Context 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
Objective 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.
Design 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.
Interventions 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
Results 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.
Conclusion 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