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Sirolimus-eluting Stents for the Treatment of Atherosclerotic Ostial Lesions
January 2005
Ostial atherosclerotic lesions constitute a distinct substrate for percutaneous interventions, as they differ from the other lesion sites in management strategies and in clinical outcomes. Since the lesions are more likely fibrotic and calcific, lesion modification techniques are often required prior to stent implantation to achieve a good luminal area after stenting. High-pressure dilatation and debulking techniques such as atherectomy, rotablation and cutting balloon angioplasty1 are sometimes used to modify the lesion morphology. As coronary stenting has shown to improve the early outcome in ostial lesions2,3 that were traditionally considered best suitable for coronary artery by pass grafting (CABG), more and more ostial lesion susbsets are being treated with percutaneous methods. Major randomized trials that evaluated the outcome of stenting versus balloon angioplasty excluded ostial lesions for various reasons.4,5 Restenosis following bare stent implantation is higher in ostial lesions as compared to other sites.6 Drug-eluting stents (DES) have been shown to reduce the incidence of restenosis but this lesion location was not included in any trial.7,8,9 The present study aims to evaluate the efficacy of sirolimus-eluting stents (SES) in ostial esions.
Materials and Methods
Study population. SES (Cypher; Johnson & Johnson Cordis Unit, Cordis Europa NV, Roden, The Netherlands) has been utilized in all coronary interventions as a device of choice in our institute from April 2002 to March 2003. Consecutive patients with all anatomical and clinical situations were considered eligible, thus representing a “real world” interventional cardiology cohort. The present study comprised of 50 patients treated with SES for atherosclerotic ostial disease of the right coronary artery (RCA), left main coronary artery (LMCA), aorto-ostial lesions of saphenous venous graft (SVG), left anterior descending artery ostium (LAD) and left circumflex artery ostium (LCX).
Methods
The study methodology has been described elsewhere.10 Angioplasty and stent implantation were performed according to the standard protocol. SESs were available in diameters of 2.25, 2.50, 2.75, and 3.00 mm. Utilization of adjunctive devices like atherectomy, rotablation and GP IIb/IIIa antagonists were left to the operatorís discretion according to the clinical situation. Post-intervention antiplatelet regimen included lifelong asprin and clopidogrel for 3 months unless any of the following situations was present: LMCA stenting, in-stent restenosis intervention, more than 3 stents, total stented length more than 36 mm and bifurcation stenting. Clopidogrel was continued for 6 months in the above mentioned situations. All patients were followed up prospectively for major adverse cardiac events (all-cause death, myocardial infarction (MI), target vessel and target lesion revascularization). All deaths were considered cardiac unless proved otherwise. MI was diagnosed by an increase in the creatine kinase level to more than twice the normal limit with an increased MB fraction. Target lesion revascularization (TLR) was defined as any re-intervention to treat a stenosis within the stent or in the 5 mm distal or proximal segments adjacent to the stent. TLR was defined as any reintervention driven by other lesions located in the same epicardial coronary artery.
Statistical analysis. Continuous variables were presented as mean ± standard deviation and categorical variables were presented as counts and percentages. Survival-free of adverse events was estimated using the Kaplan-Meier method.
Results
Baseline characteristics. These 50 patients with ostial lesions constitute 5% of the total population who received drug-eluting stents during the study period. Baseline characteristics are shown in Table 1. The age ranged from 42 to 80 yrs. Clinical indication for treatment was as follows: acute MI in 7 patients (14%), unstable angina in 20 patients (40%) and chronic stable angina in 23 patients (46%). Among the 15 patients with previous percutaneous intervention one patient received SES for instent restenosis in the right coronary ostium and the remaining patients were treated for de novo lesions. In patients with previous CABG, aorto-SVG ostial lesions were stented in 4 cases and the rest had native vessel intervention, including 2 LMCA lesions. Half of the lesions were in the left anterior descending artery ostium, followed by the right coronary ostium (30%). Lesion modification strategies were adopted in 12% of patients as per the operatorís discretion. Half of the lesions were predilated including the use of cutting balloons in 2 patients; 30% of the stents required post dilatation with larger diameter balloon. The mean maximum dilatation pressure was 17.4 ± 3.3 atmospheres. GP IIb/III antagonists were used in 10 patients (20%).
Immediate and late follow-up. Complete follow-up data were available for a period of 414.5 ± 54.9 days. The event-free survival rate was 90% at one year. There were 3 myocardial infarctions (MI) during the entire follow-up, of which 2 were non-Q-wave MIs. In both cases, the event was due to side branch occlusion/dissection at a non-ostial site during the procedure. The third MI occurred 6 months after discharge and coronary angiography performed on the basis of recurrent symptoms showed a completely occluded graft at the proximal stent. This patient received 4 SES in the SVG graft during the index procedure. The TVR and TLR rates were 10% (5 patients) and 8% (4 patients). One of the patients who required TLR showed geographical miss of the ostium of the RCA on IVUS assessment. Other repeat lesion revascularizations were required for 1 LCX, 1 LAD and 1 aorto-SVG ostium. There was 1 death during the follow-up period. Figure 1 shows the event-free survival rate.
Discussion
A high technical success rate can be achieved in ostial lesions with the advent of new techniques which include atherectomy, rotablation and cutting balloon followed by stent implantation. In spite of this, long-term outcome is hampered by restenosis which is higher in this location compared to other sites.3,11 Stenting of ostial lesion in the LAD was associated with better event-free survival and less TLR (10.5%) compared to directional atherectomy alone (50%).12 Palmaz-Schatz stents in this location have improved clinical success rates and was associated with 22% of angiographic restenosis.13 In one study, the slotted tube stents were found to have better outcomes compared to coil stents.14 Even though other devices such as polytetrafluoroethelene-covered stents have been shown to improve early outcomes, the incidence of angiographic restenosis and TLR remained unaffected.15 SES have been shown to reduce restenosis, even in complex lesions.16,17 The present study evaluates the efficacy of SES in the treatment of true ostial lesions.vijayTab56303.jpgVijayTab68379.jpgsubendsub**
SES implantations for ostial lesions appears feasible in all clinical situations and is associated with low subsequent TLR.
Study limitation. The main limitation of this study is that it is a non-randomized prospective study involving a small number of patients. Data were presented on the basis of clinical follow-up.
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