Evaluation of resynchronization therapy for heart failure in patients with a QRS duration greater than 120 ms (GREATER-EARTH) trial: rationale, design, and baseline characteristics

Abstract

Background: Heart failure is considered an epidemic of the modern era. In selected candidates on optimal medical therapy, cardiac resynchronization therapy (CRT) has emerged as a valuable adjunctive treatment. Despite its demonstrated salutary effects on clinical evolution, left ventricular (LV) function, and overall survival, at least 30% of patients fail to respond to CRT.

Methods: The Greater Evaluation of Resychronization Therapy for Heart Failure (GREATER-EARTH) (ClinicalTrials.gov Identifier NCT00901212) is a randomized, double-blind, multicentre study involving 11 centres across Canada and compares LV CRT with biventricular CRT in patients with severe LV dysfunction and a QRS duration>120 ms.

Results: This article describes the rationale and design of the study and presents the baseline characteristics of all randomized patients. The primary outcome consists of the effects of CRT on submaximal exercise tolerance (treadmill test), and secondary outcomes explore mechanisms of asynchrony and effects of CRT on asynchrony and LV function.

Conclusion: The study was initiated in November 2003, with the last patient randomized on February 12, 2009. As expected, follow-up was in February 2010 and the results are presently being analyzed in March 2010.