This prospective observational study was designed to investigate the one-year clinical outcomes of unprotected left main coronary artery disease revascularization by percutaneous coronary intervention in a “real-world” setting among Egyptian patients in a prospective single-center registry (at Ain Shams University Hospitals). It aims at exploring the trend of LM PCI at our cardiac cath laboratory. The aim is to express our outcomes and the extent of correlation with international centers.
The study was conducted within the period from May 1, 2020, to the end of April 2021, including patients diagnosed with LM disease who underwent LM percutaneous intervention. All of them were recruited from the department of cardiovascular medicine at Ain Shams University Hospitals. Patients' participation was voluntary, and the subject had the right to withdraw from the study at any time without affecting his/her further medical care. Patients were considered eligible for the study if they were symptomatic, whether as a chronic coronary syndrome or acute coronary syndrome (including acute STEMI) and underwent PCI to a significant unprotected LM disease (whether located in the ostium, shaft, or distal). Significant LM disease was defined as visually assessed stenosis diameter ≥ 50%, fractional flow reserve ≤ 0.80, or documented stress-induced myocardial ischemia on non-invasive imaging. The patient was assigned to the percutaneous revascularization modality at the operator's discretion considering each patient's SYNTAX and STS scores in agreement with the 2018 ESC guidelines for myocardial revascularization . Patients with high SYNTAX scores were discussed by the heart team, and the decision to resort to PCI was due to high surgical risk, surgical ineligibility, or the patient's refusal to undergo CABG.
The main exclusion criteria in the study were protected left main, acute ST-elevation myocardial infarction with cardiogenic shock, chronic total occlusion of either LAD and/or LCX, PCI done using bare-metal stents, severely impaired left ventricular ejection fraction (LVEF ≤ 20%), patients indicated for concomitant valvular or aortic surgery or patient life expectancy below 1 year. Approval was obtained from the ethical committee at Ain Shams University before starting the research. (FWA 000017585).
Preprocedural data were collected from the patients regarding their presentation (chronic coronary syndrome or acute coronary syndrome), comorbidities (peripheral arterial disease, chronic lung disease, chronic kidney disease), and risk factors (smoking, diabetes mellitus, hypertension, dyslipidemia, positive family history, obesity assessed by body mass index). Laboratory data were collected, including cardiac enzymes, glycated hemoglobin and serum LDL. ECG and echocardiography to estimate left ventricular ejection fraction (using the Modified Simpson method) were collected as well. During the procedure, intravenous unfractionated heparin 70 IU/kg was given at the beginning of the procedure to keep an activated clotting time of > 250 s. Access site, use of glycoprotein inhibitors, and use of IVUS or FFR were at the discretion of the operator. All patients were on acetyl salicylic acid (aspirin) and P2Y12 inhibitor (either clopidogrel or ticagrelor).
The choice of stenting technique was at the operator's discretion considering the European Bifurcation Club (EBC) recommendations .
Stepwise provisional single-stent group
Coronary guidewires were passed to the left anterior descending (LAD) and circumflex (LCx) arteries, respectively. Either the LAD or LCx will be designated as the main branch (MB), and the other will be the side branch (SB). Lesion preparation was undertaken as needed to be followed by stenting of the LAD, a wire jailed in the LCx to preserve side vessel flow and access. Following stenting of the left main into the LAD, proximal optimization (POT) of the left main artery part of the stent was encouraged to be done. This was occasionally followed by rewiring the LCX, opting for a distal cell crossing, and kissing balloon inflations that may eventually be followed by POT.
Angiographic success was considered if the following were absent: < TIMI 3 flow in the side vessel, severe (> 90%) ostial pinching of the SB or SB dissection. Under these circumstances, the operator resorted to implanting an SB stent in a manner of their choosing (e.g., TAP).
The TAP stenting technique is a modification of the T-stenting technique designed to optimize "bail-out" SB stent implantation in bifurcation lesions treated by the "provisional" approach. It is applied after the MB stent has been implanted and kissing balloon inflation has been performed. In particular, TAP stenting was developed to ensure full ostium coverage by DES struts while requiring the performance of final kissing inflation. For this to succeed, the SB stent is delivered with minimal protrusion inside the MB with an uninflated balloon positioned in the MB across the SB take-off. After SB stent deployment, kissing balloon inflation is immediately performed with the stent's balloon and the balloon which was previously positioned in the MB .
Systematic, planned two-stent group
Coronary guidewires were passed to the LAD and LCx/intermediate arteries. Pre-stenting balloon inflation was performed. The stent technique was at the discretion of the operator but could be one of culotte, DK crush, minicrush, or TAP. Steps varied according to the technique chosen . However, no planned culotte technique was done in our study.
The DK-crush technique consists of stenting the SB, balloon crush, first kissing, stenting the MB, and final kissing balloon inflation. Careful rewiring from the proximal cell of the MB stent and keeping the wire in the true lumen of the SB stent are very important for optimal angiographic results. Balloon anchoring from the MB, alternative inflation, and each kissing inflation using large enough noncompliant balloons at high pressure and the POT technique are mandatory to improve both angiographic and clinical outcomes .
When describing the minicrush technique, pre-dilatation of all branches was performed with balloon kissing of both the MB and the SB at first, then between the MB and the proximal branch afterward. This was followed by the positioning of stents in both side branches (SB stent's proximal dot was situated in the MB at a length of 1–2 mm proximally to the carina of the bifurcation). SB stents were then deployed sequentially and crushed at the same time by high-pressure balloon inflation positioned in the MB .
Aspirin 75–100 mg daily was continued long-term in addition to a P2Y12 inhibitor, whether clopidogrel or ticagrelor, according to the operator's choice. Statin therapy was continued for the duration of the study, whether rosuvastatin or atorvastatin.
The primary endpoint of the study was a composite of all-cause death and four-point major adverse cardiovascular and cerebrovascular events (MACCE) during the 12 months follow-up, including cardiovascular mortality, myocardial infarction, and cerebrovascular accidents (TIA, embolic or hemorrhagic stroke), and hospitalization for unstable angina or revascularization procedures.
The Universal Definition of Myocardial Infarction was used to define myocardial infarction in this study. Coronary intervention-related MI (MI type 4a) is defined by the rise of cTn values more than five times the 99th percentile upper reference limit (URL) in patients with normal baseline values. In patients with an increased pre-procedure cTn in whom the cTn levels are stable (≤ 20% change) or falling, the post-procedure cTn must rise by > 20%. However, the absolute post-procedural increase must still be at least five times the 99th percentile URL. In addition to that, one of the following elements is mandatory: new-onset ischemic ECG changes; development of new pathological Q waves; or angiographic findings indicating a procedural flow-limiting complication such as coronary dissection, occlusion of a major epicardial artery, or an SB occlusion/thrombus, disruption of collateral flow or distal embolization .
Technical success is defined as completion of stent placement, balloon dilatation, rewiring, and final kissing balloon therapy as required by the protocol. Procedure success is defined as the placement of stents as per randomization with TIMI 3 flow and < 30% stenosis in any stented vessel and TIMI 3 flow in any unstented vessel .
Target vessel failure (TVF) is defined as a combined endpoint by the presence of re-occlusion, restenosis, or target vessel revascularization (defined as a necessity for a repeated PCI within the formerly intervened vessel) .
The collected data were revised, coded, tabulated, and introduced to a PC using the Statistical Package for Social Science (SPSS 25). Data were presented, and suitable analysis was done according to the type of data obtained for each parameter. Student t-test was used to assess the statistical significance of the difference between the two study group parametric variables, and the Mann–Whitney test (U) test was used for nonparametric variables. For categorical variables, the Chi-square test was used, while Fisher's exact test was used when the expected count is less than 5 in more than 20% of cells.