Twenty-Seven Percent of Children with Congenital Heart Disease Have a Thrombotic Event Detected in the Post Operative Period: A Prospective Cohort Study.

BACKGROUND: Only recently, thromboembolic events have emerged as one of the most serious and frequent secondary complications to occur in children who, with modern therapy, are surviving previously life-threatening diseases. One of the most common primary disorders is congenital heart disease (CHD), accounting for approximately 1/3 of children presenting with thrombosis. However, rigorous determination of the actual prevalence in order to establish how pervasive this newly appreciated thromboembolic disease is in children with CHD is lacking. The current standard of practice in children with CHD is not to use anticoagulants for primary prophylaxis, predominantly because of the lack of firm data on prevalence of thrombosis. The primary objective of the current study was to determine the incidence of thrombosis in children with CHD in the post operative period. The secondary objective was to determine clinical risk factors for thrombosis. STUDY DESIGN. A prospective cohort of non-selected children undergoing surgical intervention for CHD at Stollery Children’s Hospital, Edmonton, Canada. To be eligible for inclusion in the study, children had to be planned to undergo cardiopulmonary bypass and too have a central venous line placed. All patients were screened for thrombosis by ultrasound in either the upper or lower venous system depending on the location of the central venous line and echocardiogram of the heart. Testing was performed on children in the post operative period when the patients were stable and after the central venous line was removed. Clinically significant thrombosis was defined as thrombi greater than 3mm. Demographic data on the cohort where collected prospectively. The study was reviewed by the ethics board and informed consent was obtained from all guardians and/or children. RESULTS: A total of 128 children were recruited, median age 10 months (range 0.23–192) 44% were females and 70% were Caucasian. A total of 63 children (49%) had evidence of a thrombosis, but some of the thrombi were small, non occlusive and considered clinically nonsignificant. However, 34 patients 27% (95% Confidence Interval 19%-35%) had evidence of a thrombotic event with significant occlusion that required therapeutic anticoagulant therapy. Fifty percent of thrombosis was in the right internal jugular reflecting the primary location of the central venous line. Children with clinically significant thrombosis were younger and had more complex underlying cardiac disorders (see table below). CONCLUSION: There is a significant incidence of thrombosis in children with CHD in the post operative period. Younger children and children with complex cardiac disorders are at increased risk. Carefully designed clinical trials of prevention are urgently needed. Risk factors for thrombosis Thrombosis Positive (n=34) Thrombosis negative (n=94) Age (months) 6 (1–168) 28 (0.23–192) UNDERLYING DIAGNOSIS Single Ventrical 35% (n=12) 16%(n=15) Transposition of the great arteries 9% (n=3) 3% (n=3) Tetraology of Fallot 23% (n=8) 11% (n=10) Venticular Septal defect 3% (n=1) 18% (n=17) Arterial Septal defect 6% (n=2) 20% (n=19) Other 23% (n=8) 32% (n=30)