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Therapeutics

Atherectomy led to a greater gain in lumen size than did balloon angioplasty but restenosis rates and clinical events did not differ at 6 months in coronary artery disease

ACP J Club. 1994 Jan-Feb;120:4. doi:10.7326/ACPJC-1994-120-1-004


Source Citation

Topol EJ, Leya F, Pinkerton CA, et al. A comparison of directional atherectomy with coronary angioplasty in patients with coronary artery disease. N Engl J Med. 1993 Jul 22;329:221-7.


Abstract

Objective

To compare clinical outcomes after directional atherectomy and angioplasty for patients with coronary artery disease (CAD).

Design

Randomized controlled trial with 6-month follow-up.

Setting

35 hospitals in the United States and Europe.

Patients

1012 patients (mean age 59 y, 73% men) with symptomatic CAD who were eligible for either atherectomy or angioplasty. Inclusion criteria were angiography-proven diseased native coronary vessels with no previous coronary interventions, stenosis of ≥ 60% on visual assessment, lesion length of 12 mm, and suitability for either a 6-French cutter or larger or for a 3.0-mm balloon or larger. Multivessel CAD was allowed but only a single vessel was designated for study. Angiographic follow-up was 90%.

Intervention

512 patients were allocated to atherectomy and 500 patients to angioplasty. All patients received aspirin, ≥ 160 mg/d for ≥ 1 day; ≥ 1 dose of calcium channel blockers; and heparin as a bolus of 10 000 U with additional boluses to maintain clotting time > 350 seconds during the procedure.

Main outcome measures

Angiography-proven stenosis ≤ 50% 6 months after the procedure. Secondary outcomes were safety (death, emergency bypass surgery, acute myocardial infarction [MI], and abrupt vessel closure), quality of life, and cost.

Main results

17% of patients assigned to atherectomy had angioplasty, and 4% of patients assigned to angioplasty had atherectomy. Nonstudy methods of revascularization were used for 26% of patients assigned to atherectomy and for 14% assigned to angioplasty. Compared with angioplasty, atherectomy had a higher angiography-proven initial success rate (reduction to ≤ 50% stenosis 89% vs 80%, P < 0.001), higher gains in vessel diameter (1.05 vs 0.86 mm, P = 0.035), higher rates of in-hospital MI (6% vs 3%, P = 0.035), higher rates of in-hospital complications (11% vs 5%, P < 0.001), higher mean hospital costs ($11 904 vs $10 637/patient, P = 0.006), and higher rates of MI at 6 months (8% vs 4%, P = 0.04). Patients in the atherectomy group showed a trend toward a lower rate of restenosis at 6 months (50% vs 57%, P = 0.06). At 6 months the groups did not differ for death, bypass surgery, need for other coronary interventions, or adverse clinical outcomes.

Conclusion

Initially, atherectomy resulted in a greater gain in lumen size and a higher initial success rate (reduction to ≤ 50% stenosis) compared with angioplasty, but early complications were higher, costs were increased, and no clinical benefit was apparent at 6 months.

Sources of funding: Devices for Vascular Intervention and Eli Lilly.

For article reprint: Dr. E.J. Topol, Department of Cardiology, Cleveland Clinic Foundation, Desk F25, 9500 Euclid Avenue, Cleveland, OH 44195, USA. FAX 216-445-9595.


Commentary

Atherectomy led to better postprocedural luminal dimensions but was similar to angioplasty for 6-month outcomes in left anterior descending coronary arteries

Coronary atherectomy, endoluminal stenting, and laser angioplasty are alternative interventions to balloon angioplasty (PTCA) for the percutaneous revascularization of obstructive CAD. They were developed because of the persistent unacceptably high restenosis rate (30% to 50%) associated with PTCA. The Coronary Angioplasty versus Excisional Atherectomy Trial (CAVEAT) by Topol and colleagues and the Canadian Coronary Atherectomy Trial (CCAT) by Adelman and colleagues are important because they are the first randomized trials to compare PTCA with an alternative intervention device. In fact, only 2 other randomized trials with PTCA have been reported: the Angioplasty Compared to Medicine (ACME) trial in patients with single-vessel disease and the Randomized Intervention Treatment of Angina (RITA) trial comparing PTCA with bypass graft surgery.

The studies by Topol and Adelman and their colleagues tested the hypothesis that directional coronary atherectomy (DCA) is superior to PTCA in reducing restenosis. Despite initial claims by atherectomy enthusiasts and persistent claims by industry representatives that CAVEAT showed lower restenosis rates with DCA, the published studies clearly show no clinical advantage for DCA as a general primary intervention strategy. The slightly higher success rate and mild angiographic benefit claimed for DCA in CAVEAT are probably explained by the higher crossover rate (17% vs 4%) and the higher use of nonstudy revascularization techniques (26% vs 14%). No differences existed between strategies in these trials in clinical restenosis, exercise test performance, or clinical outcome at 6 months. Patients treated with DCA in CAVEAT actually had more acute and late complications. Moreover, DCA was associated with longer procedure times, longer fluoroscopy times, greater use of radiographic contrast media, and higher cost.

Do these trials disprove the possibility that DCA is superior to PTCA in reducing restenosis? No. It may have been premature to test a new technology with a first-generation device against an established technology used by experienced operators. The coronary atherectomy catheter (Simpson Coronary Atherocath) has subsequently been modified, guiding catheter technology has evolved, and procedural experience has been gained. DCA advocates can claim that the angiographic results showing postprocedure luminal stenoses of 29% and 25% in these studies represent incomplete atherectomy. The current goal with DCA is to achieve a ≤ 10% residual stenosis with larger devices, more aggressive tissue removal, or adjunctive PTCA. The proposed theory to support this strategy suggests that "bigger is better," that greater postprocedure luminal enlargement will produce a larger lumen at 6 months. Contrary to the CAVEAT report, this theory is not supported by the data in these trials but was not fairly tested because the magnitude of the initial differences in the angiographic outcomes for the treatment strategies was smaller than desired. The competing theory, "the greater the gain, the greater the loss," is based on laboratory and clinical studies that show that the development of intimal hyperplasia after vascular trauma is proportional to the depth of arterial injury. A third trial of PTCA and DCA is being organized, the results of which may help resolve this important mechanistic question and help focus future efforts on reducing restenosis rates.

Although PTCA should be the primary percutaneous revascularization strategy for several reasons, DCA has an important role. Bulky or ulcerated lesions in large native arteries or vein grafts are often inadequately dilated with PTCA but seem to respond better to DCA. Likewise, elastic recoil in ostial or eccentric lesions can prevent an optimal result with PTCA but can be successfully approached with DCA. CAVEAT and CCAT did not emphasize these lesions but studied lesions the investigators thought were suitable for either PTCA or DCA.

Eric R. Bates, MD
University of Michigan Medical CenterAnn Arbor, Michigan, USA


Commentary Update

Two subsequent randomized trials have compared DCA with PTCA. The CAVEAT-II Trial showed that DCA in aortocoronary venous bypass grafts was associated with a higher incidence of distal embolization, but no difference existed in restenosis rates (1). However, the 1000-patient Balloon versus Optimal Atherectomy Trial (BOAT) did DCA differently than in CAVEAT and CCAT and achieved superior results (2). Larger devices, more extensive tissue removal, and routine balloon postdilation to obtain a diameter stenosis < 20% (“optimal atherectomy”) resulted in lower acute residual diameter stenosis (15% vs 28%) and lower angiographic restenosis rates (31% vs 40%). Although periprocedural creatine kinase-MB elevations were more common with DCA, there was no increase in death, Q-wave MI, or emergent bypass graft surgery rates. Now that optimal DCA has been shown to offer some advantages compared with PTCA, the procedure has become irrelevant in most interventional cardiology laboratories because of the widespread introduction of endoluminal stenting. Improved stent designs and implantation techniques and the substitution of antiplatelet therapy for anticoagulation therapy make stenting technically easier than DCA with angiographic and clinical outcomes superior to PTCA.


References:

1. CAVEAT-II Investigators. A multicenter, randomized trial of coronary angioplasty versus directional atherectomy for patients with saphenous vein bypass graft lesions. Circulation. 1995;91:1966-74.

2. Baim DS, Cutlip DE, Sharma SK, et al. Final results of the Balloon vs Optimal Atherectomy Trial. Circulation. 1998;97:322-31.