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Response by Timal and Jukema to Letter Regarding Article, "Random Controlled Trials of Sudden Cardiac Death: Use of Autopsy to Refine Sudden Cardiac Death Outcomes".

Circulation. 2019;140:e744–e745. DOI: 10.1161/CIRCULATIONAHA.119.043148 e744 Rohit J. Timal, MD J. Wouter Jukema, MD, PhD In Response: We read with great interest the Letter to the Editor by Simpson et al, and we are grateful for their important observation. The authors point to the importance of autopsy data for sudden cardiac death (SCD) identification. Unfortunately, in daily clinical practice, ascertainment of cause of death by gold standard autopsy is frequently omitted because of felt lack of clinical relevance, rendering sudden death easily misclassified as SCD.1 Indeed, we also feel that in the context of medical research, autopsy should ideally be performed on all patients participating in randomized, controlled trials with SCD as an end point. However, clinical practicability could be reduced as study protocol mandated postmortem pathological examination could pose a hurdle in obtaining informed consent, stagnating patient enrollment to a significant extent. Also, legislation concerning consent to perform autopsy is not homogenous across nations. In our ICD2 (Implantable Cardioverter Defibrillators in Dialysis Patients) study, patient inclusion already was laborious, taking many years to include 188 dialysis patients, randomized 1:1 to receive implantable cardioverter defibrillator implantation for primary prevention versus standard care.2 Moreover, it is difficult to explain to relatives of participants that an autopsy should be carried out in the context of a study, especially in elderly patients. Relatives of participants, in particular those randomized to a control group and who already have had long follow-up, are often uninformed of participation in the trial. In this light, permission of relatives for autopsy will possibly encounter resistance. In case of lacking autopsy data, retrospective adjudication of cause of death by clinical event committee based on current (World Health Organization) definitions of sudden arrhythmic death/SCD is an often used but suboptimal surrogate, associated with an overestimation of sudden death attributable to ventricular arrhythmia. Chugh et al1 performed a prospective evaluation of SCD and found that SCD accounts for 5.6% of annual mortality. The authors concluded that death certificate–based surveillance is unlikely to be a useful surveillance tool for SCD. Second, Tseng et al3 convincingly demonstrated that conventional definitions of SCD, often used as end points in clinical trials, have limited accuracy for arrhythmic death. We acknowledge the recommendation of Tseng et al to refine definitions and complement the authors for developing 2 predictive models, for witnessed and unwitnessed sudden death, using premortem variables for identifying true sudden arrhythmic death among SCDs, defined by conventional criteria.4 However, the authors acknowledge the lower performance of the unwitnessed sudden death model. In the subset of patients at high risk of SCD who received an implantable cardioverter defibrillator, we propose (compulsory) standard postmortem device interrogation to provide critical insight in cardiac rhythm in moribund patients and to assess implantable cardioverter defibrillator behavior. This could greatly increase our understanding regarding the benefit–harm balance. © 2019 American Heart Association, Inc. RESPONSE TO LETTER TO THE EDITOR