Comparative analysis of stent placement versus balloon angioplasty in small coronary arteries with long narrowings (the Intracoronary Stenting or Angioplasty for Restenosis Reduction in Small Arteries [ISAR-SMART] Trial)

Abstract

S vessel size and increased lesion length have been identified as important lesion-related predictors for adverse long-term outcome after coronary intervention. In large coronary arteries (e.g., 3 mm) with short lesions (e.g., 15 mm) the BElgian NEtherlands STENT (BENESTENT) study and the STent REStenosis Study (STRESS) have shown that stent placement compared with conventional percutaneous transluminal coronary angioplasty (PTCA) results in both lower restenosis rates and fewer adverse cardiac events. In the Intracoronary Stenting or Angioplasty for Restenosis Reduction in Small Arteries (ISAR-SMART), we investigated the angiographic and clinical outcome of patients treated with conventional PTCA or systematic stent placement in small coronary arteries. In 404 patients randomized to either treatment group the angiographic restenosis rate at 6 months and the 1-year event-free survival rate did not differ between both groups. Patients presenting with the combination of both lesion-related predictors—long lesions in small coronary arteries—represent a patient subset that is most difficult to treat with an acceptable long-term outcome with both interventional methods. Because of the absence of prospective randomized studies in this patient subset, a potential superiority of either treatment is not known. Therefore, in the present study the angiographic and clinical outcomes of a prespecified subgroup of patients in ISAR-SMART with long lesions were investigated. • • • The methods of the ISAR-SMART trial have been described in detail elsewhere. In brief, patients with symptomatic coronary artery disease were randomly treated with PTCA or coronary stenting if the size of the artery to be treated was between 2.0 and 2.8 mm by on-line quantitative coronary angiographic measurements. In the following subgroup analysis, only patients with a lesion length of 15 mm were included. Stent placement and balloon angioplasty were performed according to standard methods to achieve a final diameter stenosis 30% with a Thrombolysis in Myocardial Infarction (TIMI) flow grade 3 at the end of the procedure. The premounted MultiLink stent (Guidant, Advancd Cardiovascular Systems, Inc., Santa Clara, California) was the recommended stent type in this trial. Crossover of patients from the PTCA to the stent group was allowed in the presence of large dissections ( 5 mm) or TIMI flow grade 3 at the end of the PTCA procedure. The quantitative angiographic parameters including minimum lumen diameter (MLD), reference diameter, and percent diameter stenosis were analyzed on preand postprocedural angiograms as well as at follow-up. Acute lumen gain (MLDpost MLDpre), late lumen loss (MLDpost MLDf-u), and net lumen gain (MLDf-u MLDpost) were calculated from the respective MLD values. Loss index was calculated by dividing late lumen loss by acute lumen gain. The primary end point of the study was the angiographic restenosis rate at 6-month follow-up (defined as diameter stenosis 50%). The secondary end points were the adverse clinical events such as allcause death, myocardial infarction, and target vessel revascularization (angioplasty or bypass). Target vessel revascularization was performed in the presence of angiographic restenosis and symptoms or signs of ischemia. Cardiac events were monitored throughout the 12-month follow-up period. The analysis was performed on an intention-to-treat basis and the results are expressed as mean SD or proportions (%). The differences between groups were assessed by the chisquare test or Fisher’s exact test for categorical data and the t or Wilcoxon’s test for continuous data. Statistical significance was accepted for 2-sided p values at 0.05. • • • In the ISAR-SMART trial, a total of 404 patients were enrolled. Twenty-four percent of these patients (n 98) presented with a lesion length of 15 mm and were included in this analysis. Tables 1 and 2 list the clinical and baseline angiographic characteristics of 54 patients assigned to stenting and 44 patients to PTCA. There were no significant differences in baseline characteristics between the 2 study groups. Procedural data are presented in Table 3. Of the 54 patients randomly assigned to stenting, 2 (3.7%) did not receive a stent but were treated successfully with balloon angioplasty. The reason for this crossover was failure to deploy the stent at the target site. In 12 of 44 From the German Heart Center, Munich; and Krankenhaus GarmischPartenkirchen, Garmisch-Partenkirchen, Germany. Dr. Hausleiter’s address is: Deutsches Herzzentrum, Lazarettstrasse 36, 80636 Munchen, Germany. E-mail: hausleiter@dhm.mhn.de. Manuscript received May 29, 2001; revised manuscript received and accepted September 4, 2001.