Study population
This observational cohort study included 180 consecutive “all comers” patients with true CBLs (≥ 50% diameter stenosis) diagnosed by angiography who were treated with either MC or DKMC with drug-eluting stents (DES) between January 2010 and March 2015. Patients were treated with upfront or rescue two stent strategy (MC group: 70 cases of upfront two stent strategy and 13 cases of rescue two stent strategy; DKMC group: 80 cases of upfront two stent strategy and 17 cases of rescue two stent strategy). Clinical flow charts of this mini-culotte stent techniques work are demonstrated in Fig. 1.
The study was conducted in accordance with the Declaration of Helsinki. The protocol approval was obtained from the Medical Ethics Committee of Union Hospital, Fujian Medical University. The identity of patients remained anonymous, and the requirement for informed consent was waived due to the observational nature of the study14,15
PCI was determined by an experienced heart team (interventional cardiologists) based on clinical risk, angiographic characteristics, and patients’ preferences. All patients signed written informed consent.
The synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) score was calculated for every patient so as to evaluate cardiac operative risk scores.
Procedures
All interventional procedures were performed as previously described10,16,17. The proximal optimizing technique (POT) was conducted in two stent strategy18,19. The stents were mainly selected from Resolute (Medtronic Cardiovascular, Santa Rosa, California), Xience V (Abbott Vascular, Santa Clara, California), Firebird-2 (Microport Co., Shanghai, China), and Excel (JW Medical System, Weihai, China). Bifurcation lesions were treated using either MC or DKMC 16. The stenting strategy was at the discretion of operators according to the lesions' characteristics and their experiences. Final kissing balloon dilation was performed with a non-compliant balloon according to named time and pressure in the two-stent procedure. Intra-aortic balloon pump (IABP) was used in high-risk patients with severe heart failure. The use of intravascular ultrasound (IVUS) and the choice of a particular drug-eluting stent (DES) were at the discretion of the operators. Within 48 h after the procedure, cTn values above 5 times the 99th percentile URL after PCI or 10 times after CABG were used to define periprocedural PCI or CABG related MI in patients with normal baseline cTn levels" + " graft occlusion was defined according to ARC-like definition (for CABG). No patients undergoing CABG were enrolled.
All patients undergoing PCI were administered with a loading dose of aspirin (300 mg) plus clopidogrel (300 or 600 mg) or ticagrelor (180 mg) before or during intervention procedures. Periprocedural anticoagulation followed the standard treatment. During the procedure, patients received unfractionated heparin 100 IU/kg intravenously, which was corrected to maintain an activated clotting time > 300 seconds. Whether to use glycoprotein IIb/IIIa receptor inhibitor was left to the discretion of the operators. After discharge, all patients treated with PCI were prescribed a standard dual antiplatelet therapy regimen (aspirin 100 mg daily, and clopidogrel 75 mg daily or ticagrelor 90 mg twice daily) for at least 12 months and were indefinitely continued with aspirin.
Other post-procedure medication treatments such as statins, angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), and beta-blockers were prescribed to patients undergoing PCI according to current clinical practice.
Follow-up
Clinical follow-up was scheduled at 1, 6, 12 months (1 year), 3 years and 5 years after revascularization, and then annually thereafter. Routine angiographic follow-up was recommended at 12 months after PCI. Angiography was performed beforehand if symptoms of angina recurred. Subjects who did not adhere to the recommended follow-up processes were interviewed by telephone.
Study endpoints and definitions
The primary endpoint of this study was a patient-oriented composite of major adverse cardiac and cerebrovascular events (MACE) at 1 year, 3 year and 5 year follow-up, which included all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR) or target lesion revascularization (TLR). In the analysis of cumulative endpoints, events were counted only once, whichever occurred first.
The secondary endpoints were a composite safety endpoint of all-cause death/MI/stroke, individual components of MACE, and stent thrombosis (ST).
Death was defined as post-procedure death from any cause and was classified as from either cardiac or noncardiac causes, according to the Academic Research Consortium (ARC) definition20. Death was considered as cardiac origin unless a noncardiac origin has definitely been proved. Cardiac death was defined as any death due to a cardiac cause (e.g., MI, low-output heart failure, fatal arrhythmias), procedure-related death, or death of unknown cause.
Myocardial infarction (MI) was defined according to the third universal definition of myocardial infarction21. Evidence for MI mainly included elevated cardiac troponin (cTn) with at least one value > 99th percentile upper reference limit (URL), symptoms of myocardial ischemia, electrocardiographic changes, and angiographic characteristics. Within 48 h after the procedure, cTn values > 5 times the 99th percentile URL after PCI or 10 times after CABG were used to define periprocedural PCI or CABG-related MI in patients with normal baseline cTn levels (≤ 99th percentile URL). If the baseline values were elevated or stable or falling, a rise of cTn values > 20% was also considered evidence of periprocedural PCI-related MI. Q-wave MI was defined as MI together with a new pathologic Q-wave in no less than 2 contiguous leads after index treatment.
TVR was defined as any surgical or percutaneous repeat revascularization of any segment of the stented vessel (target lesion, upstream or downstream branches) within 1-year, including the left main, left anterior descending, and left circumflex coronary arteries. A planned staged PCI was not considered as a TVR.
The occurrence of definite stent thrombosis (ST) was defined according to the ARC definition (for PCI), and graft occlusion was defined according to ARC-like definition (for CABG) 22,23.
Statistical analysis
Continuous variables were presented as mean ± SD, and categorical variables were presented as number (%). Comparisons between the MC and DKMC groups in baseline characteristics were performed by t-test or Wilcoxon rank-sum test for continuous data, and the chi-square test or Fisher’s exact test for categorical data, as appropriate. Cumulative event curves of the MC and DKMC groups were constructed by the Kaplan-Meier method and were compared using the log-rank test.
A P value < 0.05 was considered statistically significant, and all tests were two-tailed. All the statistical analyses were performed with SPSS software (version 22.0, SPSS, IBM Corporation, Armonk, New York).