population-based prospective evaluation of risk of sudden cardiac death after operation for common congenital heart defects

Objectives. This study sought to define 1) the risk of sudden death after operation for common congenital heart defects; and 2) factors associated with an increased risk of sudden death. Background. Although the prognosis for patients with congenital heart defects is improved by surgical treatment, they remain at well recognized but poorly defined risk of late sudden death. Methods. This population-based study evaluated all patients <19 years old undergoing surgical treatment of common forms of congenital heart disease in the state of Oregon between 1958 and 1996. Patients were identified retrospectively through 1958, with prospective biannual follow-up beginning in 1982. The incidence and cause of late sudden death were evaluated for 3,589 patients surviving operation for the following defects: atrial, ventricular and atrioventricular septal defects; patent ductus arteriosus; pulmonary stenosis; aortic stenosis; coarctation of the aorta; tetralogy of Fallot; and image-transposition of the great arteries. Results. There were 41 unexpected late sudden deaths during 45,857 patient-years of follow-up, an overall event rate of 1/1,118 patient-years. Thirty-seven of the 41 late sudden deaths occurred in patients with aortic stenosis, coarctation, transposition of the great arteries or tetralogy of Fallot, an event rate of 1/454 patients-years. In contrast, only four sudden deaths occurred among the other defects, an event rate of 1/7,154 patient-years (p < 0.01). The risk of late sudden death increased incrementally 20 years after operation for tetralogy of Fallot, aortic stenosis and coarctation. However, risk was not dependent on patient age at operation or surgical era. The causes of sudden death were arrhythmi in 30 patients, circulatory (embolic or aneurysm rupture) in 7 and acute heart failure in 4. Conclusions. The risk of late sudden death for patients surviving operation for common congenital heart defects is 25 to 100 times greater than an age-matched control population. This increased risk is primarily represented by patients with cyanotic or left heart obstructive lesions. The risk of sudden death appears to be time dependent, increasing primarily after the second postoperative decade.