Andersons pediatric cardiology 1905

Risk Factors for Late Mortality Identification of risk factors for long-term outcome and the development of models for risk stratification have the potential to target treatments to the highest risk patients and to guide the development of new treatment strategies To date, risk stratification has been hampered by a relatively small number of patients and by institutional differences in patient selection and treatment regimens However, with the increasing numbers of patients and the trend toward multiinstitutional networks and registries, it is likely that risk stratification will become an essential tool to guide the development of effective surveillance regimens and targeted interventions Preoperative Factors Preoperative risk factors for late death include male gender13,15 and the diagnosis of hypoplastic left heart syndrome.12,16 A higher pre-Fontan mean pulmonary arterial pressure is an important predictor of morbidity and mortality in both the early perioperative and late stages, with a threshold of 15 to 17 mm Hg or less being associated with a better outcome.14,15,17 A higher pulmonary artery pressure is also associated with prolonged pleural effusions in the early postoperative period,18 as well as the development of PLE in the late stage,14 both of which independently predict late mortality Having a common atrioventricular valve (CAVV) is also a predictor of late death,19 with almost 50% of CAVVs having failed 20 years after Fontan surgery.20 Moreover, a CAVV is frequently associated with heterotaxy syndrome and anomalies of pulmonary and systemic venous drainage, both of which are also risk factors for late failure (Table 73.1) Table 73.1 Risk Factors for Late Mortality Preexisting (preFontan) factors Perioperative factors Early postoperative Male gender Hypoplastic left heart syndrome Common atrioventricular valve Higher mean pulmonary artery pressure (>16–18 mm Hg) Type of Fontan (atriopulmonary worse) Older age at Fontan operation (>7 years) Operative complexity (e.g., aortic cross clamp time, bypass time, concomitant atrioventricular valve replacement) Elevated Fontan circulation pressure (>20 mm Hg) factors Late postoperative factors Elevated ventricular filling pressure (>13 mm Hg) Prolonged pleural drainage (>3 weeks) Protein-losing enteropathy Tachyarrhythmia Ventricular pacing Reduced exercise capacity (peak VO2) Perioperative Factors Those with an atriopulmonary Fontan are at greater risk of late death when compared with the more recent variations (Video 73.1).13,21 However, a survival advantage of the extracardiac conduit over the lateral tunnel has not been demonstrated.7,22 When Fontan and colleagues reviewed 160 Fontan surgeries from 1968 to 1988, they found older age at Fontan surgery was predictive of late death.23 A more recent experience similarly demonstrated a poorer late survival when the Fontan operation was undertaken after 7 years of age.13 Surrogate markers for surgical complexity including longer aortic cross-clamp time,24 bypass time,25 and concurrent atrioventricular valve replacement14 also impact on late survival The main factors in the postoperative course that influence late mortality relate to the presence of elevated pulmonary arterial or Fontan pathway pressure A postoperative left atrial pressure greater than 13 mm Hg or Fontan pressure greater than 20 mm Hg is associated with a twofold increase in risk of late death.14 Prolonged pleural effusions, usually described as chest tube drainage for more than 3 weeks after surgery, is one of the strongest predictors of late death.12–14 Besides being a marker for elevated pulmonary arterial pressures, it may also be influenced by other factors, including longer cardiopulmonary bypass time,26 the presence of aortopulmonary collateral vessels,27 and the absence of a fenestration.28,29 Late Predictors Beyond the perioperative period, the identification of risk factors becomes more challenging due to the insidious nature of disease progression The development of late complications, including PLE and arrhythmia, and the requirement for ventricular pacing are markers for late failure and are described in detail later in this chapter Cardiopulmonary exercise stress testing is an important prognostic tool in the Fontan population Of all the measured exercise variables, peak VO2 is the most robust in predicting late morbidity and mortality.30,31 Those with a peak VO2 of less than 16.6 mL/kg/min have a mortality risk seven times of those with a higher peak VO2 (Fig 73.6).32 A lower peak heart rate33 or reduced heart rate reserve,21 defined as the difference between peak exercise and resting heart rates, has also been identified as a useful marker of function and prognosis However, it is important to recognize that confounding factors such as antiarrhythmic therapy and pacemaker-dependence may influence exercise capacity and reduce its prognostic power FIG 73.6 Survival curve for Fontan patients with peak VO2 of greater or