Clark Papers Feature Important Outcomes Research

Since its inception in 1989, the STS National Database has generated hundreds of key clinical research papers. Three of the latest practice-changing studies—one each from the Congenital Heart Surgery Database (CHSD), the Adult Cardiac Surgery Database (ACSD), and the General Thoracic Surgery Database (GTSD)—will be presented as the 2016 Richard E. Clark Memorial Papers from 8:15 a.m. to 9:00 a.m. this morning during the General Session in Exhibit Halls 2-3.

Dr. Clark was a key leader behind the creation of the Database, serving as Chair of the STS Ad Hoc Committee to Develop a National Database for Thoracic Surgery.

Underweight and Severe Obesity Similarly Dangerous for Lung Resection

Body mass index (BMI) has long been used to evaluate risk and stratify patients for lung resection due to lung cancer. And while obesity is commonly recognized as a risk factor, being underweight is emerging as a largely underappreciated source of surgical risk.

Researchers queried the GTSD to find more than 41,000 patients who underwent anatomic lung resection for cancer between 2009 and 2014. The patients were grouped by BMI: underweight, less than 18.5 kg/m2; normal, 18.5-24.9; overweight, 25.0-29.9; obese I, 30.0-34.9; obese II, 35.0-39.9; and obese III, 40.0 and higher. With more than 435,000 thoracic surgery procedure records and more than 800 participating surgeons, the GTSD is particularly useful for identifying under-recognized associations.

Lead author Trevor Williams, MD, Cardiothoracic Surgery Resident at The University of Chicago, will present the 2016 Richard E. Clark Memorial Paper for General Thoracic Surgery, “Operative Risk for Major Lung Resection Increases at Extremes of Body Mass: Analysis of the STS General Thoracic Surgery Database.”

As expected, the most obese patients were at significantly increased risk for surgical complications. The surprise finding was that patients who are underweight are at similarly increased risk for pulmonary and postoperative complications.

“We think that many patients who are underweight are frail, which is associated with impaired strength, reduced activity, and being easily fatigued. There also may be an association with immune system impairment. All of these factors adversely affect outcomes after lung surgery,” Dr. Williams said.

Researchers also found that patients who were overweight or somewhat obese had fewer postoperative and pulmonary complications compared to patients of normal weight, although the reason is unclear.

New Clinical Risk Factor Score Developed for Isolated Tricuspid Valve Surgery

The Clark Paper for Adult Cardiac Surgery showcases the development of a novel risk prediction score for tricuspid valve (TV) surgery. The literature shows consistently high mortality from TV surgery—about 8%-10%—but this is the first clinical risk score to successfully predict mortality and major morbidity using preoperative patient data.

Damien J. LaPar, MD, MSc

Lead author Damien J. LaPar, MD, MSc, Cardiothoracic Surgery Fellow at the University of Virginia in Charlottesville, will present “Development of a Risk Prediction Model and Clinical Risk Score for Isolated Tricuspid Valve Surgery: Analysis of the STS Adult Cardiac Surgery Database.”

Researchers analyzed data within the ACSD on more than 2,000 isolated TV repair and replacement surgeries performed for any reason across 49 hospitals. More than 90% of US programs that perform adult cardiac surgery participate in the ACSD. To date, the ACSD has more than 5.8 million surgical records.

This research identified risk scores for both mortality and major morbidity associated with 13 patient factors, such as age, sex, specific comorbidities, New York Heart Association Functional Classification, reoperation, and urgent or emergency status. A simple clinical risk score of 0-10 based on the sum of numerical scores for each factor was strongly associated with incremental increases in predicted morbidity and mortality. The predicted mortality risk ranged from 2% to 34% and predicted major morbidity risk ranged from 3% to 71%.

This is the first successful clinical risk score to be developed for TV surgery. Surgeons may be able to use this score to better identify candidates for TV surgery, as well as to counsel patients and guide perioperative management.

Presence of Noncardiac and Genetic Abnormalities Varies Dramatically in CHD

The Clark Paper for Congenital Heart Disease will explore the prevalence of genetic abnormalities across various types of congenital heart disease.

Angira Patel, MD, MPH

“Neonates and infants with congenital heart disease have had improved outcomes with regard to morbidity and mortality over the past half century,” said Angira Patel, MD, MPH, Pediatric Cardiologist and Assistant Professor at the Northwestern University Feinberg School of Medicine in Chicago. “We know that when you have a congenital heart disease, the coexistence of another abnormality—whether it is a noncardiac congenital anatomic abnormality, a chromosomal abnormality, or a syndrome—can affect clinical outcomes. Understanding the prevalence of coexisting conditions across congenital heart disease diagnostic groups has been a challenging area of research.”

Dr. Patel is the lead author of “Prevalence of Noncardiac and Genetic Abnormalities in Neonates Undergoing Cardiac Surgery: Analysis of the STS Congenital Heart Surgery Database.” Researchers analyzed the CHSD for presence of an associated abnormality in neonates who underwent index cardiac operations between January 2010 and December 2013 at centers across North America. The cohort of more than 15,000 neonates was divided into 10 diagnostic groups based on each infant’s most complex cardiac anomaly or condition.

Researchers then queried the CHSD to determine the prevalence and distribution of non-cardiac anomalies, genetic anomalies, and syndromes across each of the diagnostic groups. The CHSD is the largest database in North America dealing with cardiac malformations. Since its launch in 2002, the CHSD has collected more than 373,000 congenital heart surgery procedure records. The prevalence of these anomalies varied dramatically across different diagnostic groups, ranging from 4% to 59%.

“This is the first large database study in the contemporary era across multiple centers that evaluates the distribution of these anomalies across different cardiac malformations,” Dr. Patel said. “We know that the association of these anomalies has an impact on cardiac outcomes. Understanding the prevalence across diagnostic groups may be useful for patient counseling, recommendations for screening for anomalies and genetic disorders, and perioperative management.”