Goldenberg et al. wrote an excellent review of patient selection for implantable cardioverter-defibrillator (ICD) therapy, device selection, and programming, providing a comprehensive overview for clinical practice, including current guidelines for ICD implantation. Although the authors describe the discrepancy that exists between the American and European guidelines concerning primary prevention ICD implantation in New York Heart Association (NYHA) Functional Class I patients, NYHA Class I patients as a potential group for prophylactic defibrillator therapy were not included in their takehome figure showing an algorithm for ICD patient selection. We recently described that NYHA Class I patients receiving an ICD for primary prevention of sudden cardiac death (SCD) experienced more appropriate ICD therapy for ventricular arrhythmias compared to NYHA Classes II–III patients (hazard ratio 1.5, 95% confidence interval 1.04–2.31; P = 0.03). This finding is consistent with a recently published prospective registry, showing asymptomatic ischaemic cardiomyopathy ICD patients with a reduced ejection fraction to have a two-fold higher risk for appropriate ICD therapy compared to symptomatic ICD patients. Unfortunately, the more recent randomized prophylactic ICD trials, such as the SCD-HeFT and DANISH, exclusively enrolled symptomatic heart failure patients. The MADIT-II study (2002) did include almost one-third of asymptomatic ischaemic cardiomyopathy patients and reported a similar survival benefit across the three NYHA classes after 8 years of follow-up. However, MADIT-II was performed almost two decades ago, and improved medical heart failure therapy and coronary revascularization techniques hamper extrapolation to the current heart failure population. Nevertheless, a sub-analysis of the DANISH trial (2016) revealed that younger patients and patients with a lower NT-proBNP have an increased benefit of ICD implantation, suggesting an incremental value of ICD therapy in the less vulnerable heart failure patient. Although the mechanism between the occurrence of ventricular arrhythmias and heart failure symptoms is unknown, we hypothesized that patients who are without limitation of physical activity (i.e. asymptomatic patients) are exposing themselves to a greater risk of exercise-induced arrhythmias. Furthermore, Sabbag et al. suggest that a competing risk between ventricular arrhythmias and cardiovascular death by NYHA class results in a higher burden of arrhythmias in patients with a less advanced stage of heart failure. Since recommendations between the American and European SCD guidelines differ and randomized data concerning SCD in asymptomatic heart failure patients is scarce, eligibility of NYHA Class I patients for primary prevention ICD implantation remains ambiguous and based on the physicians’ judgement and patients preference. Nonetheless, we believe that our data and that of others suggests that NYHA Class I patients with a reduced left ventricular ejection fraction are at increased risk of SCD, and should be considered for primary prevention ICD implantation. Future studies focusing on SCD in asymptomatic heart failure patients are needed to evaluate the value of ICD therapy in the modern era.

中文翻译：

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植入式心律转复除颤器在纽约心脏 I 级心力衰竭患者中的​​作用：暂时不要放弃无症状者

戈登伯格等人。撰写了一篇关于植入式心律转复除颤器 (ICD) 治疗、设备选择和编程的患者选择的优秀评论，提供了临床实践的全面概述，包括 ICD 植入的当前指南。尽管作者描述了美国和欧洲关于在纽约心脏协会 (NYHA) 功能 I 级患者中植入一级预防 ICD 的指南之间存在的差异，但作为预防性除颤器治疗的潜在组的 NYHA I 级患者并未包括在他们的总结中图显示了 ICD 患者选择的算法。我们最近描述了与 NYHA II-III 级患者相比，接受 ICD 用于心源性猝死 (SCD) 一级预防的 NYHA I 级患者经历了更合适的 ICD 治疗室性心律失常（风险比 1.5，95% 置信区间 1.04-2.31； P = 0.03）。这一发现与最近发表的前瞻性登记一致，表明射血分数降低的无症状缺血性心肌病 ICD 患者与有症状的 ICD 患者相比，接受适当 ICD 治疗的风险高两倍。不幸的是，最近的随机预防性 ICD 试验，如 SCD-HeFT 和 DANISH，专门招募了有症状的心力衰竭患者。MADIT-II 研究（2002 年）确实包括了近三分之一的无症状缺血性心肌病患者，并报告了 8 年随访后三个 NYHA 级别的相似生存获益。然而，MADIT-II 是在大约 20 年前进行的，改进的医疗心力衰竭治疗和冠状动脉血运重建技术阻碍了对当前心力衰竭人群的外推。尽管如此，DANISH 试验（2016 年）的一项子分析显示，年轻患者和 NT-proBNP 较低的患者植入 ICD 的益处增加，表明 ICD 治疗在较不脆弱的心力衰竭患者中具有增量价值。虽然室性心律失常的发生与心力衰竭症状之间的机制尚不清楚，我们假设身体活动不受限制的患者（即无症状患者）将面临更大的运动诱发心律失常风险。此外，Sabbag 等人。表明室性心律失常和 NYHA 分类的心血管死亡之间的竞争风险导致心力衰竭晚期阶段患者的心律失常负担更高。由于美国和欧洲 SCD 指南之间的建议不同，并且关于无症状心力衰竭患者 SCD 的随机数据很少，NYHA I 级患者一级预防 ICD 植入的资格仍然不明确，并且基于医生的判断和患者的偏好。尽管如此，我们相信我们的数据和其他人的数据表明左心室射血分数降低的 NYHA I 级患者发生 SCD 的风险增加，应考虑进行一级预防 ICD 植入。未来的研究需要关注无症状心力衰竭患者的 SCD，以评估 ICD 治疗在现代时代的价值。