Quantitative Coronary Arteriography and Its Assessment of Atherosclerosis: Part I. Examining the Independent Variables

Background. Previous work has demonstrated that quantitative coronary arteriography (QCA) can accurately measure phantom images to within ±0.1 mm and has been accepted as a reliable and reproducible method of measuring human coronary artery disease (CAD). Assessment of CAD by QCA involves the measurement of numerous variables, which are currently required to calculate stenosis flow reserve (SFR). Methods and Results. In this study 1040 stenotic lesions were analyzed by two well- accepted methods with demonstrated accuracy and reproducibility. These methods measure percent diameter stenosis (%DS), absolute diameter, percent area stenosis, length, as well as entry and exit angles to and from a stenotic coronary artery lesion respectively Based upon these results, the mean ± standard deviations and range seen in CAD were determined for each of these independent variables. This study demonstrated that atherosclerotic coronary artery lesions do not appear to exceed an entry angle of -39°, an exit angle of +35°, or an absolute length of 4.84 cm when accurately measured by QCA. It was also noted that, once percent diameter stenosis exceeded 89% (regardless of the visual estimate) or percent area stenosis exceeds 99%, coronary arteries become completely occluded as measured by QCA. Conclusions. While previously suspected that once certain critical limits are exceeded in the deposit of cholesterol and calcium within the coronary artery, the artery will close, this study demonstrated by QCA what the limitations in human coronary arteries appear to be. These limits may be in part due to turbulent factors resulting in platelet activation or local mediators from endothelium of the coronary artery. Contemporary quantitative coronary arteriography (QCA) was used to measure the different variables present in atherosclerotic coronary arteries. While the interaction of each of the independent variables undoubtedly plays a role in the determination of coronary artery blood flow and closure, the limitations of each of these variables have not yet been defined in humans. This study, based on the results of human coronary arteri ograms as analyzed by QCA, demonstrates the limitations of each of these variables, after which coronary arteries close and blood flow equals zero.