Quantitative hyperemic reactivity in opposed limbs during myocardial perfusion imaging: a new marker of coronary artery disease.

OBJECTIVES: We sought to evaluate the feasibility and validity of a new method to quantify the hyperemic response of the forearms that can be incorporated into a rest myocardial perfusion protocol.
BACKGROUND: Evaluation of the hyperemic response could provide useful clinical information in the detection and risk stratification of atherosclerotic vascular disease.
METHODS: Patients with proven coronary artery disease (CAD) (n = 46) were compared with low-risk subjects without such evidence (n = 47). A regular dose of Myoview was injected after 5 min of right arm ischemia. Three dimensionless parametric ratios (right/left) were derived from the analysis of activity-time curves of the hyperemic right forearm and that of the contralateral left forearm.
RESULTS: The maximal ingress upslope ratio was 40% lower in the CAD group (3.0 +/- 0.2 vs. 4.2 +/- 0.3, p < 0.0005), and the integral to peak ratio was also lower (23 +/- 4 vs. 52 +/- 11, p < 0.01), whereas the peak activity ratio was nonsignificantly lower (3.0 +/- 0.3 vs. 3.8 +/- 0.3, p = 0.07). Using a value of 3.55 for the maximal upslope ratio, this approach could predict the presence of CAD with a sensitivity of 0.70 and a specificity of 0.60.
CONCLUSIONS: This simple and noninvasive method is feasible and can discriminate between patients with known CAD and those at low risk of atherosclerosis. Refinements of this approach and its inclusion in larger clinical trials are needed to determine whether it could provide additional value to myocardial scintigraphic imaging.