[Reduction of ventricular tachycardia by programmed electric stimulation. Clinical implications]

The mode of termination by programmed electrical stimulation of sustained ventricular tachycardia (VT) (more than 30 seconds) and induced by stimulation was investigated in 33 patients. In 27 patients (82%) programmed stimulation was possible because VT did not require an immediate electric shock or did not terminate spontaneously, but constant reduction of VT was obtained with one extrasystole in only 1 patient (3%), with two extrasystoles in 5 patients (15%) and by overdrive stimulation in 12 patients (36%). The remaining 15 patients (45%) required an external electric shock either because VT was poorly tolerated clinically, or because stimulation had failed. In 8 of the 27 cases in whom stimulation was attempted (30%), acceleration of VT was observed. A significant correlation was found between the need for electrical shock and the VT cycle length. It is concluded that reduction of VT by programmed electrical stimulation can only be successful in a limited number of patients and carries a significant risk of acceleration. These data must be taken into account when temporary treatment of VT by stimulation is contemplated. They should incite to considerable caution in the use of implantable pacemakers for tachycardia termination.