Anti-tachycardia pacing and cardioversion: By what mechanisms do they terminate tachyarrhythmias?

Implantable cardioverter defibrillators (ICDs) effectively prevent sudden cardiac death. These devices can terminate tachyarrhythmias not only by cardioversion but also by anti-tachycardia pacing.
While early ICDs were only capable of shock therapy, their current anti-tachycardia pacing function allows for painless treatment. Importantly, however, ventricular fibrillation and similar arrhythmias may require early shock treatment. Anti-tachycardia pacing is used for ventricular tachycardia, and it is up to the attending physician to decide what arrhythmias should be treated with shock. To achieve proper ICD programming and improve therapeutic efficacy, here we aim to deepen our understanding of arrhythmias as well as the mechanisms of shock therapy and anti-tachycardia pacing.