CORRESPONDENCE: LETTER TO THE EDITOR
Clarification and Correction About the Design and Implementation of the PROSPECT Trial
Dan Schaber, PharmD*
* VP CRDM Clinical Research, Medtronic, Inc., 8200 Coral Sea Street Northeast MVS33, Mounds View, Minnesota 55112 (Email: dan.schaber{at}medtronic.com).
In his commentary in the May 26, 2009, issue of the Journal, Sanderson (1) makes assertions about the design and implementation of the PROSPECT (Predictors of Response to CRT) trial as well as the role of the sponsor, Medtronic, that require clarification and correction. The author claims that study sites were selected solely because they were high-volume cardiac resynchronization therapy (CRT) implantation centers rather than on the basis of echocardiographic experience. The PROSPECT trial included academic and large private practice centers in Europe, the U.S., and Hong Kong. The CRT implantation experience was 1 criterion for selection, because placement of the left ventricular lead is viewed as an important contributor to therapeutic response. Additional and equally important criteria included cooperation among echocardiography, electrophysiology, and heart failure specialties within the center; the ability to collect standard echocardiography data; and a demonstrated ability to execute clinical trials. Furthermore, sites were accredited by their regional core echocardiography laboratory by providing high-quality images before enrolling subjects (2).
Contrary to Sanderson's statement (1), enrolling centers were not required to analyze tissue Doppler imaging (TDI); this was the responsibility of the core echocardiography laboratories (2). Hence, training the centers to analyze tissue Doppler images was not necessary. The PROSPECT trial was not originally powered to assess the validity of TDI measures, and as such, sites were not required to have echocardiography machines with this capability. During the study but before any analysis, Medtronic supported the physician Steering Committee's request to expand the enrollment of patients at centers with TDI-capable equipment, to properly power the study for analysis of TDI parameters. Enrollment was increased from an originally planned 300 subjects to 498. The Steering Committee—comprising prominent echocardiographers, heart failure specialists, and electrophysiologists—was involved in the trial design and the collection, monitoring, and analysis of data (3). Throughout the execution of the trial, the sponsor followed their recommendations, which included a quality control initiative to ensure consistent measurements of images by the core laboratories (2).
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Footnotes
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Please note: Dr. Schaber is the Vice President of Clinical Research of Medtronic Inc.
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References
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1. Sanderson JE. Echocardiography for cardiac resynchronization therapy selection—fatally flawed or misjudged J Am Coll Cardiol 2009;53:1960-1964.[Abstract/Free Full Text]2. Chung ES, Leon AR, Tavazzi L, et al. Results of the Predictors of Response to CRT (PROSPECT) trial Circulation 2008;117:2608-2616.[Abstract/Free Full Text] 3. Yu CM, Abraham WT, Bax J, et al. Predictors of response to cardiac resynchronization therapy (PROSPECT)—study design Am Heart J 2005;149:600-605.[CrossRef][Web of Science][Medline]
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