Mechanical Atherectomy and Thrombectomy

To overcome some of the limitations previously described for conventional PTCA, coronary atherectomy was developed as a method of excising or ablating atherosclerotic tissue by using directional, rotational, and extractional devices. Thrombectomy can be achieved by the installation of intracoronary thrombolytic or by rheolysis.

Directional Coronary Atherectomy

Directional coronary atherectomy (DCA) enlarges the stenotic coronary lumen primarily by cutting and extracting the atherosclerotic tissue, and secondarily via the Dot-tering effect. The catheter is designed with a 9-mm-long cutting window that is open 120° in its cross-sectional dimension. The cutting surface is apposed to atherosclerotic tissue by inflation of a contralateral balloon. Rotation of the catheter at 2500 rpm carves out an arc of tissue, which is then isolated in a storage chamber. Progressive inflation pressures are used to appose the catheter and atheroma, and the catheter's position is serially rotated to face the circumference of lesions.

Whereas initial single-center experiences reported DCA to be a highly effective interventional therapy (17), subsequent randomized-controlled trials of DCA vs conventional PTCA, such as the Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT-I) (18), the Canadian Coronary Atherectomy Trial (CCAT) (19) in native coronary lesions, and CAVEAT-II (20) in saphenous vein graft lesions, did not show a significant reduction in angiographic restenosis rates for DCA, although there was a trend favoring DCA over conventional PTCA in the CAVEAT-I trial (50 vs 57%, p = 0.06) (Table 1). The 1-yr follow-up in CAVEAT-I showed a higher mortality rate in patients treated with DCA than in patients treated with conventional PTCA (2.2 vs 0.6%, p = 0.035), however, these results are confounded by noncardiac deaths (21). Because routine balloon postdilation was discouraged in these trials, the postprocedural residual stenosis was >25%, a value similar to that of conventional PTCA. Indeed, a multivariate analysis of CAVEAT-1 angiographic data showed the postprocedural lumen diameter to be the most significant determinant of angiographic restenosis, regardless of the

Table 1

Results from Randomized Trials Comparing PTCA with DCA

Table 1

Results from Randomized Trials Comparing PTCA with DCA

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