FEASIBILITY OF SERIAL INTRACORONARY ULTRASOUND IMAGING FOR ASSESSMENTOF PROGRESSION OF INTIMAL PROLIFERATION IN CARDIAC TRANSPLANT RECIPIENTS

Background Serial quantitative coronary angiography is used to assess progression of coronary disease; however, pathology studies have demon strated angiographic insensitivity for determining atheroma. Intracoro nary ultrasound (ICUS) can define and measure the components of the ar terial wall and offers the potential for precise quantitative assessme nt of disease progression on serial examinations. The present study wa s done to test the feasibility of serially assessing intimal prolifera tion at the same coronary site with ICUS imaging in cardiac transplant recipients. Methods and Results ICUS imaging was done with a 30-MHz, 5F or 4.3F ultrasound imaging catheter at the time of angiography in 7 0 cardiac allografts (3.8 sites per patient) initially and 1 year late r. Mean intimal thickness (IT), luminal area (LA), and total area (TA) of lumen plus intima and an index of intimal thickness (II=TA-LA/TA) were measured at each site. Additionally, vessels were graded using a scale incorporating criteria of intimal thickness and circumferential involvement. Side-by-side comparisons of paired angiograms were perfor med both to verify the similarity of ICUS imaging site and to detect n ew angiographic abnormalities. At least one site could be assessed ser ially by ICUS in 100% of patients, but only 189 of the original 263 co ronary sites (72%) (2.7 sites per patient) could be matched satisfacto rily on the second study. Thirty-nine patients (56%) had mild IT and 3 1 patients (44%) had moderate or severe IT on the initial study. Both groups showed the same IT progression the following year (Delta= 0.05/-0.13 versus 0.07+/-0.15 mm; P=NS). Twenty-seven of the 70 patients ( 39%) showed progression by ICUS. The 23 patients with ICUS progression and angiographically normal vessels had the same progression in intim al thickening as the 4 patients with ICUS progression but showing angi ographic disease (Delta=0.17+/-0.13 versus 0.22+/-0.10 mm; P=NS). Conc lusions Replication of the intracoronary imaging site by judgment of t wo observers at an initial study and at a second study 1 year later wa s possible in at least one vessel site in 100% of the 70 patients and in 72% (189 of 263) of the original imaging sites (2.7 sites per patie nt). Serial ICUS demonstrates progression of intimal thickening at spe cific sites in only some cardiac transplant patients. Progression of i ntimal proliferation can occur in individuals in the presence or absen ce of initially increased intimal thickening,or of angiographic diseas e at the time of the initial studies. Angiography is insensitive for r ecognizing early intimal thickening of the coronary vessels.