Ischemia change in stable coronary artery disease is an independent predictor of death and myocardial infarction.
OBJECTIVE
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.
Section of Cardiology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA.
Afshin
A
Farzaneh-Far
Harry R
HR
Phillips
Linda K
LK
Shaw
Aijing Z
AZ
Starr
Mona
M
Fiuzat
Christopher M
CM
O'Connor
Ashwani
A
Sastry
Leslee J
LJ
Shaw
Salvador
S
Borges-Neto
D000368:Aged; D002317:Cardiovascular Agents / Q000009:adverse effects; D016009:Chi-Square Distribution; D017023:Coronary Angiography; D001026:Coronary Artery Bypass / Q000009:adverse effects; D003324:Coronary Artery Disease / Q000150:complications* / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality* / Q000628:therapy; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality* / Q000628:therapy; D055414:Myocardial Perfusion Imaging / Q000379:methods; D009657:North Carolina; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome
D002317:Cardiovascular Agents