Brian Olshansky, MD, lead investigator on the study announced by Boston Scientific Corporation www.bostonscientific.com, says "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."

Olshansky and others recently completed the largest implantable pacemaker-defibrillator trial ever performed, the Intrinsic RV Study, involving 1,530 patients from 108 centers around the world. The University of Iowa was one of the coordinating centers for this multicenter international study. Results of the largest implantable cardioverter defibrillator (ICD) study to date, known as INTRINSIC RV, showed that dual-chamber pacing in combination with Boston Scientific's AV Search Hysteresis (AVSH) programming performs as well as single-chamber pacing in reducing heart failure hospitalization and all cause mortality.

"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," Olshansky says. Approximately 330,000 American adults experience sudden cardiac death (SCD) annually, and only one in 20 survives. SCD claims more lives each year than AIDS, breast cancer and lung cancer combined. SCD occurs six to nine times more often among heart-failure patients than in the general population. ICDs have been shown to prevent SCD, and this technology continues to provide new opportunities for improved patient care.

The goal of the Intrinsic RV Study was to show that the more sophisticated two-lead systems were at least as safe as the simpler systems. Findings showed that not only were dual chamber ICDs shown to be as safe as single chamber devices (primary end-point achieved) but that they may also confer a survival advantage. Over a mean follow-up of nearly one year, the combined end-point of hospitalizations for heart failure and total mortality was 9.5 percent in the simple single lead pacemaker-defibrillator arm and 6.4 percent in the more sophisticated dual lead pacemaker-defibrillator arm. This represents a 33 percent decrease in heart failure hospitalizations and mortality with more advanced technology programmed correctly.

Brian Olshansky, MD

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UI Heart and Vascular Center