ICM and NICM
Supported by strong evidences from RCTs, prophylactic implantation of an
ICD, a class I recommendation in HF patient with ICM and reduced left
ventricular systolic function, can reduce mortality compared with
conventional drug therapy [36,37]. Contrarily, DANISH trials
demonstrated that ICD for primary prevention in patients with heart
failure caused by non-ischemic etiology did not improve survival
benefits [38]. This meta-analysis presented a similar result that
ICM patients with CRT indication can benefit from an additional ICD
therapy rather than NICM patients. It may be explained by a higher risk
of death from fatal arrhythmia in patients with ICM. Moreover, several
studies reported that patients with NICM have a better improvement in LV
systolic function and LV reverse remodeling compared with patients with
ICM [39,40], which resulted in a further reduction of the risk of
SCD and ventricular tachyarrhythmias [41]. Above all, it may suggest
a less needed of an additional ICD for primary prevention in NICM
patients due to a sufficiently reduction of fatal tachyarrhythmias by
CRT-P alone.