Johns Hopkins All Children's Heart Institute

Heart Surgery Outcomes and Volumes

Information about a heart surgery program's outcomes (results) can help parents make choices about their child's cardiac care.

About 40,000 babies in the United States are born each year with congenital heart defects, which are structural problems with the heart, according to the Centers for Disease Control and Prevention. Many will need surgical procedures at some point in their childhood to repair the defect.

Congenital heart disease includes relatively minor problems, such as a small hole in the heart, and more complex conditions that require specialized hospital care. Children also may acquire a heart condition they weren’t born with that could require an operation. Parents can depend on Johns Hopkins All Children’s Hospital to provide the information they need to understand their child’s medical condition, how common it is and how it should be addressed.

Johns Hopkins All Children’s Hospital reports its pediatric surgical outcomes to the Society of Thoracic Surgeons (STS), which maintains an independent database and establishes benchmarks for various procedures. Parents should be cautious about comparing outcome data without taking the STS benchmarks into account because some procedures are more complex than others.

What is the Society of Thoracic Surgeons?

The STS is a not-for-profit organization representing more than 7,500 surgeons, researchers and allied health care professionals worldwide. It maintains several databases, including the Congenital Heart Surgery Database (CHSD), which has more than 475,000 congenital heart surgery procedure records making it the largest database of such procedures in North America.

The STS tracks congenital cardiothoracic operations in five “STAT” categories with Level 1 the least complex and Level 5 procedures the most complex. The STS “STAT” level applies to the procedure and may not take into account other factors that may increase the risk to a child, such as premature birth.

Understanding Children’s Heart Surgery Data

The STS data tracks how many patients die within 30 days of a heart procedure, dividing the number of deaths (mortality) by the number of procedures to establish a “mortality rate.” A lower mortality rate may not mean one hospital is better than another. For instance, a higher mortality rate may indicate a hospital takes patients with more challenging conditions requiring more complex operations.

Longer term survival is extremely important, but the 30-day rate is chosen to most closely evaluate the surgical and immediate post-operative care without the influence of further treatment. 

STS also evaluates a hospital’s “case mix,” which takes into account factors such as the patient’s age, weight, procedure types and existing health conditions. STS uses the case mix to estimate an “expected” mortality rate overall, by STAT category and by procedure. Comparing a hospital’s mortality rate to its expected rate can help to evaluate its performance.