Percutaneous coronary angioscopic comparison of thrombus formation during percutaneous coronary angioplasty with ionic and nonionic low osmolality contrast media in unstable angina.

Patients with unstable coronary syndromes are more likely to have a lesion containing thrombus and have a higher procedural complication and restenosis rate. The aim of this study was to evaluate the effect of an ionic (ioxaglate) and a nonionic (iohexol) low osmolality contrast media on thrombus generation using percutaneous intracoronary angioscopy in patients with unstable angina undergoing percutaneous transluminal coronary angioplasty (PTCA). Thirty patients with unstable angina pectoris randomized to either ioxaglate or iohexol (15 patients in each group), underwent percutaneous intracoronary angioscopy before and after PTCA and 15 minutes after PTCA. Angioscopically visible thrombus was defined using the Ermenonville classification and the lesion divided into 3 zones-proximal, mid, and distal. Angiographic filling defects were seen in 3 patients before PTCA, and in 10 after PTCA. Angioscopically visible thrombus was seen in 10 patients before PTCA in the ioxaglate group and 8 in the iohexol group. After PTCA 5 patients (33.3%) in the ioxaglate and 11 (73.6%) in the iohexol group developed new thrombus, p = 0.028. Total thrombi before PTCA were 16 versus 13, after PTCA 25 versus 27, and at 15 minutes after PTCA 23 versus 25, ioxaglate versus iohexol respectively, p = NS. There was no correlation between type or extent of intimal dissection and angioscopically visible new thrombus formation. Angiography underestimated the incidence of intracoronary thrombus before and after PTCA. Nonionic low osmolality contrast medium was associated with significantly more patients developing angioscopically visible new thrombus. This has clinical implications in the choice of contrast medium used in PTCA, particularly in the setting of unstable angina.