LOS ANGELES — Improved programming of ICD therapies for tachyarrhythmias of 200 bpm or higher or with a 60-second duration delay in therapy at 170 bpm or higher was associated with reductions in inappropriate therapy and all-cause mortality during 1.4 years of follow-up, as compared with conventional programming.
The three-arm MADIT-RIT trial involved 1,500 patients with a primary prevention indication. Patients were enrolled from 98 centers in the United States, Canada, Europe, Israel and Japan. Arthur J. Moss, MD, and colleagues randomly assigned patients to one of three arms:
- High-rate therapy with a 2.5-second delay before initiation of therapy at a heart rate of 200 bpm or faster;
- Duration-delay therapy with 60-second monitoring before initiation of therapy at 170 bpm or faster;
- Conventional therapy with a 2.5-second delay at 170 bpm or greater and a 1-second delay at 200 bpm or faster.
The primary endpoint was first episode of inappropriate therapy. During follow-up, high-rate therapy and delayed-duration therapy reduced the first occurrence of inappropriate therapy, as compared with conventional device programming (high-rate vs. conventional: HR=0.21; 95% CI, 0.13-0.34; delayed vs. conventional: HR=0.24; 95% CI, 0.15-0.4). Similar reductions were observed for all-cause mortality (high-rate vs. conventional: HR=0.45; 95% CI, 0.24-0.85; delayed vs. conventional: HR=0.56; 95% CI, 0.3-1.02), according to results simultaneously published in The New England Journal of Medicine.
“Looking at the HRs, there was a fivefold reduction in the first occurrence of inappropriate therapy with high-rate programming vs. conventional therapy, and a fourfold reduction in inappropriate therapy with delayed-duration programming vs. conventional therapy,” Moss said at a late-breaking clinical trials session.
The researchers reported no significant differences in procedure-related adverse events among patients assigned to the three treatment arms.
“Improved ICD programming with high-rate or duration-delay therapy is associated with a significant, approximate 75% reduction in first inappropriate therapy and approximate 50% reduction in all-cause mortality,” Moss said during his presentation. “We believe the decrease in mortality is related to improved ICD programming with reduced ATP and inappropriate shocks.”
The trial used Boston Scientific devices. – by Katie Kalvaitis
For more information:
Moss AJ. Late-breaking clinical trials: Management of LV dysfunction: Devices and drugs. Presented at: the American Heart Association Scientific Sessions; Nov. 3-7, 2012; Los Angeles.
Moss AJ. N Engl J Med. 2012;doi:10.1056/nejmoa1211107.
Disclosure: The trial was funded by Boston Scientific. Moss reports receiving research grants from Boston Scientific.