Propensity-matched analysis may suggest it’s time for “Ross Centers of Excellence”

The Ross procedure was associated with a “striking” survival advantage over bioprosthetic aortic valve replacement (AVR) surgery for young and middle-age adults in a propensity-matched analysis.

Over a mean 14.5 years of follow-up among a cohort of consecutive patients getting either procedure, Ross recipients had a hazard ratio of 0.35 for all-cause mortality (95% CI 0.14-0.90) compared with patients who underwent bioprosthetic AVR, with seven (6.5%) versus 21 deaths (19.4%), respectively.

At 20 years, the difference remained significant (9.6% vs 25.1%, P=0.028), Maral Ouzounian, MD, PhD, of the University of Toronto, and colleagues reported in the Journal of the American College of Cardiology.

Other outcomes that also significantly favored the Ross procedure in the 108 matched pairs of patients in an analysis with death considered as a competing risk were:

• Reintervention (HR 0.21, 95% CI 0.10-0.41)
• Valve deterioration (HR 0.25, 95% CI 0.14-0.45)
• Thromboembolic events (HR 0.15, 95% CI 0.05-0.50)
• Permanent pacemaker implantation (HR 0.22, 95% CI 0.07-0.64)

Bicuspid aortic valve was present in 75% of patients, and aortic stenosis was the indication for 49%. Median age was 41 years, with a range from 17 to 59. Exclusion criteria included active endocarditis, acute aortic dissection, end-stage renal disease, and emergency surgery.

Prior series had also suggested a benefit to the Ross procedure in restoring normal life expectancy to young and middle-age adults, which bioprosthetic AVR doesn’t do in this population. Similar propensity-matched results also showed superior survival with the Ross procedure compared with mechanical valve implantation.

“However, patients in the Ross series tend to be carefully selected,” Ouzounian’s group noted. “Some have argued that the excellent long-term outcomes observed in these cohorts may be related to favorable patient characteristics rather than the operation itself.”

While the propensity score matching in the study couldn’t rule out unmeasured confounding, the two groups yielded comparable cohorts who were “young, generally healthy, and presented a low surgical risk.”

“If these findings are reproduced in other specialized centers with sufficient expertise, the Ross procedure may be considered the preferred option for selected young and middle-aged adults undergoing AVR,” the researchers concluded.

However, an accompanying editorial noted that “these findings are remarkable in their magnitude but should again be interpreted with caution.”

Direct comparisons at other centers are needed in particular because a single expert surgeon did all of the Ross procedures and most of the rest in Ouzounian’s study, which “limits the external validity of the results for nonexperts in aortic root reconstructive surgery,” wrote Ismail El-Hamamsy, MD, PhD, of the Icahn School of Medicine at Mount Sinai in New York City.

Still, such a large survival benefit “is more likely a reflection of the fundamental differences in biology and hemodynamics between the pulmonary autograft and a prosthetic valve” than experience or patient selection, they argued.

Because it’s a more complex procedure for which the special surgical skill and experience are limited, perhaps the time has come for “Ross Centers of Excellence,” based on publicly reported case volumes, operative mortality, and so on, they added.

“Cardiologists will play an important role in expanding the accessibility to the Ross procedure, by appropriate referral to selected surgeons in their center or region so Ross experience can be concentrated, while patient safety remains the foremost concern,” El-Hamamsy’s group continued. “In this era of large data collection, patients deserve no less than to know the scientific community is transparent, and importantly, dedicated to their safety, health, and wellness.”