Trial: INTRINSIC RV

Authors: Olshansky B, Day JD, Moore S, Gering L,  Rosenbaum M, McGuire M, Brown S, Lerew D.

Reference: Circulation. 2007;115:9-16.

ClinicalTrials.gov Identifier: NCT00148967.

Purpose: to test the hypothesis that dual-chamber rate-responsive (DDDR) with atrioventricular search hysteresis (AVSH) 60-130 programming is not inferior to single-chamber (VVI)–40 programming in an implantable cardioverter defibrillator with respect to all-cause mortality and heart failure hospitalizations.

Methods: Patients undergoing ICD implantation for standard indications were programmed to DDDR AVSH 60-130 for the first week. Those who had RV pacing for less than 20% of the time were randomized to DDDR with AV search hysteresis (AVSH 60-130) or to VVI-40.  The primary endpoint was a composite of mortality and hospitalization for heart failure. 

Number of Patients:1530 patients implanted and assessed for RV pacing for the first week;  988 who had RV pacing for less than 20% of the time, were randomized and followed.

Number of Centers:108

Design: Randomized noninferiority trial

Authors Conclusion: DDDR with AV search hysteresis was not inferior to VVI backup programming with regard to all-cause mortality and heart failure hospitalization.

Key words:  arrhythmia, tachyarrhythmias, defibrillation, electrophysiology, pacing

Comments: The DAVID trial showed that DDD pacing at 70 beats per minute increased the combined endpoint of mortality and heart failure hospitalizations compared to VVI pacing at 40 beats/min in patients who had depressed LV function, were receiving ICDs, but had no indication for bradycardia pacing.  It has been suggested that hemodynamic effects of forced RV pacing at the programmed rate were adverse in the DDD group.  INTRINSIC RV demonstrates that DDD pacing can be used safely in those patients for whom the pacing algorithm results in RV pacing less than 20% of the time.  It should be recognized that the event rate was low (6.4% in the DDDR  AVSH arm and 9.5% in the VVI arm) over a relatively short mean follow-up of 10.4 months.  Thus, a small effect would not have been detected.

Ongoing Related Studies:

1. Dual-Chamber and VVI Implantable Defibrillator (DAVID) II Trial Results.
Webcast of the DAVID II Late-Breaking Clinical Trial from Heart Rhythm 2007

Summary written by William G. Stevenson, MD, FHRS