The impact of untreated coronary dissections on acute and long-term outcome after intravascular ultrasound guided PTCA

Aim Vessel size adapted PTCA results in the use of larger balloons with an increased incidence of severe vascular dissections. The aim of our trial wa s (a) to evaluate the effect of severe dissections on the acute outcome and (b) to study the natural history of dissections after 1 year. Methods and Results One hundred and seventy-eight patients with 195 lesions underwent v essel size adapted PTCA using intravascular ultrasound. Clinical and angiog raphic I year follow-up was obtained for all patients. Intravascular ultras ound was performed before PTCA to measure the external elastic membrane dia meter at the lesion site so that the balloon size could be adopted (externa l elastic membrane - 10%) and post-interventionally to determine the proced ural success and the incidence of intracoronary dissections. Stent implanta tion was reduced to persistently flow limiting dissections (TIMI I, II). Di ssections were detected by intravascular ultrasound in 128/195 (66%) lesion s (by angiography in 111/195 [58%] lesions) and classified by intravascular ultrasound criteria into four groups: group I: no dissection (67 lesions [ 34%]), group II: mild dissections (21 lesions [11%]), group III: medium dis sections (19 lesions [10%]) and group IV: severe dissections (88 lesions [4 5%]). Because of threatened vessel closure, GPIIb/IIIa antagonists were use d in eight (4.5%) patients and a stent was implanted in two (1.1%) patients . The cumulative event rate after 1 year was 12% and the global angiographi c restenosis rate was 19%. The postinterventional evidence of severe dissec tions was associated with a decrease in clinical events during long-term fo llow up (group I: 13 events [19%] vs group IV: seven events [7%]; P=0.03). This was also true for the occurrence of restenosis which was significantly lower in patients with severe dissections (group I: 19 [28%] lesions vs gr oup IV:10 [11%] lesions. P=0.01). Conclusions According to the theory of 't herapeutic dissections', our data suggest that substantial dissections foll owing PTCA, which do not diminish antegrade blood flow, do not lead to an i ncrease in acute or long-term events. The natural history of vessel injury seems to provide favourable wound healing without increase of restenosis. T hus, stenting for treatment of large dissections without flow limitation do es not seem to be mandatory. (C) 2000 The European Society of Cardiology.