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Increasing the length of time an arrhythmia can persist before an implantable cardioverter-defibrillator activates resulted in fewer shocks, both appropriate and inappropriate, the randomized ADVANCE III trial found.

Patients in the group that had a prolonged interval had a 37% lower rate of delivered therapies -- antitachycardia pacing (ATP) and shocks -- than those in the standard-interval detection group at a median follow-up of 12 months, reported Maurizio Gasparini, MD, of the Humanitas Clinical and Research Center in Rozzano, Italy.

The long-interval detection group also had a 45% reduction in the rate of inappropriate shocks, while the frequency of appropriate shocks was similar between the groups, according to the study published in the May 8 issue of the Journal of the American Medical Association.

The occurrence of syncope was not significantly different between the two groups.

Emerging evidence suggests that ICD therapies, both appropriate and inappropriate, are associated with an increased risk of death and worsening of heart failure. But despite the reductions in appropriate and inappropriate therapies, Gasparini and colleagues did not see a reduction in mortality associated with the longer delay.

In the MADIT-RIT randomized trial, which also tested various algorithms for therapy deliverance, researchers saw a significant 55% reduction in mortality when patients were followed out to 3 years.

"It was between the first and third year of the follow-up in MADIT-RIT that we saw the reduction in mortality," Arthur J. Moss, MD, of the University of Rochester Medical Center in Rochester, N.Y., told 木瓜直播.

The short follow-up in ADVANCE III probably contributed to the lack of a mortality benefit, Moss said.

"Regardless of whether these programming interventions lead to reduced mortality, the unequivocal reduction in ICD shocks and the reduction in hospitalization without an increase in adverse events such as syncope suggests that this programming approach should be considered for adoption in the care of patients with ICDs and clinical characteristics similar to those enrolled in these studies," commented Merritt H. Raitt, MD, of the Portland Veterans Administration Medical Center, Ore., in an accompanying editorial.

Trials such as ADVANCE III and MADIT-RIT attempt to reduce both appropriate and inappropriate therapies by identifying the best device programming strategies, either by delaying the time before ATP interrupts ventricular tachyarrhythmias or by prolonging the time before shocks are delivered for ventricular fibrillation, researchers noted.

In addition, the use of more intervals to detect ventricular tachyarrhythmias has been associated with reducing unnecessary ICD therapies," they added.

In ADVANCE III, Gasparini and colleagues randomized 1,902 primary and secondary prevention patients on a 1:1 basis to programming with long-detection (30 of 40 intervals to detect ventricular arrhythmias) or standard detection (18 of 24 intervals). Long detection during spontaneous fast ventricular tachyarrhythmias episodes reduces ATP and shock delivery more than standard detection.

The average age of patients was 65 and 84% were men. About three-fourths were designated for primary prevention ICD with ischemic and nonischemic etiology undergoing first ICD implant at one of 94 international centers between March 2008 and December 2010.

"ADVANCE III demonstrated that the use of a long detection setting, in ICDs with the capability of delivering ATP during capacitor charge, significantly reduced the rate of ventricular therapies delivered and inappropriate shocks compared with the standard detection setting," the authors wrote. "This programming strategy may be a useful approach for ICD recipients."

The authors said the study was limited in that only one manufacturer's device was used for all patients and there was the potential of lost arrhythmic episodes because of limitations in the device's memory.

From the American Heart Association:

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