Diffuse atherosclerotic left main coronary artery disease unmasked by fractal geometric law applied to quantitative coronary angiography: an angiographic and intravascular ultrasound study

Abstract

Angiographic analysis of left main coronary artery (LMCA) stenosis can be hindered by the lack of any reference segment when the LMCA is short or there is diffuse atheroma. Fractal geometric law (FGL) enables the theoretic diameter of one bifurcation vessel to be calculated from those of the other two (Dmother=0.678*(Ddaughter1+Ddaughter2). Applied to the LMCA, the FGL can help the quantification of stenoses. Fifty-two patients with angiographically mild focal LMCA disease (n=14) or normal to nearly normal LMCA (n=38) who had undergone intravascular ultrasound (IVUS) were included. IVUS analysis confirmed all 14 focal stenoses (group C); of the 38 angiographically normal patients, however, 10 were found to present diffuse LMCA disease (group B), the remaining 28 showing a truly healthy LMCA (group A). LMCA stenosis in groups A,B and C was respectively 3%,4% and 42% on usual quantitative coronary angiography(QCA) and 5%, 31% and 43% on QCAfractal applying the FGL. In cases of diffuse atheroma, the FGL corrected the underestimation of LMCA diameter, which averaged 1.2 mm. conclusions: Angiographic underestimation of LMCA stenosis can be corrected by applying the FGL to obtain a theoretic LMCA diameter, thereby unmasking any diffuse atherosclerotic LMCA disease, or to quantify focal stenosis more precisely where the adjacent segments are also pathological.