The implantable cardioverter-defibrillator (ICD) has consistently demonstrated benefit in reducing sudden cardiac death in patients at high risk of ventricular arrhythmias, but inappropriate ICD activations are a common occurrence with potential adverse effects on patient well-being and increased costs for health services. Strategies to reduce the frequency of inappropriate device activation without reducing efficacy in life-threatening situations would therefore be highly beneficial.

In the multi-centre MADIT-RIT trial, 1500 patients with a primary-prevention ICD implant were randomly assigned to a series of pre-specified programming configurations with the primary objective to determine whether high-rate therapy (with initiation at a heart rate of ≥200 beats per minute) or delayed therapy (with a 60-second delay at 170 to 199 beats per minute, a 12-second delay at 200 to 249 beats per minute, and a 2.5-second delay at ≥250 beats per minute) was associated with a decrease in occurrence of inappropriate antitachycardia pacing or shocks. Secondary end-points included death from any cause and the first episode of syncope. The results strongly favoured the novel programming algorithms. During an average follow-up of 1.4 years, high-rate and delayed therapy were associated with reductions in a first inappropriate therapy (HR with high-rate vs. conventional, 0.21; 95% CI, 0.13 to 0.34; P<0.001; HR with delayed vs. conventional, 0.24; 95% CI, 0.15 to 0.40; P<0.001) and an impressive reduction in all-cause mortality (HR with high-rate vs. conventional, 0.45; 95% CI, 0.24 to 0.85; P=0.01; HR with delayed vs. conventional, 0.56; 95% CI, 0.30 to 1.02; P=0.06). There was no difference in rates of syncope between any of the groups.

Conclusion

In this large randomised study, programming of ICD therapies for tachyarrhythmias of 200 beats per minute or higher – or with a prolonged delay in therapy at 170 beats per minute or higher – was associated with reductions in inappropriate therapy and all-cause mortality during long-term follow-up, with no evidence of adverse effects.

• Moss AJ, Schuger C, Beck CA, Brown MW, Cannom DS, Daubert JP, Estes NA 3rd, Greenberg H, Hall WJ, Huang DT, Kautzner J, Klein H, McNitt S, Olshansky B, Shoda M, Wilber D and Zareba W. Reduction in inappropriate therapy and mortality through ICD programming. N Engl J Med. 2012 Dec 13;367(24):2275-83.