Abstract 17984: Abnormal Transient Ischemic Dilation Ratio with Regadenoson Myocardial Perfusion Imaging Does Not Predict Severe and Extensive Coronary Artery Disease

Abstract

Objectives: An abnormal transient ischemic ratio has been shown to be a clinically useful marker for severe and extensive coronary artery disease (S+E CAD) in many different myocardial perfusion imaging (MPI) protocols. However it has not been well validated with regadenoson MPI. The purpose of this study is to: 1) Define a normal TID ratio among a cohort of patients with low risk for CV. 2) Determine the sensitivity and specificity for an abnormal TID ratio (mean +2 SD) to predict severe and extensive (S + E) CAD

Methods: Normal limits for TID were defined by a group of 56 patients with low risk for CV disease (<10% Framingham Risk) stratified by gender. An abnormal TID was tested in a pilot group of 219 patients who also underwent coronary angiography. 40 pts (18.2%) had S + E CAD, defined as ≥ 90% stenosis in the proximal left anterior descending artery or in ≥ 2 major epicardial arteries.

Results: Among patients with low risk for CV disease, the mean TID was 1.00 ± 0.10 in men (n=25) and 0.98 ± 0.10 in women (n=31), p=0.949. Abnormal TID was defined at 1.19 in both genders. Severity of ischemia was predictive of S+ E CAD. An abnormal TID ratio had poor sensitivity (12.5%) but moderate specificity (81.4%) for S+E CAD. Similarly, abnormal TID ratio had poor sensitivity (23.1%) and moderate specificity (83.5%) for obstructive CAD (>70% stenosis).

Conclusions: In patients undergoing regadenoson stress testing, there is no significant difference of abnormal TID based on gender. An abnormal TID ratio had moderate specificity, but poor sensitivity to predict S+E CAD on coronary angiography.