The wearable cardiac defibrillator dilemma: quantifying risk and appropriateness in the GDMT era

This commentary refers to ‘Sudden cardiac death in newly diagnosed non-ischaemic or ischaemic cardiomyopathy assessed with a wearable cardioverter-defibrillator: the German nationwide SCD-PROTECT study’, by D. Duncker et al., https://doi.org/10.1093/eurheartj/ehaf668 and the discussion piece ‘Sudden cardiac death risk in the early vulnerable phase of heart failure: clarifying the SCD-PROTECT findings’, by D. Duncker et al., https://doi.org/10.1093/eurheartj/ehag054. We read the SCD-PROTECT study1 with great interest and congratulate the authors on reporting granular data from the largest wearable cardiac defibrillator (WCD) registry to date. We would be grateful if the authors could provide their thoughts on the following three points. The title suggests that patients with only newly diagnosed cardiomyopathy were included. Given this, we seek clarification regarding the observed median left ventricle ejection fraction of 32% before index hospital admission (Figure 4). Second, the authors discuss that their findings of high incidence rate of sudden cardiac arrest (SCA) contradict previous findings from pooled analysis of 12 randomized trials in similar population published by Shen et al.2 The pooled analysis reported a decline in risk of sudden cardiac death (SCD) from 6.5% in the earliest heart failure trials to around 3.3% in the latest PARADIGM trial (the pooled analysis did not include trials with SGLT2i).2 We would note that the definition of SCD in these randomized trials differed from the definition of SCA in the current study (i.e. appropriate WCD shock). Further, even if all appropriate WCD shock had let to SCD, the rate would be 1.3%, which supports declining rate of SCD with goal directed medical therapy.