Unresolved matters related to implantable cardioverter defibrillators: How can we avoid shock therapy?

Implantable cardioverter defibrillators (ICDs) have become very useful for patients with a high risk of sudden cardiac death, based on the results of several clinical trials. Although ICDs can improve survival when used in patients with heart failure (HF) and reduced left ventricular (LV) function, a recent subanalysis of major clinical trials regarding ICDs has revealed that ICD shock is associated with worsening HF or increase in mortality. ICD settings must be programmed appropriately, guided by clear evidence, to avoid unnecessary and inappropriate shocks. We discuss the benefits and pitfalls of ICD programming, such as tachycardia pacing, detection intervals, detection rates, and discriminators, to offer programming tips in this review.