Four-Year Outcomes of Unprotected Left Main Lesion PCI with Self-Apposing Stents versus Balloon-Expandable Stents

Percutaneous coronary intervention (PCI) in unprotected left main coronary artery disease (ULMCAD) has become a safer and more efficient treatment method. Although coronary artery bypass grafting (CABG) was the standard treatment for complex left main lesions, an increasing number of patients with ULMCAD are treated by PCI [1,2,3]. Here we can include both patients with low or intermediate syntax scores and more and more patients with high syntax scores who have contraindications for surgery due to comorbidities or due to local surgical expertise [2, 4,5,6].

Developments in stents have made it possible to address complex cases of left main stenosis [7, 8]. The introduction of the self-apposing stent (Stentys) made it possible to treat left main lesions in which there were aneurysms or significant dilatations of the coronary arteries – large discrepancies between the diameter of the main proximal vessel and the distal proximal vessel – due to the special properties of this stent. The stent Stentys (Stentys, France) is a self-apposing device constructed of nickel and titanium alloy characterized by the ability to push externally, increasing its dimensions only upon reaching the vessel wall, or a predictable maximal diameter dependent on the size of the device used [9].

These properties of the Stentys stent have removed, at least in theory, several problems of left main angioplasty: -

the difference in diameter between left main and left anterior descending artery (LAD), making the use of proximal optimization technique (POT) unnecessary

Many of these assumptions made at the introduction of the stent have been tested, some being refuted, and others confirmed [10, 11]. Leaving aside the above, the left main angioplasty technique must remain standardized according to the recommendations in use.

The aim of current study was to compare the four-year outcomes of patients with ULMCAD treated by PCI with a balloon expandable stent or a self-apposing stent (Stentys stent), including both elective patients and patients presenting with acute coronary syndrome (ACS).

A total of 146 patients undergoing left main PCI were included, age ranging from 33 to 86 years (median of 63 years). Group A consisted of n=84 (57.5%), Group B of the remaining n=62 (42.5%). Detailed demographic and baseline clinical characteristics by group are presented in Table 1. We found few significant differences among the two groups, namely more patients with peripheral artery disease in Group A (25% Group A vs 6.6% Group B, p=0.004).

SYNTAX, SYNTAX II (PCI and CABG, with respective predicted mortality) and EuroSCORE II scores for the two groups are detailed in Table 2. SYNTAX scores are higher in patients treated with balloon-expandable stents compared to patients treated with self-apposing stents.

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Late outcomes

Mortality, TLR and MACE at 4 years were 21.9%, 14% and 32.5% overall, 9.6%, 15% and 24.1% in non-ACS patients and 33.3%, 12.8% and 40.1% respectively in ACS-patients, respectively. Unadjusted comparisons of mortality, TLR and MACE at 4 years between Group A and Group B are shown in Figure 1. Mortality rate and MACE rates at 4-year follow up were higher in Group B compared to Group A but have not reached statistical significance in univariable or multivariable analysis.

Figure 1

Implantation of a self-apposing stent has an independent predictor for TLR in multivariable analysis (HR 0.06, CI − 1.11–11.7, =0.03).

The study included an unselected population of patients with ULMCAD treated by PCI. Thus, patients who presented with acute coronary syndrome were not excluded from the study, considering in the analysis also severe patients with cardiogenic shock. The aim of this study was to highlight the results obtained after left main angioplasty performed with different stent platforms in an interventional cardiology center with a large volume of cases, both in elective patients and in priority or urgent patients. The study included 146 patients with ULMCAD PCI, of whom 52.06% had acute coronary syndrome. The study population was divided into 2 groups depending on the type of stent used for left main PCI: group A – balloon-expandable stents and group B - self-apposing stents. There is little data on the comparison of the two types of stents in current practice in both elective and acute coronary patients.

A first significant difference is that patients treated with self-apposing stents had lower risk scores, both anatomical and combined, than patients treated with balloon-expandable stents. Thus, we could say that self-apposing stents are implanted in less complex cases. This is since the implantation of a self-apposing stents requires the most appropriate predilation of the lesion and the passage of the stent through the lesion is more difficult due to the higher profile than the balloon-expandable stents [9, 10].

There is a preference for a particular type of stent depending on the location of the lesion in the left main. Patients with ostial and mid-segment lesions were not treated using a self-apposing stent. Self-apposing stents are considered to have a lower radial force than balloon-expandable stents. This makes their use in aortoostial lesions lower, due to the high resistance of this area and the greater tendency to “recoil” of the implanted stent. The self-apposing stent was preferred in distal left main lesions, especially in patients with LAD ostial lesion, Medina 0/1/0 [9].

POT and KBPD were performed much more frequently in the case of balloon-expandable stents. This is due to the properties of the self-apposing stents to self-appose to the vessel wall (hence the theoretical lack of the need for proximal optimization) and minimal deformation when the struts to the side branch are opened (hence the theoretical lack of the need for kissing balloon) [10, 11].

There was no difference in mortality rate and 4-year MACE rate between the two groups. However, the rate of revascularization of the target lesion was significantly higher when a self-apposing stent was used. Although there is no evidence from studies of exvivo models, self-apposing stents tend to narrow the ostium of the secondary vessel over time, precisely because of their properties of continuing to expand over time.

This study was a nonrandomized study in which operator bias may have influenced the final conclusion. Although it might have offered more data on restenosis, routine angiographic reevaluation is no longer recommended and was not performed. The small number of early events prevented multivariable analyses, so the results are subject to confounding. The use of various types of stents introduces a degree of heterogeneity.

Although there are differences in the technique of angioplasty between patients treated with self-apposing stents compared to those treated with balloon-expandable stents, the mortality and MACE rates at 4 years did not differ between the two types of stents. However, TLR was significantly higher in patients with left main lesion treated by PCI with self-apposing stents.