Impact of Gender on Survival after Norwood Palliation: Single-center Experience in 302 Patients

Objectives: Studies in adults have shown that women have higher rates of both major adverse cardiac events and mortality from myocardial infarction compared with men. Very limited data are available if gender affects the outcome of patients after Norwood operation in large single-center series. Our objective was to determine if female sex (F) is associated with increased mortality after Norwood compared with male (M) patients.

Methods: All 302 patients with single ventricle physiology who underwent stage I Norwood palliation between January 2002 and June 2017 were included in this retrospective study. Survival analysis was performed using the Kaplan-Meier method with log-rank testing. The primary clinical outcome (mortality) and secondary outcomes were analyzed using univariate and multivariate comparisons.

Results: Thirty-six percent patients (n = 110) were female, the remaining 64% male (n = 192). The distribution of the high-risk subtype mitral stenosis with aortic atresia was similar among the two groups. The mean pre-Norwood comprehensive Aristotle score was practically identical in both groups (F: 18.4 vs M: 18.3, p = 0.8). In 7.8% of male patients a pulmonary artery banding was performed vs 13.6% in female group (p = 0.07) prior to the Norwood procedure. The median age at time of Norwood procedure (7 days) was not significantly different between the two groups. However, the body weight at Norwood palliation was significantly lower in the female group (F: 3.08 ± 0.62 vs M: 3.32 ± 0.66 kg, p = 0.006). Postoperative use of extracorporeal membrane oxygenation was not statistically different between the groups (F: 21.8% vs M: 16.7% (p = 0.2). Overall mortality (including in-hospital mortality and late outpatient mortality) was 29/110 (26.4%) in female patients compared with 34/192 (17.7%) in male patients (p = ns). In the past 3 years the average mortality rate was 15%. The rate of postoperative morbidity (bleeding, shunt thrombosis, wound infection, renal failure, neurological injury) was similar in the both sexes. Multivariate analysis revealed that lower body weight at the time of Norwood has a negative impact on survival after the Norwood procedure.

Conclusion: Gender is not an independent risk factor for mortality after stage I palliation. In our study population patient weight at time of the Norwood procedure and concomitant anomalies of pulmonary venous return are the highest predictors for hospital death following Norwood procedure.