The success of cardiac resynchronization therapy (CRT) depends on a high percentage of
ventricular pacing. We present the electrocardiography and electrograms of a patient who
underwent an implantable cardioverter-defibrillator (ICD) with CRT implantation showing
a low percentage of ventricular pacing as a result of T wave oversensing of paced QRS. The
patient showed no clinical improvement.
We suggest finding a good sensitivity of F waves in induced ventricular fibrillation during
ICD implantation in order to overcome the harm of possible oversensing