Experience Matters as Ross Procedure Gains Popularity in North America

Aortic valve replacements (AVRs) performed with the Ross procedure are on the rise in North American centers, with the best results achieved at higher-volume centers and with experienced surgeons, according to a new analysis.

In 2023, 6.7% of all surgical AVRs performed in adults younger than 60 years old were Ross procedures, and while early mortality declined over the 16-year study period, it appeared to creep back up a little in the last couple of years, report investigators.

“The risk profile of the patients has not changed much over the last couple decades,” senior investigator Maral Ouzounian, MD, PhD (University Health Network, Toronto, Canada), told TCTMD. “These are still young, low-risk, healthy patients with good ventricles.  We did see a concerning uptick in mortality in the last few years of the study, but when we looked at high-volume centers and everybody else, the uptick was only observed in the low-volume centers.”

That same relationship with volume and 30-day mortality was also seen amongst individual surgeons.

Ismail El-Hamamsy, MD, PhD (Icahn School of Medicine at Mount Sinai, New York, NY), who helped write a European Association for Cardio-Thoracic Surgery expert consensus statement on the Ross procedure alongside Ouzounian, said the new study is both encouraging and concerning. The increasing number of Ross procedures done per year reflects the strong evidence supporting the surgery, but he said it is worrisome to see so many low-volume centers performing this highly specialized operation.

“Any time you dabble with anything that’s complex, you will get burned every once in a while,” El-Hamamsy told TCTMD. “Whether that is a complex robotic mitral valve repair, heart transplantation, or congenital heart surgery, the Ross is no different. I’m obviously deeply concerned about these centers that are doing one or two or three cases a year. I think this is ill-advised.”

We do want to disseminate Ross and increase availability to patients all over North America. Maral Ouzounian

For young people in need of a new aortic valve, the Ross procedure represents an excellent solution, said Gilbert Tang, MD (Icahn School of Medicine at Mount Sinai).

“The problem we’re facing is that a mechanical valve is not a great option for a lot of young people, particularly because they require anticoagulation,” he told TCTMD. “Even though the thrombosis rate is low, if you look at the historical data with mechanical AVR, the lifetime risk of bleeding is very high.” Developing other valves with different materials in an effort to eliminate the need for anticoagulation hasn’t panned out, he added.

“At the end of the day, people realize that it needs to be a bioprosthetic valve,” said Tang. “For young patients, we know that TAVI or SAVR would not be durable and that’s why the Ross procedure is so attractive.”

The resurgence of the procedure, however, reflects a growing number of inexperienced sites doing the surgery, which is worrisome, he said. “It’s like anything in life,” said Tang. “If you try to take out a gall bladder once a year, you’re going to forget.”

The results were published this week in JACC.

Waves of Interest in Ross

The Ross procedure, a highly specialized surgery that involves replacing the diseased aortic valve with the pulmonary valve and then replacing the latter with a pulmonary homograft, was developed in the late 1960s. Studies have shown that survival and need for reoperation are better with the Ross procedure than with conventional AVR. In fact, from centers across the world, those studies have shown that survival with the Ross procedure is restored to normal age- and sex-matched survival of the general population.

Over recent years, though, there has been a perception that the Ross procedure poses higher operative risks than conventional AVR, and there have been reports of autograft failure. Reoperation following a Ross failure is also technically challenging.

“The procedure has had a couple of waves of interest in the past few decades since it was developed,” said Ouzounian, head of the division of cardiovascular surgery at the Peter Munk Cardiac Centre. “One of the reasons for the decline in the Ross procedure was that a few papers were published showing a concerning early mortality with Ross.”

One paper, a 2015 publication, showed the risk of early mortality was threefold higher with the Ross procedure compared with conventional AVR. However, that analysis did not address the possibility of a volume-outcome relationship. “Of course, we know across all of medicine there’s a very strong volume-outcome relationship in nearly everything we do, particularly for complex procedures,” said Ouzounian.

Any time you dabble with anything that’s complex, you will get burned every once in a while. Ismail El-Hamamsy

For the new analysis, using the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (ACSD), the group identified 2,268 Ross procedures (median patient age 43 years) performed at 194 centers between 2008 and 2013. The number of cases at each site varied considerably, ranging from one to 506 procedures done over the 16-year study period. After the center performing the most Ross procedures, the next highest-volume site did 118 cases.

In all, 44% of the centers did just a single Ross procedure between 2008 and 2023, with a median of two cases per center. The 10 highest-volume hospitals performed 53% of the surgeries. At these 10 centers, the median number of Ross procedures was 81 during the study period.

In 2008, 116 surgeries were performed in the US plus the five Canadian hospitals participating in the STS ACSD registry. In 2017, the number of surgeries bottomed out at 63 cases, but the number rose since then, with 149, 250, 357, and 531 Ross procedures done in 2020, 2021, 2022, and 2023, respectively. Among patients 60 years and younger who underwent AVR, the Ross procedure accounted for 0.9% of surgeries in 2017 and 6.7% in 2023. Between 2018 and 2023, 55 centers reported performing their first Ross procedure.

Among patients, STS Predicted Risk of Mortality (PROM) was approximately 1% throughout the study period. Operative mortality, defined as death occurring within 30 days or during the index hospitalization, declined throughout the study period, although it rose in the last 2 years. In 2008, operative mortality was 4.4%, declining to a low of 1.0% in 2020, but rising to 2.5% in 2023. In the analysis based on observed and expected (O/E) mortality, the O/E ratio increased above 1 in 2022, which suggests a relative increase in the risk of 30-day deaths.

Operative mortality stayed low and did not increase among the 10 highest-volume centers, however. In 2021 to 2023, the period of rising operative mortality, 29 of the 79 centers (37%) who performed the Ross procedure had not done a case prior to 2020 and 56 centers (71%) reported five or fewer procedures. Amongst the top 10 highest-volume sites, the O/E mortality ratio indicated consistent outcomes in line with expectations.

In a volume-outcome analysis, mortality rates were highest in the low-volume centers (≤ 10 Ross procedures during the study period), while mortality was lowest in the high-volume centers (> 50 procedures). In an adjusted model that accounted for year of surgery and STS PROM, operative mortality was threefold higher at sites that performed one or two Ross cases per year than those that did more than 10. Similar results were evident when analyzed by individual operator experience.

The secondary outcome, which included in-hospital mortality, any reoperation, stroke, renal failure requiring dialysis, and prolonged ventilation, was also strongly linked to center and surgeon experience.

Avoiding Past Mistakes

Like others, Tang emphasized the importance of experience, adding that sites that infrequently encounter Ross-eligible patients should be referring to specialized centers. High-volume centers have seen a wider variety of pathology and anatomy, and they may be better equipped to provide pre-, intra-, and postoperative care for patients.

“The Ross operation is a great operation with durable results in experienced hands, but in inexperienced hands, it could definitely have a higher mortality risk because of the operation itself,” said Tang.

For young patients, we know that TAVI or SAVR would not be durable and that’s why the Ross procedure is so attractive. Gilbert Tang

Both Ouzounian and El-Hamamsy said they don’t want to see the current wave of interest in the Ross procedure undone by poor outcomes in the less-experienced centers, which happened in the past. “It’s really a case of fool me once,” said El-Hamamsy. “In 2026, if we repeat the same mistake, it’s really on us and it’s unacceptable.”   

"The bottom line is that experience with this complex procedure matters," said Ouzounian.

“We do want to disseminate Ross and increase availability to patients all over North America,” she continued. “If only 10 places are doing it, obviously, patients across North America won’t have access. But if you are a new program starting out, you really need to concentrate the experience. Make sure you have your cardiologists on board so they understand the benefits and are going to refer you patients. Make sure you have enough volume of young patients with aortic valve disease who could be eligible.”

El-Hamamsy said that while the current analysis identified experienced centers as those doing 10 or more per year, the ideal number would be 25 cases annually.

“That’s every other week,” he said. “That’s not a very high bar. If you asked me, I would put that even higher, but you don’t things to be too exclusive. I would also say that’s not just 25 Ross procedures, but 25 plus 50 aortic-root procedures a year. At the end of the day, Ross is an aortic-root procedure.”

At a center of excellence for the Ross procedure, in addition to the volume requirement, El-Hamamsy said important safety and efficacy thresholds should also be established. This means operative mortality and 1-year reintervention rates both at less than 1%.

For Ouzounian, low-volume surgeons and hospitals should be referring Ross-eligible patients to more experienced sites until they are sufficiently experienced. There should be no such thing as a “casual Ross surgeon.”

“You can’t do this periodically, but it is a very trainable skill set,” she said. “If you do a lot of aortic-root surgery, valve-sparing root replacement, Bentalls, aortic valve repair, then you’re in the perfect place to then extend that to be able to do Ross with appropriate mentorship and dedicated program infrastructure.”