United Kingdom Pacing and Cardiovascular Events - UKPACE

Description:

The goal of the United Kingdom Pacing and Cardiovascular Events (UKPACE) trial was to evaluate the efficacy and cost-utility of dual chamber (DDD/R) pacing versus single chamber ventricular (VVI) pacing in elderly patients with high-grade atrioventricular (AV) block.

Hypothesis:

Treatment with dual chamber pacing will result in a lower rate of all-cause mortality than single chamber pacing (fixed or adaptive) in elderly patients with high-grade AV block.

Study Design

Study Design:

Patients Enrolled: 2,021
Mean Follow Up: Mean 4.6 years for mortality and 3 years for other event end points
Mean Patient Age: Mean age 80 years

Patient Populations:

Age ≥70 years and high-grade AV block

Exclusions:

Established atrial fibrillation, severe cognitive dysfunction, total immobility, class IV heart failure, and advanced malignancy

Primary Endpoints:

All-cause mortality

Secondary Endpoints:

Quality of life (SF-36 and EQ-5D), New York Heart Association class, exercise capacity (six-minute walk), and cardiovascular morbidity (atrial fibrillation, heart failure, suspected pacemaker syndrome, and stroke; TIA or other thromboembolism)

Drug/Procedures Used:

Patients at 46 sites in the UK were randomized to either dual chamber (DDD/R) pacing (n=1012) or single chamber ventricular pacing. Patients in the single chamber arm were randomized to either fixed rate (VVI; n=504) or adaptive rate (VVI/R; n=505) pacing.

Principal Findings:

All cause mortality did not differ between the VVI, VVI/R, and DDD/R arms (hazard ratio [HR] 0.96 for VVI and VVI/R combined vs. DDD/R, p=0.56; HR 1.03 for VVI vs. DDD/R, p=0.74; HR 0.89 for VVI/R vs. DDD/R, p=0.22). There was also no difference in stroke or transient ischemic attack (TIA) for the VVI and VVI/R combined versus DDD/R analysis (HR 1.28, p=0.20) or the VVI/R versus DDD/R (HR 0.98, p=0.93), but there was an increase associated with DDD/R versus VVI (HR 1.58, p=0.035).

Heart failure also did not differ between the arms (8% with VVI vs. 11% with VVI/R vs. 10% with DDD/R) or did myocardial infarction (2.4% with VVI vs. 2.2% with VVI/R vs. 3.2% with DDD/R).

Interpretation:

Among elderly patients with high-grade AV block, treatment with DDD/R was not associated with a difference in all-cause mortality compared with VVI or VVI/R. The trial was designed given the observed lower use of dual chamber pacing in elderly patients in a UK utilization analysis.

It is possible that longer follow-up would be needed to see an effect on atrial fibrillation or heart failure such as in the Danish Mode trial, which had a mean follow-up of 5.5 years compared with only three years for nonfatal clinical events in the present trial. Quality of life, exercise tolerence test, and other secondary end point data are not yet available.

References:

Toff WD, et al. Single-Chamber versus Dual-Chamber Pacing for High-Grade Atrioventricular Block. N Engl J Med 2005;353:145-55.

Presented at Late-Breaking Clinical Trials, ACC 2003.

Clinical Topics: Arrhythmias and Clinical EP, Implantable Devices, EP Basic Science

Keywords: Atrioventricular Block, Myocardial Infarction, Stroke, Follow-Up Studies, Ischemic Attack, Transient, Quality of Life, Dichlorodiphenyldichloroethane, Exercise Test


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