Implantable cardioverter defibrillator (ICD) therapy with backup ventricular
pacing increases survival in patients with life-threatening ventricular arrhythmias.
Most currently implanted ICD devices provide dual-chamber pacing therapy.
The most common comorbid cause for mortality in this population is congestive
To determine the efficacy of dual-chamber pacing compared with backup
ventricular pacing in patients with standard indications for ICD implantation
but without indications for antibradycardia pacing.
The Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial, a
single-blind, parallel-group, randomized clinical trial.
Setting and Participants
A total of 506 patients with indications for ICD therapy were enrolled
between October 2000 and September 2002 at 37 US centers. All patients had
a left ventricular ejection fraction (LVEF) of 40% or less, no indication
for antibradycardia pacemaker therapy, and no persistent atrial arrhythmias.
All patients had an ICD with dual-chamber, rate-responsive pacing capability
implanted. Patients were randomly assigned to have the ICDs programmed to
ventricular backup pacing at 40/min (VVI-40; n = 256) or dual-chamber rate-responsive
pacing at 70/min (DDDR-70; n = 250). Maximal tolerated medical therapy for
left ventricular dysfunction, including angiotensin-converting enzyme inhibitors
and β-blockers, was prescribed to all patients.
Main Outcome Measure
Composite end point of time to death or first hospitalization for congestive
One-year survival free of the composite end point was 83.9% for patients
treated with VVI-40 compared with 73.3% for patients treated with DDDR-70
(relative hazard, 1.61; 95% confidence interval [CI], 1.06-2.44). The components
of the composite end point, mortality of 6.5% for VVI-40 vs 10.1% for DDDR-70
(relative hazard, 1.61; 95% CI, 0.84-3.09) and hospitalization for congestive
heart failure of 13.3% for VVI-40 vs 22.6% for DDDR-70 (relative hazard, 1.54;
95% CI, 0.97-2.46), also trended in favor of VVI-40 programming.
For patients with standard indications for ICD therapy, no indication
for cardiac pacing, and an LVEF of 40% or less, dual-chamber pacing offers
no clinical advantage over ventricular backup pacing and may be detrimental
by increasing the combined end point of death or hospitalization for heart