The rapid development and advancement of catheter interventional techniques has made PCI treatment of unprotected left main lesions no longer contraindicated, especially since the results of the SYNTAX study showed that PCI treatment of patients with intermediate-risk (Syntax score 23-32) and low-risk (Syntax score 0-22) left main lesions (Syntax score <33) had comparable efficacy to CABG, and only high-risk patients ( Based on this, at the US Left Trunk and Bifurcation Lesion Summit in June 2009, Professor Martin Leon et al. recommended that the indication for elective PCI for unprotected left trunk lesions should be raised from IIb to IIa. Despite this, due to the high risk of left trunk interventions are particularly important due to their high-risk nature, their treatment strategies, and interventional techniques. Wei Feng, Department of Cardiology, Bengbu First People's Hospital
I. Treatment strategy for PCI of LM lesions
PCI or stenting strategy for LM lesions involves two levels: 1. PCI or CABG selection; 2. PCI strategy development, the core issue is to ensure patient safety.
1. PCI or CABG selection
Because CABG surgery in Western developed countries was well established before the introduction of PCI treatment, CABG has been the preferred treatment for LM in coronary artery disease treatment and coronary interventional guidelines, and PCI is listed as contraindicated. Even after entering the BMS era to obtain fat ひひ cellar еぞ葜С cure Wei; after the effective and safe BMS implantation, the guidelines still recommend that CABG is preferred and PCI is only a class IIb indication. Our guidelines recommend the treatment of patients with LM lesions due to the absence of more fat ひ窖Ы峁捕枷坝梦鞣街改隙LM lesions.
The national situation in China is clearly different from that in the West: CABG started late and was slow to develop and spread, and the level of technology is extremely uneven across the country, whereas PCI started relatively early and spread quickly, especially in the last decade with the introduction of DES and the improvement and maturation of PCI technology, and the level of technology is relatively more balanced across the country. Therefore, for patients with LM lesions, the preference for CABG or PCI must be based on the premise of technical maturity and patient safety as the primary consideration.
2. Strategy of PCI for LM lesions
The core of the PCI strategy for LM lesions is either a single-stent technique or a double-stent technique.
In general, single stenting is available for left main stem orifice and body stenosis. Open-loop stents are more suitable than closed-loop stents for left main stem orofacial lesions because they are more likely to radiate at the orifice, most closely resembling its “flare” shape. The principle of choosing the stent size for left main stem lesions is “choose a large stent rather than a small one”, and the length of the stent should not be too short, because it is not easy to position the stent and it is easy to fall off.
Left trunk bifurcation lesion should be treated with single stent (crossover) or double stent technology such as crush, culotte, T-type, V-type or kissing stent according to the specific situation. The current radial artery intervention with the 6F Lancher catheter can be completed with double stenting using the step crush (step crush) or even step Kissing (step Kissing) technique.
II. Technical points of PCI for left main lesions
PCI of LM is high-risk, complex and variable, requiring the operation of experienced interventional surgeons, supported by bailout measures such as IABP, a well thought-out operation plan, emergency equipment and medications should be prepared, and IVUS should be routinely used to evaluate the stent effect. Postoperatively, patients should be sent to a qualified CCU for monitoring and treatment, and after discharge, they should be advised to take medications as prescribed, followed up closely, and reviewed immediately and urgently at the first sign of symptoms. The core remains to ensure the safety of patients intraoperatively and postoperatively, during hospitalization and after discharge, thus ensuring both immediate and long term outcomes. The focus should be on the following aspects.
(1). Strict safety indications. CABG should be preferred for those with left main + three coronary lesions and high-risk lesions, such as bifurcation lesions with severe stenosis, unstable lesions and severely hypoplastic left ventricular function, severe calcification or left mains shorter than 8 mm. Those who are at high risk for PCI and cannot guarantee its safety are strongly discouraged from doing it.
(2). Strict surgical consultation procedures to adequately evaluate and compare the risks of CABG versus PCI in order to provide even or recommend a choice to the patient and family.
(3). High-risk patients should be performed under IABP bailout to avoid sudden complications arising from acute occlusion, near occlusion or even aggravation of stenosis affecting blood flow in the left main stem and its two main branches intraoperatively to ensure patient safety.
(4). Adequate exposure of the stenotic lesion (see later).
(5). Operate gently and delicately in order to greatly reduce the chance of injury to the left main stem and its two major branch openings, or even acute occlusion.
(6). Ensure adequate pre-expansion of the stenotic lesion without serious entrapment affecting blood flow, ensure easy delivery of the stent into place, accurate positioning, and successful implantation in one accurate time, and complete the interventional operation well and quickly.
(7). When choosing stents, especially the left trunk and branch caliber should be considered, and technical parameters of stents should be understood, such as stent diameter Cypher 3.5mm, TAXUS 3.5mm, 4.0mmm, maximum mesh diameter 3.0mm, 3.70mm, 4.25mm, maximum expandable diameter 4.75mm, 4.25m, 5.75mm respectively.
(8) To ensure adequate stent expansion and good wall apposition to eliminate the potential for acute, subacute or even late thrombosis. For this purpose, both the stent selection and implantation pressure should be sufficiently large (≥16 atm), and the stent apposition should be routinely checked by IVUS after surgery, especially double stents should be confirmed to be well apposed to the wall, and sent to CCU for monitoring for 24 hours after surgery if possible.
III. Key points of stent positioning for LM orofacial lesions
The stent implantation in the left main trunk is easy to slip into or out of the left main trunk because of the dilated release placement, so the accurate positioning of the stent is very important. The key is that the stent should be long rather than short, so that the stent can be fixed by the artificial “dog bone” phenomenon when it is released under pressure and accurately placed under pressure. In order to ensure accurate positioning of the implant, it is crucial to choose the best position for projection. Generally speaking, left anterior oblique cephalic position, foot position, and right anterior oblique cephalic position are the best positions, and it is advisable to extend the proximal edge of the stent 1~2mm out of the left main trunk orifice to completely cover the lesion. After stent placement, the balloon should be retracted by 2-3 mm and then dilated under high pressure to ensure adequate expansion of the stent against the ascending aortic wall. Special attention should be paid to short balloon expansion time (<10 seconds) and high pressure (≥16 atm) to ensure adequate stent expansion and good wall apposition.
IV. Recommended optimal projection position for LM lesions
According to the anatomical site, left main stem lesions can be divided into: lesions at the opening; lesions at the body; and lesions at the distal bifurcation (including the opening of the anterior descending branch and the gyral branch).
The commonly used projection angles for interventional treatment of left main stem openings and corporal lesions are: right anterior oblique + head or foot position, left anterior oblique + head or foot position; left anterior oblique foot position is often used for distal bifurcation lesions, and the post-stenting evaluation should choose the position that exposes the opening of the anterior descending branch and the gyral branch better.
In the case of combined multibranch lesions of the left main stem, the orthogonal + cephalic position is generally used, and two positions of orthogonal + foot position can expose most of the lesions.
In particular, it should be noted that in cases of left main stem lesions, especially severe stenosis, multiple positions or pushing in too much contrast medium for too long or in too large a volume at one time are very dangerous and can lead to heart failure, cardiogenic shock, or even cardiovascular collapse and death. Therefore, in order to avoid serious complications during coronary angiography, the standard practice is: ① The contrast catheter or guiding catheter should not be in place at one time to avoid left main stem injury. ② The pressure curve changes should be closely observed throughout the catheter’s entry into the left main stem to avoid pressure entrapment, resulting in severe myocardial ischemia. ③ Select 1-2 key positions, push a small dose of contrast agent to complete the imaging, and fully expose the lesion. ④ Choose emergency or elective CABG or PCI according to the condition.
V. Value of IVUS in left main stem PCI
IVUS can provide quantitative and qualitative anatomical information of coronary lesions. IVUS can provide accurate quantitative information about these lesions to help determine the indications for PCI, the best strategy and technique, and the selection of the appropriate balloon and stent, especially in moderate left main stenosis, where the severity is often difficult to determine on imaging.
Currently, IVUS measurements of luminal internal diameter stenosis >50%, area stenosis >60%, patients with symptoms of myocardial ischemia and absolute left main area <7 mm2, or patients without symptoms and absolute left main area <6 mm2, are considered indications for PCI.
In addition, IVUS after stent implantation is useful to evaluate whether the implanted stent is well inflated and apposed, with or without entrapment, thrombosis, and residual stenosis.Park et al. reported a significant reduction in 1-year mortality with IVUS-guided left main stem intervention compared with contrast-guided left main stem intervention alone (4.4% vs. 16.0%, P=0.048).Stone and Mintz noted that available data from randomized and registry studies, as well as clinical experience, support the use of IVUS-guided DES implantation in unprotected left main stem interventions to ensure maximum stent expansion and coverage of residual lesions. Therefore, the routine use of IVUS in left main stem interventions is strongly recommended, firstly to provide evidence for the indication of the need for PCI and secondly to obtain satisfactory immediate and long-term clinical results. However, special attention should be paid to the use of IVUS before PCI for severe left main stenosis lesions, as it may completely occlude the left main trunk and cause massive myocardial ischemia, with serious consequences.