ROLE OF COMPENSATORY ENLARGEMENT AND SHRINKAGE IN TRANSPLANT CORONARY-ARTERY DISEASE - SERIAL INTRAVASCULAR ULTRASOUND STUDY

Background Compensatory enlargement of the vessel wall has been descri bed in the early stages of native atherosclerosis. Whether compensator y enlargement plays a role in transplant coronary artery disease is no t known. The objective of this study was to determine, by use of seria l intravascular ultrasound (IVUS), whether compensatory dilation occur s in transplant coronary artery disease over time. Methods and Results Seventy-five heart transplant recipients with 151 matched coronary se gments were selected for the presence of intimal disease progression a s detected by serial IVUS examinations 1 to 3 years apart. Intimal dis ease progression was defined as a >10% increase in intimal area (IA). IVUS catheter location in follow-up studies was verified angiographica lly in relation to branch vessels. Luminal area (LA) and total vessel area (TA) were measured at each site. Intimal area (IA=TA-LA) was calc ulated. Changes in IA (Delta IA) and TA (Delta TA) between baseline an d follow-up IVUS were compared: Delta IA, 2.9+/-0.2 mm(2), Delta TA, 2 .7+/-0.4 mm(2). A remodeling index (RI) was defined as RI=Delta TA/Del ta IA. Three subgroups could be distinguished: overcompensation (RI >1 ), partial compensation (RI 0 to 1), and no compensation or shrinkage (RI less than or equal to 0). Seventy-four segments (49%) showed overc ompensation, 44 (29%) showed partial compensation, and 33 (22%) showed no compensation or shrinkage. Conclusions In this study, serial IVUS shows that early after cardiac transplantation, a large proportion of the coronary segments with progression of intimal thickening have comp ensatory dilation of the vessel wall. However, a substantial number of coronary segments (22%) show no compensatory dilation or shrinkage. T he progressive luminal narrowing in transplant patients may be due in part to vessel shrinkage or the lack of compensatory dilation over tim e.