Exploiting SMART pass filter deactivation detection to minimize inappropriate subcutaneous implantable cardioverter defibrillator therapies: a real-world single-centre experience and management guide

AIMS: The SMART Pass™ (SP) algorithm is a high-pass filter that aims to reduce inappropriate therapy (IT) in subcutaneous internal cardiac defibrillator (S-ICD), but SP can deactivate due to low amplitude sensed R waves or asystole. The association between IT and SP deactivation and management strategies were evaluated, hypothesizing SP deactivation increases the risk of IT and device re-programming, or lead/generator re-positioning could reduce this risk. METHODS AND RESULTS: Retrospective single-centre audit of Emblem™ S-ICD devices implanted 2016 to 2020 utilizing health records and remote monitoring data. Cox regression models evaluated associations between SP deactivation and IT. A total of 348 patients (27 ± 16.6 months follow-up) were studied: 73% primary prevention. Thirty-eight patients (11.8%) received 83 shocks with 27 patients (7.8%) receiving a total of 44 IT. Causes of IT were oversensing (98%) and aberrantly conducted atrial fibrillation (2%). SP deactivation occurred in 32 of 348 patients (9%) and was significantly associated with increased risk of IT (hazard ratio 5.36, 95% CI 2.37-12.13). SP deactivation was due to low amplitude R waves (94%), associated with a higher defibrillation threshold at implant and presence of arrhythmogenic right ventricular cardiomyopathy. No further IT occurred 16 ± 15.5 months after corrective interventions, with changing the sensing vector being successful in 59% of cases. CONCLUSION: To reduce the risk of IT, the cause of the SP deactivation should be investigated, and appropriate reprogramming, device, or lead modifications made. Utilizing the alert for SP deactivation and electrograms could pro-actively prevent IT

Ischemic Ventricular Tachycardia Presenting as a Narrow Complex Tachycardia

This report describes a patient presenting with a narrow complex tachycardia in the context of prior myocardial infarction and impaired ventricular function. Electrophysiological studies confirmed ventricular tachycardia and activation and entrainment mapping demonstrated a critical isthmus within an area of scar involving the His-Purkinje system accounting for the narrow QRS morphology. This very rare case shares some similarities with upper septal ventricular tachycardia seen in patients with structurally normal hearts, but to our knowledge has not been seen previously in patients with ischemic heart disease

Therapeutic benefits of distal ventricular pacing in mid-cavity obstructive hypertrophic cardiomyopathy

INTRODUCTION Hypertrophic cardiomyopathy (HCM) patients with left ventricular (LV) mid-cavity obstruction (LVMCO) often experience severe drug-refractory symptoms thought to be related to intraventricular obstruction. We tested whether ventricular pacing, guided by invasive haemodynamic assessment, reduced LVMCO and improved refractory symptoms. METHODS Between December 2008 and December 2017, 16 HCM patients with severe refractory symptoms and LVMCO underwent device implantation with haemodynamic pacing study to assess the effect on invasively defined LVMCO gradients. The effect on the gradient of atrioventricular (AV) synchronous pacing from sites including right ventricular (RV) apex and middle cardiac vein (MCV) was retrospectively assessed. RESULTS Invasive haemodynamic data were available in 14 of 16 patients. Mean pre-treatment intracavitary gradient was 77 ± 22 mmHg (in sinus rhythm) versus 21 ± 21 mmHg during pacing from optimal ventricular site (95% CI: -70.86 to -40.57, p < 0.0001). Optimal pacing site was distal MCV in 12/16 (86%), RV apex in 1/16 and via epicardial LV lead in 1/16. Pre-pacing Doppler-derived gradients were significantly higher than at follow-up (47 ± 15 versus 24 ± 16 mmHg, 95% CI: -37.19 to -13.73, p < 0.001). Median baseline NYHA class was 3, which had improved by ⩾1 NYHA class in 13 of 16 patients at 1-year post-procedure (p < 0.001). The mean follow-up duration was 4.6 ± 2.7 years with the following outcomes: 8/16 (50%) had continued symptomatic improvement, 4/16 had symptomatic decline and 4/16 died. Contributors to symptomatic decline included chronic atrial fibrillation (AF) (n = 5), phrenic nerve stimulation (n = 3) and ventricular ectopy (n = 1). CONCLUSION In drug-refractory symptomatic LVMCO, distal ventricular pacing can reduce intracavitary obstruction and may provide long-term symptomatic relief in patients with limited treatment options. A haemodynamic pacing study is an effective strategy for identifying optimal pacing site and configuration

Atrioventricular node ablation is an effective management strategy for atrial fibrillation in patients with hypertrophic cardiomyopathy

BACKGROUND: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) patients and can be challenging to manage. Atrioventricular node (AVN) ablation may be an effective management strategy for AF in these patients. OBJECTIVE: Assess the efficacy of AVN ablation in HCM patients who have failed medical therapy and/or catheter ablation for AF. METHODS: Multi-centre study with retrospective analysis of a prospectively collated HCM registry. AVN ablation patients were identified. Baseline characteristics, device and procedural indication were collected. Symptoms defined by NYHA and EHRA classification and echocardiographic findings during follow-up were assessed. RESULTS: Fifty-nine patients were included. Indications for AVN ablation were: 6 (10.2%) inappropriate ICD shock, 35 (59.3%) ineffective rate control and 18 (30.5%) to regularize rhythm to improve symptoms. During post-AVN ablation follow-up of (79.4±61.1 months), left ventricular ejection fraction (LVEF) remained stable (pre-LVEF 48.9±12.4%, post-LVEF 49.8±10.9%, p=0.68) even in those without a CRT device (pre-LVEF 54.3±8.0% vs post-LVEF 53.8±8.0%=0.65). Forty-nine (83.1%) patients reported an improvement in symptoms regardless of AF type (17/21, 81.0% paroxysmal vs. 32/38, 84.2% persistent AF; p=1.00), presence of baseline LV impairment (22/26, 84.6% LVEF≤50% vs. 27/33, 81.8% LVEF≥50%; p=1.00) or CRT device (27/32, 84.4% CRT vs. 22/27, 81.5% no CRT; p=1.0). Symptoms improved in 16 (89%) patients who underwent AVN ablation to regularize rhythm. CONCLUSION: AVN ablation improved symptoms without impacting LV function in a majority of the patients. AVN ablation is suggestive to be an effective and safe management approach for AF in HCM and should be further evaluated in larger prospective studies

Procedural and quality assessment data on catheter ablation for fascicular ventricular tachycardia

Data presented in this article are supplementary materials to our article entitled “Catheter Ablation for Fascicular Ventricular Tachycardia: A Systematic review” (Creta et al., 2018). The current article provides additional procedural data regarding the catheter ablation for fascicular ventricular tachycardia (FVT) performed in the patients enrolled in our analysis. Furthermore, we provide data regarding the quality assessment of the studies included in our systematic review