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Angiography underestimates the presence and depth of dissections seen following atherectomy and adjunctive balloon angioplasty of femoropopliteal arteries. The i-Dissection classification was recently introduced to evaluate the circumference (<180 degrees, ≥ 180 degrees) and depth (A to C from intima to adventitia) of dissections using intravascular ultrasound (IVUS) (J Invasive Cardiol 2018;30(7):240-244). The inter-core lab variability in classifying and identifying dissections using the iDissection grading system remains unknown.
The IVUS scans for 15 patients who underwent atherectomy (13 Jetstream (Boston Scientific), 2 B-laser (Eximo Medical)) of femoropopliteal arteries were independently evaluated by two core labs (Midwest Cardiovascular Research Foundation, Davenport, IA (Core 1) and St. John Providence Health System, Detroit, Michigan (Core 2)) for the presence and grades of dissections as introduced in the i-Dissection classification. The i-Dissection grading system consists of 6 grades (A1, A2, B1, B2, C1, C2). In addition, dissection lengths were calculated independently and ompared between the 2 core labs. Total number of dissections were compared using the Fisher’s exact test. The i-Dissection grading system and median dissection length were compared using the Kruskal-Wallis exact test.
Of the total 15 patients in the i-Dissection trial, Core 1 identified 43 dissections (A1 22, B1 11, C1 2, A2 2, B2 5, C2 1) post-atherectomy and 40 dissections post-adjunctive balloon. Core 2 identified 46 dissections post-atherectomy (A1 26, B1 10, C1 4, A2 2, B2 3, C2 1) and 40 dissections post-adjunctive balloon (p=0.8781) in the same treated segment length. Also, there were no significant differences in the grading severity of dissections (p=0.6001). Similarly, there were no differences in the number of dissections and their classifications post-adjunctive angioplasty. Finally, there were no differences in the post-atherectomy dissection length for each grade of dissection, with the exception of grade B2 (12.14 mm vs. 20.05 mm; p= 0.0179).
The inter-core lab assessment of the i-Dissection grading system indicates a high reproducibility in identifying the number and severity of dissections using IVUS following atherectomy and adjunctive balloon angioplasty. A difference was noted in the length of B2 dissections post-atherectomy. Special attention is needed when evaluating the length of these deeper dissections with concomitant wider circumference.