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REVIEW
Systematic Review: Cardiac Resynchronization in Patients with Symptomatic Heart Failure
Finlay A. McAlister, MD, MSc;
Justin A. Ezekowitz, MB, BCh, MSc;
Natasha Wiebe, Mmath;
Brian Rowe, MD, MSc;
Carol Spooner, MSc;
Ellen Crumley, MLIS;
Lisa Hartling, MSc;
Terry Klassen, MD, MSc; and
William Abraham, MD
7 September 2004 | Volume 141 Issue 5 | Pages 381-390
Background: Even with optimal pharmacotherapy, symptomatic heart failure is associated with substantial morbidity and mortality.
Purpose: To determine the efficacy and safety of cardiac resynchronization therapy in adults with advanced systolic heart failure.
Data Sources: The Cochrane Central Register of Controlled Trials (2002, volume 4), MEDLINE (1980–2003), EMBASE (1980–2003), other electronic databases, and U.S. Food and Drug Administration reports. We contacted primary study authors and device manufacturers, and we hand searched bibliographies of relevant papers and conference proceedings.
Study Selection: Randomized, controlled clinical trials for efficacy and controlled trials plus prospective cohort studies for safety.
Data Extraction: Two reviewers chose studies and extracted data independently; random-effects models were used for analyses.
Data Synthesis: Nine trials were included in the efficacy review (3216 patients). All trial participants had reduced ejection fraction and prolonged QRS duration, and 85% had New York Heart Association (NYHA) class III or IV symptoms. Cardiac resynchronization therapy improved ejection fraction (weighted mean difference, 0.035 [95% CI, 0.015 to 0.055]), quality of life (weighted mean reduction in score on the Minnesota Living with Heart Failure Questionnaire, 7.6 points [CI, 3.8 to 11.5 points]), and function (58% vs. 37% of patients improved by at least 1 NYHA class). Heart failure hospitalizations were reduced by 32% (relative risk [RR], 0.68 [CI, 0.41 to 1.12]), with benefits most marked in patients with NYHA class III or IV symptoms at baseline (RR, 0.65 [CI, 0.48 to 0.88]; number needed to treat for benefit [NNTB], 12). All-cause mortality was reduced by 21% (RR, 0.79 [CI, 0.66 to 0.96]; NNTB, 24), driven largely by reductions in death from progressive heart failure (RR, 0.60 [CI, 0.36 to 1.01]). Eighteen studies (total of 3701 patients with cardiac resynchronization devices) were included in the safety review. Implant success rate was 90% (CI, 89% to 91%), and 0.4% of patients died during implantation (CI, 0.2% to 0.7%). Over a median 6-month follow-up, leads dislodged in 9% of patients (CI, 7% to 10%) and mechanical malfunctions occurred in 7% (CI, 5% to 8%).
Limitations: These trials enrolled only patients with heart failure with NYHA class III or IV symptoms despite medical therapy, a prolonged QRS duration, and reduced ejection fraction; in addition, experienced providers implanted the devices. Because all but one of these trials randomly assigned patients after device implantation, their results may overestimate the potential benefits of cardiac resynchronization. Finally, since few patients in these trials had bradyarrhythmias or atrial fibrillation, the role of cardiac resynchronization in such patients is uncertain.
Conclusions: In selected patients with heart failure, cardiac resynchronization therapy improves functional and hemodynamic status, reduces heart failure hospitalizations, and reduces all-cause mortality.
Editors' Notes
Context
- A biventricular pacemaker to resynchronize ventricular contraction is a new therapy for heart failure. A 2003 meta-analysis included only 2 published and 2 unpublished trials, but 5 additional studies have since become available.
Contribution
- Data from 3216 patients who participated in 9 trials demonstrate that cardiac resynchronization improves many outcomes, including mortality. Data from 3701 patients participating in 18 studies showed that leads dislodged in 9% of patients during 6 months of follow-up and that the device malfunctioned in 7%.
Implications
- In select patients, cardiac resynchronization is an effective therapy for heart failure.
–The Editors
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Author and Article Information
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From The University of Alberta and Capital Health Evidence-based Practice Center, Edmonton, Alberta, Canada; and Ohio State University, Columbus, Ohio.
Acknowledgments: The authors thank the following individuals, who provided data from their studies: Drs. S. Cazeau, C. Leclerq, and S. Garrigue. The authors also thank the reviewers of the AHRQ report from which this manuscript is derived: Drs. Joanne Siegel and David Atkins (AHRQ), Dr. Bruce Wilkoff (Cleveland Clinic Foundation, Cleveland, Ohio), Dr. Donald Casey (Catholic Healthcare Partners, Cincinnati, Ohio), Dr. Robert Rea (Mayo Clinic, Rochester, Minnesota), Dr. Robert Kowal (University of Texas Southwestern Medical Center, Dallas, Texas), and Dr. Clyde Yancy (St. Paul University Hospital/University of Texas Southwestern Medical Center, Dallas, Texas).
Grant Support: The evidence report was produced by the University of Alberta Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (contract no. 290-02-0023). Dr. McAlister is supported by the Alberta Heritage Foundation for Medical Research, Drs. Ezekowitz and McAlister are supported by the Canadian Institutes of Health Research, and Dr. Rowe is supported by a Canada Research Chair.
Potential Financial Conflicts of Interest:Honoraria: W. Abraham (Medtronic Inc., Guidant Corp., St. Jude Memorial); Grants: W. Abraham (Medtronic Inc., Guidant Corp.).
Requests for Single Reprints: Finlay A. McAlister, MD, MSc, 2E3.24, University of Alberta Hospital, 8440 112 Street, Edmonton, Alberta T6G 2R7, Canada; e-mail, Finlay.McAlister{at}ualberta.ca.
Current Author Addresses: Dr. McAlister: 2E3.24, University of Alberta Hospital, 8440 112 Street, Edmonton, Alberta T6G 2R7, Canada.
Dr. Ezekowitz: University of Alberta, 2-51 Medical Sciences Building, Edmonton, Alberta T6G 2H7, Canada.
Ms. Wiebe and Ms. Hartling: University of Alberta Campus, 9417 Aberhart Centre One, 11402 University Avenue, Edmonton, Alberta T6G 2J3, Canada.
Dr. Rowe: Division of Emergency Medicine, University of Alberta Hospital, 8440 112 Street, Edmonton, Alberta T6G 2R7, Canada.
Ms. Spooner: University of Alberta, Room 1814, 8215 112 Street, Edmonton, Alberta T6G 2C8, Canada.
Ms. Crumley: University of Alberta Campus, 9419 Aberhart Centre One, 11402 University Avenue, Edmonton, Alberta T6G 2J3, Canada.
Dr. Klassen: Department of Pediatrics, University of Alberta Hospital, 8440 112 Street, Edmonton, Alberta T6G 2R7, Canada.
Dr. Abraham: Ohio State University, 473 West 12th Avenue, Columbus, OH 43210.
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