Comparison of the incidence of slow flow after rotational atherectomy with IVUS-crossable versus IVUS-uncrossable calcified lesions

Although the usefulness of intravascular ultrasound (IVUS) in rotational atherectomy (RA) has been widely recognized, an IVUS catheter may not cross the target lesion because of severe calcification. The aim of this study was to compare the incidence of slow flow following RA between IVUS-crossable versus IVUS-uncrossable calcified lesions. We included 284 RA lesions, and divided into an IVUS-crossable group (n = 150) and an IVUS-uncrossable group (n = 134). The primary endpoint was slow flow just after RA. The incidence of slow flow (TIMI flow grade ≤ 2) was significantly greater in the IVUS-uncrossable group than in the IVUS-crossable group (26.1% vs. 10.7%, p = 0.001). The incidence of severe slow flow (TIMI grade ≤ 1) was also greater in the IVUS-uncrossable group than in the IVUS-crossable group (9.7% vs. 2.7%, p = 0.022). The multivariate logistic regression model showed a significant association between slow flow and pre-IVUS uncrossed lesions (vs. crossed lesions: odds ratio 2.103, 95% confidence interval 1.047–4.225, p = 0.037). In conclusion, the incidence of slow flow/severe slow flow just after RA was significantly greater in the IVUS-uncrossable lesions than in the IVUS-crossable lesions. Our study suggests the possibility that the IVUS-crossability can be used as a risk stratification of severe calcified lesions.