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Prevention of thrombosis and embolism in children and adolescents with mechanical valve prostheses: warfarin versus antiplatelet agents.

BACKGROUND AND AIM OF THE STUDY
Postoperative thromboembolic complications associated with mechanical valve prosthesis implantation can be reduced with either antiplatelet agents or warfarin. Warfarin been shown to be more effective in adults, but the data are less clear in the pediatric population.


METHODS
Seventy-two children and adolescents who survived mechanical valve implantation on the left side of the heart at the authors' institution were followed prospectively from August 1979 until December 2003. All patients underwent surgery before the age of 20 years, and follow up was included up to the age of 20 years. Initially, 53 patients received warfarin alone; mean follow up was 5.9 years, and total follow up 312 patient-years (pt-yr). Likewise, 19 patients received antiplatelet agents; mean follow up was 5.2 years, and total follow up 99 pt-yr. Results were examined using intent-to-treat analyses.


RESULTS
Age, gender, race, valve size and position, mean time of follow up and crossover rates were not different between groups. No differences were detected in survival or freedom from thromboembolic and hemorrhagic events. Complications associated with warfarin use were substantially more severe than those associated with antiplatelet agents.


CONCLUSION
The study results were inconclusive due to the small numbers of patient-years of follow up, but suggest that antiplatelet agents may be associated with less severe complications than warfarin. Moreover, warfarin and antiplatelet agents may be equally effective for clotting prophylaxis in children after valve replacement with St. Jude Medical prostheses.