The choice of treatment modality for multi-branch coronary artery lesions has been controversial. The ongoing SYNTAX, FREEDOM, and CARDia trials have randomly compared the efficacy of PCI with CABG in the treatment of multiple lesions. The SYNTAX trial showed comparable efficacy of PCI and CABG in low- to intermediate-risk left main/three branch lesions. It is expected that PCI will play an important role in the treatment of multibranch lesions.
1. Classification of multi-branch lesion revascularization modalities
There are two types of multi-branch lesion revascularization: complete and incomplete. There is no universally accepted definition of complete revascularization, and different studies have different criteria, so it is prudent to compare the results of different trials. The concept of complete revascularization originates from cardiac surgery and is broadly defined to include the size of the diameter of the lesion, the degree of stenosis and the extent of surviving myocardium, and in some cases to distinguish between main and branch vessels. Another approach is to calculate the number of stenoses and the number of distal anastomoses (equal to both is considered complete revascularization). Others introduce a scoring system (e.g., the SYNTAX score) to assess the extent of the lesion and thus the completeness of the revascularization, where the extent of the lesion and its treatment outcome is a variable. Complete revascularization in the general cardiac surgical sense is defined as successful CABG of all lesions with ≥50% stenosis and ≥2.0 mm diameter; PCI anatomic complete revascularization is defined as successful treatment of all lesions with ≥1.5 mm diameter and ≥50% stenosis, regardless of the presence of surviving myocardium, with the same results as CABG; PCI functional complete revascularization is defined as All lesions with ≥50% stenosis and surviving myocardium are treated. Incomplete revascularization refers to the presence of at least one coronary artery with a residual stenosis of 1.5 mm or more in diameter and ≥50% of the stenosis, and also refers to the treatment of only the “culprit vessel” causing clinical symptoms.
2. Comparative study of complete and incomplete revascularization
For multiple lesions, complete revascularization with PCI can significantly reduce the incidence of adverse cardiac events (MACE) and benefit patients significantly by reducing revascularization, which is the preferred goal of interventional therapy. However, incomplete revascularization has recently been partially recognized. In reality, many patients have difficulty achieving complete revascularization, and in some specific situations, incomplete revascularization is even intentionally performed to treat only the symptomatic offender vessels in multiple lesions, but not the other non-offender vessels. A number of comparative studies and trials have been conducted in recent years regarding complete and incomplete revascularization of multiple lesions with PCI.
(1) In the “PTCA” era, two early non-randomized studies of MC and NHLBI were conducted. (2) In the “BMS” era, data from the ARTS I and BARI trials were combined and complete revascularization with PCI was found to be an independent predictor of long-term prognostic improvement in multi-branch lesions. 3. Tamburino C et al. compared the long-term prognosis of patients with multiple lesions undergoing PCI with complete and incomplete revascularization with DES. 212 patients underwent complete revascularization and 296 patients underwent incomplete revascularization, and follow-up showed a significant reduction in both primary and secondary endpoint adverse events (death, nonfatal myocardial infarction, and revascularization) with complete revascularization.
3. High-risk patients
3.1 Left ventricular insufficiency and diabetes mellitus
In patients with multiple lesions with left ventricular insufficiency, BoekenU et al. compared the effects of complete and incomplete revascularization with CABG and confirmed that complete revascularization improved the prognosis of patients with multiple lesions with left ventricular insufficiency. Therefore, complete revascularization is recommended for patients with multibranch lesions with diabetes mellitus and left ventricular insufficiency.
3. 2 Non-ST-segment elevation acute coronary syndrome
Shishehbor MH et al. enrolled a total of 1240 patients from 1995 to 2005, of whom 479 underwent multiple PCI and 761 were treated with infarct-related arteries only, and the rates of death, myocardial infarction, and revascularization were lower with multiple PCI. ShishehborMH et al. concluded that the offender vessel in non-ST-segment elevation acute myocardial infarction is often difficult to identify and that staging of the offender vessel and other serious lesions should be based on careful assessment of risk and benefit, and that intravascular ultrasound or FFR testing may be considered when the severity of the non-offender vessel is in doubt.
3.3 Acute ST-segment elevation myocardial infarction
Previously, emergency PCI for acute myocardial infarction usually dealt only with the infarct-related artery, without considering other diseased vessels. However, recent studies have shown that acute myocardial infarction is often accompanied by a state of systemic inflammation that can lead to instability of other vulnerable lesions, and many imaging studies have found that at least 50% of acute myocardial infarction is associated with multiple vascular lesions.SorajjaP et al. demonstrated that severe lesions in vessels other than the infarct-related artery in patients with acute myocardial infarction with multiple lesions can reduce the success rate of reperfusion after direct PCI and lead to a poor prognosis van der SchaafRJ et al demonstrated that 1-year mortality was higher in patients with acute myocardial infarction with multiple lesions than in patients with single lesions, mainly due to the presence of chronic total occlusion in non-infarct-related arteries. Is there a benefit to disposing of noninfarct-related arteries? Proponents argue that complete revascularization may reduce the number of reinterventions, prevent recurrent infarction or ischemia, and improve left ventricular function, while opponents argue that complete revascularization increases potential operative risk, contrast dosage, and late TVR and MACE rates, that some revascularization is unnecessary, and that the 2005 ACC/AHA/SCAI PCI guidelines clearly state that management of hemodynamically decompensated non-infarct-related arteries in patients with acute myocardial infarction. Therefore, a careful evaluation of revascularization strategies for acute myocardial infarction with multiple vascular lesions is warranted.
Most of the above trials are single-center and non-randomized, and the results are sometimes contradictory, which shows the complexity and difficulty in deciding the revascularization strategy for PCI of multiple lesions, but with the continuous advances in PCI technology, devices and drugs, complete revascularization is the general trend, as confirmed by recent trials. The ongoing FACE randomized study will provide stronger evidence-based evidence for the development of a multi-branch lesion PCI revascularization strategy.
4. Indications for incomplete revascularization
Although complete revascularization is the ideal goal for PCI of multi-branch lesions, it is often accompanied by potential damage from radiation and contrast agents, and optimal incomplete revascularization is also feasible when considering various factors such as lesion, patient, operator, technique, and economy, and weighing the risks and benefits. Incomplete revascularization may be considered for multi-branch lesions in the following circumstances.
(1) Certain lesions have anatomic features that make intervention difficult: e.g., chronic completely occlusive lesions, diffuse lesions, severely distorted, calcified or angular lesions, stenosis with adjacent angiomatous dilatation, etc. (2) Some lesions may not be considered for intervention: ① Critical lesions without myocardial ischemia; ② Non-dominant right coronary lesions; ③ Non-dominant right coronary lesions
(2) Non-dominant right coronary lesions; (3) Small coronary vascular lesions (<1.5 mm) with a small myocardial supply (less than 10%); (4) Chronic occlusive lesions with no or only a small amount of viable myocardium in the supply area. (3) Direct PCI for acute myocardial infarction only treats the infarct-related vessels, while other lesions can be treated with elective intervention. (4) Palliative intervention: For some patients of advanced age, combined with tumors, severe organ insufficiency or end-stage patients, only the "criminal" lesions can be treated by intervention.
Incomplete revascularization must be performed by correctly determining the “offender” lesion. The lesion that directly causes the current myocardial ischemia is the “offender lesion”, which is usually easy to identify, but is more difficult to determine when there are more than two lesions. confirmed, and of the remaining 63% who could identify an offender lesion, 49% had a single offender lesion (36% a single incomplete occlusion lesion and 13% a single complete occlusion lesion) and 14% had multiple offender lesions. ECG changes, nuclear loading myocardial perfusion scans and ultrasound loading myocardial imaging, coronary angiographic lesion features (ulceration, thrombosis, entrapment, stenosis versus occlusion, etc.), antegrade flow up to TIMI class II, intravascular ultrasound (IVUS), optical interferometric imaging (OCT), and pressure guidewire measurements all helped identify “offender lesions “. When the offender vessel cannot be identified, PCI can be performed on the vessel with the most important blood supply among the multiple lesions.
In conclusion, the management of multiple lesions should take into account the patient’s clinical condition, medical conditions and lesion characteristics to reasonably select complete and incomplete revascularization modalities for PCI.