Intravascular ultrasound detected classification of coronary lesions as a predictor of dissections after balloon angioplasty.

Dissection after balloon angioplasty of coronary arteries may give rise to an unfavourable early outcome. Compared with coronary angiography, intravascular ultrasound (IVUS) allows more detailed characterisation of dissections. We investigated the incidence and type of dissections after balloon angioplasty in calcified coronary lesions. IVUS was performed in 43 patients with 48 lesions before and after percutaneous balloon angioplasty. Significant calcification was defined as an arc of more than 90 degrees with typical acoustic shadowing. Dissections were classified as type A when the media was not involved by the dissection and as type B when media involvement had occurred. In the group with significant calcification dissection was observed in 79% of the cases vs 38% in the control group (p < 0.03). Type B dissection was present in 71% of the dissections in the calcified lesions vs. 15% in the control group (p < 0.02). The balloon diameter and the ratio of balloon area to vessel area was not different in both groups but the required pressure for the first complete balloon inflation was significantly greater in the group with calcified lesions (9.46 +/- 3.6 atm vs. 6.65 +/- 2.6 atm; p < 0.001). Thus balloon angioplasty in calcified coronary lesions is more likely to lead to dissection with frequency involve the media.