909-25 Clinical Outcomes of Patients not Undergoing Coronary Artery Revascularization as a Result of Intravascular Ultrasound Imaging

Abstract

Ambiguous and intermediate angiographic lesions remain an important diagnostic dilemma despite advances in non-invasive testing. In part, alternative imaging modalities, including intravascular ultrasound (IVUS), have been developed to help solve this clinical problem. However, no follow-up data is available after IVUS-based decision making. From July 1, 1991 through April 30,1994, IVUS imaging was performed in 1968 lesions in 1660 pts, all of whom were referred for catheter-based h8. Pre-intervention IVUS was performed in 1446 lesions (73%) and was used to assess lesion severity in 293 lesions (20%). 195 lesions either had previous intervention within 6 months or were found to be severe enough to warrant catheter-based or operative intervention. In 98 de novo lesions (18 vein graft and 80 native vessel including 29 LM) in 90 pts, planned interventions were aborted as a result of IVUS assessment of lesion severity. These patients had the following clinical characteristics: 74% unstable angina, 72% multivessel disease, 32% previous operative revascularization, and 92% risk factors for coronary artery disease. Lesions had the fol1owing characteristics: external elastic membrane (EEM) area = 22.7 ± 12.2 mm 2 , lumen area = 6.8 ± 5.5 mm 2 , plaque area = 14.5 ± 8.0 mm 2 , %cross-sectional narrowing (%CSN = plaque/EEM area) = 67.0 ± 18.6, and arc of calcium = 74 ± 103°. Furthermore, 19/98 lesions (19%) had, at most, mild disease (%CSN < 50), 4 of which were normal. Quantitative angiographic assessment of minimum lumen diameter 12.33 ± 0.65 mm) correlated moderately well with IVUS (12.4 ± 0.8 mm, r = 0.571, P < 0.0001). In general, the threshold for intervention was a minimum lumen area < 5.0 mm 2 (minimum lumen diameter < 2.5 mm) for vein graft or left main lesions or < 3.5 mm 2 (diameter < 2.0 mm) for other native vessel lesions. Pts were interviewed at 3, 6, 9, and 12 mo intervals. As of September 1, 1994, clinical follow-up was available in 96% with a mean follow-up duration of 9.7 mos. During the 1 yr follow-up period, only 9 pts (10%) required target lesion-related revascularization. Another 12 undervvent either non-target lesion related revascularization (because of progression of native or vein graft disease elsewhere) or operative revascularization as part of valve replacement surgery. Assessment of lesion severity is an important part of IVUS evaluation. IVUS criteria can be used to differentiate significant disease from insignificant lumen compromise. The low frequency of 1 yr target lesion revascularization validates this approach.