Why Heart Surgery Hospital Rankings Are Not as Straightforward as They Seem
When you or someone you love is facing heart surgery, one of the first things most people do is search for the "best cardiac surgery centers" near them. That instinct is sound. Where you have your operation matters. But the way hospitals are ranked and rated is far more complicated than a simple list from one to ten, and understanding what these rankings actually measure is critical to making a good decision.
I have spent my career operating in cardiac surgery programs and evaluating outcomes data. I can tell you that no single ranking system tells the whole story. Some emphasize reputation. Others rely on volume. A few use risk-adjusted mortality data. And some conflate cardiac surgery quality with the quality of the entire cardiology department, which is not the same thing at all.
This article will walk you through the major systems used to rate cardiac surgery programs, explain what each one measures, highlight what they miss, and give you a practical framework for evaluating hospital quality on your own. If you have already been told you need surgery, consider using our free cardiac surgery risk calculator to better understand your individual risk profile before comparing hospitals.
Understanding the Major Heart Surgery Hospital Rankings and Rating Systems
There are several well-known systems that rank or rate hospitals for cardiac surgery. Each has strengths and limitations.
U.S. News & World Report
This is probably the most widely recognized hospital ranking in the country. Their "Best Hospitals for Cardiology & Heart Surgery" list combines several inputs: patient outcomes, patient experience scores, nursing stafficiency, technology, and — importantly — reputation surveys sent to physicians. Reputation accounts for a meaningful portion of the overall score.
The problem is that reputation tends to favor large, well-known academic centers. A smaller hospital with outstanding surgical outcomes may rank lower simply because fewer surveyed physicians have heard of it. Additionally, this ranking blends cardiology and cardiac surgery together. A hospital might have a world-class catheterization lab but a mediocre surgical program, or vice versa. The combined ranking does not allow you to distinguish between the two.
STS Star Ratings
The Society of Thoracic Surgeons (STS) maintains the most robust cardiac surgery outcomes database in the world. STS star rating hospitals are evaluated based on risk-adjusted outcomes for specific procedures: coronary artery bypass grafting (CABG), aortic valve replacement, and mitral valve repair or replacement. Programs receive one star (below expected), two stars (as expected), or three stars (above expected) based on a composite quality score that includes mortality, major morbidity, and certain process measures like use of internal mammary artery grafts in bypass surgery.
This is the closest thing we have to an apples-to-apples comparison. Because the data is risk-adjusted, a hospital that operates on sicker patients is not unfairly penalized. However, STS star ratings are voluntary. Not every hospital participates, and not every participating hospital publicly reports its results. If a hospital does not display its STS star rating, that does not necessarily mean the rating is poor — but it is worth asking why.
CMS (Medicare) Hospital Compare
The Centers for Medicare & Medicaid Services publicly reports mortality and complication rates for certain procedures, including CABG. These outcomes are risk-adjusted using Medicare claims data. While this is publicly available for every hospital that treats Medicare patients, the methodology is less granular than STS data because it relies on administrative billing codes rather than clinical records submitted by surgeons.
Leapfrog Group and Other Safety Ratings
Organizations like the Leapfrog Group rate hospitals on overall safety metrics — infection rates, medication errors, falls, and other system-level quality measures. These are important for any hospitalization but are not specific to cardiac surgery. A hospital with an "A" safety grade may or may not have strong surgical outcomes, and the reverse is also true.
The Metrics That Best Predict Cardiac Surgery Outcomes
So if no single ranking tells the whole story, what should you actually look at? Based on decades of outcomes research, the following factors have the strongest correlation with better results after heart surgery.
1. Surgical Volume
This is one of the most consistent findings in the cardiac surgery literature. Studies published in journals including The Annals of Thoracic Surgery and The Journal of the American College of Cardiology have repeatedly demonstrated that hospitals performing higher volumes of cardiac surgery tend to have lower mortality rates. The relationship is particularly strong for complex operations like mitral valve repair, aortic root replacement, and reoperative surgery.
There is no universally agreed-upon threshold, but many experts consider programs performing fewer than 100 to 200 cardiac cases per year to be lower volume. For specific procedures like mitral valve repair, individual surgeon volume may matter even more than institutional volume. A surgeon who performs 50 or more mitral repairs per year will, on average, achieve better durability and lower complication rates than one who performs five.
2. Risk-Adjusted Mortality and Morbidity
Raw mortality numbers can be misleading. A program that takes on the most complex, high-risk patients may have higher raw mortality than one that is more selective about whom it operates on. Risk-adjusted outcomes account for patient factors like age, kidney function, diabetes, and prior surgeries. The STS composite score is the best publicly available risk-adjusted metric for cardiac surgery in the United States.
3. Procedure-Specific Outcomes
A hospital may have excellent CABG outcomes but average mitral valve results, or vice versa. If you need a specific operation, look for data on that operation at that hospital. This is especially important for valve repair, where the repair rate (as opposed to replacement) for degenerative mitral valve disease should be above 95 percent at a high-quality center.
4. Complication Rates and Rescue Metrics
Mortality is only one outcome measure. Rates of stroke, deep sternal wound infection, prolonged ventilation, renal failure, and reoperation for bleeding are all critically important. Furthermore, "failure to rescue" — the ability of a hospital to recognize and manage complications when they do occur — is an emerging metric that reflects the quality of the entire perioperative team, not just the surgeon.
5. The Surgeon, Not Just the Hospital
You are not having surgery at a hospital. You are having surgery by a surgeon at a hospital. Individual surgeon experience, subspecialty training, and case volume are often more predictive of your outcome than the institution's overall ranking. A three-star STS hospital has surgeons on its staff who individually may perform at very different levels. Ask about your specific surgeon's experience with your specific procedure.
How to Research the Best Cardiac Surgery Centers for Your Situation
Here is a practical approach I recommend to patients and families who are comparing programs:
- Start with STS star ratings. Visit the STS public reporting website and see if the hospitals you are considering have reported their data. A three-star rating is a strong positive signal. A one-star rating warrants further questions. Absence of reporting warrants even more questions.
- Check CMS Hospital Compare. Look at CABG mortality rates on Medicare's site. Compare the hospital's rate to the national average and see whether outcomes are "better than," "no different from," or "worse than" expected.
- Ask about volume. Call the hospital or the surgeon's office directly. Ask how many of your specific procedure the surgeon performs per year and how many the hospital performs per year. Be wary of vague answers.
- Ask about repair rates. If you need mitral valve surgery for degenerative disease, ask the surgeon directly: "What is your mitral valve repair rate?" The answer should be well above 90 percent. If it is not, or if the surgeon cannot give you a number, that is a red flag.
- Look beyond the ranking. A hospital ranked number 45 on U.S. News may have a three-star STS rating and a surgeon with outstanding individual results for the exact procedure you need. A hospital ranked number 5 may be renowned for its catheterization lab but may not be the ideal place for a complex redo valve operation.
- Get a second opinion. If you are uncertain whether you are at the right hospital or with the right surgeon, an independent review of your case can provide clarity. At WhiteGloveMD, this is exactly what we do — a board-certified cardiac surgeon reviews your records and imaging and gives you an honest assessment. Learn more about how our process works.
What the Rankings Cannot Tell You — and Why a Second Opinion Fills the Gap
Even the best rating systems have blind spots. They cannot tell you whether the operation being recommended is the right one for you. They cannot tell you whether a less invasive approach might be appropriate, or whether the timing is right, or whether medical management would serve you better for now. They do not evaluate whether the diagnostic workup has been thorough enough to support the recommendation.
I have reviewed cases where patients were sent to highly ranked hospitals for surgery they did not need. I have also seen patients at lower-ranked hospitals receiving excellent, appropriate care. The ranking of the hospital is one data point. It is not a substitute for having an experienced surgeon independently review your specific case, your imaging, and your risk factors.
According to studies on surgical second opinions, a meaningful percentage of patients — some research suggests up to 30 percent or more — receive a change in diagnosis or treatment recommendation when an independent expert reviews their case. For a decision as consequential as open-heart surgery, that number should give every patient pause.
If you want to understand your individual surgical risk, our free cardiac surgery risk calculator can give you a starting point. But numbers only go so far. Context matters. Your anatomy matters. Your other medical conditions matter. And the quality of the surgical plan matters.
Making Your Decision with Confidence
Choosing where to have heart surgery is one of the most important decisions you will ever make. Rankings and ratings are useful tools, but they are just that — tools. Use them to narrow your options, not to make the final call. Ask hard questions. Request specific data. And do not feel pressured to move forward until you feel informed and confident.
The best cardiac surgery centers welcome scrutiny. Surgeons who are proud of their outcomes will share their data openly. Hospitals with strong programs will encourage you to seek additional opinions, because they know their quality speaks for itself.
If you are facing a recommendation for heart surgery and want to make sure you are at the right hospital with the right surgeon and the right surgical plan, a WhiteGloveMD second opinion can help. Our team, led by a board-certified cardiovascular and thoracic surgeon, will review your complete medical records, imaging, and test results and provide a clear, written assessment — typically within days. No waiting lists. No bureaucracy. Just an honest expert evaluation to help you move forward with confidence. Start your review today.