Does Hospital Volume Still Matter in Contemporary Transcatheter Aortic Valve Replacement? A Systematic Review and Dose– Response Meta-Analysis

For decades, the rule of thumb in complex medicine has been simple: the more often a hospital performs a specific, difficult procedure, the better its patients tend to do. This idea, known as the volume-outcome relationship, suggests that experience breeds excellence. When a team performs a surgery hundreds of times a year, they refine their technique, anticipate complications, and coordinate care more smoothly than a team that only does it occasionally. This principle has long guided how healthcare systems organize care for heart interventions, often pushing for centralization so that patients are sent to high-volume centers. However, as medical technology evolves, the question arises: does this old rule still hold true? Specifically, for a procedure called transcatheter aortic valve replacement, which involves replacing a narrowed heart valve without open-heart surgery, has the field matured enough that the sheer number of procedures a hospital performs no longer guarantees a better survival rate?

Transcatheter aortic valve replacement has transformed the treatment of severe aortic stenosis, a condition where the heart's main valve narrows and restricts blood flow. Initially reserved for patients too sick for traditional surgery, it has become a standard option for people across the entire spectrum of surgical risk. Over the last twenty years, the tools used for the procedure have improved, the techniques have become more standardized, and the training for doctors has become more rigorous. These advances have made the procedure safer for everyone. But this progress raises a critical question for hospital administrators and patients alike: in this modern era of high-tech, standardized care, does a hospital still need to perform a massive number of these replacements to ensure its patients survive the short term?

To answer this, a team of researchers from China Medical University and other institutions conducted a massive review of existing scientific literature. They gathered data from seventeen different studies involving more than 440,000 patients who underwent the valve replacement procedure. Their goal was to see if there was a clear link between the number of procedures a hospital performed annually and the risk of the patient dying during their hospital stay or within thirty days of the operation. They did not just look at whether high-volume hospitals were better; they also looked at how this relationship has changed over time, whether it differs between countries, and exactly how many procedures are needed to see a benefit.

The researchers found that, overall, patients treated at hospitals that perform many of these procedures do have a lower risk of short-term death compared to those at hospitals that perform fewer. However, the story is not the same as it used to be. When the team looked at data from the early years of the procedure, between 2002 and 2014, the advantage of being at a high-volume center was very strong. During that time, hospitals with more experience saw significantly better survival rates. But when they examined data from the more recent era, from 2015 to 2020, that strong link disappeared. In contemporary practice, the number of procedures a hospital performs no longer predicts a significant difference in survival rates. This suggests that as the procedure has become more routine and standardized, the gap in quality between busy and less busy hospitals has narrowed considerably.

The study also mapped out exactly how the number of procedures relates to patient safety. They discovered that the relationship is not a straight line where more is always better. Instead, there is a point of diminishing returns. As a hospital increases its annual volume, the risk of patient death drops, but this improvement slows down and eventually levels off. The researchers identified that this benefit reaches a plateau at approximately 200 procedures per year. Once a hospital performs around 200 of these replacements annually, doing even more does not appear to provide a further measurable reduction in short-term mortality risk. This finding implies that there is a threshold of experience that is sufficient to ensure high-quality care, and pushing beyond that number does not necessarily make the hospital safer.

Geography also played a role in the findings. The data showed that in Western countries, the trend of better outcomes at high-volume centers was consistent, even if the effect was weaker in recent years. In contrast, studies from Eastern regions showed more mixed results, though the researchers noted that there was less data available from these areas to draw firm conclusions. This variation highlights that healthcare systems, patient selection, and how hospitals are organized can influence how much volume matters. The researchers emphasized that while hospital volume remains a useful indicator, it should not be the only factor used to judge a program's quality.

Ultimately, this research suggests that the old metric of simply counting procedures is no longer a complete picture of hospital quality for this specific treatment. While high-volume centers still tend to have better outcomes, the dramatic advantage seen in the past has faded as the procedure has become safer and more standardized. The findings indicate that once a hospital reaches a certain level of experience, around 200 procedures a year, other factors likely become more important in determining patient success. For healthcare systems and patients, this means that while experience matters, it is no longer the sole determinant of safety, and quality assessments should look at a broader range of performance measures to ensure the best care.