Stent in the Percutaneous Coronary Intervention of Coronary Bifurcation Lesions

Use of R™ stent in the percutaneous coronary intervention of coronary bifurcation lesions

Mazhar M Khan, Vaikom S Mahadevan, Vincent P Moohan and Samuel W Webb

Regional Medical Cardiology Centre, BACKGROUND: Percutaneous Coronary which had unstable angina. The mean age Royal Victoria Hospital, Intervention (PCI) of coronary bifurcation was 59 6 10 and 89% were male. Adjunc- Belfast, BT12 6BA lesion is technically quite demanding. It tive medical therapy included clopidro- Northern Ireland has been associated with a lower proce- gel, aspirin and intraprocedure heparin. dural success, higher rates of complica- Abciximab (ReoPro) was given to 9 Correspondence: tion and restenosis. Side-branch patients. Mazhar M Khan occlusion and plaque shifting or ‘snow RESULTS: Successful stent deployment Regional Medical Cardiology Centre Royal Victoria Hospital plow’ effect are not uncommon. Stenting was achieved in all patients. Thirty-four R Belfast of the main vessel may cause ‘stent jail’ of Stents and 16 other stents were used. BT12 6BA the side-branch. Modern stent design Two patients had post-procedure rise in Northern Ireland may allow passage of a balloon or stent cardiac enzymes. There were no major into the side-branch through the struts of adverse events at 30 days. LAD/D1 with Received 6 March 2001 the stent placed in the main vessel. A LAD/diagonal was the target lesion in the Revised 5 October 2001 newly developed 316 stainless steel majority of patients. Stenting of the side- Accepted 15 February 2002 tubular stent, the R™ stent is uniquely branch was done in 18 and balloon designed to provide exibility, radial dilatation in 9 patients. At 3–23 months strength on deployment and conformabil- (mean 11.8) follow-up, repeat angiogra- ity. Its large cell size facilitates PCI of phy was done in 18 patients with bifurcation lesion. restenosis in 4, two of them had repeat AIM: To assess the feasibility of R™ stent PCI and one had coronary artery bypass in the treatment of symptomatic patients graft (CABG). with bifurcation coronary lesions. The CONCLUSION: Coronary bifurcation main objective was to assess the ease of lesions are not uncommon. Current deployment, side-branch access and advances in stent technology offer a safe overall success of the R™ stent in this and effective revascularisation strategy group of patients without any major for such complex lesions. The R™ stent adverse events. appears to be a suitable device that pro- METHODS: Between December 1998 and vides good wall coverage, radial strength, September 2000 the R™ stent was used conformability and easy side-branch as a main stent in 28 consecutive patients access. (Int J Cardiovasc Intervent 2002; 4: with coronary bifurcation lesions, 46% of 173–180)

Keywords: bifurcation stenting – R™ stent – percutaneous intervention of bifurcation lesion.

Introduction nicant side-branch disease. Vessel bifurcation may be pre- disposed to atheromatous plaque formation because of Percutaneous intervention of coronary bifurcation lesion turbulent ow and increased shear stress.5 Although true represents a technical challenge to the interventional cardi- bifurcation lesions account for 4–11% of all PTCA proce- ologist. It has been associated with lower procedural dures, the vast majority involves LAD/diagonal bifurca- success, higher complication and restenosis rates.1–4 A tion.5–7 bifurcation lesion is dened as the presence of signicant Balloon angioplasty of such lesions is often associated (greater than 50%) stenosis involving a parent (main) with a signicant risk of side-branch occlusion.4–6 Several vessel at the ostium of the side-branch with or without sig- techniques including debulking or stenting have been 174 MM Khan, VS Mahadevan, VP Moohan and SW Webb

developed to improve the outcome of intervention.7–10 Important considerations include the likelihood of immediate and future revascularisation of the side-branch, the size of the side-branch and the amount of myocardium Type 1 Type 2B supplied by the side-branch. Stenting of the parent vessel frequently leads to plaque shift or ‘stent jail’ of the side- branch.9 Modern stent designs allow placement of the stent in the parent vessel across the side-branch and passage of a second balloon or stent through the struts of the rst.8 The outcome of such a measure is often variable. It depends upon the type of stent and the size and angulation of the Type 2A Type 3 branch vessel. Stenting both vessels in a complex bifurcation lesion can be difcult. It is often associated with plaque shift, stent overlap and uncovered area at the carina of the bifurcation.10 With improvement in the implantation technique, stent and balloon technology and potent adjunctive pharmacological therapy, stenting of bifurcation lesion has become an accepted PCI procedure with acceptable risk. However, stent deformity following balloon dilatation of the side-branch is a known risk.11 Type 4 The rst attempt at treating bifurcation lesions was with the rst generation Palmaz–Schatz 153 or Cook stent. Initial experience proved to be unpredictable and unsatis- factory as side-branches were sacriced in a substantial proportion of cases. The other major problem is plaque shifting at side-branch ostium after stent implantation, particularly in patients without signicant disease of the Figure 1 side-branch. This observation is not uncommon after stent Classication of coronary bifurcation lesion. implantation and can result in minor or major complica- tions including non-Q-wave myocardial infarction or signicant cardiac enzyme elevation.12 The recent generation of stents has provided a new Subjects and methods dimension in the management of such lesions, with the availability of low prole balloons and large internal Since December 1998, angioplasty and stenting utilizing lumen of guide catheters. It is now possible to treat such the R™ stent (ORbus Medical Technologies, Fort Landale, lesions with greater success. Intra-coronary stenting thus FL, USA) as a primary stent for bifurcation lesion has been represents one of the most important advances in the prac- performed on 28 consecutive patients. Informed consent tice of coronary intervention.13 Greater operator experience was obtained from all patients. The R™ coronary stent is and improvement in stent design with greater tractability, designed to overcome major problems of rst– and exibility and conformability have extended the indica- second–generation stents of the slotted tube, coil and tions of stenting. modular designs. It is a balloon expandable stainless steel stent with a dual helical conguration, thus providing the radial strength of a slotted tube and the exibility of coil Classication of bifurcation lesions design. Each cell is expandable to at least 4.5mm in diameter and permits side-branch access. Initially unmounted Several classications have been proposed for bifurcation stents of 9 and 16 mm in length crimped on a low prole lesions.12,14 The likelihood of signicant side-branch occlu- balloon were used, later pre-mounted stents of 9, 13, 16 sion depends largely on the lesion location and the origin and 18 mm lengths were used. of the side-branch in relation to the primary lesion in the Table 1 gives the clinical characteristics of the patients: main vessel. We classied bifurcation lesions into four 46% had unstable angina: 89% of patients were male with Types and Type 2 is further divided depending upon the a mean age of 59 (6 10) years. All patients received side-branch involvement (Figure 1). 6000–12000 units of heparin for a target ACT of > 250 The classication adopted here is a modication of the seconds, 300mg aspirin and clopidrogel 75 mg once daily. classication proposed by Lefevre et al12 except that it does Those patients not on clopidrogel already were com- not include ostial lesions of the individual branches. menced on 300mg loading dose followed by 75 mg daily. All patients had cardiac enzymes and electrocardiogram checked 6–8 hours after the procedure and the next day. Twenty-six out of 28 patients were discharged the follow- Use of R™ stent in the percutaneous coronary intervention of coronary bifurcation lesions 175

Number (%) 28 (100%) Left main stem 2 Male 25 (89%) – Unprotected 1 Mean age 59 (42–76 years) – Protected 1 Unstable angina 13 (46%) LAD / D1 17 Previous MI 10 (38%) RCA / PDA 4 Diabetic 10 (36%) Circumex / OM 5 Hypertension 11 (39%) Smoking 14 (50%) Table 3 Previous CABG 03 (11%) Target vessel.

Table 1 Bifurcation stenting: patient characteristics.

Type 1 11 Type 2 12 Double kissing balloon 27 Type 3 2 Side-branch stents 18 Type 4 3 Side-branch PTCA only 9 Number of R™ stents 34 Table 4 Other stents 16 Lesion classication (bifurcation type). ReoPro 9 7 French Guide 25 6 French Guide 3 vessel was stented rst. The side-branch was then entered through the struts of the main vessel stent and after Table 2 balloon angioplasty, through the stent struts; a stent was Procedure details. placed if necessary. Side-branch stenting can be accomplished with any low prole stent. Our choice here is S 670™ stent (Medtronic AVE, Galway, Ireland), Carbo ing day. The procedure was accomplished using 6 or 7 Medic™ stent (Sorin Biomedic, Italy), R™ stent mounted on French Guide Catheter. Procedure details are shown in a low prole balloon like Maxum™ (Boston Table 2. Scientic/Sciemed, Galway, Ireland) or recently introduced Talos™ and Evolution™ (Orbis Technologies, Netherlands) stent delivery system. Technique of stent deployment Final kissing balloon dilatation is an important step in the treatment of bifurcation lesions. Stent conformability LAD/Diagonal was the target lesion in the majority of is maintained with simultaneous dilatation of both patients (Table 3). Thirty-four R™ stents and 16 other vessels. Other approaches that have recently been stents were used. In our series, the majority of patients had described include the Y technique, a T technique, the either Type 1 or Type 2A/Type 2B lesions (Table 4). Stent- ‘culotte’ technique and double or triple wire technique.15–19 ing of the side-branch was done in 18 patients and 9 had In the last technique, two guide wires are placed in the balloon angioplasty. One other patient with a Type 3 main vessel and the side-branch and kissing balloon lesion did not require kissing balloon for side-branch dilatation is performed rst. The stent is then placed in the dilatation. Double (kissing) balloon ination (Figure 2) main vessel with entrapment of the side-branch wire. The was carried out in 27 patients. Nine patients received main vessel wire is then withdrawn and reintroduced abciximab (ReoPro, Eli Lilly & Co) for complex vessel through the stent into the side-branch or a third wire is morphology, intra-coronary thrombus, complex and dif- used to enter the side-branch while keeping the entrapped cult procedure or unstable symptoms. wire in place and once the third wire is in the side-branch, Lesions involving a side-branch of greater than 2 mm in the trapped wire is removed. The struts are dilated with the diameter by visual assessment were considered a bifurca- dilatation of the side-branch and if necessary a stent is tion lesion requiring treatment. The angulation of the placed in the side-branch. The modication of this tech- bifurcation was also taken into account as this is an impor- nique that we use, is to keep a balloon in the main vessel tant factor and may inuence the nal outcome of the pro- so that the struts of the side-branch stent do not protrude cedure.12 The risk of ‘snow plowing’ seems to be higher in into the main branch during deployment of the stent in certain types of lesion especially T type lesions where a the side-branch. This technique was used in the majority side-branch is arising perpendicular to the main vessel. of patients. With the greater ease of reintroducing the wire Our main strategy of stenting was to use double wire through the struts of the R™ stent, leaving the wire trapped and dilatation of both branches and main vessel in Type 1 outside the stent is not necessary in every case. T stenting and Type 2 lesions. In the T-junction type of side-branch was carried out in 5 patients and consisted of side-branch (5 patients), the side-branch was stented rst, followed by stenting rst, followed by main vessel stenting. Three the main vessel (Figure 3), while in other cases the main patients had inverted V stenting for Type 4 lesions. Nine 176 MM Khan, VS Mahadevan, VP Moohan and SW Webb

other patients had stenting of the parent vessel followed by side-branch stenting through the rst stent. Final kissing balloon dilatation was done in 27 of the 28 patients (Figure 4). Foreshortening of the stent was noted in two cases following high-pressure balloon dilatation, requiring further short stent deployment to optimize the angiographic result.

Results The results are summarised in Table 5. The procedure was successful in all patients with TIMI grade 3 ow. Success was dened as angiographic evidence of successful dilatation with <50% residual stenosis without death, acute closure, Q-wave MI or need for CABG during hospital stay. Two patients had a non-Q-wave myocardial infarction as (A) suggested by greater than three times the cardiac enzymes. There were no major cardiac events at 30 days. All patients completed a minimum of 3 months follow up. During the follow-up of 3–23 months (mean 11.8) angiographic restenosis was noted in four patients. Eighteen patients had repeat angiography either for other vessel PCI, recurrence of symptoms, or positive Exercise Stress Test. Two patients had repeat percutaneous intervention. One had bypass graft surgery. The other patient had reocclusion of the diagonal branch, which previously had balloon dilatation. There was no mortality during the follow-up period.

Discussion Intra-coronary stent implantation across side-branch is associated with the increased risk of side-branch occlusion (B) or loss and restriction of future access to the side-branch. These considerations have therefore limited their use in bifurcation lesions. Previous studies of stenting across bifurcation lesions are limited to a few case reports. The choice of stent for bifurcation lesions depends upon good lesion and wall coverage and easy access to the side- branch. It is important to maintain the shape of the stent during side-branch dilatation. The R™ stent is a new 316 stainless steel tubular coronary stent uniquely designed to provide maximum exibility, tractability and radial

Follow-up 3–23 months (11.8) Success 28 (100%) Non-Q-wave MI 2 (7%) Re-angiogram 18 (64%) Target lesion restenosis 4 (22%) Repeat PTCA 2 (7%) (C) Bypass surgery 1 (3.6%) Figure 2 (A) Bifurcation lesion Type 1 before intervention (B) Final double balloon Table 5 angioplasty with stents in the main vessel and side-branch (C) Final result. Results/Outcome. Use of R™ stent in the percutaneous coronary intervention of coronary bifurcation lesions 177

(A) (B)

Figure 3 (A) Pre- and nal kissing balloon of the bifurcation lesion of the LAD and diagonal (B) Pre- & post-stenting of the LAD and diagonal. strength on deployment.20,21 It also facilitates PCI of bifur- experience of treating side-branches within stented cation lesion by virtue of large cell size for side-branch segment, there has been an enhanced interest in develop- access. No ‘sh scaling’ or plaque prolapse is observed ing a practical approach for stenting both the main vessel after deployment over tortuous curving vessels. It has been and a large side-branch of a true bifurcation lesion. observed that tubular stents behave better than non- Colombo et al reported a ‘kissing stent’ technique, but tubular stents for bifurcation lesions, particularly if contact of the two stents impeded full endothelialisation balloon dilatation is needed for side-branch lesion of struts proximal to the bifurcation at its carena with a (Figure 4). possibility of stent thrombosis in this segment.16 One The optimal management strategy for bifurcation approach to this problem is to position a stent in the lesions has remained unresolved. Few recent studies ostium of the side-branch followed by placement of a describe larger experience.12,22–24 With increasing second stent in the main vessel spanning the origin of the 178 MM Khan, VS Mahadevan, VP Moohan and SW Webb

(A) (B)

Figure 4 (A) Severe disease of RCA Type 2A lesion (B) Double wire to enter both branches (C) Final double balloon after stent placement in PDA (D) Final result. side-branch. Placement of such T stent may need dilata- vessel only, spanning the ostium of the side-branch and tion into the side-branch to improve the strut orientation dilating the side-branch through the struts of the stent. In overlaying the ostium and thus minimizing subsequent our study, an attempt was made to stent both vessels if difculties in treating late restenosis of the bifurcation. there was any compromise to the ow. In one third of our This technique may also leave an unstented gap within the patients stenting of the side-branch was not done and the bifurcation or cause protrusion of the stent into the main follow-up of these patients did not show any worse prog- vessel. The potential risk is the inability to cross the rst nosis. Others have also suggested that the treatment of true stent. The other simple approach is to stent the main bifurcation lesion with stents in both vessels may not offer Use of R™ stent in the percutaneous coronary intervention of coronary bifurcation lesions 179

an advantage over stenting of one vessel and balloon sis of 22%. The incidence of death, myocardial infarction angioplasty/ atherectomy of the other. The stenting for and need for CABG are lower than average for this cohort both parent vessel and side-branch was done only if there at a mean follow-up of 11.8 months. They also show that was dissection resulting in reduced or compromised blood the R™ stent, because of its unique design and remarkable ow in the side-branch or inadequate dilatation of side- ability to adapt to the shape and complex coronary artery branch lesion. Direct stenting without predilatation is pos- morphology appears to be a suitable stent for bifurcation sible but results in signicant plaque shift; we therefore, lesion. 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