13.9 years, p < .01), with lower left ventricular ejection fraction (30.2 ± 11.5% vs. 34.8 ± 13.6%, p < .01) and more ischemic heart disease (82.5% vs. 39.3%, p < .01) but less likely to undergo epicardial mapping or ablation (9.0% vs. 38.1%, p<.01) compared to those without prior surgery. When epicardial mapping was performed, a significantly greater proportion required surgical intervention for access (19/52 [36.5%] vs. 14/504 [2.8%]; p < .01). Procedural complications, including epicardial access-related complications, were lower (5.7% vs. 7.0%, p < .01) in patients with versus without prior cardiac surgery. VT-free survival (75.1% vs. 74.1%, p = .805) and survival (86.5% vs. 87.9%, p = .397) were not different between those with and without prior heart surgery, regardless of etiology of cardiomyopathy. VT recurrence was associated with increased mortality in patients with and without prior cardiac surgery. CONCLUSION: Despite different clinical characteristics and fewer epicardial procedures, the safety and efficacy of VT ablation in patients with prior cardiac surgery is similar to others in this cohort. The incremental yield of epicardial mapping in predominant ischemic cardiomyopathy population prior heart surgery may be low but appears safe in experienced centers.

Stroke and dementia risk in patients with and without atrial fibrillation and carotid arterial disease.

BACKGROUND: Patients with carotid arterial disease (CD) with and without atrial fibrillation (AF) are at risk of stroke. Patients with AF are at a higher risk of stroke and dementia. OBJECTIVES: We sought to understand the risks of stroke, transient ischemic attack (TIA), and dementia in patients with and without AF and CD or a combination of both as well as to determine whether therapies for each disease may influence risks. METHODS: A total of 11,572 patients were included in 4 groups, with 2893 patients populating each group (1: no AF or CD; 2: AF, no CD; 3: CD and no AF; 4: AF and CD) and matched for age, sex, and comorbidities. Long-term outcomes of stroke/TIA and dementia were assessed. Subset analyses of these outcomes were performed in patients with CD treated with revascularization and in patients with AF treated with ablation. RESULTS: CD increased the risk of stroke/TIA (hazard ratio [HR] 2.74; P < .0001) and dementia (HR 1.44; P < .0001). Similarly, AF increased the risk of stroke/TIA (HR 2.08; P < .0001) and dementia (HR 1.30; P = .004). The coexistence of AF and CD further augmented the risk of both end points. CD revascularization was associated with a decreased risk of dementia (HR 0.47; P < .0001) but not stroke. Ablation of AF improved outcomes of stroke/TIA (HR 0.55; P = .002), particularly in those with CD (HR 0.36; P < .0001), and was associated with a reduced risk of dementia (HR 0.51; P = .04). CONCLUSION: CD and AF augment risk of stroke/TIA and dementia in the general population, and the coexistence of both diseases is additive in risk. Ablation of AF was associated with lower risk, the magnitude of which was greater in those with CD.

Partnering with robotic technology in electrophysiology: have we arrived at a tipping point?

PURPOSE OF REVIEW: Bring readers up to date on the rationale for, current state of, and promising innovations in remote and robotic technology in electrophysiology. RECENT FINDINGS: There is a growing peer-reviewed literature regarding existing nontraditional technology for mapping and ablation. There also is accelerated innovation under early evaluation that promises significant impact. SUMMARY: The development and adoption of remote technologies in electrophysiology has faced considerable challenges yet holds tremendous promise for our patients. First principles must include benefit for patients in both safety and effectiveness, optimization of the process for providers, and sound economic and clinical justification for integration into healthcare systems. The limitations of traditional methods and tools that dominate current practice are discussed as a rationale for considering remote robotic systems. The growing library of published outcomes as well as the emergence of promising new technology merits fresh consideration.

Long-term outcomes after low power, slower movement versus high power, faster movement irrigated-tip catheter ablation for atrial fibrillation.

BACKGROUND: High power, shorter duration (HPSD) ablation strategies have been advocated to increase efficacy and minimize posterior wall deep tissue thermal injury during atrial fibrillation (AF) ablation. OBJECTIVE: The purpose of this study was to determine the long-term outcomes of arrhythmia-free survival from AF and atrial flutter (AFL) between HPSD and low power, longer duration (LPLD) ablation strategies. METHODS: Of a total of 1333 first time AF ablation procedures with 3 years of follow-up, propensity-matched populations for baseline risk factors were created, comprising 402 patients treated with LPLD ablation (30 W for 5 seconds: posterior wall; 30 W for 10-20 seconds: anterior wall) and 402 patients treated with HPSD ablation (50 W for 2-3 seconds: posterior wall; 50 W for 5-15 seconds: anterior wall). AF/AFL outcomes after a 90-day blanking period were assessed. RESULTS: HPSD ablation was associated with shorter procedure and fluoroscopy times (P < .0001 for both). The recurrence of AF at 1 year (12.9% vs 16.2%; P = .19) and 3 years (26.5% vs 30.7%; P = .23) was similar between LPLD and HPSD groups. AFL was higher at 1 year (7.2% vs 11.2%; P = .03) and 3 years (16.1% vs 21.8%; P = .06; P = .04 after multivariate adjustment) with HPSD ablation. Patients who underwent an LPLD approach had lower rates of need for repeat ablation (21% vs 30%; P = .002). CONCLUSION: Long-term freedom from AF rates were not significantly different between both approaches. An HPSD ablation strategy compared with an LPLD approach was associated with an increased risk of AFL and need for repeat ablation but with lowered procedure times.

The Impact of Repeated Cardioversions for Atrial Fibrillation on Stroke, Hospitalizations, and Catheter Ablation Outcomes.

BACKGROUND: Long-term outcomes after direct current cardioversion (DCCV) in patients that receive anticoagulation have demonstrated to have no adverse sequela. Less is known about the impact on atrial fibrillation (AF) outcomes and resource utilization of repeated DCCVs that are often required for long-term rhythm control. METHODS: A total of 4,135 AF patients >18 years of age that underwent DCCV with long-term system follow-up were evaluated. Patients were stratified by the number of DCCVs received: 1 (n=2,201), 2-4 (n=1,748), and ≥5 (n=186). Multivariable Cox hazard regression was used to determine the association of DCCV categories to the outcomes of death, AF hospitalization, AF ablation, DCCVs, and stroke/transient ischemic attack. RESULTS: The average follow-up of the patient population was 1,633.1±1,232.9 (median: 1,438.0) days. Patients who underwent 2-4 and ≥5 DCCVs had more comorbidities, namely hypertension, hyperlipidemia and heart failure. Anticoagulation use was common at the time of DCCV in all groups (89.1%, 91.2%, 91.9%, p=0.06) and amiodarone use increased with increasing DCCV category (30.1%, 43.4%, 52.2, p<0.0001). At 5 years, patients that received more DCCVs had higher rates of repeat DCCVs, AF hospitalizations, and ablations. Stroke rates were not increased. Though not statistically significant, 5-year death was increased when comparing DCCV >5 vs. 1, (HR=1.32 [0.89-1.94], p=0.17). CONCLUSIONS: This study found that the increasing number of DCCVs, despite escalation of other pharmacologic and nonpharmacologic therapies, is a long-term independent risk factor for repeat DCCVs, ablations, and AF hospitalizations among AF patients.