The long-term risk of warfarin sodium therapy and the incidence of thromboembolism in children after prosthetic cardiac valve replacement.

Thirty children less than 18 years of age underwent cardiac valve replacement with a prosthetic valve between 1967 and 1984 and have been followed up for a mean of 6 years (range 1 to 17 years). Their mean age at the time of operation was 13 years (range 6 to 17 years). All patients were begun on a regimen of warfarin before hospital discharge. One major and four minor bleeding episodes occurred in 211 patient-years of warfarin therapy, an incidence of 2.3 per 100 patient-years. Three of those five episodes occurred in patients who were receiving excessively anticoagulation or who were participating in physical activities inappropriate for a patient on warfarin therapy. Thus, the majority of the bleeding episodes were preventable. There were five thromboembolic events in 211 patient-years, an incidence of 2.3 per 100 patient-years. Three of those five patients had intentionally stopped their warfarin therapy. The majority of thromboembolic episodes, like the bleeding episodes, were preventable. Eight teenage patients were noncompliant with the warfarin therapy. More than one third of that group experienced a thromboembolic event, an incidence of 5.5 per 100 patient-years (55 patient-years). Twenty-two patients adhered to the warfarin regimen and only two (9%) of them had a thromboembolic event, an incidence of 1.3 per 100 patient-years (156 patient-years). Warfarin therapy presented no greater risk of serious bleeding to this pediatric age group than it does to an adult age group. The incidence of thromboembolism among these patients was less than that which is generally reported for adult patients. Discontinuation of or noncompliance with warfarin therapy substantially increased the risk of thromboembolism. Continuous warfarin therapy is recommended for every child after prosthetic valve replacement.