Quantitative and qualitative coronary angiographic analysis: Review of methods, utility, and limitations

Coronary angiography continues to be the pivotal study in the diagnosis and treatment of ischemic cardiac disease. Although angiographic equipment and imaging techniques have advanced over the past three decades, the analysis of coronary angiograms, by visual estimated percent diameter stenosis, has remained unchanged in most clinical catheterization laboratories. Rapid, computerized angiographic analysis systems are now available that remedy the inherent imprecision and inaccuracies plaguing visual coronary analysis. Despite its advantages, successful QCA is quite dependent on meticulous attention to radiographic and angiographic technique, even more so than with visual analysis. Although the available QCA systems can reproducibly and accurately define the site and degree of coronary stenosis, they cannot routinely determine whether an obstruction is flow limiting. Several methods, some based on extrapolations of quantitative measures alone, and others based on digital subtraction angiography, have been developed to determine the physiologic impact of a given coronary lesion. Recent observations have demonstrated, however, that even if the physiologic consequences of an obstruction are known, the prognosis of the lesion over time cannot be predicted. The qualitative, morphologic characteristics of a lesion are as, or more, important than the quantitative lesion attributes in determining an atheroma's behavior and stability, and hence, qualitative descriptors should be incorporated into QCA analyses. Although not currently available, future QCA systems will provide, by automated analysis, reproducible and accurate measures of absolute obstruction, physiologic data describing the flow limiting characteristics of a lesion, and qualitative, morphologic lesion descriptors. Implementation of these systems should provide more consistent and accurate prognostic and pathophysiologic information, thereby helping to refine and more effectively direct therapeutic interventions in coronary artery disease.