QUANTITATIVE ASSESSMENT WITH INTRACORONARY ULTRASOUND OF THE MECHANISMS OF RESTENOSIS AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY AND DIRECTIONAL CORONARY ATHERECTOMY

The mechanisms of immediate and late changes after percutaneous transl uminal coronary angioplasty (PTCA) and directional coronary atherectom y (DCA) were assessed by serial ultrasound imaging in 18 patients trea ted with PTCA and 16 treated with DCA before, immediately after, and 6 months after coronary interventions, A reduction in plaque area was t he main operative mechanism of DCA, explaining 66% of lumen enlargemen t, In the PTCA group the increase in lumen area was the result of a mo re balanced combination of plaque reduction (52% of lumen increase) an d increase in total lumen area (48%); p < 0.05 versus DCA. In the PTCA group, this last mechanism was prevalent (p < 0.05) in the lesions sh owing wall fracture or dissection after treatment and in the lesions w ith a mixed or calcific composition, In the PTCA group, concentric les ions showed a greater plaque compression than eccentric lesions (p < 0 .02). plaque increase was responsible for 92% and 32% of the late lume n loss after DCA and after PTCA, respectively (p < 0.05). In PTCA pati ents, a chronic reduction in total vessel area was the main operative mechanism of lumen reduction (67%) and was prevalent in lesions with a mixed or calcific composition (p < 0.05).