Pacing to Avoid Cardiac Enlargement - PACE


The goal of this trial was to compare biventricular pacing versus right ventricular (RV) pacing in patients with bradycardia and normal left ventricular (LV) function.


Biventricular pacing would prevent LV dysfunction and adverse remodeling.

Study Design

  • Blinded
  • Randomized
  • Parallel
  • Stratified

Patients Screened: 251
Patients Enrolled: 177
Mean Follow Up: 1 year, 2 years, 5 years
Mean Patient Age: 69 years
Female: 47%
Mean Ejection Fraction: 62%

Patient Populations:

  • Patients with advance atrioventricular block or sinus-node dysfunction


  • Persistent atrial fibrillation
  • Unstable angina
  • Acute coronary syndrome
  • Percutaneous coronary intervention or coronary artery bypass grafting within the last 3 months
  • Life expectancy less than 6 months
  • Recipient of an orthotopic heart transplant
  • Pregnancy

Primary Endpoints:

  • LVEF at 12 months LV end-systolic volume at 12 months

Secondary Endpoints:

  • Hospitalization for heart failure
  • Distance in 6-minute walk test
  • Quality of life

Drug/Procedures Used:

Patients with bradycardia and normal LV ejection fraction (EF) were randomized to biventricular pacing (n = 89) versus RV pacing (n = 88).

Concomitant Medications:

At baseline in the biventricular pacing group, the use of antiplatelet agent or warfarin was 39%, beta-blocker was 18%, angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker was 33%, statin was 19%, and antiarrhythmic agent was 20%.

Principal Findings:

Overall, 177 patients were randomized. There was no difference in baseline characteristics between the groups. In the biventricular pacing arm, the mean age was 69 years, 47% were women, body mass index was 25 kg/m2, LVEF was 62%, and history of diabetes was 26%.

There were no periprocedural deaths.

At 12 months, LVEF was 62% with biventricular pacing versus 55% with RV pacing (p < 0.001).

Hospitalization for heart failure within 12 months occurred in 6% versus 7%, respectively. Distance in 6-minute walk test was 380 m versus 374 m (p = 0.81) and quality of life was similar between the groups (p = 0.75).

The difference in LVEF between the biventricular pacing and RV pacing groups was 6.3% at 1 year, 9.2% at 2 years, and 10.7% at longer-term follow-up (p < 0.001 for all comparisons). The differences in LV end-systolic volume were +7.4, +9.9, and +13.1 ml, respectively, for the same time points (p < 0.001 for all comparisons).


Among patients with bradycardia due to sinus-node dysfunction or atrioventricular block, and with normal LV function, the use of biventricular pacing is beneficial. In contrast to RV pacing, biventricular pacing resulted in preserved LV function and dimensions. Hospitalization for heart failure, distance in 6-minute walk test, and quality of life were similar between the groups.

Although this was a relatively small study, it builds upon our accumulating knowledge of the deleterious effects of RV pacing. While these findings are compelling, future studies will be needed to determine if similar patients should routinely receive a biventricular device, which is more expensive and requires more expertise for implant.


Presented by Dr. Cheuk-Man Yu at the European Society of Cardiology Congress, Barcelona, Spain, September 1, 2014.

Yu CM, Chan J, Zhang Q, et al. Biventricular pacing in patients with bradycardia and normal ejection fraction. N Engl J Med 2009;361:2123-2134.

Presented by Dr. Cheuk-Man Yu at the American Heart Association Scientific Sessions, Orlando, FL, November 15, 2009.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, EP Basic Science, Acute Heart Failure

Keywords: Atrioventricular Block, Follow-Up Studies, Body Mass Index, Cardiac Pacing, Artificial, Ventricular Function, Left, Quality of Life, Heart Failure, Bradycardia, Ventricular Dysfunction, Left, Diabetes Mellitus, Cardiac Resynchronization Therapy, ESC Congress

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