Ejection fraction assessment and survival: An analysis of the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)
Received 29 May 2008; accepted 5 August 2008. published online 07 November 2008.
Background
Ejection fraction (EF) is an important method of mortality prediction among cardiac patients, and has been used to identify the highest risk patients for enrollment in the defibrillator primary prevention trials. Evidence suggests that measures of EF by different imaging modalities may not be equivalent. In the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial), the type of imaging modality for EF assessment was not mandated.
Methods
Baseline assessment of EF was performed using either echocardiography, radionuclide angiography (RNA), or contrast angiography. Multivariable analysis using a Cox proportional hazards model was used to examine whether the modality of assessing EF affected the likelihood of survival.
Results
Among the 2,521 patients enrolled in SCD-HeFT, EF was measured by RNA in 616 (24%), echocardiography in 1,469 (58%), and contrast angiography in 436 (17%). Mean EF as measured by RNA was 25.1% ± 6.9%; by echocardiography, 23.8 ± 6.9%; and by angiography, 21.9 ± 6.9%. These measures were significantly different (P < .001), and each pairwise comparison differed significantly (P < .001 for each). Multivariable analysis showed no significant difference in survival between patients enrolled based on RNA versus echocardiography (HR 1.06, 95% CI 0.88-1.28), RNA versus angiography (HR 1.25, 95% CI 0.97-1.62), or echocardiography versus angiography (HR 1.18, 95% CI 0.94-1.48).
Conclusions
Among patients enrolled in SCD-HeFT, the distribution of ejection fractions measured by radionuclide angiography differed from those measured by echocardiography or contrast angiograms. Survival did not differ according to modality of EF assessment.
aUniversity of Western Ontario, London, Ontario, Canada
cSeattle Institute for Cardiac Research, Seattle, WA
dUniversity of Washington Medical Center, Seattle, WA
Reprint requests: Lorne J. Gula, MD, London Health Sciences Centre, Arrhythmia Service, 339 Windermere Road, London, Ontario, Canada N6A 5A5.
SCD-HeFT was supported by grants (UO1 HL55766, UO1 HL55297, and UO1 HL55496) from the National Heart, Lung, and Blood Institute, National Institutes of Health (both in Bethesda, MD), and by Medtronic (Minneapolis, MN), Wyeth-Ayerst Laboratories (Madison, NJ). This substudy was supported by a grant from Medtronic of Canada (Mississauga, Ontario, Canada).
Author Disclosures: Dr Bardy: Research funding from Medtronic and Wyeth-Ayerst Pharmaceuticals; founder of, board member of, consultant to, and equity holder in Cameron Health (San Clemente, CA). Dr Gula: grant support from Medtronic of Canada. Dr Klein: consultant fees from Medtronic. Dr Krahn: consultant fees from Boston Scientific and Transoma. Dr Lee: research funding from Medtronic and Wyeth-Ayerst Pharmaceuticals. Dr Mark: grant support and speaking fees from Medtronic. Dr Poole: speaking fees from Boston Scientific (Natick, MA), Medtronic, and Biotronic (Ann Arbor, MI). Dr Yee: Consultant fees from Medtronic.
ABSTRACT