Interrelation of coronary angiographic reference lumen size and intravascular ultrasound target lesion calcium

Intravascular ultrasound (IVUS) detects target lesion calcium twice as often as does coronary angiography. Target lesions in smaller vessels are thought to be more calcified than target lesions in large vessels. This study determined whether the presence and magnitude of target lesion calcium is related to angiographic reference lumen size. Preintervention IVUS imaging and coronary angiography were performed to study 1,454 non-aortoostial native vessel lesions in 1,342 patients. Target lesions and reference segments were evaluated according to previously published methods and are presented as mean +/- 1 SD. By angiography, 37% of lesions contained calcium, and 68% of calcium-containing lesions were classified as moderately calcified, and 32% as severely calcified. There was no relation between angiographic reference lumen size and angiographic calcium detection (p = 0.7066) or classification (none/mild vs moderate vs severe, p = 0.8135). By IVUS, 73% of lesions contained calcium. There was a consistent relation between decreasing angiographic reference lumen size and increasing IVUS lesion-associated calcium: the presence of any calcium (p = 0.0122), arc of calcium (p = 0.002), percent of lesions with an arc of calcium > 180 degrees (p = 0.0018), length of calcium (p < 0.0001), presence of any superficial calcium (p < 0.0001), arc of superficial calcium (p < 0.0001), percent of lesions with an arc of superficial calcium > 180 degrees (p = 0.0021), and length of superficial calcium (p < 0.0001). This was especially true for arteries with an angiographic reference lumen dimension < 2.00 mm. There is a distinct relation between decreasing angiographic reference lumen size and increasing lesion calcium, most striking in vessels < 2.00 mm. This increased target lesion calcium in small vessels is not seen angiographically.