Introduction
Heart failure (HF), as a final common stage of many cardiovascular diseases, is a major public health problem affecting approximately 40 million people globally.[1] A spontaneous progressive clinical syndrome with dyspnea, water and sodium retention, pump failure underlying causes, pathophysiological complexities, and concomitant comorbidities, which made both diagnosis and treatment particularly challenging.[2]Ischemic cardiomyopathy (ICM) and idiopathic dilated cardiomyopathy (DCM) share common structural alterations with a high mortality from sudden cardiac death (SCD) and pump failure.[3] According to New York Heart Association (NYHA) classification, the all-cause mortality of patients with NYHA class II is 5% to 15%, of which 50% -60% is sudden death. The all-cause mortality rate of NYHA class III increases to 30% to 50%, and class IV usually exceeds 50%.[4]
During the past decades, great progresses have been made in decreasing the occurrence of SCD. In particular, ICD implantation has become a priority for primary prevention ICDs in patients with indication.[5] However, individual DCM trials have failed to gain the conclusion of a mortality benefit with prophylactic ICD implantation.[6] European guidelines have recommended that ICD therapy to prevent SCD in patients with symptomatic HF (NYHA class II–III) and LVEF ≤35% after ≥3 months of optimal medical therapy who are expected to survive for at least 1 year with good functional status.[7, 8] Nevertheless, in most studies HF patients with DCM represent a minor subgroup of the overall study population.[9] Whether there is a difference in prognosis between primary prophylactic ICD therapy in patients with ICM and DCM remains unclear. To address this issue, we conducted a retrospective study, which enrolled 82 patients with DCM or ICM and with guideline indications for primary prophylactic ICD or CRT-D treatment. We aimed to identify subgroups with greater or lesser advantage from ICD therapy.