Pediatric Cardiac Surgery Outcomes

Hearing that your child needs heart surgery can be overwhelming. At the Heart Institute at Children’s Hospital Colorado, our caregivers understand the anxiety and stress that can come with a serious diagnosis. We’re here to guide you throughout your child’s care, from diagnosis to treatment and beyond.

In our history, we’ve cared for thousands of infants, children, teens and even adults with a vast variety of congenital heart defects (CHDs). As the largest pediatric heart surgery program in the region, we have performed more than 500 heart surgeries every year since 2018. Our highly specialized surgeons take on the most complex heart problems and achieve some of the best outcomes in the nation.

It’s all in support of the measure that matters most: the long and productive lives our patients go on to lead.

What are pediatric cardiac surgery outcomes?

In the medical world, the term “outcomes” means “success rates.” Many – but not all – pediatric cardiology centers measure and report their surgical outcomes to help parents make the best decision about where to take their child for heart surgery.

Here, we evaluate our success by monitoring and comparing our cardiac surgery statistics with other top pediatric hospitals. We also routinely check and publish other quality and patient safety metrics and heart transplant outcomes to ensure that families have the latest information when deciding who should care for their child.

Why transparency matters

We believe that families have the right to know every heart surgery program’s outcomes. Our Heart Institute is the only pediatric heart surgery program in Colorado and one of the few in our region to publicly report our cardiac surgery outcomes data. This transparency is one of the keys to our success as one of the best hospitals for congenital heart surgery in the country.

When researching heart surgery programs, parents should look for multiple outcome measures, such as total survival, survival by surgical complexity and length of stay, and consider these statistics together. No single metric should stand alone.

View some of the many things we measure and see our latest outcomes data below.

Heart surgery survival rates

Heart surgery programs typically report their overall survival rate as well as survival rates based on the complexity of the surgery.

What we measure:

The percentage of heart surgery patients who survive their cardiac surgery.

At Children’s Colorado, our overall survival rate for all cardiac surgery patients, regardless of how complex the surgeries are, is 98.2%. This is higher than the national average that the Society of Thoracic Surgeons (STS) reported, which was 97.4%.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

Having a higher survival rate indicates that a pediatric heart center is more experienced and better equipped for congenital heart surgery, and that fewer patients pass away during or after surgery.

Some heart centers take more complicated cases than others, which is why it’s important to also compare survival rates by complexity and type of defect.

Cardiac surgery survival rates by complexity

Some congenital heart defects are more complex than others. And because there are so many types of heart defects, no pediatric heart program will see the exact same defects each year.

The Society of Thoracic Surgeons (STS), the organization with the largest congenital heart surgery database, organizes the types of surgeries into five categories, which are referred to as “STAT categories.”

What are STAT categories?

STAT categories classify heart surgeries into groups based on how risky or complex they are. The STAT 1 category indicates surgeries with the lowest risk of death, while the STAT 5 category indicates the surgeries with the highest risk of death. A hospital that has a high survival rate for STAT 5 cases indicates success at handling unpredictable situations during the operation and during recovery. By organizing different surgeries into STAT categories, it allows the STS to produce a more accurate comparison of outcomes from one hospital and another.

What are risk-adjusted rates?

To help compare programs, the STS reports what are called “risk-adjusted” rates. This is a statistical evaluation developed by STS that predicts a patient’s risk of undergoing surgery. This evaluation attempts to include patient-related risk factors prior to surgery, such as age, weight and genetic abnormalities, in addition to the patient’s surgical risk. Using this method, STS compares the actual patient outcomes (observed outcomes) to expected outcomes (those predicted by the statistical model). Ultimately, a heart center should strive to have observed survival rates that are the same or higher than the expected survival rates.

Newborn cardiac surgery survival

Performing heart surgery on newborn babies is more challenging due to the young age and small size of the patients. Here, we show the survival rate across all STAT categories, as well as the survival rate in the STAT 5 category so parents can get an idea of how well our surgeons perform in the most challenging cases.

Newborn survival rate across all levels of surgical complexity (STAT categories)

What we measure:

We look at survival rates for newborn patients and compare them to the national benchmark across all STAT levels, regardless of the level of surgical complexity.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

Looking at an average across all STAT categories, Children's Colorado has a newborn survival rate of 96% compared to a national benchmark of 92.7%.

Newborn survival rates for the most complex (STAT 5) surgeries 

What we measure:

STAT 5 newborn survival measures the percentage of babies with the most complex heart defects who survive their surgery and have been discharged from the hospital.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

At Children’s Colorado, our surgical team specializes in some of the most complex cardiovascular procedures, with special expertise in surgical repair during the newborn period. Having a high STAT 5 survival rate means that the newborn babies we treat are more likely to survive their operation than the national average, even though we accept many more complex patients.

Measuring congenital cardiac surgery survival

Open-heart surgeries can be risky, and some deaths and complications are inevitable. Unfortunately, no program has a 100% survival rate. When researching a pediatric heart surgery center, it’s also important to compare the survival rate by patient age, type of operation and STAT category (complexity). This is because these rates can be much different than the program’s overall survival rate.

Cardiac surgery survival by procedure

Cardiac surgery programs can also report survival rates by each specific operation. These are called “benchmark operations,” and they are one of the ways surgical centers can compare outcomes. Note that these data do not include a patient’s specific risk factors prior to surgery.

In the table below, we report the total number of benchmark operations at Children’s Colorado, as well as the survival rates here compared to the national average.

Index case survival rates

What we measure:

Index case survival shows the percentage of patients who received a specific operation and were alive 30 days after their operation. It also includes patients who needed to be in the hospital longer than 30 days who were alive and successfully able to go home.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

For the majority of the open-heart surgeries listed above, our survival rates are higher than the national benchmark.

It is challenging to compare outcomes by procedure alone. The procedure-alone data does not include important health-related factors such as age, other health conditions (called comorbidities), and genetic conditions that can make procedures riskier. This is why pediatric heart surgery programs should report a wide range of outcomes, including how well patients do when they are at higher risk due to other health conditions.

About the data:

This data is taken from surgeries that took place between July 2020 and June 2024. We are comparing this data to other organizations that do at least 10 surgeries in each category in order to show a more accurate comparison.

Survival by level of surgical complexity (STAT category)

Survival of all age groups grouped by how complex or difficult the surgery is

What we measure:

There are five STAT categories for congenital heart surgeries and they are based on the likelihood of mortality with STAT 1 having the lowest chance and STAT 5 having the highest chance. We are able to compare our current STAT category surgery survival rate with the outcomes from the latest STS report.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

For the highest risk surgeries (STAT 5), we perform consistently better than the expected outcome and the national average. Looking at all five STAT categories, Children's Colorado has a survival rate of 98.2% compared to a national benchmark of 97.4%.

Survival of all age groups for the most complex surgeries (STAT 5)

What we measure:

STAT 5 survival outcomes measure the percentage of patients with the most complex heart defects who survive their surgery and have been discharged from the hospital.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

For the highest risk surgeries (STAT 5), we perform consistently better than the expected outcome and the national average. For these complex surgeries, Children's Colorado has a survival rate of 92.3% compared to a national benchmark of 84.7%.

Length of stay

The length of stay (LOS) is the number of days a person stays at a hospital after surgery. After most cardiac surgeries, hospitals require patients to stay so the medical staff can monitor them and make sure they are safe to return home. The length of time someone stays in the hospital depends on factors such as the type of surgery they had, how complex the surgery was, the age of the patient and whether the patient has other medical conditions that can affect their recovery.

A shorter LOS generally means that the surgery went well and the medical staff expects less complications while the patient is recovering. Comparing the LOS between different hospitals can tell you which programs have a history of more effective, safer surgeries with less complications afterwards.

Median postoperative LOS (days) by benchmark procedure: Children's Colorado median vs STS median of participant averages

What we measure:

The chart below shows the median number of days that children stay in the hospital for heart surgery by benchmark procedure.

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

In any set of numbers, the number that falls in the middle is called the median. This graph shows the median length of stay, or days spent in the hospital post-procedure, for our patients for different benchmark procedures. In each case, half of our patients stayed fewer days than the median and the other half stayed more. As an example, for a ventricular septal defect repair, half of our patients stayed in the hospital for fewer than five days, and the other half stayed for more than five days.

Each hospital that reports their data to the STS provides their average length of stay (LOS) by procedure. The STS looks at all these reported average lengths of stay, identifies the median, and uses that hospital’s average LOS to set the national benchmark. In this bar graph, you’ll see how the Children’s Colorado’s median length of stay compares to the STS national benchmark.

Median LOS (days) by STAT category

What we measure:

The chart below shows the median number of days that children stay in the hospital for heart surgery by STAT category (STAT 1 surgeries are the least complex and have the lowest likelihood of mortality, while STAT 5 are the most complex and have the highest risk of mortality).

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

For the least complex procedures (STAT 1), the number of observed days (postoperative length of stay) for half of our patients was less than five days, while for the other half, it was more than five days. This is compared to a national median of 8.9 days. For the most complex procedures (STAT 5), the number of observed days for half of our patients was less than 41 days, while for the other half, it was more than 41 days. This is compared to a national median of 57.3 days.

Observed length of stay compared to expected length of stay

What we measure:

For each procedure, we can estimate the number of days a person might need to stay in the hospital after surgery based on the type of surgery they receive, how complex it is and what risk factors are involved. We call this estimate an “expected” length of stay. The “observed” length of stay is the number of days the patient actually stays in the hospital after surgery. Here we look at the average number of days we expect a person to stay at our hospital after surgery compared to the average number of days the patient ended up staying.

Adjusted	Observed	Expected	O/E ratio
14.1 days	14.7 days	18.2 days	0.81

Source:  Pediatric Cardiac Critical Care Consortium (PC4), from January 1, 2024 through December 31, 2024. 

What it means:

The number of days after surgery we observed the patient staying is less than the number of days we expected the patient to stay. Looking at all cardiac surgeries, we have an average expected length of stay of 18.2 days. Our observed length of stay is 15.6 days, which means that patients usually get to return home from our hospital sooner than expected. Comparing these two numbers means our ratio of observed vs. expected (O/E) is 0.81 – hospitals aim for an O/E ratio of 1.00 or less.

Pediatric heart surgery volumes

When it comes to congenital heart surgery, volume matters. Studies show that kids who need heart surgery do better when they are treated by medical teams that perform a high number (or volume) of surgeries. This is because surgeons in high-volume centers get more experience and see a wider range of heart defects than surgeons who perform only a handful of surgeries per year.

Performing hundreds of surgeries each year indicates that the hospital is a high-volume center and is likely to have better patient outcomes. This is particularly true for patients with complex heart defects.

Number of heart surgeries performed at Children’s Colorado

What we measure:

Surgical volume indicates the number of heart surgeries performed at a hospital.

Cardiopulmonary bypass indicates when a patient has to be connected to a machine that does the work of the heart and lungs while surgeons repair the heart. These surgeries are more complex than those without cardiopulmonary bypass.

Cardiac surgery volumes

Operation type	2020	2021	2022	2023	2024
Cardiopulmonary bypass	373	386	380	447	492
No cardiopulmonary bypass	192	191	195	212	207
Other	118	99	101	75	99
Total	683	676	676	734	798

Source: Society of Thoracic Surgeons (STS) data from July 1, 2020 through June 30, 2024. STS compiles the largest congenital heart surgery database. Data taken from the fall 2024 risk-adjusted report.

What it means:

Children’s Colorado is a high-volume cardiac surgery center, performing more than 600 surgeries each year for patients with congenital heart disease. We also perform hundreds of surgeries with cardiopulmonary bypass each year. This means we have the team, the experience and the facilities to treat kids, teens and even adults with a wide variety of congenital heart defects.