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22-04-2012 | Stroke | Article

Contrast agent impact on thrombolysis uncertain


Free abstract

MedWire News: Use of X-ray contrast agents in patients with acute stroke could have a small impact on the efficacy of intravenous thrombolysis, say researchers from the Calgary Stroke Program.

Patients who underwent computed tomography angiography (CTA) before thrombolysis had a nonsignificant 3% reduction in the likelihood for having a favorable outcome. But this rose to 10% in a propensity-matched analysis.

"So overall, our data does not rule out a small magnitude negative biological effect of radio-contrast media," say Imanuel Dzialowski (University of Calgary, Alberta, Canada) and colleagues.

But they caution: "We regard this observation as hypothesis generating and requiring confirmation."

The team identified 111 patients who underwent CTA before thrombolysis and compared their outcomes with 1119 control patients who underwent thrombolysis without CTA in the Canadian Alteplase for Stroke Effectiveness Study (CASES).

Favorable functional outcome, defined as a modified Rankin Scale score of 0-2 at 90 days, occurred in 47.7% and 49.5% of the CTA and control groups, respectively. After accounting for confounders, this equated to a nonsignificant 3% reduction in the likelihood for a favorable outcome if patients underwent CTA.

However, when the researchers matched the CTA patients to controls using a score for the propensity to undergo CTA, patients who underwent the procedure were a significant 10% less likely to have a favorable outcome than those who did not.

On multivariate analysis, undergoing CTA was associated with a 38% reduction in the likelihood for a favorable outcomes, but this was only just statistically significant (p=0.049). Other factors predicted outcomes more strongly; these included age, baseline National Institutes of Health Stroke Scale score, and Alberta Stroke Program Early CT Score (ASPECTS).

"Until additional data are available, the potential diagnostic advantage of performing a CTA in acute stroke patients may outweigh the risks of iodinated contrast agent application," conclude Dzialowski and team.

By Eleanor McDermid

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