Subcutaneous Implantable Cardioverter-defibrillator Explantation-A Single Tertiary Center Experience.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. The objective of this study was to assess the incidence and indications for S-ICD explantation at a large tertiary referral center. We conducted a retrospective study of all S-ICD explantations performed from 2014-2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation were collected. A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution, of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7 ± 20.1 months. The mean age of the patients at explantation was 44.8 ± 15.3 years, and 42% (n = 27) were women. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of patients, respectively. The most common reason for explantation was infection (32.8%), followed by abnormal sensing (25%) and the need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7 ± 13.6 vs. 42.3 ± 14.6 years, P = 0.005) with a wider QRS duration (111 ± 19 vs. 98 ± 19 ms, P = 0.03) at device implantation compared to patients who underwent explantation for other indications. The incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for one-third of the explantations, a significant number of explantations were due to sensing abnormalities and the need for pacing. These data may have implications for patient selection for S-ICD implantation.

Effect of Transcutaneous Magnetic Stimulation in Patients With Ventricular Tachycardia Storm: A Randomized Clinical Trial.

IMPORTANCE: Autonomic neuromodulation provides therapeutic benefit in ventricular tachycardia (VT) storm. Transcutaneous magnetic stimulation (TcMS) can noninvasively and nondestructively modulate a patient's nervous system activity and may reduce VT burden in patients with VT storm. OBJECTIVE: To evaluate the safety and efficacy of TcMS of the left stellate ganglion for patients with VT storm. DESIGN, SETTING, AND PARTICIPANTS: This double-blind, sham-controlled randomized clinical trial took place at a single tertiary referral center between August 2019 and July 2021. The study included 26 adult patients with 3 or more episodes of VT in 24 hours. INTERVENTIONS: Patients were randomly assigned to receive a single session of either TcMS that targeted the left stellate ganglion (n = 14) or sham stimulation (n = 12). MAIN OUTCOMES AND MEASURES: The primary outcome was freedom from VT in the 24-hour period following randomization. Key secondary outcomes included safety of TcMS on cardiac implantable electronic devices, as well as burden of VT in the 72-hour period following randomization. RESULTS: Among 26 patients (mean [SD] age, 64 [13] years; 20 [77%] male), a mean (SD) of 12.7 (10.3) episodes of VT occurred within the 24 hours preceding randomization. Patients had recurrent VT despite taking a mean (SD) of 2.0 (0.6) antiarrhythmic drugs (AADs), and 11 patients (42%) required mechanical hemodynamic support at the time of randomization. In the 24-hour period after randomization, VT recurred in 4 of 14 patients (29% [SD 47%]) in the TcMS group vs 7 of 12 patients (58% [SD 51%]) in the sham group (P = .20). In the 72-hour period after randomization, patients in the TcMS group had a mean (SD) of 4.5 (7.2) episodes of VT vs 10.7 (13.8) in the sham group (incidence rate ratio, 0.42; P < .001). Patients in the TcMS group were taking fewer AADs 24 hours after randomization compared with baseline (mean [SD], 0.9 [0.8] vs 1.8 [0.4]; P = .001), whereas there was no difference in the number of AADs taken for the sham group (mean [SD], 2.3 [0.8] vs 1.9 [0.5]; P = .20). None of the 7 patients in the TcMS group with a cardiac implantable electronic device had clinically significant effects on device function. CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, findings support the potential for TcMS to safely reduce the burden of VT in the setting of VT storm in patients with and without cardiac implantable electronic devices and inform the design of future trials to further investigate this novel treatment approach. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04043312.

Supraventricular Tachycardia: In Search of an Underlying Mechanism.

A 12-lead electrocardiogram of a regular narrow complex tachycardia with electrocardiographic characteristics used to help elucidate the arrhythmia mechanism. (Level of Difficulty: Intermediate.).

A left ventricular assist device interfering with leadless pacemaker implantation.

Left ventricular assist devices (LVAD) produce electromagnetic interference (EMI) which can have implications when patients require cardiac implantable electronic devices. Leadless pacemakers have been successfully implanted in patients with Heartmate 2 and Heartmate 3 LVADs without evidence of EMI or device-to-device interaction. Here we report a case of a Heartmate 3 LVAD and Micra VR transcatheter pacing system interaction requiring device repositioning.

An unusual tachycardia - Tale of a hidden P wave.

Traditional rules of arrhythmia mechanisms may not apply in altered anatomical states such as heart transplantation. We present a case of a young man presenting with incessant tachycardia that violates routine electrocardiographic criteria for rhythm analysis. Meticulous attention to surgical techniques and anastomotic sites is crucial when approaching post-operative arrhythmias.

Substrate Characterization and Outcomes of Ventricular Tachycardia Ablation in TTN (Titin) Cardiomyopathy: A Multicenter Study.

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Feasibility of "natural surface" epicardial mapping from the pulmonary artery for management of atrial arrhythmias.

BACKGROUND: The right and left pulmonary artery branches (RPA, LPA) overlie inaccessible left atrial (LA) epicardium, containing the Bachmann bundle (BB), that participate in arrhythmia pathogenesis and offer an opportunity for natural surface epicardial mapping (NSEM). OBJECTIVE: We sought to assess the feasibility of NSEM of BB and LA roof arrhythmias. METHODS: Electrogram recording, pacing, and ablation was performed in 2 swine. Subsequently, NSEM and pacing from the RPA and LPA was performed in 11 consecutive patients undergoing ablation of atrial fibrillation or flutter. Pacing entrainment and ablation of LA epicardium, from the pulmonary artery (PA), was performed in cases of atypical flutter. RESULTS: Swine specimens revealed no vascular disruption and LA epicardial lesions up to 7 mm in diameter and 3 mm in depth. In clinical cases, RPA mapping was performed in 11 (100%) and LPA mapping in 6 (55%) patients. Simultaneous leftward activation of the BB followed by rightward activation of the opposing LA endocardium was recorded during crista pacing. Right and left PA median signal amplitudes were 0.71 mV and 0.30 mV, respectively. Endocardial LA median distance was 9 mm to the RPA and 15.6 mm to the LPA and LA capture was successful in 7 of 8 (88%). In cases of atypical flutter, entrainment was successful in 3 of 3 (100%) and ablation was performed. CONCLUSION: PA NSEM can enable safe recording and entrainment of the BB, providing otherwise inaccessible epicaridal arrhythmia measurements. The safety and efficacy of ablation from the PA requires further study.

Progression of electrocardiographic changes in a patient with apical hypertrophic cardiomyopathy.

A 58-year-old man asymptomatic from the cardiovascular point of view and with no known relevant family history was found by transthoracic echocardiography to have apical hypertrophic cardiomyopathy (AHCM). His electrocardiogram (ECG) revealed prominent precordial R-waves, particularly in V3-V4 leads, and "giant" (>1.0 mV), inverted T-waves, previously associated with AHCM. ECGs recorded 17 and 13 years previously, did not disclose such abnormalities, as the ones of his current ECG. The presented case illustrates a potential role of serial ECGs (along with serial imaging testing) in detecting the development and progression of regional left ventricular hypertrophy in patients with AHCM, and probably in other hypertrophic cardiomyopathy phenotypes.

Thromboembolism in the Absence of Atrial Fibrillation.

Atrial fibrillation (AF) is associated with thrombus formation in the left atrial appendage and systemic embolic events including ischemic stroke. Cardiogenic thromboembolism can also occur in the absence of clinical AF as a result of various pathological conditions affecting the endocardium. The inconsistent temporal relation between AF and ischemic events has stimulated exploration for factors other than clinical AF that contribute to thromboembolism. These include subclinical AF, a thrombogenic atrial cardiomyopathy, and left atrial appendage dysfunction and embolism from other sources. In conclusion, thromboembolism during normal sinus rhythm is likely multifactorial, involving intertwined pathologic processes. Patients at risk, if accurately identified, could theoretically benefit from anticoagulation.

The relationship between oesophageal heating during left atrial posterior wall ablation and the durability of pulmonary vein isolation.

AIM: During ablation of the posterior wall (PW), luminal oesophageal temperature elevation (OTE) prompts attenuation of radiofrequency (RF) energy delivery to minimize oesophageal injury. This strategy on lesion efficacy is unknown. The goal of this study was to analyse the relationship between OTE and pulmonary vein reconnection (PVR). METHODS AND RESULTS: During the index antral pulmonary vein (PV) isolation procedure with an irrigated RF ablation catheter, OTE was detected with a multisensor oesophageal temperature probe. Posterior wall ablation did not exceed 25 W and was terminated when the temperature was ≥38.5°C. Patients undergoing redo procedures (n = 142) were studied for PW sites of PVR along 4 segments: left and right superior, and left and right inferior. Pulmonary vein reconnections had occurred in 51 of the 142 patients (36%), in 58 of 284 PV pairs (20%). Among these 58 reconnected pairs, 83% (n = 48) were along the PW. Oesophageal temperature elevation had occurred in 30 patients (59%). No difference in characteristics was seen between the patients with OTE (n = 30) and those without (n = 21). For superior segments, there was no interaction between the presence or absence of OTE and PVR. For inferior segments, there were more PVRs in the group with OTE: for the right-inferior segment, the PVR rate was 72% for OTE cases vs. 42% without (P = 0.04), and for the left-inferior segment, the PVR rate was 44% for OTE cases vs. 22.9% without (P = 0.12). CONCLUSION: Pulmonary vein reconnections are predominantly posteriorly located. Along the right- and left-inferior PW segments, there was an association with elevated oesophageal temperature during the index procedure.