Outcome after a "perfect" Fontan operation

Abstract

A study was undertaken to determine the early and long-term outcomes dictated by the Fontan state per se (a state in which the force driving pulmonary blood flow is solely or largely a residue, in the systemic venous pressure, of the main ventricular chamber's contractile force) and the transition (by surgery) to it from the state of congenital heart disease under optimal conditions (after a "perfect" Fontan operation). The primary study design used a solution of a multivariate risk factor equation for death, by which survival rate under optimal conditions was predicted to be 92%, 89%, 88%, 86%, 81%, and 73% at 1 month, 6 months, and 1, 5, 10, and 15 years, respectively, after the Fontan operation. The hazard function (instantaneous risk of death at each moment in time after the operation) had an early rapidly declining phase of hazard that at about 6 months began to give way to a late hazard phase, which was rising by about 6 years after surgery. A secondary study design, using the theory of competing risks, yielded survival and hazard function information very similar to that of the primary study design. The functional capacity of the patients as expressed by New York Heart Association class was less, the longer the period of follow-up. No risk factors (other than older age at time of surgery) were found for the late decline in survival or the decline in functional status. The inference is that the premature decline in survival and functional status and the late rise in hazard function are from the Fontan state per se and that the Fontan operation is, therefore, palliative but not curative.