Risk of clot formation with ionic and nonionic contrast media in cerebral angiography

Rationale and Objectives. The introduction of low-osmolality contrast media has improved patient tolerance to angiographic procedures, How ever, nonionic contrast media map be associated with an increase in the risk of clot formation. The objective of this study was to test whether there is more clotting with nonionic agents than with ionic agents. Methods. Ninety-eight patients undergoing transfemoral cerebral angiography were randomly assigned to receive ionic (ioxaglate) (n = 62) or nonionic (iopamidol or iohexol) (n = 36) contrast material, Incidence of clot formation was examined by observation of catheters. Results. Clot formation was found in 4.8% of patients in the ionic contrast material group and 22.2% of patients in the nonionic contrast material group (P < .05). Conclusion. Nonionic contrast media resulted in a statistically significantly higher incidence of clot formation than ionic media during cerebral catheter angiography. These results suggest that ionic contrast media are preferable in patients with risk of thrombosis.