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Introduction: Most of avoidable defibrillator therapies can be reduced by evidence-based programming, but defining tachycardia configurations across all device manufacturers is not straightforward.

Aims: To determine if a uniform programming of tachycardia zones, independently of the manufacturer, result in a lower rate of avoidable shocks in primary-prevention heart failure (HF) patients and also if programming high-rate or delayed therapies can have some benefit.

Methods: Prospective cohort with historical controls. HF patients with a primary-prevention indication for a defibrillator were randomized to receive one of two new programming configurations (high-rate or delayed therapies). A historical cohort of patients with conventional programming was analyzed for comparison. The primary endpoint was any therapy [shock or anti-tachycardia pacing (ATP)] delivered. Secondary endpoints were appropriate shocks, appropriate ATP, appropriate therapies, inappropriate shocks, syncope and death.

Results: 89 patients were assigned for new programming group [high rate (n=47) or delayed therapy (n=42)]. They were compared with 94 historical patients with conventional programming. During a mean follow-up of 20±7 months, the new programming was associated with a reduction in any therapy (HR = 0.265, 95% CI 0.121-0.577, p=0.001), even after adjustment. Aproppriate ATP and any shock were also reduced. Syncope did not occur.  Sudden, cardiovascular and all-cause deaths were not different between the groups.  In the new programming group, neither highrate nor delayed programming were better than the other.

Conclusions: In our study, programming tachycardia zones homogeneously across all manufacturers was possible and resulted in a lower rate of therapies, shocks and appropriate ATP.