PCI vs. CABG for Multivessel CAD
Abstract & Commentary
Synopsis: In a group of multivessel disease patients, percutaneous coronary intervention resulted in better survival and freedom from MI than did coronary artery bypass graft surgery.
Source: Rodriguez A, et al. J Am Coll Cardiol 2001;37:51-58.
Eraci II (estudio randomisado argentino cirugia angioplastia II) is a randomized, multicenter trial comparing percutaneous coronary intervention (PCI) to coronary artery bypass graft (CABG) surgery for revascularization in patients with multivessel coronary artery disease (CAD). The study was performed at seven centers in Argentina and enrolled patients between 1996 and 1998. Patients were eligible if they had severe angina (CCS class III or IV, unstable or postinfarction angina) despite "maximal" medical therapy, or a large area (> 2 vascular distributions) of myocardium at risk by perfusion imaging. Angiographic entry criteria included: two-vessel disease (one vessel with > 70% stenosis, remainder with > 50% stenosis) with significant lesions being amenable to either PCI (> 3 mm vessel) or CABG, and when functional revascularization was felt to be achievable by either as surgical or a PCI-based strategy.
The primary end point was the composite of death, nonfatal Q-wave MI, stroke, or need for repeat revascularization at 30 days. Additional follow-up at one, three, and five years was planned. Secondary end points included angina status and completeness of revascularization, assessed anatomically (by angiography or intraoperatively), as well as functionally (by perfusion imaging within 30 days), and cost.
A total of 5619 patients undergoing diagnostic catheterization were screened; of these, 1076 met entry criteria and 450 were ultimately randomized. The remaining eligible patients were not randomized due to patient or physician preference. A total of 225 patients were randomized to PCI and 225 were randomized to CABG. There were no significant differences in baseline clinical or angiographic characteristics between the groups. PCI patients received ASA, ticlopidine, and periprocedural heparin. Twenty-eight percent received abciximab and 315 Gianturco-Roubin II (GR-II) stents were implanted. There was a 92% success rate in planned vessels treated (chronic total occlusion were generally not treated), resulting in an angiographically complete revascularization rate of 50%. There were no periprocedural deaths in the PCI group and only three patients crossed over to CABG (all nonemergent) in the in-hospital phase of follow-up. Patients randomized to CABG using arterial or reversed saphenous vein conduits with standard surgical techniques, result in an anatomically complete revascularization rate of 85%. There were three perioperative deaths and 16 patients randomized to CABG that crossed over to early PCI.
The composite end point (death, Q-wave MI, stroke or need for repeat revascularization at 30 days) occurred in 3.6% of PCI patients vs. 12.3% of CABG patients (P = 0.002). This included significantly lower rates of death (0.9% vs 5.7%; P < 0.013) and Q-wave MI (0.9% vs 5.7%; P < 0.013) for patients randomized to PCI. Rodriguez and colleagues note that mortality was highest in patients with unstable angina, particularly those with Braunwald class III or C.
There were no differences between the groups with respect to "functionally" complete revascularization as assessed by perfusion imaging within 30 days. Late clinical follow-up at 18.5 ± 6.4 months (9-33 months) showed that PCI patients had persistently better survival (96.9% vs 92.5%; P < 0.017), as well as survival free from Q-wave MI (97.7% vs 93.7%; P < 0.017). However, as in previously published studies, patients undergoing CABG had higher rates of freedom from angina (92% vs 84.5%; P = 0.01) and freedom from repeat revascularization (95.2% vs 83.2%; P < 0.001) with 11 PCI patients (4.8%) crossing over to undergo CABG. Economic analysis revealed no differences in cost at one year. Rodriguez et al concluded that in this high-risk group of multivessel disease patients, PCI resulted in better survival and freedom from MI than did CABG.
Comment by Sarah M. Vernon, MD
The efficacy of PCI vs. CABG for revascularization of patients with multivessel CAD has been evaluated in several large randomized clinical trials, most of which were conducted and published in the early to mid-1990s. All of these trials demonstrated equivalent safety and survival (with the exception of diabetic patients in BARI), but there were higher rates of recurrent angina and repeat revascularization in patients treated with PCI than in those receiving CABG. As a whole, these studies evaluated highly selected patient populations with relatively stable clinical syndromes, low-risk baseline characteristics, and with a predominance of two-vessel coronary disease. These studies were performed before the widespread use of glycoprotein IIb-IIIa inhibitors and coronary stents, which have been shown to reduce acute complications and restenosis rates in contemporary PCI procedures. In addition, surgical techniques and outcomes have also improved over the same time frame. All of these limitations make application of randomized clinical trial data to a given patient in 2001 somewhat problematic.
ERACI-II is the first published study in the "stent era" to compare PCI with CABG for the treatment of patients with multivessel CAD and, therefore, might be expected to be more reflective of current clinical outcomes. However, this study has many significant limitations. ERACI-II included a somewhat higher risk patient population than previously studied, including higher proportions of elderly, unstable angina, and three-vessel disease. However, as in previous studies, this remains a highly selected population (16% of patients screened were enrolled) that excluded many patients who would need to be considered for revascularization in clinical practice. While the PCI procedures included a relatively high rate of stenting, the Gianturco-Roubin II stent used preferentially in this trial, has subsequently been shown to be associated with high rates of restenosis and is, therefore, no longer used in the United States. In addition, the rate of GP IIb-IIIa inhibitor use during PCI (28%), while higher than in earlier published trials, remains significantly lower than most interventional laboratories today. More concerning however, is the relatively high rate of perioperative (5.7%) mortality seen in the patients undergoing CABG. Rodriguez et al attribute this to the higher proportion of high-risk patients included in the study, and indeed subgroup analysis, albeit of a relatively small sample size, suggests that adverse events may have been more common in patients with unstable angina. However, there are other potential contributors such as the longer delay between randomization to treatment in the CABG group. If perioperative mortality had been more in keeping with the majority of previous randomized controlled trails, the advantage for a PCI approach would have been less notable. Lastly, and perhaps most importantly, the choice of a 30-day primary end point may be construed as "stacking the deck" in favor of a percutaneous revascularization strategy. It is well established that surgical revascularization carries an inherently higher "up-front" risk, while the limitations of percutaneous revascularization may not become evident until later, when restenosis becomes clinically manifest. The longer-term "softer" secondary outcomes in this trial, including increased need for repeat revascularization and higher frequency of angina among patients randomized to PCI, are entirely in keeping with previously published studies.
Because of these limitations, the results of ERACI II, while intriguing, do not really demonstrate the superiority of a PCI based strategy or help to guide us in the selection of the most appropriate revascularization strategy in for a given patient. However, there is promise for continued improvement in outcomes of PCI procedures including reduction of acute complications and prevention and treatment of restenosis. Stent design, deployment technique, and adjuvant antiplatelet therapy have continued to improve in the four years since ERACI-II was initiated. This, in combination with more recent advances such as pharmacologically coated stents and brachytherapy, may "raise the bar" again and may ultimately make PCI the preferred strategy for revascularization in a larger number of patients with multivessel disease.
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