Abstract
Implantable cardioverter-defibrillator undersensing may delay therapy in ventricular fibrillation with low-amplitude signals. Ventricular fibrillation therapy assurance (VFTA) detected persistent VF after initial shock failure, enabling timely shock delivery and successful resuscitation. VFTA may help optimize device programming by preventing misclassification and treatment delay in life-threatening arrhythmias.