Between April 2016 and October 2019, 58 patients who underwent PCI with DCA for LM bifurcation lesions were retrospectively identified. Of these, 27 patients were excluded because 18, two, and seven patients underwent implantation of drug-eluting stents after DCA, DCA alone, and DCA for proximal stent edge restenosis at the left anterior descending artery (LAD) ostium, respectively. Finally, 31 patients who underwent stent-less therapy with DCA followed by DCB angioplasty for de-novo LM bifurcation lesions were enrolled in this study. Among them, one patient underwent DCA followed by DCB angioplasty for the LAD and LCX ostium; therefore, in this study, we analyzed the IVUS findings after performing DCA in 32 lesions of 31 patients.
The indications of DCA for LM bifurcation lesions were as follows: 1) stable angina pectoris with LM bifurcation lesion involving the distal LM trunk, the LAD ostium, or the LCX ostium; 2) a reference diameter in the main branch of > 2.5 mm using visual estimation; and 3) IVUS findings suitable for DCA (no lipid-rich plaque, no thrombus, no severe superficial calcification, and plaque location to be debulked by DCA was accurately evaluated using IVUS). The exclusion criteria were as follows: 1) unstable angina pectoris and myocardial infarction; 2) poor patient’s general condition and renal insufficiency (Cr > 1.5 mg/dL); 3) severe angle lesion; and 4) angiographic severe calcified lesions. This study was approved by the institutional review board of our hospital and complied with the Declaration of Helsinki. Written informed consent was obtained from all patients for the procedure and subsequent data collection.
Procedure and follow-up examinations
All PCIs were performed via the femoral artery using an 8Fr sheath introducer and an 8Fr guiding catheter. During the procedure, the activated coagulation time was maintained at > 300 s with heparin administration. We carefully evaluated plaque distribution and plaque characteristics using IVUS after crossing the lesion with a conventional guidewire. We decided to perform DCA after plaque distribution to be debulked was adequately evaluated using IVUS and after confirming that there were no lipid rich plaque, thrombus, and severe superficial calcification. ATHEROCUT (Nipro Corporation) was used for all lesions and size selection, and was dependent on the reference diameter of IVUS. DCA was initiated with low balloon pressure (0 or 1 atm) and gradually increased based on the IVUS findings. We repeated IVUS evaluation after several cuts of DCA, and again repeated to obtain residual %PA < 60% when possible . The performance of the stent-less strategy was decided after careful evaluation of the IVUS and angiographic findings by experienced operators. DCB angioplasty using SeQuent Please (Nipro Corporation) was performed after DCA when the IVUS findings revealed that there was no large residual plaque burden, no huge dissection, and no hematoma formation. The DCB size was selected according to the reference lumen diameter by IVUS, and the balloon inflation time was 30 s with nominal pressure. Dual antiplatelet therapy with 100 mg/day aspirin and either 75 mg/day clopidogrel or 3.75 mg/day prasugrel was administered before the procedure and continued for 3 months following the procedure. Complications during the procedure and procedure-related major events during hospitalization including death, emergent target lesion revascularization (TLR) and coronary artery graft bypass, myocardial infarction, and access site complications, were recorded. Myocardial infarction was defined as any postprocedural creatine kinase elevation more than two times than normal. All patients underwent a follow-up examination at 30 days after discharge and every 2–3 months subsequently. Follow-up coronary angiography was scheduled at 9–12 months after the procedure. TLR at 12 months and a major adverse cardiac event (MACE) defined as a composite of cardiac death, myocardial infarction, and any repeat revascularization at 12 months were investigated.
Quantitative coronary angiography analysis
Quantitative coronary angiography (QCA) analysis was performed using the computer-based software (Heart II ver 184.108.40.206, GADELIUS, Tokyo, Japan) before the procedure, after the procedure, and at follow-up examinations using a guiding catheter to calibrate the magnification. Optimal views of the lesions were obtained at baseline, and the same projection angle was used at follow-up examinations. Independent physicians who were blinded to all clinical information analyzed the minimal lumen diameter (MLD), reference diameter, lesion length, and percent diameter stenosis (%DS). The acute gain was defined as the increase in the MLD after PCI; late lumen loss was defined as the difference between the post-procedural MLD and MLD at follow-up.
Intravascular ultrasound analysis
All IVUSs were performed using commercially available IVUS catheters (OptiCross™, Boston Scientific, Marlborough, MA, USA; or ViewIT; Terumo, Tokyo, Japan) with automatic pull-back at a 0.5-mm/s rate. At the lumen site where the lumen area was the smallest, the lumen diameter, lumen area, vessel area, and %PA were analyzed. PA was defined as the vessel area minus the lumen area. %PA was defined as follows: %PA=(vessel area minus lumen area)×100/vessel area.
The changes in the vessel area, lumen area, PA, and %PA after DCA were defined as post-procedure minus pre-procedure values for the vessel area (Δ vessel area), lumen area (Δ lumen area), PA (Δ PA), and %PA (Δ %PA), respectively. These measurements were compared between the small and large vessel lesions, which were determined based on the median vessel area value. Incidences of hematoma, intimal dissection, and medial dissection were recorded. All images were analyzed using computerized planimetry software (echoPlaque; INDEC Medical Systems, Los Altos, CA, USA) by independent physicians who were blinded to all clinical data.
Data are presented as numbers with percentages or as means ± standard deviations. Comparisons of categorical variables were performed using Fisher’s exact test. Comparisons of continuous variables were performed using Student’s t-test or the Mann–Whitney U test. The Spearman rank correlation method was applied to estimate correlations between continuous variables. All P-values were two-sided and P-values < 0.05 were considered statistically significant. All analyses were performed using SPSS software (version 19; IBM Corp., Armonk, NY, USA).