Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

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

ACP J Club. 1994 Jan-Feb;120:5. doi:10.7326/ACPJC-1994-120-1-005


Source Citation

Adelman AG, Cohen EA, Kimball BP, et al. A comparison of directional atherectomy with balloon angioplasty for lesions of the left anterior descending coronary artery. N Engl J Med. 1993 Jul 22;329:228-33.


Abstract

Objective

To compare the efficacy and safety of directional atherectomy with balloon angioplasty for patients with lesions of the left anterior descending coronary artery.

Design

Randomized, single-blind, controlled trial with median follow-up of 6 months.

Setting

9 hospitals in Canada.

Patients

Patients with angina or objective evidence of myocardial ischemia and stenosis of ≥ 60% in the proximal third of the left anterior descending coronary artery that was suitable for either procedure. Exclusion criteria were restenosis lesions, lesion > 10 mm, involvement of the ostium or a branch vessel ≥ 2.5 mm in diameter, total vessel occlusion, vessel size < 3 mm, heavy calcification or severe tortuosity, stenosis of the left main coronary artery > 25%, myocardial infarction (MI) in the previous week, severe left ventricular dysfunction, cardiogenic shock, or potential difficulties with follow-up. 274 patients (mean age 56 y, 84% men) were studied. Follow-up was 97%.

Intervention

Patients received aspirin, calcium channel blockers, and nitrates from ≥ 12 hours before to 24 hours after the procedure. Intracoronary nitroglycerine and heparin were given during the procedure. 138 patients were assigned to atherectomy. Any approved balloon-dilation system could be used (n = 136) to achieve optimal results.

Main outcome measures

Angiography-proven stenosis of ≤ 50%, major complications (death, MI, or bypass surgery), or other complications (abrupt vessel closure or vascular injury).

Main results

15 patients assigned to atherectomy did not have the procedure done and 5 patients assigned to angioplasty had alternative procedures (3 atherectomies and 2 stents). Atherectomy took longer (92 vs 70 min, P < 0.001) but showed a trend toward a higher rate of procedural success than angioplasty (94% vs 88%, P = 0.06) and better postprocedural angiographic results (minimum luminal diameter 2.3 vs 2.1 mm, P < 0.001). The groups did not differ for restenosis or minimum luminal diameter at 6 months, rate of in-hospital complications, or 6-month clinical outcomes.

Conclusion

When compared with angioplasty for lesions of the proximal left anterior descending artery, atherectomy resulted in better postprocedural luminal dimensions with a similar in-hospital complication rate; however, atherectomy took longer, and no differences between the procedures were seen in 6-month restenosis rates, luminal dimensions, and clinical outcomes.

Sources of funding: Medical Research Council of Canada; Devices for Vascular Intervention; Advanced Cardiovascular Systems.

For article reprint: Dr. A.G. Adelman, Cardiovascular Clinical Research Laboratory, Mount Sinai Hospital, 1609-600 University Avenue, Toronto, Ontario M5G 1X5, Canada. FAX 416-586-8413


Commentary

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 in coronary artery disease

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