Aims: To validate and test in vivo a new modality of quantitative coronary angiography (QCA), dual QCA (D-QCA), developed to quantify intracoronary thrombotic burden (ITB).
Methods and results: Calculation of ITB with D-QCA is based on the discrepancy of luminal areas assessed with edge detection (ED) and video-densitometry (VD), measured with Cardiovascular Angiography Analysis System II. Experimental validation was first performed in phantoms with known obstructive volumes. In vivo assessment of thrombotic burden changes was performed in angiograms from 19 patients with large ITB, obtained before and after antithrombotic treatment, and compared with semi-quantitative assessment (TIMI thrombus grade (TTG)). A good correlation between D-QCA and true occlusive volumes was found (y = 9.21+0.99x, r = 0.996). Intra- and inter-observer variability was 2.77 +/- 10.97 mm3 (p = 0.50) and -1.28 +/- 6.99 mm3 (p = 0.62) respectively. In vivo, D-QCA demonstrated a significant reduction in ITB resulting from treatment (137.22 +/- 120.13 mm3 before and 104.72 +/- 99.19 mm3 after treatment, p = 0.001). Overall, TTG also decreased (3.63 +/- 0.68 before and 3.11 +/- 1.20 after, p = 0.008), but in those nine (47%) patients in which remained unchanged D-QCA detected a reduction in ITB (pre 148.17 +/- 154.03 mm3, post 112.86 +/- 117.82 mm3, p = 0.05).
Conclusions: D-QCA appears as a useful approach to quantify IC thrombus volume, being more sensitive than TTG in assessing changes in ITB resulting from treatment strategies.