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Efficacy of Stenting after Rotational Atherectomy for Ostial LAD and Ostial LCX Stenosis in Patients with Diabetes
January 2005
Coronary interventions of non-aorto ostial stenoses remain a challenging task with a high rate of procedural complications and restenosis. The lack of efficacy of conventional balloon angioplasty in non-aorto ostial coronary intervention has been attributed to the high incidence of vessel recoil, resulting in suboptimal residual stenosis,1 and this leads to a higher restenosis rate as documented in the literature.2 Rotational atherectomy with the Rotablator system (Boston Scientific, Northwest Technology Center, Redmond, Washington) has been previously reported to be effective in treating ostial stenoses, but the restenosis rates are less than acceptable.3 Recently, coronary stent implantation has been routinely done during angioplasty to reduce procedural complications and restenosis. Coronary stenting after rotational atherectomy (rotastent) for non-aorto ostial stenoses may be associated with excellent long-term outcomes. It has been well documented that diabetic patients experience excessive intimal hyperplasia after intervention. Also, heat generated by rotational atherectomy is reported to cause tissue damage.4 Therefore, for diabetic patients, long-term outcomes for non-aorto ostial stenoses treated by rotastent are not clear. The aim of this study was to assess long-term outcomes for diabetic patients with non-aorto ostial stenoses who were treated by rotastent.
Materials and Methods
Patients. From September 1997 through October 2002, 70 patients with single de novo coronary non-aorto ostial stenosis who underwent successful elective stenting after rotational atherectomy (rotastent) at our institution, were the subjects of this study. These patients were divided into 2 groups: 30 patients with diabetes (male 20 patients, age 67 ± 10 years; DM group) and 40 patients without diabetes (male 29 patients, age 71 ± 7 years; non-DM group). Baseline clinical, angiographic and procedural characteristics, as well as acute and chronic angiographic results, were obtained for all patients.
Procedural technique. Each patient received aspirin (100 mg daily) and ticlopidine (200 mg daily) prior to rotational atherectomy. All patients were given 10,000 units of heparin before the procedure to achieve an activated clotting time of >= 250 seconds. Patients who received coronary stents were administered ticlopidine (200 mg) and aspirin (200 mg) for at least 1 month. The ablation technique was performed using a repetitive pecking motion of the burr, increasing the burr size by not more than 0.5-mm increments, with the goal of achieving a final burr-to-artery ratio of 0.70 based on visual estimates. Platform speeds were generally 170,000 rotations per minute for 2-mm burrs and smaller, and 160,000 rpm for 2.15-mm burrs and larger. Care was taken to avoid a decrease in rpm greater than 5,000 during each Rotablator run; shorter runs of not more than a 10-second duration were used to minimize slow flow. Lesions were pre-dilated after rotablation, followed by stent implantation using balloon inflation pressures of 12–18 atm until a satisfactory angiographic result was obtained. The Multi Link (Guidant, Santa Clara, California), and Nir (Boston Scientific, Scimed) stents were utilized. The proximal stent edge is positioned at the middle point of the balloon marker and there is 0.5 mm between the proximal balloon marker edge and the proximal stent edge for these 2 stents. Prior to stent deployment, the proximal balloon marker edge was positined at the vessel ostium. The stent deployment technique was meticulous to ensure that the ostium of the vessel was covered.
Quantitative coronary angiography (QCA). All pre- and post-procedures and follow-up angiography were conducted immediately after administration of intracoronary nitroglycerin. Angiography was performed so that each lesion was viewed from at least 2 angles. Offline QCA was conducted utilizing the view revealing the highest degree of stenosis. Calculations were made using the Cardiovascular Measurement System (CMS, MEDIS; Medical Imaging Systems, Nuenen, the Netherlands) by an experienced angiographer who was not involved in the ablation procedure and was unaware of the purpose of this study. The angiographically normal-appearing distal segment adjacent to the stenotic lesion was used as the reference diameter. Reference vessel diameter, minimal luminal diameter (MLD) and lesion length of pre-intervention, post-intervention and follow-up were measured.
Definitions. Patients were classified as having diabetes if they were taking insulin or oral hypoglycemic agents, or on the basis of elevated levels (140 mg/dl) of fasting blood glucose. An ostial lesion was defined as >= 75% stensosis within 3 mm from the ostium of the left anterior descending coronary artery (LAD) or the left circumflex coronary artery (LCX).2,5 Patients with left main artery disease or both LAD and LCX ostium disease were excluded. The lesion type was classified according to the modified American College of Cardiology/American Heart Association classification.6 Vessel calcification, identified as radiopacities without cardiac motion, was noted prior to contrast media injection. Angiographic success was defined as residual diameter stenosis /= 75%) (or LAD in case of LCX stenting) after the procedure at follow-up angiography.
Statistical analysis. Statistical analysis was performed using Statview version 5.0 (Abacus Concepts, Inc., Berkeley, California). All continuous variables are expressed as mean ± SD and categorical variables as percentages. Comparisons between groups were performed using the chi-squared test to analyze differences in categorical variables, and Student’s unpaired t-test for continuous variables. A p-value Clinical characteristics and angiographic findings (Table 1). The mean age of the DM group tended to be younger than that of the non-DM group. The degree of male gender preponderance was similar in the 2 groups. The proportion of patients with prior myocardial infarction, hypertension and hypercholesterolemia was similar in the 2 groups. There was no significant difference in frequency of multi-vessel disease or lesion location. In terms of lesion morphology, both groups had a large number of B2 lesions, followed by C lesions. There was no difference in the number of calcified lesions.
Procedural results and angiographic follow-up (Table 2). Patients with diabetes had a trend toward having smaller reference vessel diameter (2.76 ± 0.55 versus 3.00 ± 0.50; p = 0.07) and MLD post-procedure (2.72 ± 0.59 versus 2.96 ± 0.49; p = 0.06) than patients without diabetes. There was no significant difference between the 2 groups in lesion length. Burr-to-artery ratio, balloon-to-artery ratio, number of burrs, and maximum inflation pressure used were similar in the 2 groups. Angiographic follow-up was performed at a mean of 5.2 ± 1.9 months after coronary stenting in all patients. Late loss was significantly larger for the patients with diabetes compared to patients without diabetes. The restenosis rate for the patients with diabetes was 53% and the patients without diabetes 28%, which is a significant difference (p Multivariate analysis (Tables 3,4). Logistic regression analysis was used to identify the independent predictors of restenosis and lesion progression after rotastent for non-aorto ostial lesions. Diabetes mellitus was found to predict restenosis (OR = 3.168, p = 0.0456) and lesion progression (OR = 7.318; p = 0.0446) after rotastenting.
Discussion
The treatment of ostial stenosis of the left anterior descending coronary artery (LAD) continues to present difficult challenges to interventional cardiology, as evidenced by the various approaches that are currently being used for its treatment.1,2,7 These lesions remain the only discrete coronary stenoses often referred to surgery, even in patients with single vessel disease. Some reports in the literature suggest that debulking (directional atherectomy or rotational atherectomy) with or without stenting is the preferred approach in the treatment of non-aorto ostial coronary lesions due to the poor short- and long-term outcomes with plain balloon angioplasty.3,8 Previous studies with rotational atherectomy for non-aorto ostial coronary lesions have demonstrated its safety and high clinical success rate.3,8 However, the angiographic restenosis rate for non-aorto ostial lesions using rotational atherectomy was reported to be as high as 39%,3 and the long-term outcomes remain highly disappointing. Therefore, rotational atherectomy should only be considered as a preliminary treatment to be followed by stent implantation in these lesions. Tan et al. have also reported9 that the use of rotational atherectomy before stent implantation clearly reduced the risk of side branch narrowing and side branch intervention in the management of non-aorto ostial lesions. They concluded that stenting with rotational atherectomy was associated with the best long-term outcome (target lesion revascularization rate of 12%). This study demonstrated that the angiographic restenosis rate after rotastent therapy for non-aorto ostial lesions in patients with diabetes was 53% and lesion progression, which meant new left main narrowing or ostial LCX narrowing (or ostial LAD narrowing in case of LCX stenting) after rotastent, was significantly higher in patients with diabetes compared to non-diabetic patients (23% versus 5%; p 10 and subsequent cardiac events thus requiring additional revascularization procedures.11,12 The exact mechanisms by which diabetes mellitus exerts it deleterious effects are still unresolved. However, there clearly is an aggressive pattern of neointimal proliferation in high-risk patients.13 We previously examined the efficacy of rotational atherectomy for diffuse coronary artery disease and reported that the restenosis rate of patients with diabetes after rotational atherectomy was siginificantly higher than that of patients without diabetes. Furthermore, lesion length between pre-procedure and follow-up angiograms did not shorten as much in the patients with diabetes as those in the patients without diabetes.14 It is reported that rotational atherectomy induces heat injury which can cause tissue damage.4 This effect might induce exaggerated intimal hyperplasia in non-aorto ostial lesions in patients with diabetes after rotastent therapy.
Rotational atherectomy certainly improves immediate success in ostial stenoses, but even if very large burrs are used (2.50 mm) under the best circumstances (final lumen area equal to maximal burr size), the residual plaque burden will be equal to 61% of the total vessel area in a 4.0-mm vessel. Despite this insufficient debulking, these lesions with stenting after rotational atherectomy prove to have good angiographic results. But a large amount of residual plaque burden remains in these lesions. Several intravascular ultrasound imaging (IVUS) studies report that late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation.15,16 Therefore, insufficient debulking and heat injury during rotational atherectomy might be associated with unsatisfactory angiographic outcome after the rotastent procedure for non-aorto ostial lesions in patients with diabetes.
Recently, it is reported that drug-eluting stents have a consistent effect, reducing restenosis rates.17 Degertekin et al. also showed sirolimus-eluting stents are effective in inhibiting neointimal hyperplagia without affecting vessel volume and plaque behind the stent.18 If drug-eluting stenting after rotablation for non-aorto ostial stenosis inhibited in-stent neointimal hyperplasia, the problem of rotastent for non-aorto ostial stenosis in patients with diabetes could be resolved.
Study limitations. The number of patients in this study was relatively small and IVUS was not performed in all patients. Patients with diabetes tended to have smaller reference vessel diameters than non-diabetic patients. However, all patients returned for angiographic studies as a part of a routine follow-up, and 53% of patients with diabetes were found to have angiographic restenosis.
Conclusions. Rotastent therapy gives excellent acute results for non-aorto ostial lesions in diabetic patients. However, patients with diabetes are more likely to have higher rates of restenosis after rotastent therapy for non-aorto ostial lesions and develop new left main narrowing or non-treated artery-ostial narrowing compared to non-diabetic patients.
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