Coronary artery anomalies have been reported as a frequent cause of sudden cardiac death in young athletes following cardiomyopathies and channelopathies. To recognize anomalous coronary artery as a cause of sudden cardiac arrest in a structurally normal heart. N/A A 40-year-old endurance athlete with history of recurrent exertional syncope presented with wide complex tachycardia. Baseline ECG was within normal limits. An echocardiogram revealed normal biventricular function. A cardiac MRI demonstrated inferior right ventricular (RV) epicardial scarring. EP study showed easily inducible sustained monomorphic ventricular tachycardia (VT) with left bundle branch morphology and left superior axis. An anomalous right coronary artery was revealed by a CT-angiogram with slit-like origin above the commissure of the left and right aortic cusps, coursing between the aorta and the pulmonary artery. Cardiopulmonary bypass was performed, with marsupialization of the anomalous right coronary artery followed by epicardial mapping. Multiple late fractionated signals were mapped to a pale area overlying the inferior RV and cryoablation lesions were delivered. On repeat EP study, VT was no longer inducible despite aggressive programmed stimulation. Implantable cardiac monitor demonstrated no further arrhythmic events during one year follow up. Repeated ischemic insults from anomalous right coronary artery can lead to myocardial fibrosis and the generation of arrhythmic substrate. Recognition and management of this substrate with ablation and correction of the inciting coronary anomaly can prevent malignant cardiac arrhythmia.

Most Idiopathic VT originate from ventricular outflow tracts, the mitral and tricuspid annulus, the papillary muscles, the moderator band and Purkinje-Fascicular network. Idiopathic cardiac crux VT is a rare phenomenon.

Cardiac denervation, allograft rejection and vasculopathy increase the risk of cardiac arrhythmias and pose management challenges in a heart transplant patient. To discuss the management of atrial arrhythmia in a transplanted heart. N/A A 71-year-old Caucasian woman with a history of orthotopic heart transplant in 2001, paroxysmal atrial fibrillation, and transplant vasculopathy status post left circumflex artery stent presented with palpitations. External monitoring revealed supraventricular tachycardia. Twelve lead ECG confirmed an atrial flutter with variable block. Echocardiography showed normal ventricular function. Cardiac biopsy showed focal moderate cellular allograft rejection. Left heart catheterization did not show significant coronary obstruction. The finding of graft rejection prompted commencement of steroids. Following steroid therapy, repeat biopsy was negative for rejection; however, atrial arrhythmia persisted requiring multiple cardioversions. Antiarrhythmic drug therapy caused intolerable side effects. An electrophysiology study revealed atypical mitral flutter in the donor atria. Catheter ablation of the anterior mitral line terminated the flutter. Allograft rejection causes inflammation and fibrosis leading to slowing of conduction in the atria forming the substrate for intra-atrial arrhythmia. Bi-atrial anastomosis might have increased the risk of transmitral flutter in the donor heart. Catheter ablation should be considered for late onset atrial arrhythmia in transplant patients.

Introduction: LBBB results in impaired transseptal conduction and delayed posterolateral LV activation. Criteria for left bundle branch block (LBBB) vary across scientific organizations. Septal myectomy for hypertrophic cardiomyopathy (HCM) could serve as an iatrogenic anatomic model to characterize LBBB. Objective: To describe ECG features of LBBB after septal myectomy for HCM. Methods: ECG data were analyzed for 377 HCM patients (204 male) who developed post-operative LBBB after extended septal myectomy between 2004-2018. Results: Average age of the cohort at myectomy was 53 ± 14 years. Baseline QRS duration (QRSd) was 94 ± 10ms. The post myectomy QRSd was 152 ± 15ms, consistent with an average ΔQRSd of 58 ± 13ms. There was positive correlation between pre and post myectomy QRSd (r = 0.485; p < 0.0001). The average LV end-diastolic diameter (LVEDd) pre and 2 months post myectomy was 40 ± 5.6mm and 46.2 ± 6.5mm, respectively. Positive correlation between post myectomy QRSd and post myectomy LVEDd was also observed (r = 0.340; p < 0.0001). Females and males had pre myectomy QRSd of 93 ± 10ms and 95 ± 10ms respectively (p = 0.007) and post myectomy QRSd of 147 ± 13ms (120-184ms) and 157 ± 14ms (126-209ms) respectively (p < 0.0001). ΔQRSd was less in females than males (54 ± 13ms vs. 62 ± 11ms; p<0.0001). Only 13 females and 3 males had post myectomy QRSd < 130ms. Only 23 males had QRSd < 140ms. Conclusions: Surgical myectomy serves as a model to characterize LBBB. Following myectomy, QRSd correlated with LVEDd as well as pre-myectomy QRSd, and was longer in males due to delayed depolarization of larger hearts in men. Notably only 3 males and a minority of females had QRSd < 130ms. These data provide important insights for the validation of electrocardiographic LBBB criteria.

Introduction: Subcutaneous implantable cardioverter defibrillators (SICD) are an attractive option for sudden death (SCD) prevention in younger hypertrophic cardiomyopathy (HCM) patients. Conversely, SICDs have higher rate of inappropriate shock (IAS) when compared to transvenous devices. Objective: We characterize incidence of appropriate shock (AS) and IAS and analyze predictors of IAS in HCM SICD patients. Methods: Data was collected from HCM SICD patients from 2013 to 2021. We used multivariable logistic regression to assess for predictors of IAS in patients with > 6 mo follow up. Results: 94 HCM patients (age 47 ± 15 years) underwent SICD implant with mean follow up of 3.7 ± 2.0 year. Maximal LV thickness 20.5 ± 5.8 mm with massive hypertrophy (> 30 mm) in 10 patients (11.8%). Initial DFT with 65J was successful in 88 patients, with 5 more successful after device adjustment. 5 patients (5.9%) had 10 AS (3.2 AS per 100 pt-years). 10 patients (11.8%) had 19 IAS (6.0 IAS per 100 pt-years) due to T wave oversensing (n = 13), P wave oversensing (n = 2), atrial arrhythmia (n=2), and external noise (n = 1). IAS rate decreased over time, with IAS occurring in 8 patients of the initial half of the cohort and in only 2 of the second half. Time to IAS from implant was 11 ± 10.8 mo. QRS duration (OR 1.025, 95% CI 0.997-1.053; P = 0.084) showed trend to prediction of IAS, but no characteristic proved independently significant. Conclusions: This data adds to increasing evidence that in high-risk HCM patients, SICD represents a reliable treatment option for SCD prevention. IAS mainly due to cardiac oversensing, was seen in 11.8% of patients within this HCM cohort. IAS decreased over time, possibly due to improved patient selection, implant technique and device programming (SMART pass filter). A larger dataset is likely necessary to better understand this trend.

Introduction: Defibrillation threshold testing (DFT) is generally reserved for populations with perceived concern for defibrillation failure, including in hypertrophic cardiomyopathy (HCM). Higher shock impedance has been associated with risk of DFT failure with subcutaneous defibrillators (SICD). The PRAETORIAN score is a chest radiograph based tool that evaluates device positioning to predict risk of DFT failure. Objective: We assessed predictors of impedance during DFT in a single center HCM SICD cohort. Methods: Data was collected from HCM patients who underwent SICD implantation from 2013 to 2021. Predictors of impedance were evaluated with linear and logistic regression. Results: Impedance was reported in 75 HCM SICD patients during DFT with 65J. DFT was successful in 74 patients with mean impedance of 72.7 ohm and septal thickness of 20.6 mm. Ten patients had massive HCM (> 30 mm) with mean impedance of 66.4 ohm. Septal thickness was not predictive of impedance (β 0.37, 95% CI 1.24-0.50; P = .40). Independent predictors of impedance were BMI (β 1.41, 95% CI 0.61-2.21; P = .0008) and PRAETORIAN score (β 0.14, 95% CI 0.05-0.22; P = .0015). Multivariable regression revealed BMI no longer significant and PRAETORIAN score remaining significant (β 0.10, 95% CI 0.01-1.66; P = .038). Conclusion: In this HCM SICD cohort BMI and PRAETORIAN score were predictive of impedance. However, in a multivariable model, BMI was no longer predictive, highlighting importance of implant technique to improve impedance and DFT. Additionally, patients with massive hypertrophy all had successful DFT and septal thickness was not predictive of impedance. HCM has historically been portrayed as a high DFT population. Further prospective trials are necessary to establish whether standard DFT practice can be applied in HCM.

Patients with hypertrophic cardiomyopathy (HC) may require higher energies to terminate ventricular fibrillation (VF); thus, dual coil defibrillation leads are often implanted. However, single coil leads may be preferred in young patients. All patients with HCM implanted with a transvenous ICD from years 2000 to 2014 were included. Of 249 patients, 223 underwent VF testing including 150 with a dual coil lead and 73 a single coil. Patients tested with dual coil compared with single coil had lower successful VF energies (15.7 +/- 6.1 joule to 20.2 +/- 7.9 joule (p <0.0001)). Adequate safety margin for defibrillation was noted in 97.3% of patients. Notably, 6 (4 with single coil leads) had inadequate safety margins (defined as >= 10 joule). Three of these 6 patients required replacement of a single coil lead with a dual coil lead. The remaining 3 underwent waveform tilt alteration, higher energy ICD, or removal of the can from the shock vector. There were no clinical or implant predictors of inadequate safety margins. In follow-up of 16 +/- 30 months (range 0 to 170), there were 24 arrhythmias including 13 VF, all successfully terminated. In conclusion, in HC patients undergoing ICD implantation, single coil leads can provide adequate safety margins. In conclusion, defibrillation testing should be considered in all HC patients undergoing ICD implantation, and should be performed in those undergoing implantation with a single coil lead. (C) 2020 Elsevier Inc. All rights reserved.

The transvenous implantable cardioverter-defibrillator (ICD) experience in hypertrophic cardiomyopathy (HCM) now spans 20 years of reliably terminating potentially lethal ventricular tachyarrhythmia ([1][1]), and along with a matured sudden death risk stratification strategy, has resulted in

Serious cardiovascular adverse events (SCAEs) associated with intravenous sedatives remain poorly characterized.

The wearable cardioverter defibrillator has been shown to be effective in terminating ventricular arrhythmias in patients at risk for sudden cardiac death. There are numerous scenarios in which implant of a permanent implantable cardioverter defibrillator is temporarily contraindicated or not advisable and a wearable cardioverter defibrillator may be beneficial. There are no prospective randomized studies published that provide conclusive guidance toward the use of the wearable cardioverter defibrillator, and thus, patient management needs to be individualized based on the available data.

His bundle pacing (HBP) has recently emerged as a technique to avoid the negative effects of long-term right ventricular apical pacing. In addition to providing physiologic ventricular activation, HBP has been shown to correct underlying conduction abnormalities in certain patients. Although large prospective, randomized clinical trials have not yet been completed, the available observational clinical data support the safety and efficacy of this technique. Here, we review the physiology of the his bundle (HB) as it relates to HBP, describe the current clinical experience, and discuss future directions of this emerging therapy.

The rate of cardiac implantable electronic device (CIED) infection has increased disproportionately to the rate of implantation. Expanded indications for CIED implantation combined with a sicker patient population contribute to this increased rate. Device-related infections are most commonly due to perioperative contamination, and infection risk increases in conjunction with procedural complexity. Early pocket re-exploration and upgrade procedures confer a higher infectious risk. Confirmed CIED infection requires prompt removal of the CIED system combined with antimicrobial therapy. Understanding the risks of CIED infection and using preventive measures are critical. It is hoped that emerging technologies will mitigate CIED infection rates.

Ventricular Arrhythmias in HCMIntroductionTriggers and ICD interventions of ventricular arrhythmias in patients with hypertrophic cardiomyopathy (HCM) offer insight into mechanisms and treatment.Methods and ResultsIntracardiac ICD electrograms from 71 HCM patients in the HCM I and II studies were analyzed by three individuals. Rhythms were defined as VF (polymorphic ventricular arrhythmia), VT (monomorphic ventricular tachycardia), and ventricular flutter (VFL; VT ≥ 240 bpm). Physical activity and rhythm preceding the arrhythmia were ascertained. Of 149 arrhythmias, VF was present in 74, VT in 57, and VFL in 18. In those whose activity was known, moderate or intense physical activity was associated with over 50% of the tachycardias (57 of 111). Rhythms preceding ventricular arrhythmias were often sinus tachycardia (49 of 149; 33%) or rapid atrial fibrillation (7 of 149; 5%). VF and VFL were more likely preceded by supraventricular rhythms >100 bpm (30 of 68 with VF; 44%; 12 of 16 with VFL 75%, vs. 14 of 50 with VT 28%; P = 0.001). Antitachycardia pacing (ATP) was successful in 39 of 53 (74%). Multiple shocks were more often required to terminate VFL (10 of 18; 56%) compared to VF (10 of 72; 14%) and VT (2 of 25; 8%; P < 0.0001). Of arrhythmias requiring more than one shock to terminate, 16 of 22 were preceded by sinus tachycardia and/or moderate or extreme physical activity.ConclusionsRapid supraventricular rhythms, and at least moderate activity, frequently precede VT and VF, and when they occur in these situations often require multiple ICD shocks to restore sinus rhythm. ATP is successful in terminating VT and VFL, and should be a programmed in all HCM patients with ICDs.

Background The subcutaneous implantable cardioverter defibrillator (S‐ICD) has been developed to avert risks associated with transvenous defibrillator leads. The technology is attractive for younger patients, such as those with hypertrophic cardiomyopathy (HCM). However, there are limited data on S‐ICD use in HCM. Methods and Results HCM patients identified at risk for sudden death were considered for S‐ICD implantation. Patients were screened for potential oversensing by surface electrocardiography (ECG). At implant, defibrillation threshold (DFT) testing was performed at 65, 50, and 35 joules (J). Twenty‐seven patients were considered for S‐ICD implantation, and after screening, 23 (85%) remained eligible. The presence of a bundle branch block was associated with screening failure, whereas elevated body mass index (BMI) showed a trend toward association. One patient passed screening at rest, but failed with an ECG obtained after exercise. At implant, the S‐ICD terminated ventricular fibrillation (VF) with a 65J shock in all 15 implanted patients and a 50J shock was successful in 12 of 15. A 35J shock terminated VF in 10 of 12 patients. DFT failure at 50 J was associated with a higher BMI. There were no appropriate shocks after a median follow‐up of 17.5 (3–35) months, and 1 patient received an inappropriate shock attributable to a temporary reduction in QRS amplitude while bending forward, resulting in oversensing, despite successful screening. Conclusions In a high‐risk HCM cohort without a pacing indication referred for consideration of an ICD, the majority were eligible for S‐ICD. The S‐ICD is effective at recognizing and terminating VF at implant with a wide safety margin.

Objective: Commotio cordis, sudden death with chest impact, occurs clinically despite chest wall protectors worn in sports. In an experimental model of commotio cordis, commercially available chest wall protectors failed to prevent ventricular fibrillation (VF). The goal of the current investigation was to develop a chest wall protector effective in the prevention of commotio cordis. Design: In the Tufts experimental model of commotio cordis the ability of chest protectors to prevent VF was assessed. Impacts were delivered with a 40-mph lacrosse ball, timed to the vulnerable period for VF. Intervention: A chest wall protector or no chest wall protector (control) was randomly assigned to be placed over the chest. Four iterative series of 2 to 4 different chest wall material combinations were assessed. Materials included 3 different foams (Accelleron [Unequal Technologies, Glen Mills, PA], closed cell high density foam; Airilon [Unequal Technologies, Glen Mills, PA], closed cell low density soft foam; and an open cell memory foam) that were adhered to a layer of TriDur (Unequal Technologies, Glen Mills, PA), a flexible elastomeric coated aramid that was bonded to a semirigid polypropylene polymer (ImpacShield, Unequal Technologies, Glen Mills, PA). Main Outcome Measure: Induction of VF by chest wall impact was the primary outcome. Results: Of 80 impacts without chest protectors, 43 (54%) resulted in VF. Ventricular fibrillation with chest protectors ranged from a high of 60% to a low of 5%. Of 12 chest protectors assessed, only 3 significantly lowered the risk of VF compared with impacts without chest protectors. These 3 chest protectors were combinations of Accelleron, Airilon, TriDur, and ImpacShield of different thicknesses. Protection increased linearly with the thicker combinations. Conclusions: Effective protection against VF with chest wall protection can be achieved in an experimental model of commotio cordis. Clinical Relevance: Chest protector designs incorporating these novel materials will likely be effective in the prevention of commotio cordis on the playing field.

In September 2012, the United Stated Food and Drug Administration approved the use of a fully subcutaneous implantable cardiac defibrillator (S-ICD, Boston Scientific Inc). The device is implanted in the left midaxillary space and attached to a single lead that is tunneled subcutaneously from the xyphoid process in 2 directions, superiorly to the sternal manubrium joint to the left of the sternum and laterally to the pulse generator. The lead consists of a single coil in the portion of lead along the sternum and 2 sensing electrodes, 1 at the tip of the lead at the upper portion of the sternum and 1 at the xyphoid process.