Clinical presentation. On presentation, a 58-yearold man had symptoms of chest pain suggestive of unstable angina. He had negative troponins and no electrocardiographic ST-segment changes. After stabilization, he was referred for adenosine vasodilator rest/ stress gated myocardial perfusion testing.
Imaging. The imaging study was positive for multivessel disease with significant reversibility of perfusion from stress to rest noted in both the septum and inferior walls (Figure 1). Quantitative perfusion scintigraphy revealed a summed stress score of 23 and a summed rest score of 0, indicative of high risk for both cardiac death and nonfatal myocardial infarction (Figure 2). Coronary angiography revealed obstructive disease in both the left anterior descending artery (LAD) and right coronary artery (RCA) distributions. Specifically, there was an 80% proximal LAD lesion (not shown), and a 40% to 50% indeterminate lesion in the distal RCA (Figure 3). This RCA lesion was determined to be 43% stenotic by quantitative coronary angiography.Percutaneous revascularization of the LAD was carried out with primary stenting. The patient had an excellent final result with 0% residual lesion, TIMI 3 flow, and preservation of all branches of the LAD.
Clinical dilemma. Although the angiographically significant LAD lesion presented no problem in management, the indeterminate RCA lesion was discrepant with the result of the adenosine vasodilator rest/stress myocardial perfusion examination.
Further imaging, diagnosis, and treatment. To further evaluate the significance of the indeterminate RCA lesion noted on angiography, a decision was made to perform intravascular ultrasound (IVUS) immediately after stenting the LAD. The angiographically indetermi-