High-rate or delayed implantable cardioverter-defibrillator (ICD) therapy is associated with reductions in inappropriate therapy and all-cause mortality, researchers say.
The results of the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) trial imply that two simple programming alterations could provide the solution to the longstanding problem of inappropriate shocks with ICD therapy, say Arthur Moss (University of Rochester, New York, USA) and team.
Moss, who presented the findings at the American Heart Association Scientific Sessions in Los Angeles, California, USA, explained that two programming alterations to ICD therapy were made, defined as high therapy (2.5-second delay before therapy initiation at heart rate of ≥200 beats per minute) and delayed therapy (60-second delay at 170-199 beats per minute, 12-second delay at 200-249 beats per min, and 2.5-second delay at ≥250 beats per minute).
Compared with conventional programming (2.5-second delay at 170-199 beats per min for ventricular tachycardia, 1.0-second delay at ≥200 beats per min for antitachycardia pacing or shock), high-rate and delayed ICD therapy were associated with significant reductions in a first occurrence of inappropriate therapy at 1.4 years.
Indeed, high-rate therapy was associated with a significant 79% reduced risk for inappropriate therapy, while delayed therapy was associated with a significant 76% reduced risk for inappropriate therapy compared with conventional therapy.
As reported in the New England Journal of Medicine, high-rate and delayed therapy were also linked to a significantly reduced risk for all-cause mortality, at hazard ratios of 0.45 and 0.56, respectively.
There were no significant differences in procedure-related adverse events among the three treatment groups.
"Although the trial was not designed to compared the effectiveness of programmed high-rate therapy with that of delayed therapy, it is obvious from the reported findings that the overall results of these two methods of programmed therapy were similarly superior to the results of conventional programming," say the authors.
"However, programming delayed therapy together with enhanced rhythm detection is quite complex, whereas programming therapy at a heart rate of 200 beats per minute or higher is simple."
Moss and team conclude that the findings from their randomized trial "add a new chapter in the ongoing evolution of ICD therapy for primary prevention."
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