HOUSTON (FRONTLINE MEDICAL NEWS) – The optimal timing of stage 2 palliation after the Norwood operation depends on certain patient-specific risk factors, but in most cases should be done around 3-4 months of age, results from a multi-center study show.

While previous studies have investigated whether early stage-2 palliation (S2P) can be performed without increased post-S2P mortality, the effect of the timing of S2P on post-Norwood mortality remains unknown, Robert “Jake” Jaquiss, MD, said in an interview in advance of the annual meeting of the Society of Thoracic Surgeons.

“There has been a lot of dispute about how early is too early for S2P,” said Dr. Jaquiss, the study’s senior author, who is professor and division chief of pediatric cardiothoracic surgery at the University of Texas Southwestern Medical Center. “That is one of the few things that is in the control of the doctor. Most of the rest of the decisions are based entirely on the condition of the patient and the patient’s specific anatomy. So the timing of S2P is something that we can truly define most always. What we want to find out is, what is the ideal timing? How early is too early? Is there such a thing as too late?”

In an effort to determine the optimal timing of S2P that both minimizes pre-S2P attrition and maximizes long-term post-S2P survival, Dr. Jaquiss and his associates at 19 other institutions evaluated data from 534 neonates diagnosed with left ventricular outflow tract obstruction that precluded adequate systemic cardiac output through the aortic valve who initially underwent a Norwood operation from 2005 to 2016.

James M. Meza, MD, the John W. Kirklin/David Ashburn Fellow at the Congenital Heart Surgeons’ Society Data Center at The Hospital for Sick Children, Toronto, collected the data and presented the study findings at the meeting. The investigators used multiphase parametric hazard analysis to determine overall survival after Norwood and after S2P. Next, the researchers identified risk factors for death after Norwood and after S2P and used both risk-adjusted models to determine cumulative survival at 4 years post-Norwood for all patients, through Norwood and S2P. The optimal timing of S2P was determined by plotting nomograms of 4-year, risk-adjusted, post-Norwood survival vs. age at S2P.

S2P was performed in 377 patients (71%) at a mean age of 5.4 months, while 115 (22%) died after Norwood, and the rest underwent biventricular repair or heart transplantation. After S2P, 38 (10%) died, 248 (66%) underwent Fontan, and the rest were alive awaiting Fontan or underwent heart transplantation.

Risk factors for death after Norwood included requiring pre-Norwood extracorporeal membrane oxygenation (P less than .0001), birth weight of less than 2.5 kg (P less than .0001), modified Blalock-Taussig shunt vs. a right ventricle to pulmonary artery conduit (P = .0003), larger baseline right pulmonary artery diameter (P = .0002), smaller baseline mitral valve diameter (P = .0002), smaller baseline tricuspid valve diameter (P = .0001), and nonwhite race (P = .03).

Risk factors for death after S2P included lower oxygen saturation at pre-S2P clinic visit (P = .02), having moderate or severe pre-S2P right ventricular dysfunction (P = .007), younger age at S2P (P = .03), and longer post-Norwood hospital length of stay (P = .03).

The risk-adjusted, 4-year, post-Norwood survival was 72%, with a confidence interval of 67%-75%. When plotted vs. the age at S2P, risk-adjusted, 4-year, post-Norwood survival for the 534 patients was maximized by S2P at 3-6 months of age. At the same time, risk-adjusted, 4-year survival in low-risk infants was compromised only by undergoing S2P earlier than 3 months of age. In high-risk infants, survival was severely compromised, especially when undergoing S2P earlier than 6 months of age.

“The results reinforced intuitions or expectations that most of the investigators already had,” Dr. Jaquiss said. “But we are in an era where evidence-based medicine is much preferable to intuition-based medicine. I’m very confident in the findings we have. I feel more confident in suggesting that we should be planning these surgeries around 3-4 months of age in usual-risk children and also more confident in suggesting that we need to consider transplantation earlier in children who are perceived to be at high risk. There is some hope [by clinicians in] some centers that you can convert a high-risk prognosis to a lower or intermediate risk prognosis by doing the S2P earlier or at some alternative time. Our data suggests that would not be helpful.”

Dr. Jaquiss and Dr. Meza reported having no financial disclosures.


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