Background: Target lesion calcium is a marker for significant coronary artery disease and a determinant of the success of transcatheter therapy.
Methods and results: Eleven hundred fifty-five native vessel target lesions in 1117 patients were studied by intravascular ultrasound (IVUS) and coronary angiography. The presence, magnitude, location, and distribution of IVUS calcium were analyzed and compared with the detection and classification (none/mild, moderate, and severe) by angiography. Angiography detected calcium in 440 of 1155 lesions (38%): 306 (26%) moderate calcium and 134 (12%) severe. IVUS detected lesion calcium in 841 of 1155 (73%, P < .0001 versus angiography). The mean arc of lesion calcium measured 115 +/- 110 degrees; the mean length measured 3.5 +/- 3.7 mm. Target lesion calcium was only superficial in 48%, only deep in 28%, and both superficial and deep in 24%. The mean arc of superficial calcium measured 85 +/- 108 degrees; the mean length measured 2.4 +/- 3.4 mm. Three hundred seventy-three of 1155 reference segments (32%) contained calcium (P < .0001 compared with lesion site). The mean arc of reference calcium measured 42 +/- 80 degrees; the mean length measured 1.7 +/- 3.6 mm. Only 44 (4%) had reference calcium in the absence of lesion calcium. Angiographic detection and classification of calcium depended on arcs, lengths, location, and distribution of lesion and reference segment calcium. By discriminant analysis, the classification function for predicting angiographic calcium included the arc of target lesion calcium, the arc of superficial calcium, the length of reference segment calcium, and the location of calcium within the lesion. This model correctly predicted the angiographic detection of calcification in 74.4% of lesions and the angiographic classification (none/moderate/severe) of calcium in 62.8% of lesions.
Conclusions: IVUS detected calcium in > 70% of lesions, significantly more often than standard angiography. Although angiography is moderately sensitive for the detection of extensive lesion calcium (sensitivity, 60% and 85% for three- and four-quadrant calcium, respectively), it is less sensitive for the presence of milder degrees.