Chamberlain Papers Offer Latest High-Impact Research

J. Maxwell Chamberlain Memorial Papers


7:15 a.m. – 8:15 a.m.

Grand Ballroom

Strategies distinguishing coronary artery bypass grafting (CABG) from percutaneous coronary intervention (PCI) in blocked arteries, optimal timing for stage-2 palliation after the Norwood operation in neonates, and long-term outcomes for elderly lung cancer patients are the topics of the three most important scientific abstracts accepted to the 2017 Annual Meeting program.

The J. Maxwell Chamberlain Memorial Papers honor Dr. Chamberlain, who has been called “the most important influence in the formation of The Society of Thoracic Surgeons.” The Chamberlain Papers will be presented this morning as part of General Session I.

Rethinking CABG Strategies

Surgeons have long delayed CABG in patients with mild to moderate stenosis. Long-term data suggest that grafting patients with moderately stenosed coronary arteries provides long-term protection from myocardial ischemia.

Joseph F. Sabik III, MD

Joseph F. Sabik III, MD

“Studies in percutaneous interventions showed that if you stented an artery that had moderate stenosis, it was harmful. You had better outcomes if you waited until stenosis became severe,” said Joseph F. Sabik III, MD, co-author of the Chamberlain Paper for Adult Cardiac Surgery, “Natural History of Moderate Coronary Artery Stenosis After Surgical Revascularization.”   

Although many people assumed the same was true of bypass surgery, Dr. Sabik said he and his colleagues found that CABG and PCI require different revascularization strategies.

“We now know that there is value in bypassing a moderately stenosed artery because the graft is going to stay open 90% of the time. As stenosis in the native artery progresses, the graft remains patent and protects the patient,” said Dr. Sabik, from University Hospitals Cleveland Medical Center.

The study authors analyzed retrospective data on 55,567 patients with moderate stenosis (50%–69% angiographic blockage) who underwent primary isolated CABG between 1972 and 2011 at the Cleveland Clinic, Dr. Sabik’s previous institution. The study compared 1-, 5-, 10-, and 15-year outcomes for patients who were not grafted, were grafted with an internal thoracic artery (ITA), or were grafted with a saphenous vein (SV).

As expected, native vessel stenosis progressed from moderate to severe in most patients. Stenosis progression was lowest in nongrafted patients, highest in SV-grafted patients, and intermediate in ITA-grafted patients. At 1, 5, 10, and 15 years, 8%, 9%, 11%, and 15% of ITA grafts were occluded compared to 13%, 32%, 46%, and 56% of SV grafts. At those same time points, ITA grafts conferred 29%, 47%, 59%, and 61% protection from myocardial ischemia compared to nongrafted arteries.

“As disease progressed in the native vessel, the ITA graft remained open and became protective,” Dr. Sabik said. “If you bypass a moderately stenosed vessel with an ITA, you help patients live longer.”

New Timing for Stage-2 Palliation After Norwood

James M. Meza, MD

James M. Meza, MD

Clinicians may need to reconsider current protocols for stage-2 palliation following a Norwood operation in neonates with critical left ventricular outflow tract obstruction (LVOTO). Some existing protocols call for stage-2 palliation as quickly as possible following an initial Norwood operation, especially in high-risk infants. New data suggest an optimal window for stage-2 palliation for low- to average-risk infants.

“Performing the second stage operation after 3 months in low- or average-risk infants appears to maximize survival,” said James M. Meza, MD, of the Hospital for Sick Children in Toronto. “Clinicians should adopt protocols or modify existing protocols for low- and average-risk patients to ensure that the operations take place within the optimal window for the second stage. And for higher-risk patients, many may end up failing single ventricle palliation. Survival was especially poor in high-risk patients who underwent the second stage quickly after the Norwood. Earlier consideration for heart transplantation may be what maximizes their long-term survival, with the caveat that there is a limited supply of hearts available for neonates.”

Dr. Meza will present “The Optimal Timing of Stage-2 Palliation After the Norwood Operation: A Multi-Institutional Analysis From the Congenital Heart Surgeons’ Society” as the Chamberlain Paper for Congenital Heart Surgery. Researchers analyzed outcomes for 534 neonates with LVOTO from 20 institutions. Most patients (71%) had stage-2 palliation surgery at a mean age of 5.4 months; 22% of patients died after Norwood, and the remainder underwent either biventricular repair or heart transplantation.

After stage-2 palliation, 10% died, 66% underwent Fontan, and the remainder were either awaiting Fontan or underwent heart transplantation.

The most important risk factor for death after Norwood was low birth weight. The risk-adjusted 4-year survival after Norwood was 72%. In low-risk infants, survival was compromised only by stage-2 palliation earlier than 3 months. Survival in high-risk infants was severely compromised, especially when undergoing stage-2 palliation earlier than 6 months of age.

Data Linkage Helps Analyze Long-Term Lung Cancer Survival

Mark Onaitis, MD

Mark Onaitis, MD

The Chamberlain Paper for General Thoracic Surgery presents the first long-term survival analysis of elderly patients undergoing lung cancer surgery. The new analysis is the first from data linked between the STS General Thoracic Surgery Database (GTSD) and Medicare data.

“Until now, the GTSD has been limited to analyzing 30-day outcomes, which meant we could only address short-term surgical questions,” said lead author Mark Onaitis, MD, of the University of California, San Diego. “Clearly, age and stage are the strongest predictors of survival, but because we now have such a large database, we can see how medical and surgical factors also contribute to long-term survival. We will be able to better hone in on individualizing treatments for patients in order to maximize long-term survival.”

The paper, “Prediction of Long-Term Survival Following Lung Cancer Surgery for Elderly Patients in The Society of Thoracic Surgeons General Thoracic Surgery Database,” linked the GTSD to Medicare data for lung cancer resections from 2002 to 2013, creating a database of 29,899 lung cancer resection patients. Wedge resection, segmentectomy, bilobectomy, and pneumonectomy were associated with increased risk of mortality compared to lobectomy. Smoking and low body mass index increased risk, while the thoracoscopic approach was associated with improved long-term survival compared to thoracotomy.

Dr. Onaitis said key areas for future study are oncologic outcomes from limited resections, survival following sublobar resection versus lobectomy, and survival after minimally invasive versus open procedures.

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