T-wave oversensing in implantable cardiac defibrillators is due to technical failure of device sensing.

The expanded indications for the use of implantable cardioverter defibrillators (ICDs) for primary prevention of sudden cardiac death have increased concerns about inappropriate delivery of therapies. Dual-chamber systems have improved the capacity of ICDs to differentiate ventricular arrhythmias from supraventricular arrhythmias. Still, T-wave oversensing is a major source of inappropriate therapy. It is likely the true incidence of T-wave oversensing is greater than reported as documented events reflect only those stored in a device memory. Reviewing cases of T-wave oversensing that failed noninvasive correction; we found successful resolution resulted from generator replacement. We conclude that T-wave oversensing is due to inadequate signal processing by some ICD generators.