Evaluation of subcutaneous implantable cardioverter-defibrillator performance in patients with ion channelopathies from the EFFORTLESS cohort and comparison with a meta-analysis of transvenous ICD outcomes

Abstract

Background The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative to conventional transvenous ICD (TV-ICD) therapy to reduce lead complications. Objective To evaluate outcomes in channelopathy vs patients with structural heart disease in the EFFORTLESS-SICD Registry and with a previously reported TV-ICD meta-analysis in channnelopathies. Methods The EFFORTLESS registry includes 199 patients with channelopathies (Brugada syndrome 83, long QT syndrome 24, idiopathic ventricular fibrillation 78, others 14) and 786 patients with structural heart disease. Results Channelopathy patients were younger (39 ± 14 years vs 51 ± 17 years; P < .001) with left ventricular ejection fraction 59% ± 9% vs 41% ± 18% ( P < .001). The complication rate (follow-up: 3.2 ± 1.5 years vs 3.0 ± 1.5 years) was similar: 13.6% vs 11.2% ( P = .42). Appropriate shocks rates were 9.5% vs 10.8% ( P = .70), with shocks for monomorphic ventricular tachycardia being 2.0% vs 6.9% ( P < .02) and for polymorphic ventricular tachycardia/ventricular fibrillation (VT/VF) 8.0% vs 5.7% ( P = .30). Conversion effectiveness of VT/VF episodes was similar: 36 of 37 (97.3%) vs 151 of 155 (97.4%, P = .59). VT/VF storm event (2% vs 0.9%, P = .33) and lower inappropriate shock (IAS) (8.5% vs 12.5%, P = .12) rates were statistically similar between channelopathy and non-channelopathy patients, with 45.5% channelopathy vs 31.4% non-channelopathy patients managed with a conditional zone > 200 beats per minute ( P = .0002). Annualized appropriate shock, IAS, and complication rates appear to be lower for the S-ICD vs meta-analysis TV-ICD patients, particularly lead complications. Conclusion EFFORTLESS demonstrates similar S-ICD efficacy and a nonsignificant, lower rate of IAS in channelopathy patients as compared to structural heart disease. Comparable IAS rates were achieved with the device programmed to higher rates for channelopathy patients.

Catecholaminergic Polymorphic Ventricular Tachycardia: Clinical Characteristics, Diagnostic Evaluation and Therapeutic Strategies

“…The study found similar S-ICD efficacy and a reduced incidence of inappropriate shocks in channelopathy patients compared to those with structural heart disease. Similar rates of inappropriate shocks were achieved with S-ICD programming set to higher rates for channelopathy patients [ 136 ].…”

A survey study of the use of a subcutaneous implantable cardioverter-defibrillator in various clinical scenarios by expert electrophysiologists in Poland

“…Therefore, some researchers underline the importance of meticulous pre-implant screening, and in some specific situations (for example in Brugada syndrome) — they advise performing an exercise test and pharmacological provocation tests [ 21 , 22 ]. Careful screening allows avoiding future inappropriate interventions to a reasonable extent, and in the comparative analysis of S-ICDs and T-ICDs in that patient population, the efficacy of S-ICD was comparable to T-ICD with the benefit of a lower risk of lead failure [ 23 ]. One should mind though that in some channelopathies (e.g., LQTS 2) associated with bradycardia, the need for pacing may occur, especially in case of therapy with beta-blockers.…”

Arrhythmogenic Risk and Mechanisms of QT-Prolonging Drugs to Treat COVID-19

“…Mutations in 13 genes have been traditionally associated with LQTS: among those, mutations in potassiumchannel genes KCNQ1 (LQT1 locus) and KCNH2 (LQT2 locus) and the sodium-channel gene SCN5A (LQT3 locus) are the most common causes of the LQTS and account for approximately 75% of cases 30 . Once diagnosis is made, risk stratification is mandatory to tailor lifestyle changes and to deliver the adequate therapy, such as implantable cardioverter defibrillator J o u r n a l P r e -p r o o f (ICD) in high-risk patients, with the modern subcutaneous ICD potentially being the most appropriate therapeutic option [31][32][33][34][35] . All LQTS patients, regardless of the SCD risk, should avoid QT-prolonging drugs, promptly correct electrolyte abnormalities (hypokalemia, hypomagnesaemia, hypocalcemia) that may occur during diarrhea, vomiting or metabolic conditions and avoid genotype-specific triggers for arrhythmias (strenuous swimming, especially in LQTS1, and exposure to loud noises in LQTS2 patients) 36 .…”