Additional debulking efficacy of low-speed rotational atherectomy after high-speed rotational atherectomy for calcified coronary lesion

We aimed to evaluate the additional debulking efficacy of low-speed rotational atherectomy (RA) after high-speed RA by using intravascular imaging. A total of 22 severe calcified coronary lesions in 19 patients (age, 74 ± 10 years; 74% male) were retrospectively analyzed. All of these lesions underwent RA under optical coherence tomography (OCT) or optical frequency domain imaging (OFDI) guidance. At first, we performed high-speed RA with 220,000 rpm until the reduction of rotational speed disappeared; then, low-speed RA with 120,000 rpm using the same burr size was performed. OCT or OFDI was performed after both high-speed and low-speed RAs, and the minimum lumen area were compared. The initial and final burr sizes of high-speed RA were 1.5 (1.5–1.75) and 1.75 (1.5–2.0) mm, respectively. The number of sessions, total duration time, and maximum decreased rotational speed during high-speed RA were 11 ± 5 times, 113 ± 47 s, and 4000 (3000–5000) rpm, respectively. During low-speed RA, the number of sessions, total duration time, and maximum reduction of rotational speed were 3 ± 1 times, 32 ± 11 s, and 1000 (0–2000) rpm, respectively. The minimum lumen area was similar between after high-speed and after low-speed RA [2.61 ± 1.03 mm2 (after high-speed RA) vs. 2.65 ± 1.00 mm2 (after low-speed RA); P = 0.91]. Additional low-speed RA immediately after sufficient debulking by high-speed RA was not associated with increased lumen enlargement. There was no clinical efficacy of low-speed RA after high-speed RA.