Impact of frame selection on quantitative coronary angiographic analysis after coronary stenting

This study examined the impact of frame selection on the results of quantitative coronary angiographic analysis (QCA). Thirty-nine patients who had stent implantation and a follow-up angiogram 5-7 months later were studied using the CMS Medis QCA system. The acute and follow-up films (n = 39) were read in three different ways to assess the impact of frame selection: frame chosen making the stent appear least narrowed (best); frame chosen making the stent appear most narrowed (worst); and measurement from the mean value from three consecutive end-diastolic frames (core). We measured the mean percent diameter stenosis immediately postintervention and at follow-up, the binary restenosis rate, and the late lumen loss (mm). There was a statistically significant difference in all of these variables when comparing the three methods of frame selection (best vs. worst, P values < 0.001; best or worst vs. core, P values < 0.01). This study demonstrates a marked variability in the results obtained using QCA to measure the acute and late coronary stent outcomes when operators have the ability to select which frame to analyze (frame bias).