Kapa, Suraj

Research ObjectiveAn artificial intelligence (AI) algorithm based on ECG was integrated into clinical workflows to identify patients with a high likelihood of low ejection (EF), a condition that is underdiagnosed but treatable. The trial aimed to assess whether the AI‐powered clinical decision support enabled early diagnosis of low EF.Study DesignA pragmatic, cluster randomized controlled trial (RCT) was conducted in 45 primary care practices, including an academic medical center as well as community and rural clinics across Minnesota and Wisconsin. A total of 120 primary care teams, including 358 clinicians, were randomized to either intervention (access to AI results with positive results indicating a high likelihood of low EF; 181 clinicians) or control (usual care; 177 clinicians). The primary endpoint was a new diagnosis of EF≤50% within 90 days. A positive deviance qualitative study and a survey were used to assess implementation strategies.Population StudiedIn total, 22,641 adult patients (N = 11,573 intervention; N = 11,068 control) with ECG performed as part of routine care between 8/5/2019 and 3/31/2020 were included. Patients were excluded if they had known EF≤50% or a history of documented heart failure (HF) identified by clinical notes abstracted by natural language processing.Principal FindingsThe mean age of patients was 60.5 ± 17.6 years; 53.9% were women. Positive AI results were found in 6.0% of patients in both arms. Clinicians in the intervention group obtained more echocardiograms for patients with positive results (38.1% control vs. 49.6% intervention, p < 0.001), but in the overall cohort, the echocardiogram utilization was similar (18.2% vs. 19.2%, p = 0.17). The intervention increased the diagnosis of low EF in the overall cohort (1.6% vs. 2.1%, odds ratio [OR] 1.32 [1.01–1.61], p = 0.007) and among patients with positive results (14.5% vs. 19.5% OR 1.43 [1.08–1.91], p = 0.01). Results using different thresholds for low EF were consistent with the primary result. Among patients with positive results, the intervention increased echocardiography more significantly in women vs. men (p for interaction 0.02), in patients without prior echocardiogram vs. those with prior echocardiogram (p for interaction 0.04), and in patients whose ECGs were ordered in outpatient clinics (p for interaction 0.02).ConclusionsAn AI algorithm run on existing ECGs enabled the early diagnosis of low EF in a large cohort of patients managed in routine primary care practices. Because ECG is a low‐cost test frequently performed for a variety of purposes, the algorithm could improve early diagnosis and treatment of a condition that is often asymptomatic but has effective treatments, and thus, reduce the disease burden in broad populations.Implications for Policy or PracticeThe current study is one of the first RCTs that demonstrated the value of AI in routine practice. Low EF confers an increased risk of HF progression and mortality. Although there are effective therapies, low EF is undiagnosed, leading to missed opportunities for treatment. EF can be readily determined by echocardiography, but the imagining test is too resource‐intensive to screen unselected populations. The AI applied to the existing ECGs could identify high‐risk patients for further assessment.Primary Funding SourceMayo Clinic.

AbstractObjectiveEndomyocardial biopsy (EMB) is a useful diagnostic tool though the yield may be limited in many myocardial diseases. Data on the diagnostic yield and prognostic significance of EMB guided by abnormal electrograms (EGM‐Bx) in suspected cardiac sarcoidosis (CS) are scarce.MethodsSeventy‐nine patients (mean age: 56 ± 12 years; 61% men) with suspected CS based on clinical and imaging features underwent right or left ventricular EGM‐Bx guided by electroanatomic mapping. Tissue samples were obtained from sites with abnormal EGMs and/or abnormal cardiac imaging. The diagnostic yield of EGM‐Bx was evaluated in reference to histopathologic analysis. Left ventricular assist device (LVAD) and transplantation‐free survival were compared between patients with positive and negative EGM‐Bx for CS.ResultsA total of 254 samples were obtained from abnormal EGM sites, and 126 samples from normal EGM sites guided by pre‐procedure imaging findings. Abnormal histopathology was noted in 65 (26%) and 10 (8%) samples from abnormal and normal EGM sites, respectively. Histopathology confirmed CS in 16 (20%) patients, while an alternative tissue diagnosis emerged in 10 (13%) patients. Abnormal EGMs at the biopsy site had sensitivity 89% and specificity 33% for a histopathologic diagnosis of CS. LVAD and transplantation‐free survival were not significantly associated with the EGM‐Bx result (log‐rank p = .91).ConclusionIn patients with suspected CS, abnormal EGM‐Bx has high sensitivity and low specificity for establishing a definite CS diagnosis. Consideration of substrate abnormalities apparent on preprocedural imaging as an adjunct for selection of biopsy sites may further improve EGM‐Bx yield.

AbstractBackgroundLocal impedance (LI) drop measured with microfidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15–30 Ω LI drops created successful lesions, while more than 40 Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI‐guided ablation using standard (30 W) and high‐power (50 W) in a preclinical model.MethodsRF lesions were created in explanted swine hearts (n = 6) to assess the feasibility of LI‐guided ablation by targeting 10, 20, or 30 Ω (n = 20/group) drops. Subsequently, LI‐guided ablation was evaluated in a chronic animal model (n = 8 Canines, 25–29 kg, 30/50 W). During the index procedure point‐by‐point intercaval line ablation and left inferior pulmonary vein (PV) isolation were performed. RF duration was at the operators’ discretion but discontinued early if a 15–30 Ω drop was achieved. Operators attempted to avoid LI drops of more than 40 Ω. At 1‐month, durable conduction block was evaluated with electroanatomic mapping followed by necropsy and histopathology.ResultsIn explanted tissue, terminating ablation at 10, 20, or 30 Ω LI drops created statistically larger lesions (p < .05; 1.8 [1.6–2.4] mm, 3.3 [3.0–3.7] mm; 4.9 [4.3–5.5] mm). LI‐guided high‐power ablation in vivo significantly reduced RF duration per application compared to standard‐power (p < .05; intercaval: 8.9 ± 5.2 vs. 18.1 ± 11.0 s, PV: 9.6 ± 5.4 vs. 23.2 ± 10.3 s). LI drops of 15–40 Ω were more readily achievable for high‐power (90.1%, 318/353) than standard‐power (71.7%, 243/339). All intercaval lines and PV isolations were durable (16/16) at 1‐month. Necropsy revealed no major collateral injury to the pericardium, phrenic nerve, esophagus, or lungs. There was no pericardial effusion, stroke, tamponade, or PV stenosis. Vagal nerve injury was found in two 30 W animals after using 19.7 ± 13.9 and 19.5 ± 11.8 s RF applications.ConclusionLI‐guided ablation was found to be safe and efficacious in a chronic animal model. High‐power ablation more readily achieved more than 15 Ω drops, reduced RF duration compared with standard‐power, and had no major RF collateral injury.

Background: The use of direct current electroporation has the potential for significant utility because of its non-thermal approach to tissue destruction. However, the fear of inducibility of cardiac arrhythmias (particular ventricular fibrillation) when using electroporation remains of concern due to membrane poration and ion flux during periods of vulnerability occurring in ventricular repolarization. Objectives: Critically examine the incidence of arrhythmias in a series of acute canine studies to retrospectively determine cause and safe electoporative dosing margins. Methods: We performed electroporation ablation in 6 acute canine studies. These were experimental studies performed at sites critical in arrhytmogenesis. Sites included the pulmonary veins, left atrial appendage, superior vena cavae, right atrium and ventricle. Electroporation was delivered using an ECG gating algorithm so that QRS complexes are tagged and direct current energy is not delivered during the vulnerable portion of the T wave. Results: In 6 acute canine experiments, we delivered a total of 62 electroporation applications for ablation purposes. The average electroporation dosage delivered involved an average of 1427 Volts (range 750-3000 V), Pulse length of 100 ms, and number of pulses of 20.2 (range 10-100). AF was induced in 27.4% of electroporiatve applications. Atrial flutter/tachycardia occurred in 8.1%. VF occurred in only one application at a location of the left superior pulmonary vein. Conclusion: These data suggest that induction of VF is relatively uncommon with ECG gating and highlight its importance when using this modality. However, the induction of AF occurs with higher frequency. The actual mechanism as to why this occurs requires further systematic study.

Introduction: Although the vast majority of mitral valve prolapse (MVP) is benign, women with bileaflet MVP (biMVP), complex ventricular ectopy (VE), and abnormal T waves may comprise the recently described malignant biMVP syndrome. The mechanism of ventricular arrhythmia is unknown. To further characterize the arrhythmic substrate, we reviewed our center’s ablation experience in 6 biMVP patients with prior cardiac arrest and recurrent ICD shocks for drug refractory ventricular fibrillation (VF). Methods and Results: Six women with biMVP (median age 31.5 [range 24.2 - 58.7] years, EF 65 [45 - 67]%, all ≤moderate mitral regurgitation) experienced 6 (3 - 25) appropriate ICD shocks over 4.8 (2.8 - 10.7) years and underwent index ablation between 2/2007 - 10/2013. All had multiple VE morphologies (median 7 [3 - 24]) with variable coupling intervals but with a predominant VE trigger for the VF. A median 2 (1 - 4) VE foci were ablated. Sites of successful ablation of VF-triggering and other dominant VE were left ventricular papillary muscles [PM] (1 anterior, 1 posterior, 1 both), fascicles (1 anterior, 1 posterior), or both (1 both PM and posterior fascicle). Outflow tract VE was also present and targeted (1 left, 1 right)i. Two underwent repeat ablation (288 and 312 days) for recurrent complex VE without shocks, with different foci to the index ablation (1 posterior fascicle, 1 both fascicles). The VF-triggering VE in all patients was confirmed as originating from within the left fascicular system, which in 3/6 was at a papillary muscle. Acute procedural success was seen in all with no complications to date. A VF storm occurred within 24 hours of ablation in a single patient. At follow-up of a mean 662 (47 - 2099) days, 1 patient received a single shock (p=0.03 vs. preablation). Symptomatic VE was reduced in all; while 3/6 continue Class 1c antiarrhythmics and 5/6 have beta blockade. Conclusion: Malignant biMVP syndrome is characterized by fascicular and papillary muscle PVCs that trigger ventricular fibrillation, yet in all patients, the VE is multifocal. Ablation of at least one focus appears to improve symptoms and reduce shocks.

Determining whether retrograde ventriculoatrial (VA) conduction is through the AV node (AVN) or an accessory pathway (AP) is critical for successful ablation of supraventricular tachycardia (SVT). With introduction of ventricular extrastimuli (VEST), retrograde right bundle branch block (retro RBBB) may occur and result in abrupt VH interval prolongation. We hypothesized when retrograde conduction is via an AP, VA interval change is less than VH interval change, whereas with retrograde AVN conduction, VA interval change is equal to or greater than VH interval change. We retrospectively reviewed the electrophysiology (EP) studies of patients undergoing ablation for AVNRT (n=55) or AVRT (n=50). The intracardiac electrograms were reviewed for induction of retro RBBB and change in VH and VA intervals during VEST. Parahisian pacing, decremental pacing, arrhythmia diagnosis and ablation outcomes were reviewed. All results were found to be reproducible between two independent observers with inter and intra observer reliability scores of 1.00 for identification of retro RBBB and greater than 0.85 for measurement of VH and VA intervals. Of 105 patients, 84 (80%) had evidence of induced retro RBBB during VEST. The average VH interval increase with induction of retro RBBB was 53.7 ms for patients with retrograde AP conduction and 54.4 ms for patients with AVN conduction (p=ns). The average VA interval increase with induction of retro RBBB was 13.6 ms with AP conduction and 70.1 ms with AVN conduction (P < 0.001). All patients with a greater VH than VA interval change had a final diagnosis of AVRT and those with a VH change less than VA change had AVNRT, yielding sensitivity and specificity of 100%. Using a cutoff of 50 ms for change in VA interval with onset of retro RBBB to diagnose AVNRT accurately identified AVNRT in 100% and AVRT in 95%. Induction of retro RBBB during VEST is common during EP studies for SVT. The relative change in the VH and VA intervals during retro RBBB accurately differentiates retrograde AVN from retrograde AP conduction with strong predictive accuracy. The use of retro RBBB based intervals is a useful technique facilitating the diagnosis of SVT in the EP laboratory, even in the absence of inducible tachycardia.

Introduction: Endovascular procedures are traditionally performed for a variety of indications. However, guidewire/catheter manipulation and hazardous radiation exposure are limitations to manual interventions. Thus, significant work has been done to develop robotic approaches to therapies. These devices have FDA clearance for performing procedures like cardiac arrhythmias, angioplasty, aneurysm repair and stenting etc. With the increasing usage of robotic assistance in endovascular procedures, it is essential to understand the adverse events that may occur. This study aims to provide an understanding of adverse events with currently available robotic systems. Methods: The analysis of adverse events is performed with the FDA MAUDE (Manufacturer and User Facility Device Experience) database. MAUDE database is a collection of reports on medical devices reported by manufacturers, distributors, users, volunteers. In case of occurrence of adverse events, FDA regulations requires that event to be reported for further investigation. Based on the impact of events on the patient’s outcome, the reported events were grouped into 3 categories death (patient death), injury (patient injury) or device malfunction. Results: A total of 71 different events were reported collectively for all the four robotic devices (Hansen Medical- 37, Corindus Inc.-27, Stereotaxis Inc.-5 & Catheter Robotics Inc.-2). The major adverse events included death and common injuries such as perforation, pseudo-aneurysm / blockage/ tamponade/ clot, blood pressure dropped or an effusion, or hemodynamic instability. The table summarizes the events by brand of system. Conclusions: While robotic approaches to intervention reflect a potentially useful means to improve outcomes of endovascular procedures by optimizing catheter manipulation with finer robotic motions or limiting radiation exposure, there are potentially significant risks. Whether these reflect higher or lower risk than traditional manual approaches requires randomized studies. Use of robotic technologies may present additional risks in light of potential malfunctions that occur from system errors that a human system may not be prone to. Future studies will be needed to better understand incremental benefit.

Background: Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation following MVS is limited.) CA can be challenging given perivalvular substrate in the setting of mitral annuloplasty or prosthetic valves. Objective: To investigate the characteristics, safety, and outcomes of radiofrequency catheter ablation (CA) in patients with prior mitral valve surgery (MVS) and ventricular arrhythmias (VA). Methods: We identified consecutive patients with prior MVS who underwent CA for VT or PVC between January 2013- December 2018. We investigated the mechanism of arrhythmia, ablation approach, peri-operative complications, and outcomes. Results: In our cohort of 31 patients (77% men, mean age 62.3±10.8 years, left ventricular ejection fraction 39.2±13.9%) with prior MVS underwent CA (16 VT; 15 PVC). Access to the left ventricle was via transseptal approach in 17 patients, and a retrograde aortic approach was used in 13 patients. A combined transseptal and retrograde aortic approach was used in one patient, and a percutaneous epicardial approach was combined with trans-septal approach in 1patient. Heterogenous scar regions were present in 94% of VT patients and scar-related reentry was the dominant mechanism of VT. Clinical VA substrates involved the peri-mitral area in 6 patients with VT and 5 patients with PVC ablation. No procedure-related complications were reported. The overall recurrence-free rate at 1-year was 72.2%; 67% in the VT group and 78% in the PVC group. No arrhythmia-related death was documented on long-term follow-up. Conclusion: CA of VAs can be performed safely and effectively in patients with MVS