Treatment of Coronary Bifurcation Lesions by Stent Implantation Only in Parent Vessel and Angioplasty in Sidebranch: Immediate a

Treatment of bifurcation lesions still remains a challenge for interventional cardiologists and is still associated with a high rates of complications (8–22%) and restenosis (30–65%).1–5 The presence of a large plaque burden at the site of the bifurcation, even without significant stenosis at the orificium of the sidebranch, is often associated with a plaque shift (“snow plow”) after dilatation. The risk of sidebranch occlusion during main vessel angioplasty is high (12–41%)1,6 and may be associated with myocardial infarction. Although this risk may be tolerable for small sidebranches (diameter 2.2 mm) requires a different approach to achieve an optimal final result in both branches. To decrease the risk of sidebranch occlusion, various balloon and guidewire techniques have been proposed, including the “kissing” (simultaneous) and sequential balloon inflation techniques.7–9 More recently, debulking techniques have been evaluated3,10–12 with consequently increased cost and complexity and with unproven results. Recent reports13–21,28 suggest that stenting bifurcation stenosis may be the best approach for treatment of these lesions. Different practical approaches have been suggested, including T-stenting, reverse Y-stenting, “trousers-leg” stenting and use of special bifurcation stents. However, all these procedures are technically demanding, time consuming and expensive; they require considerable expertise. Recently, stent implantation only in the parent vessel with angioplasty or debulking of the sidebranch has been proposed for treatment of bifurcation lesions, with promising results.22,23 Thus, the purpose of our study was to prospectively analyze the immediate and 6-month outcomes of patients treated with the Bx Velocity™ stent (Cordis Corporation, Miami Lakes, Florida) implanted at the site of bifurcation only in the parent vessel with balloon angioplasty of the sidebranch. Methods Patient selection. Between January and November 2001, we performed 540 percutaneous transluminal coronary angioplasty (PTCA) procedures at our institution. Thirty patients (5.5% of all PTCA procedures) were treated for bifurcation lesions with stent implantation in the parent vessel and PTCA of the sidebranch. The Bx Velocity stent (Figure 1) was exclusively used in these study patients. This stent design offers one of the largest circular cell sizes (3.3 mm2) for easy sidebranch access, and the smallest integrated cell size for optimal wall coverage. Clinical indications were unstable angina (n = 12), chronic stable angina (n = 15) and direct PTCA for acute myocardial infarction (n = 3). Stenosis > 50% involving the parent vessel at the level of bifurcation (or plus > 50% stenosis in the sidebranch) was considered to be hemodynamically important. The diameter of the sidebranch was at least 2.2 mm. The severity of coronary artery disease was assessed visually, generally by two observers, using at least two orthogonal views. According to the Duke classification scheme,24 there were 15 type A stenoses, 6 type B stenoses, 3 type C stenoses and 6 type D stenoses. Bifurcation lesions were located in the left anterior descending (LAD) coronary artery (n = 23) and the circumflex artery (n = 7). The shape was “Y” in 25 patients (83%) and “T” in 5 patients. Mean artery diameter was 3.46 ± 0.40 mm in the main branch and 2.65 ± 0.40 mm in the sidebranch. Procedure. Using the transfemoral approach with a 7 French (Fr) guiding catheter, two wires were inserted in the distal bed of the 2 branches. Usually, a 0.014´´ Stabilizer™ Balanced Performance guidewire (Cordis Corporation) was introduced into the sidebranch and a 0.014´´ ACS Hi Torque Balance Middle Weight™ guidewire (Guidant Corporation, Santa Clara, California) was introduced into the main vessel. Afterward, PTCA was conducted in 23 cases by sequential inflation of a semicompliant balloon in each branch using a balloon-artery ratio between 1 and 1.1. “Kissing” predilatations were used in 7 cases. After balloon removal, the premounted Bx Velocity stent was introduced in the parent vessel while “jailing” a wire in the sidebranch. Stent length was chosen in order to cover the proximal part before the bifurcation, the ostium level, and the distal part after dilatation. We used 13-mm long stents in 3 cases, 18-mm long stents in 23 cases and 23-mm long stents in 4 cases. The stent implantations were performed at low pressure (Antithrombotic regimen. The antithrombotic regimen consisted of aspirin 100 mg before the procedure and heparin 100 IU/kg body weight with additional bolus if activated clotting time was Definitions. Procedural Q-wave myocardial infarction (MI) was defined as the presence of new Q-waves on the electrocardiogram (ECG) with either serum creatine kinase (CK) or MB fraction concentrations that were at least three times higher than normal. Non-Q wave MI was defined as an increase in serum CK or MB fraction at least three times the upper limit of normal without onset of new Q-waves on the ECG. Angiographic success was defined as residual stenosis Follow-up. At 6-months post-procedure, exercise stress test and coronary angiography were performed (unless it had been performed earlier due to symptoms). Major adverse clinical events (MACE) during the follow-up period included death, MI (Q-wave and non-Q wave) and angina. In addition, rates of angiographic restenosis, repeat coronary angioplasty and CABG were analyzed. Endpoints. The primary endpoints of this study were procedural success and complication rates as well as frequency of adverse cardiac events, angiographic restenosis and target lesion revascularization rate at 6-month follow-up. Results Patient characteristics. Baseline clinical characteristics are shown in Table 1. Angiographic characteristics and procedural performance. Stents were implanted without difficulty in all 30 patients. The mean balloon size used for the main branch was 3.63 ± 0.4 mm and 2.84 ± 0.4 mm for the sidebranch. The mean stent size for the treatment of the parent vessel was 3.3 ± 0.4 mm. Final kissing balloon post-dilatation was done in all patients. The optimal angiographic results were achieved in the main vessel in all 30 patients and in the sidebranch in 26 patients. There were suboptimal results with residual stenosis > 30% and Late clinical and angiographic results. Results are shown in Tables 3 and 4. Six months after the procedure, a total of 27 patients (90%) were asymptomatic. One patient had unstable angina 3 months after the procedure and angiography revealed diffuse restenosis within the stent; this patient was referred for minimally invasive CABG surgery with the left internal mammary artery. Two patients had slight, exercise-induced class II angina pectoris (according to Canadian Cardiovascular Society classification) with positive exercise stress test and 1 patient had silent ischemia during the stress test. In these 4 patients (13.3%), control angiography revealed restenosis (> 50%) in the main vessel and balloon angioplasty was successfully performed. Angiographic restenosis did not develop in the sidebranch. As mentioned above, one patient suffered a small non-Q wave MI after the procedure due to subtotal occlusion of the sidebranch. Thus, the total MACE rate was 16.6%, including a TVR rate of 13.3%. Discussion The optimal percutaneous management strategy for bifurcation lesions remains unclear. Several different techniques have been proposed to address this problem with limited benefit.3,10–12 The issue of stenting bifurcation lesions has evolved over the past 5–8 years, and as the experience treating sidebranches within a stented segment has grown, interest has increased toward developing a practical approach for stenting both the main vessel and a large branch or a true bifurcation lesion. One approach is the placement of the gap of the articulated version of the Palmaz-Schatz stent in front of the ostium of the sidebranch.24 Colombo et al.26 described a kissing technique with the creation of the double-barrel lumen in the main vessel proximal to the bifurcation. Another approach is the placement of two slotted stents in each origin of the bifurcation and a similar stent in the common proximal part of the principal vessel,27 but this technique requires adequate placement of each stent and can leave a gap at the precise site of the bifurcation. Carrie et al.14 has described a technique with stent implantation in the sidebranch followed by stent implantation in the main vessel using the Wiktor stent. This approach has some limitations: the ostium of the sidebranch is covered by a coil stent with limited radial force and in most cases the anatomic conditions are closer to a Y-shape than a T-shape so that the sidebranch stent may leave either a gap in the ostium of the sidebranch or a stent protrusion in the main vessel. The Cullote technique described by Chevalier et al.15 employs two stents sequentially placed with overlapping in the main vessel proximal to the bifurcation. The disadvantages of this method are a high amount of metal at the level of carina and in the proximal part of the bifurcation and sometimes difficulty recrossing the struts with the guidewire, balloon and stent, depending on the stent used and the underlying anatomy. In our previous article,20 we described treatment of bifurcation lesions using dedicated bifurcation stents. These innovative stents allowed complete coverage of the entire bifurcation site: the proximal main vessel, the ostium of the sidebranch, the carina and both distal parts of the bifurcation. However, all of the above-mentioned techniques, although nicely described, are very technically demanding, time-consuming and expensive. More importantly, they have high rates of restenosis and repeat revascularization. It may be hypothesized that the worse clinical outcomes may be either due to overlapped stent segments or to more trauma during stent implantation, possibly stimulating the formation of neointimal hyperplasia. More recently, some authors22,23 have shown that a simpler strategy with stent implantation in the parent vessel only and PTCA or atherectomy of the sidebranch provides better results in terms of procedural success and late outcomes compared to more difficult and expensive approaches with stenting of both branches. Our observational, prospective study confirmed these results. The angiographic success rate of 86.7% might be considered to be low, but the non-optimal angiographic result in sidebranches is responsible for the low value, since the results in the main vessels were all optimal. Success in the main vessel is the most important when considering a patient’s late outcome and it was obtained in all 30 patients (100%) in our study. This “conservative” approach provides low acute complication rates (3.3%), an excellent event-free survival rate (83.4%) and a low rate of both MACE and TLR (16.6%) during 6-month follow-up. Our data are consistent with results recently published by Lefévre et al,28 who have performed the largest study to date on bifurcation lesions. Procedural success was obtained in 96.3% in both branches and 99.4% in the main branch. At 7-month follow-up, the total major cardiac event rate was 21.6%, including a TVR rate of 17.2%. Analysis of the 7-month outcome according to two study periods (period I = 182 patients studied between January 1, 1996 and August 31, 1997; period II = 127 patients studied between September 1, 1997 and June 30, 1998) showed that the TVR rate decreased from 20.6% to 13.8% (p = 0.04) and the MACE rate decreased from 29.2% to 17.1% (p Study limitations. The major limitations of this study are the observational design and the small number of patients. Conclusion Stent implantation in the parent vessel only with balloon angioplasty of the sidebranch in cases of bifurcation lesions provides high procedural and clinical success rates with a low rate of acute complications and excellent 6-month event-free survival as well as a low rate of angiographic restenosis and target lesion revascularization.

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