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20-10-2011 | Cardiology | Article

Thrombotic complication rates ‘low’ during pediatric cardiac catheterization


Free abstract

MedWire News: The rates of thrombotic events (TEs) and bleeding complications are low among children undergoing cardiac catheterization (CC), irrespective of whether they are given low- or high-dose unfractionated heparin (UFH) as thromboprophylaxis, Austrian researchers report.

"TEs at the site of vascular access are the most common complication of CC in children," remark Christoph Male (Medical University of Vienna) and colleagues.

However, the true incidence of CC-related TEs is unknown because most studies to date have only used clinical assessment, rather than objective screening by ultrasound, for TE detection.

The optimal dose of UFH for primary prevention of TE during pediatric CC is also unclear, the researchers note.

To address these issues, Male and team randomly assigned 137 children (aged 0-20 years) undergoing CC to receive high-dose UFH (100 units/kg bolus, followed by 20 units/kg per hour continuous infusion) or low-dose UFH (50 units/kg bolus) during the procedure.

A further 90 patients with no consent for randomization received UFH as per standard-of-care (bolus of 50 units/kg for venous access, bolus of 100 units/kg for arterial access) and were followed-up in a parallel cohort study.

The children were assessed for TEs by clinical examination and vascular ultrasound before and within 48 hours after CC. Bleeding events were also monitored.

When the researchers conducted an interim blinded analysis approximately two-thirds of the way through patient recruitment, they observed a much lower than expected overall incidence of TE, at 4.6%.

This prompted them to open the randomization code and perform a group comparison. The comparison revealed no significant difference in TEs between dose arms, at 5% among patients randomized to the high-dose group versus 3% in the low-dose group.

Consequently, the study was stopped early due to futility.

Regarding side effects, the overall incidence of bleeding events was 6.6%, which, in all but one case, were considered minor and subsided after applying local pressure. Again there was no difference between the high- and low-dose groups, at 7% versus 12%.

Of note, there were also no between-group differences in outcome when the randomized participants were combined with those in the cohort study.

"Although the study was not designed as a non-inferiority study and lacks power due to low event rates, the results suggest that a low UFH dose of 50 units/kg is usually sufficient for prevention of TE at puncture site in pediatric CC," conclude Male and co-authors in the Journal of Thrombosis and Haemostasis.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Laura Dean

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