Improved near-term coronary artery disease risk classification with gated stress myocardial perfusion SPECT.

OBJECTIVES

We compared analytical approaches to estimate the added value of myocardial perfusion single-photon emission computed tomography (MPS) variables in estimating coronary artery disease (CAD) outcomes.

BACKGROUND

Stress MPS markers of regional ischemia are strong estimators of prognosis. Evidence published to date has not compared analytical methods to establish the added value of stress MPS and to define a clinically meaningful approach to detect improve classification of risk.

METHODS

A total of 4,575 patients were consecutively and prospectively enrolled in the Myoview Prognosis Registry. Multivariable Cox proportional hazards model were employed to estimate CAD death or myocardial infarction (MI). Risk reclassification methods were also calculated.

RESULTS

In risk-adjusted models (including age, sex, presenting symptoms, stress type, CAD history, and risk factors), stress MPS ischemia, rest and post-stress left ventricular ejection fraction (LVEF) (all p < 0.0001) were all significant estimators of CAD death or MI. In this multivariable model, 34% of the model chi-square was contributed by MPS ischemia. In receiver-operating characteristic curve analysis, the area under the curve increased from 0.61 to 0.66 when rest and post-stress LVEF were combined with pre-test CAD likelihood (p < 0.0001), increasing to 0.69 for MPS ischemia (p < 0.0001). The net reclassification improvement (NRI) by adding the Duke Treadmill Score (DTS) to a model including pre-test CAD likelihood was 0.112. The cost per NRI was $57 for the exercise test as compared with an office visit for risk stratification purposes. Further, the NRI by adding MPS ischemia to a model with the DTS and pre-test CAD likelihood was 0.358. The cost per NRI was $615 for the stress MPS as compared with an exercise test.

CONCLUSIONS

Stress-induced ischemia is independently predictive of near-term CAD outcomes. Analytical approaches that establish the reclassification of events provide a unique approach and may serve as a quality imaging metric for estimation of improved health outcomes for stress MPS as well as for comparison to other imaging modalities.