Mortality Reduction In Relation To ICD Programming In MADIT-RIT
Background—The benefit of novel ICD programming in reducing inappropriate ICD therapy and mortality was demonstrated in MADIT-RIT. However, the cause of the mortality reduction remains incompletely evaluated. We aimed to identify factors associated with mortality, with focus on ICD therapy and programming in the MADIT-RIT population.
Methods and Results—In MADIT-RIT, 1500 patients with a primary prophylactic indication for ICD or CRT-D were randomized to one of three different ICD programming arms: conventional programming (VT-zone ≥170 bpm); high-rate programming (VT-zone ≥200 bpm); and delayed programming (60 sec. delay before therapy≥170 bpm). Multivariate Cox models were used to assess the influence of time-dependent appropriate and inappropriate ICD therapy (shock and/or antitachycardia pacing [ATP]) and randomized programming arm on all-cause mortality. During an average follow-up of 1.4±0.6 years, 71 of 1500 (5%) patients died: cardiac in 40 patients (56.3 %), non-cardiac in 23 patients (32.4%), and unknown in 8 patients (11.3%). Appropriate shocks (Hazard Ratio [HR] = 6.32 [95% CI: 3.13-12.75], p<0.001) and inappropriate therapy (HR=2.61 [1.28-5.31], p=0.01) were significantly associated with an increased mortality risk. There was no evidence of increased mortality risk in patients who experienced appropriate ATP only (HR=1.02 [0.36-2.88], p=0.98). Randomization to conventional programming was identified as an independent predictor of death when compared to patients randomized to high-rate programming (HR=2.0 [1.06-3.71], p=0.03).
Conclusions—In the MADIT-RIT trial, appropriate shocks, inappropriate ICD therapy, and randomization to conventional ICD programming were independently associated with an increased mortality risk. Appropriate ATP was not related to an adverse outcome.
Clinical Trial Registration—clinicaltrials.gov; Unique Identifier: NCT00947310.
- ICD therapy
- Inappropriate ATP
- ICD programming
- implanted cardioverter defibrillator
- Received January 14, 2014.
- Revision received July 6, 2014.
- Accepted July 8, 2014.