Figure 3: Study Flowchart of Human Studies. 30 lesions in patients who underwent rotational atherectomy (RA) with 1.5 mm burr from June 2013 to January 2017. 15 lesions were ablated at 190,000 rpm, defined as high-speed RA (HSRA), and 15 lesions were ablated at 190,000 rpm followed by 110,000 rpm, defined as additional low-speed RA (LSRA) following HSRA. Post-RA minimum lumen diameter (MLD) and minimum lumen (MLA) were measured immediately afterwards by optical frequency domain imaging (OFDI).