Factors Associated with Improvement in Utilization of Cardiac Resynchronization Therapy in Eligible Heart Failure Patients: Findings from IMPROVE HF


  • Clinical trial registration information—URL: http://www. clinicaltrials.gov. Unique identifier: NCT00303979.

  • Financial Support for the study: The IMPROVE HF registry and this study are supported by Medtronic, Inc., Minneapolis, Minnesota.

  • Anne B. Curtis: Research grants: Medtronic (modest), honoraria: Medtronic (modest), consultant: Medtronic (modest), advisory board: Sanofi-Aventis (modest), St. Jude Medical (modest), Biosense Webster (modest); Janssen Pharmaceuticals (modest); Bristol-Myers-Squibb (modest).

  • Mandeep R. Mehra: Consultant: Medtronic (modest), Johnson & Johnson (modest), St. Jude Medical (modest); Grants/research support: National Institutes of Health/NHLBI (significant), American Board of Internal Medicine (modest).

  • Nancy Albert: honoraria: Medtronic (modest).

  • Mihai Gheorghiade, Consultant: Abbott Laboratories (modest), Astellas (modest), Astra Zeneca (modest), Bayer Schering Pharma AG (significant), CorThera, Inc (modest), Cytokinetics, Inc (modest), DebioPharm SA (significant), Errekappa Terapeutici (Milan, Italy) (modest), GlaxoSmithKline (modest), Johnson & Johnson (modest), Medtronic (significant), Merck (modest), Novartis Pharma AG (significant), Otsuka Pharmaceuticals (significant), Pericor Therapeutics (significant), Protein Design Laboratories (modest), Sanofi-Aventis (modest), Sigma Tau (significant), Solvay Pharmaceuticals (significant).

  • J. Thomas Heywood, Research grants: Biosite (modest), Medtronic (significant), St.Jude (significant); Speakers Bureau/honoraria:GlaxoSmithKline (modest), Medtronic (significant), AstraZeneca (modest), Novartis (modest); Actelion (significant), St. Jude (modest), Otsuka (modest), Boston Scientific (modest); Consultant/advisory board: Emerge (modest), Medtronic (significant), Actelion (modest).

  • Yang Liu: Employee of Medtronic, Inc.

  • Christopher M. O'Connor, Consultant: Forest (significant), Medtronic (significant), Amgen (significant), Medpace (significant), Impulse Dynamics (significant), Actelion (significant), Cytokinetics (modest), Roche (modest), Trevena (modest).

  • Dwight Reynolds: Research grants: Medtronic, Biotronik; Speakers Bureau: Medtronic, Sorin; Consultant: Medtronic (all significant).

  • Mary Norine Walsh: Consultant: United HealthCare (modest).

  • Gregg C. Fonarow, Research grants: National Institutes of Health (significant); Consultant: Medtronic (modest), Novartis (significant); Honoraria: Medtronic (modest).

  • Conflicts of Interest: Ashish Shukla and Clyde W. Yancy: No relationships to disclose.

Address for reprints: Gregg C. Fonarow, M.D., Ahmanson–UCLA Cardiomyopathy Center, Ronald Reagan UCLA Medical Center, 10833 LeConte Avenue, Room A2-237 CHS, Los Angeles, CA, 90095-1679. Fax: 310-206-9111; e-mail: gfonarow@mednet.ucla.edu



There is a well-recognized gap between the number of patients in whom cardiac resynchronization therapy (CRT) is indicated based on current guidelines and its actual utilization. In the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) study, there was a significant increase in the use of CRT at 24 months in patients with heart failure (HF) in comparison to baseline. This study evaluated patient, physician, and practice factors associated with this increase in CRT utilization.


Patients with reduced left ventricular ejection fraction and chronic HF who met the eligibility criteria for CRT at baseline and 24 months were analyzed. Multivariate analyses using patient, physician, and practice characteristics were performed to evaluate factors associated with increased CRT utilization at 24 months.


There were 440 patients eligible for CRT both at baseline and 24 months, with 217 (49.3%) treated at baseline and 374 (85%) treated at 24 months, leading to an absolute increase in use of CRT of 35.7%, P < 0.001. Although serum sodium and the absence of rales had modest associations, none of the patient, physician, or practice characteristics had any significant association with the extent of increase in CRT utilization. There was a significant reduction in the variation of CRT utilization across practice sites after the implementation of the performance improvement initiative.


The performance improvement initiative in IMPROVE HF was the most important factor associated with an increase in guideline-recommended CRT utilization. This improvement in CRT utilization and reduced practice variability was found across a variety of cardiology and multispecialty practice sites.