Boston Scientific publishes results of Dual-Chamber Pacing study

Jan 2 2007

Boston Scientific Corporation has announced that results of the largest implantable cardioverter defibrillator (ICD) study to date, known as INTRINSIC RV, were published in the January issue of the journal Circulation.

INTRINSIC RV met its primary endpoint, showing that dual-chamber pacing in combination with Boston Scientific's AV Search Hysteresis (AVSH) programming -- a proprietary feature that proactively reduces right ventricular (RV) pacing when the heart's natural rhythm is present -- performs as well as single- chamber pacing in reducing heart failure hospitalization and all cause mortality (p<0.001, non inferiority).

"The results of this landmark study are important because dual-chamber ICD programming can provide benefits to patients that single-chamber programming may not, such as improved heart function and enhanced arrhythmia detection," said Brian Olshansky, M.D., Professor of Medicine, Director of Cardiac Electrophysiology, University of Iowa Hospitals and a lead investigator of the trial. "Prior studies have suggested that dual-chamber devices may lead to unnecessary RV pacing, which in some patients may pose safety concerns. This study showed that these perceived safety concerns were not present in the patient arm where dual-chamber pacing with AV Search Hysteresis was used."

INTRINSIC RV (Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs) is a multi-center, randomized, prospective, non- inferiority trial that enrolled 1,530 patients with a current indication for an ICD at 108 centers in the United States, Germany, Italy and Australia. The primary endpoint was a composite of all-cause mortality and heart-failure hospitalization. Patients in the dual-chamber pacing with AVSH group experienced 33 percent fewer deaths and heart-failure hospitalizations compared to single chamber pacing (p=0.072, superiority).

"INTRINSIC RV represents Boston Scientific's ongoing commitment to clinical science, and is part of our larger program to demonstrate the distinctive value of these sophisticated, life-saving devices to patients and physicians," said Steven Zelenkofske, D.O., F.A.C.C., Vice President, Clinical Sciences and Chief Patient Safety Officer, Boston Scientific CRM.