The Pacing to Avoid Cardiac Enlargement (PACE) trial: clinical background, rationale, design, and implementation.
BACKGROUND
Deleterious effect on left ventricular (LV) function was observed with conventional right ventricular apical (RVA) pacing. Preliminary data suggested that biventricular pacing (BiV) may be superior to RVA pacing in patients with LV systolic dysfunction. However, the optimal pacing mode and site(s) for patients with normal LV systolic function remain controversial.


METHODS
The Pacing to Avoid Cardiac Enlargement (PACE) trial is a prospective, multicenter, randomized, double blinded, parallel, controlled study aiming to determine if BiV pacing is better than conventional RVA pacing in preserving LV systolic function and preventing remodeling in patients with LV ejection fraction (EF) > or = 45% indicated for pacing. This study targets to recruit 200 patients from various centers in Asia, all of whom will receive BiV pacemaker implantation before being randomized to either atrial-based RVA or BiV pacing for 1 year. Their echocardiographic parameters including LV volumes, left ventricular ejection fraction (LVEF), and dyssynchrony index by tissue Doppler imaging, exercise capacity, quality of life assessment, neurohormone levels, and clinical events will be assessed before and after pacing. The primary endpoints are changes in LV end-systolic volume and LVEF 1 year after pacing. It is designed with 90% power to detect a 5% difference in the LVEF after 1 year of pacing. The enrollment began in 2006. It is expected to conclude at the end of 2008.


CONCLUSIONS
The PACE trial will determine whether atrial-based BiV pacing can preserve LV systolic function and prevent LV adverse remodeling induced by conventional RVA pacing in patients with normal LV systolic function and standard pacing indication.
Fung
Jeffrey Wing-Hong
JW
Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong.
Chan
Joseph Yat-Sun
JY
Omar
Razali
R
Hussin
Azlan
A
Zhang
Qing
Q
Yip
Gabriel
G
Lam
Kai Huat
KH
Fang
Fang
F
Yu
Cheuk-Man
CM
D001208:Asia / Q000453:epidemiology; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D006332:Cardiomegaly / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D004311:Double-Blind Method; D005500:Follow-Up Studies; D006801:Humans; D015337:Multicenter Studies as Topic / Q000379:methods; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design; D016277:Ventricular Function, Left / Q000502:physiology