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

Pier D Lambiase; Lars Eckardt; Dominic A Theuns; Timothy R Betts; Andreas L Kyriacou; Elizabeth Duffy; Reinoud Knops

doi:10.1016/j.hroo.2020.10.002

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

Heart Rhythm O2. 2020 Oct 28;1(5):326-335. doi: 10.1016/j.hroo.2020.10.002. eCollection 2020 Dec.

Authors

Pier D Lambiase¹, Lars Eckardt², Dominic A Theuns³, Timothy R Betts⁴, Andreas L Kyriacou⁵, Elizabeth Duffy⁶, Reinoud Knops⁷

Affiliations

¹ Barts Heart Centre, London, Edgware, United Kingdom.
² Department of Cardiology II, University Hospital, Muenster, Germany.
³ Erasmus MC, Rotterdam, Netherlands.
⁴ Oxford Biomedical Research Centre, Oxford, United Kingdom.
⁵ Sheffield Teaching Hospitals, Sheffield, United Kingdom.
⁶ Boston Scientific, St Paul, Minnesota.
⁷ Academic Medical Center, Amsterdam, Netherlands.

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.

Keywords: Arrhythmia; Channelopathy; Implantable cardioverter-defibrillator; Subcutaneous ICD; Sudden cardiac death; Ventricular arrhythmias.