Methods:

In the MADIT-RIT trial, 1,500 patients (mean age 63 years) who received an ICD for primary prevention of sudden cardiac death (SCD) were randomly assigned to either: 1) conventional programming: a detection zone of 170-199 bpm with a 2.5-second delay and atrial discriminators turned on, and a second zone at ≥200 bpm with a 1-second delay before delivery of the ICD therapy (n = 514); 2) high-rate group: therapy zone of ≥200 bpm, with a 2.5-second monitoring delay (n = 500); or 3) delayed-therapy group: a zone of 170-199 bpm with rhythm detection on and a 60-second therapy delay, a zone at ≥200 bpm with rhythm detection on and a 12-second therapy delay, and a third zone at ≥250 bpm with a 2.5-second therapy delay (n = 486). The patients were seen in a device clinic every 3-6 months. The primary endpoint was the first inappropriate ICD therapy.