Is a Routine Stent Strategy Superior to POBA?
Abstract & Commentary
Synopsis: Due to the ability of a stent to provide a large lumen diameter and a lower rate of restenosis, it is the preferred approach for patients who met the criteria in this study.
Source: Weaver WD, et al. Lancet 2000;355:2199-2203.
The opus i trial asks the question whether a policy of routine stenting in large, noncomplex lesions in stable coronary disease achieves better results than balloon angioplasty (POBA) with the option of provisional or conditional stenting if POBA is thought to be less optimal. This is a practical study attempting to simulate daily clinical practice. Experienced interventionalists representing 44 centers in the United States and Canada conducted this study. Study design is straightforward. Subjects with a single coronary lesion with more than 70% stenosis, no more than 20 mm in length, and a minimal coronary artery diameter of 3.0 mm were eligible. Exclusion criteria included calcification, more than 45% vessel angle, or ostial stenosis. Multiple stents and abciximab were allowed at the investigator’s discretion, as were most decisions of therapy. All patients were treated with ticlodipine for four weeks as well as aspirin. High-pressure balloon inflations were mandated by protocol for stent placement. The angiographic end point was residual target vessel diameter of stenosis of less than 10%. In the POBA-provisional stent cohort, less than a 20-30% residual was required; otherwise, a stent was used. The original protocol sought to enroll almost 2200 patients; however, enrollment was discontinued after only 19 months after 479 patients were entered due to funding restrictions and a low recruitment rate.
Patient criteria included the following: average age was 60 years, and 75% were male. Half had elevated cholesterol or hypertension, and almost 20% had diabetes. Forty percent had a history of myocardial infarction (MI), half of which were recent. There was a low rate of prior revascularization. Most patients presented with unstable angina. Left ventricular function was well preserved. Sixty-five to 70% of the overall cohort had single-vessel disease, and 20% had double-vessel disease.
Weaver and colleagues were encouraged to use the Palmaz-Schatz stent (77% overall). In the routine stent strategy, individuals received an average of 1.2 stents compared to 0.5 in the optimum POBA group. The initial coronary lesions had a mean 90% stenosis, a reference diameter of 3.3 mm, and a lesion length ranging between 7-15 mm. The primary end point of the study was a composite of MI, target vessel revascularization, bypass surgery, or death within six months. A variety of secondary end points, including cost assessment, were included, as well as a quality-of-life survey. The results demonstrated that routine stenting was superior, resulting in fewer subsequent procedures, and comparable and even slightly lower outpatient and hospital costs at six months, although there were no obvious clinical differences between the two groups at six months. Initial hospital length of stay was comparable between the two groups; initial hospital costs were essentially $1000 greater for routine stenting, but at six months, stent costs were equal to POBA with provisional stenting. Thirty-seven percent of the POBA group received provisional stenting because of coronary dissection or failure to achieve optimal stenosis reductions. Readmission rates were twice greater in the optimum POBA group. However, functional status was similar, without differences in physical limitations, angina frequency, or treatment satisfaction at six months. Nevertheless, the subjects who had a subsequent revascularization procedure had more symptoms and a lower quality of life. Weaver et al conclude that due to the ability of a stent to provide a large lumen diameter and a lower rate of restenosis, it is the preferred approach for patients who meet the criteria in this study.
Weaver et al discuss the difference between their trial and one other published trial, in which 14% of the POBA patients crossed over to stent placement; however, that trial used a postprocedure 30-minute angiogram, whereas in OPUS I, any technique was available to the investigators, of which few were used to assess angiographic outcome other than at the time of the procedure. Weaver et al stress that OPUS I was an effectiveness trial, which deliberately encouraged clinical judgment, giving interventionalists a wide range of options for stent deployment and assessment of results. IVUS, quantitative angiography, or Doppler flow wires were allowed. The latter procedures lengthened the study by an average of 36 minutes. Weaver et al conclude that OPUS I supports the use of routine stenting during POBA, given large vessels, stable patients, the absence of complex arteries, or calcium. Multivessel angioplasty and stenting were not investigated in this trial, nor was the use of IIb/IIIa inhibitors or heparin. Weaver et al recognize that complications from stenting that might accrue after six months would not have been found in this study. Weaver et al believe that OPUS I results are concordant with the widespread use of stenting in the United States for similar patients, which probably approaches 60-70%.
Comment by Jonathan Abrams, MD
This small trial is disappointing in part because of the short duration and the marked reduction in the scheduled enrollment. Nevertheless, the outcomes would appear to speak for themselves, indicating a modest benefit with stenting with respect to repeat procedures. It is odd that the clinical satisfaction ratings were not different between the two groups. At six months, the total number of study end points were 6.1% in the routine stent strategy group (229 patients) and 14.9% in the optimum POBA/provisional stent strategy. The bulk of the differences were related to target vessel revascularization and subsequent revascularization procedures, which were threefold higher in the provisional stent cohort. The effect that both Weaver et al and the patients knew the enrollment strategy had is uncertain, but may have contributed to the benign view that the POBA/provisional stenting patients had regarding their clinical status. Furthermore, there was no subsequent functional testing, although a positive stress test or a recent MI was necessary for entry into this trial. Use of various medications was not provided, and there may be important differences in antianginal use between the cohorts that are important. A comparable French study has just been reported (STENTIM-2) that randomized 211 patients with acute MI to primary POBA with or without Wiktor stent placement. Six-month outcomes, including target lesion revascularization and restenosis rates, were better with routine stent use. One-year eventfree survival and revascularization rates were also improved with stenting (Maillard L, et al. J Am Coll Cardiol 2000;35:1729-1736).
Thus, it seems that the stent is out of the barn, so to speak, in that interventionalists in the United States, as well as in Europe, are now using stents for the majority of angioplasty procedures. Nevertheless, a policy of provisional or conditional stenting does not appear to be unattractive; OPUS I does not provide strong support to abandon this policy among experienced interventionalists who believe that visual angiographic, Doppler, or IVUS assessment of POBA results in the catherization laboratory are sufficient. While the costs of routine stenting at six months were comparable to POBA, it would be of interest to know whether there is an increasing use of IIb/IIIa platelet inhibitors, both at the time of the first intervention and in 37% of individuals in POBA who had subsequent intervention.
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