Acute complications and restenosis in the first few months after a successful procedure remain the two major limitations of coronary balloon angioplasty. New devices have been developed in order to avoid these limitations. We tested the directional atherectomy catheter clinically and compared the immediate quantitatively analysed results with two other recently developed devices and conventional balloon angioplasty. A gain in luminal diameter of 1.7 mm after atherectomy was observed in 7 patients. This is far more than could be accomplished by balloon angioplasty, stenting and rotablation. Furthermore, the size of the device in relation to the size of the obstructed vessel suggests that a Dotter effect is partly responsible for the gain in luminal diameter. Whether this large gain can prevent restenosis remains to be confirmed. Preliminary literature data suggest that this is not the case.