Quantitative coronary angiography in regression trials: a review of methodologic considerations, endpoint selection, and limitations.

Several quantitative angiographic methods (visual assessment, digital hand-held calipers, and automated edge detection) have been successfully used to assess coronary atherosclerosis regression. These methods are applicable for (1) continuous measures of disease progression and regression, including patient-based, segment-based, and lesion-based analyses; and (2) categorical assessment of disease progression and regression (the use of a predefined threshold to categorize the course of disease). Angiographic methods and criteria for assessing disease progression each have distinct advantages and disadvantages, which accounts for the methodologic diversity seen in clinical trials.