QUANTITATIVE CORONARY ANGIOGRAPHY IN PREDICTING FUNCTIONAL-SIGNIFICANCE OF STENOSES IN AN UNSELECTED PATIENT COHORT

Objectives. This study investigated the value of quantitative coronary angiography for predicting coronary flow reserve, as calculated from the transstenotic pressure gradient in a large, unselected patient coh ort. Background. In patients with extensive coronary artery disease, q uantitative coronary angiographic findings fan to correlate with funct ional variables of coronary stenoses. New developments in pressure-mon itoring wire technology permitted validation in humans of the concept of myocardial fractional how reserve as assessed from coronary pressur e measurements. Methods. One hundred ten patients with normal left ven tricular function were studied in the setting of coronary angioplasty, Quantitative coronary angiography was performed on-line using the ACA system. Myocardial and coronary fractional how reserve were calculate d from aortic and distal coronary pressures during maximal coronary hy peremia. Results. The data before and after angioplasty were pooled, a curvilinear relation was found between myocardial fractional how rese rve and both diameter stenosis (r = 0.79) and minimal lumen diameter ( r = 0.82), and a linear relation was found between myocardial fraction al flow reserve and angiographic stenosis flow reserve (r = 0.78). Cor relations between quantitative angiographic and pressure-derived index es, although significant, were characterized by a large dispersion of the values of myocardial fractional flow reserve for a similar angiogr aphic degree of stenosis. Nevertheless, the sensitivity and specificit y of a minimal lumen diameter <1.5 mm to predict myocardial fractional flow reserve <0.72 were 96% and 89%, respectively. The corresponding values for a diameter stenosis >50% were 93% and 85%, respectively. Co nclusions. 1) In an unselected patient cohort, geometric indexes of st enosis severity derived from quantitative coronary angiography correla te significantly with physiologic variables, although these relations are imprecise in individual patients. 2) Nevertheless, the diagnostic accuracy of quantitative coronary angiography in predicting myocardial fractional flow reserve <0.72 is high and allows its use for clinical decision making in the individual patient during diagnostic or interv entional procedures.