title: A randomized controlled trial to evaluate the safety and efficacy of cardiac contractility modulation in patients with moderately reduced left ventricular ejection fraction and a narrow QRS duration: study rationale and design.
abstract: Cardiac contractility modulation (CCM) signals are nonexcitatory electrical signals delivered during the cardiac absolute refractory period that enhance the strength of cardiac muscular contraction. The FIX-HF-5 study was a prospective randomized study comparing CCM plus optimal medical therapy (OMT) to OMT alone that included 428 New York Heart Association (NYHA) functional class III or IV heart failure patients with ejection fraction (EF) ≤45% according to core laboratory assessment. The study met its primary safety end point, but did not reach its primary efficacy end point: a responders analysis of changes in ventilatory anaerobic threshold (VAT). However, in a prespecified subgroup analysis, significant improvements in primary and secondary end points, including the responder VAT end point, were observed in patients with EFs ranging from 25% to 45%, who constituted about one-half of the study subjects. We therefore designed a new study to prospectively confirm the efficacy of CCM in this population. A hierarchic bayesian statistical analysis plan was developed to take advantage of the data already available from the first study. In addition, based on technical difficulties encountered in reliably quantifying VAT and the relatively large amount of nonquantifiable studies, the primary efficacy end point was changed to peak VO2, with significant measures incorporated to minimize the influence of placebo effect. In this paper, we provide the details and rationale of the FIX-HF-5C study design to study CCM plus OMT compared with OMT alone in subjects with normal QRS duration, NYHA functional class III or IV, and EF 25%-45%. This study is registered on www.clinicaltrials.gov with identifier no. NCT01381172.
authors.affiliation: Division of Cardiovascular Medicine, The Ohio State University, Columbus, Ohio.
authors.forename: William T
authors.initials: WT
authors.lastname: Abraham
authors.affiliation: Division of Cardiology, University of Colorado, Denver, Colorado.
authors.forename: JoAnn
authors.initials: J
authors.lastname: Lindenfeld
authors.affiliation: Division of Cardiology, Helmsley Electrophysiology Center, Mount Sinai School of Medicine, New York, New York.
authors.forename: Vivek Y
authors.initials: VY
authors.lastname: Reddy
authors.affiliation: Department of Cardiology and Pneumology, Georg-August University Goettingen, Goettingen, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Hasenfuss
authors.affiliation: Department of Cardiology, The Asklepios Klinik St. Georg, Hamburg, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Kuck
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, California.
authors.forename: John
authors.initials: J
authors.lastname: Boscardin
authors.affiliation: Department of Health Studies, University of Chicago, Chicago, Illinois.
authors.forename: Robert
authors.initials: R
authors.lastname: Gibbons
authors.affiliation: Division of Cardiology, Columbia University, New York, New York. Electronic address: db59@columbia.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Burkhoff
mesh_terms: D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000592:standards*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*
keywords: Heart failure; cardiac resynchronization therapy; cardiopulmonary stress testing; quality of life