A method and device for delivering anti-tachycardia pacing (ATP) therapy that includes an electrode to sense cardiac signals and to deliver the therapy, sensing circuitry, electrically coupled to the electrode, to detect the tachycardia event in response to the sensed cardiac signals, and a processor to control delivery of the therapy. The processor determines whether a return cycle length generated subsequent to the delivery of the first plurality of pacing pulses is greater than a cycle length associated with the tachycardia event and less than a sum of the cycle length associated with the tachycardia event and a total prematurity associated with the first plurality of pacing pulses, and adjusts delivery of a second plurality of pacing pulses in response to the return cycle length not being greater than the cycle length associated with the tachycardia event and less than the sum of the cycle length associated with the tachycardia event and the total prematurity associated with the first plurality of pacing pulses.