ACUTE MYOCARDIAL INFARCTION
A risk score to estimate the likelihood of coronary artery bypass surgery during the index hospitalization among patients with unstable angina and nonST-segment elevation myocardial infarction
Saihari Sadanandan, MD*,*,
Christopher P. Cannon, MD ,
C. Michael Gibson, MS, MD ,
Sabina A. Murphy, MPH ,
Peter M. DiBattiste, MD ,
Eugene Braunwald, MD the TIMI Study Group
* Oklahoma University Health Sciences Center, Oklahoma City, Oklahoma, USA
Harvard Medical School and the Department of Medicine, Brigham & Women's Hospital, Boston, Massachusetts, USA
Merck & Co., West Point, Pennsylvania, USA
Manuscript received January 19, 2004;
revised manuscript received March 24, 2004,
accepted March 29, 2004.
* Reprint requests and correspondence: Dr. Saihari Sadanandan, Division of Interventional Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, One Deaconess Road, Baker 4, Boston, Massachusetts 02215 (Email: ssadanan{at}bidmc.harvard.edu).
OBJECTIVES: A simple risk score on admission to estimate the likelihood of in-hospital coronary artery bypass graft surgery (CABG) might be useful in selecting patients for early clopidogrel therapy.
BACKGROUND: Routine early use of clopidogrel in patients with unstable angina (UA) and nonST-segment elevation myocardial infarction (NSTEMI) is associated with increased risk of bleeding in patients who undergo early CABG.
METHODS: The test cohort utilized to derive the score was the 2,220 patients with UA/NSTEMI enrolled in the Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative StrategyThrombolysis in Myocardial Infarction-18 (TACTICSTIMI-18) trial. Patients who underwent CABG after randomization during index hospitalization were identified and were compared with patients who did not undergo in-hospital CABG.
RESULTS: Overall, 362 patients (16.3%) underwent CABG during the index hospitalization. Patients with a history of prior CABG (n = 484) were significantly less likely to undergo in-hospital CABG (odds ratio [OR], 0.34). Five additional variables independently associated with CABG were identified: elevated troponin (OR, 3.9), prior stable angina (OR, 1.8), ST-segment deviation 0.5 mm (OR, 1.7), male gender (OR, 1.6), and history of peripheral arterial disease (OR, 1.6). A CABG risk score was generated by assigning numerical values to each of the variables based upon these odds ratios. Coronary artery bypass surgery rates increased significantly with increasing risk scores (6.2% for a risk score <3.0, 21.9% for 3 to 5, and 54.6% for >5.0). The association of the risk score with CABG was highly significant (p < 0.0001, c-statistic 0.72). The association remained significant in the validation cohorts from TIMI-11B trial and TIMI-III registry.
CONCLUSIONS: Among patients with UA/NSTEMI, a novel risk score based on admission clinical variables can be used to estimate the likelihood of CABG. These data may assist in the identification of patients who might derive optimal benefit from early initiation of clopidogrel therapy.
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Abbreviations and Acronyms
| | CABG = coronary artery bypass graft surgery | | IQ = inter-quartile | | NSTEMI = nonST-segment elevation myocardial infarction | | OR = odds ratio | | PAD = peripheral arterial disease | | PCI = percutaneous coronary intervention | | TACTICSTIMI-18 = Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative StrategyThrombolysis In Myocardial Infarction-18 | | UA = unstable angina |
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