Study Design and Population
This is a retrospective single-center study of all patients who underwent PCI using RA because of heavily calcified lesions at our hospital from January 2017 to December 2018. Severely calcified lesion was defined as: radiopacities noted without cardiac motion before contrast injection, generally compromising both sides of the arterial lumen. All the patients were divided into 2 groups according to the indication for RA. Planned RA was defined as initial strategy without previous device failure. Bailout RA was defined as RA after incomplete expansion of balloon or failure delivery of any devices. Pre-intervention intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was performed in partial patients, the patients will receive planned RA if the IVUS/OCT showed calcium angle>270°and calcium length >5mm (Figure 1) or the IVUS/OCT catheter cannot cross the lesions. When discharge from hospital, all the patients were received standard pharmacological treatment (double antiplatelet therapy at least 1 year), and followed-up regularly in clinic.
The demographic and clinical characteristics of all patients included age, gender, medical history, left ventricular function on admission, lipid profiles, serum creatinine, hemoglobin and procedual costs. The angiographic and procedural characteristics included number of diseased vessels, target vessel, the size of burr, total number of stents and total length of stents.
The primary outcome (all-cause death, target vessel revascularization and stent thrombosis) at 3 years were collected during follow-up by telephone or electronic record system.
Before procedural, all patients received an oral loading dose of 300 mg aspirin and 300mg clopidogrel. During procedural, all patients received unfractionated heparin at a dose of 70–100 U/kg to maintain an activated clotting time (ACT) >300 seconds. In both groups, the choice of vascular access, burr size, IVUS/OCT was left at the operators’ discretion. The IVUS/OCT catheter was advanced beyond the target lesion using a commercially available IVUS/OCT system (40 MHz IVUS catheter; OptiCross, Boston Scientific. ILUMIEN C7-XR, Abbott). RA was performed by using the Rotablator (Boston Scientific Scimed, Inc., Maple Grove, MN, USA). The burr size was selected to reach a burr/vessel ratio of 0.5-0.6. RA speed ranged between 150,000 and 180,000 rotation per minute. Each RA time was 10-15 seconds. During RA, A continuous intracoronary infusion of a cocktail with unfractionated heparin and nitroglycerin was employed. Success of RA was defined as complete expansion of balloon of target lesion after RA.
Study endpoints and definitions
Procedural success was defined as a final residual stenosis＜30% after stents and grade 3 TIMI flow. Procedural outcomes included total number of balloon and stents used, procedure time, fluoroscopy amount, and volume of contrast used in the two groups. Procedure time was defined as the interval from initial angiography by guiding catheter to final angiography of the target lesion. PCI-related myocardial infarction is defined following the third universal definition of myocardial infarction. Procedure complications included bradycardia, Slow flow/no reflow, dissection, burr entrapment and perforation. Bradycardia was defined as heart rate less than 45 beats per minute which can influence hemodynamics. Dissection was defined as grades C to F according to NHLBI type. The primary outcome was a composite of all-cause death, target vessel revascularization and stent thrombosis at 3 years.
Statistical analysis was performed using SPSS for Windows 18.0 (SPSS, Chicago, IL). Continuous variables areexpressed as mean ± SD, categorical variables are given as frequencies (%). Univariate comparisons between the two groups were performed using Pearson’s chi-square test for categorical variables, and a Student t test for continuous variables. Kaplan-meier was used to analyze the cumulative incidence of clinical events during the follow-up. Difference was considered to be statistically significant at P < 0.05.