Letter by Madias and Madias Regarding Article, "Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial".

Abstract

HomeCirculationVol. 146, No. 4Letter by Madias and Madias Regarding Article, “Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial” Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBLetter by Madias and Madias Regarding Article, “Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial” Christopher Madias and John E. Madias Christopher MadiasChristopher Madias Cardiac Arrhythmia Center, Tufts Medical Center, Boston, MA (C.M.). Search for more papers by this author and John E. MadiasJohn E. Madias https://orcid.org/0000-0001-6669-1703 Icahn School of Medicine at Mount Sinai, New York, NY (J.E.M.). Division of Cardiology, Elmhurst Hospital Center, NY (J.E.M.). Cardiac Arrhythmia Center, Tufts Medical Center, Boston, MA (C.M.). Search for more papers by this author Originally published25 Jul 2022https://doi.org/10.1161/CIRCULATIONAHA.122.059815Circulation. 2022;146:e8–e9To the Editor:Knops et al1 reported in Circulation the shock efficacy in 426 patients with a subcutaneous implantable cardioverter defibrillator (S-ICD) compared with 423 patients with transvenous implantable cardioverter defibrillator (TV-ICD), using a prespecified secondary ad hoc analysis of the PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy), which has shown noninferiority of S-ICD compared with TV-ICD in the rate of inappropriate shocks and complications. The authors1 and the accompanying editorialists2 elaborated comprehensively on the differences between S-ICD and TV-ICD (the former cannot provide antitachycardia pacing for monomorphic ventricular tachycardia but has the advantage of not requiring intravascular and cardiac leads and is less associated with the inherent TV-ICD procedural complications, infections, and antitachycardia pacing–induced acceleration of ventricular tachycardia). The authors did not find any difference in the shock efficacy of S-ICD compared with TV-ICD, with the total number of appropriate shocks not different between the 2 groups. The authors1 and the editorialists2 delved into the limitations of the study and the necessity for future investigations comparing S-ICD and TV-ICD, considering that technologies are being upgraded constantly and that these 2 implantable cardioverter defibrillator methodologies should be compared in patients without the exclusions implemented in the PRAETORIAN trial so that conclusions can be extrapolatable to all patients needing S-ICD or TV-ICD. Last, the authors recommend implementation of a single antitachycardia pacing attempt because repeat antitachycardia pacings have a low rate of ventricular tachycardia cardioversion.1S-ICD may be an alternative to TV-ICD, although it is associated with inappropriate shocks attributable to dynamic electrocardiographic changes. Eligibility for S-ICD implementation requires a preimplantation screening with either a manual screening tool or various automated screening tools.3 Both the manual screening tool and the automated screening tool predict sensing electrocardiographic vectors, but they may perform differently in detecting legibility or illegibility of sensing electrocardiographic vectors in some patients. The automated screening tool may have some advantages owing to its standardized and objective nature, although it still lacks specificity.3 Patients with heart failure or end-stage renal failure undergoing hemodialysis (RF-HEMO) experience major changes in their edematous states, make up a population often requiring implantable cardioverter defibrillators, and thus may be candidates for S-ICD. Major electrocardiographic changes are noted in patients with heart failure in their course of decompensation and effective diuresis4 and in patients with RF-HEMO before and after hemodialysis. In brief, there is a significant augmentation of the amplitude of the QRS complexes as a result of effective diuresis,4 and the same thing is noted in patients with RF-HEMO after hemodialysis. Because patients with heart failure have attenuated QRS voltage when in a state of decompensation and peripheral edema4 and patients with RF-HEMO are more likely to fail S-ICD screening, particularly before hemodialysis, compared with patients not receiving hemodialysis,5 preimplantation screening for S-ICD in patients with heart failure and RF-HEMO should be carried out while the former are in their peak edematous state4 and in the latter before hemodialysis.5 Indeed, updated guidelines for S-ICD implantation should inform about the relevance of patients’ edematous state in the prescreening for S-ICD implantation.Article InformationDisclosures None.FootnotesCirculation is available at www.ahajournals.org/journal/circ