Original Research
Ischemia Change in Stable Coronary Artery Disease Is an Independent Predictor of Death and Myocardial Infarction

https://doi.org/10.1016/j.jcmg.2012.01.019Get rights and content
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Objectives

The aim of this study was to evaluate the independent prognostic significance of ischemia change in stable coronary artery disease (CAD).

Background

Recent randomized trials in stable CAD have suggested that revascularization does not improve outcomes compared with optimal medical therapy (MT). In contrast, the nuclear substudy of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial found that revascularization led to greater ischemia reduction and suggested that this may be associated with improved unadjusted outcomes. Thus, the effects of MT versus revascularization on ischemia change and its independent prognostic significance requires further investigation.

Methods

From the Duke Cardiovascular Disease and Nuclear Cardiology Databanks, 1,425 consecutive patients with angiographically documented CAD who underwent 2 serial myocardial perfusion single-photon emission computed tomography scans were identified. Ischemia change was calculated for patients undergoing MT alone, percutaneous coronary intervention, or coronary artery bypass grafting. Patients were followed for a median of 5.8 years after the second myocardial perfusion scan. Cox proportional hazards regression modeling was used to identify factors independently associated with the primary outcome of death or myocardial infarction (MI). Formal risk reclassification analyses were conducted to assess whether the addition of ischemia change to traditional predictors resulted in improved risk classification for death or MI.

Results

More MT patients (15.6%) developed ≥5% ischemia worsening compared with those undergoing percutaneous coronary intervention (6.2%) or coronary artery bypass grafting (6.7%) (p < 0.001). After adjustment for established predictors, ≥5% ischemia worsening remained a significant independent predictor of death or MI (hazard ratio: 1.634; p = 0.0019) irrespective of treatment arm. Inclusion of ≥5% ischemia worsening in this model resulted in significant improvement in risk classification (net reclassification improvement: 4.6%, p = 0.0056) and model discrimination (integrated discrimination improvement: 0.0062, p = 0.0057).

Conclusions

In stable CAD, ischemia worsening is an independent predictor of death or MI, resulting in significantly improved risk reclassification when added to previously known predictors.

Key Words

coronary revascularization
ischemia
perfusion
stable coronary artery disease

Abbreviations and Acronyms

CABG
coronary artery bypass grafting
CAD
coronary artery disease
LV
left ventricular
LVEF
left ventricular ejection fraction
MI
myocardial infarction
MPS
myocardial perfusion single-photon emission computed tomography
MT
medical therapy
NRI
net reclassification improvement
PCI
percutaneous coronary intervention

Cited by (0)

Dr. Phillips has served on the Speakers' Bureau for Gilead and Daiichi Sankyo; has been a consultant to Frederick Medical; and his wife holds stock in Abbott. Dr. O'Connor has consulted for and received research funding from GE Healthcare and Medtronic. Dr. Leslee J. Shaw has received grant support from Astellas Healthcare and Bracco Diagnostics.

All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. H. William Strauss, MD, served as Guest Editor for this paper.