Atherosclerotic coronary lesions with inadequate compensatory enlargement have smaller plaque and vessel volumes: Observations with three dimensional intravascular ultrasound in vivo

Objective - To compare vessel, lumen, and plaque volumes in atherosclerotic coronary lesions with inadequate compensatory enlargement versus lesions with adequate compensatory enlargement. Design - 35 angiographically significant coronary lesions were examined by intravascular ultrasound (IVUS) during motorised transducer pullback. Segments 20 mm in length were analysed using a validated automated three dimensional analysis system. IVUS was used to classify lesions as having inadequate (group I)or adequate (group H) compensatory enlargement. Results - There was no significant difference in quantitative angiographic measurements and the IVUS minimum lumen cross sectional area between groups I (n = 15) and II (n = 20). In group I, the vessel cross sectional area was 13.3 (3.0) mm² at the lesion site and 14.4 (3.6) mm² at the distal reference (p <0.01), whereas in group II it was 17.5 (5.6) mm² at the lesion site and 14.0 (6.0) mm² at the distal reference (p < 0.001). Vessel and plaque cross sectional areas were significantly smaller in group I than in group II (13.3 (3.0) v 17.5 (5.6) mm², p < 0.01; and 10.9 (2.8) v 15.2 (4.9) mm², p < 0.005). Similarly, vessel and plaque volume were smaller in group I (291.0 (61.0) v 353.7 (110.0) mm³, and 177.5 (48.4) v 228.0 (92.8) mm³, p < 0.05 for both). Lumen areas and volumes were similar. Conclusions - In lesions with inadequate compensatory enlargement, both vessel and plaque volume appear to be smaller than in lesions with adequate compensatory enlargement.