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Addressing moderate or lesser tricuspid regurgitation (TR) during mitral valve surgery improved outcomes, largely by halting progression of the leaky tricuspid, a randomized trial from the Cardiothoracic Surgical Trials Network showed.

Mitral valve surgery with tricuspid annuloplasty led to 63% lower combined risk of reoperation for tricuspid regurgitation (TR), progression of TR by two grades from baseline or the presence of severe TR, or death at 2 years compared with mitral valve surgery alone (3.9% vs 10.2%, P=0.02).

TR progression drove the benefit of the combined surgery (0.6% vs 6.1%, RR 0.09, 95% CI 0.01-0.69), reported James Gammie, MD, of the Johns Hopkins School of Medicine in Baltimore, at the American Heart Association (AHA) virtual meeting. The findings were published simultaneously online in the (NEJM).

Mitral plus tricuspid surgery resulted in significant, nearly six-fold increased incidence of permanent pacemaker implantation (14.1% vs 2.5%). Other outcomes didn't differ between groups, including all-cause mortality, readmission, major adverse cerebro- and cardiovascular events, quality of life, and functional status.

Operating on 20 patients to save one from severe tricuspid regurgitation at the cost of two needing a permanent pacemaker, "for me, that tradeoff is worth it," said AHA press conference discussant Joanna Chikwe, MD, of Cedars-Sinai Medical Center in Los Angeles. "I think I would be repairing the tricuspid valve in these moderate tricuspid regurgitation patients."

"We see it often; we just don't know 'Should we be operating?'" commented press conference moderator Roxana Mehran, MD, of Icahn School of Medicine at Mount Sinai in New York City. "We as clinicians believe that if you fix the mitral valve, maybe the tricuspid regurgitation will get better. And it seems like that is not what is happening. I think that's a big takeaway."

Still, "I would have liked to have seen a clinical outcome value of this," Mehran lamented.

Two-year mortality came out similar in the 401-patient trial between the combined surgical approach and mitral-valve-only approach (3.2% vs 4.5%, RR 0.69, 95% CI 0.25-1.88).

Chikwe agreed but noted that the hardest endpoints -- mortality and reoperation -- "happen so rarely, in part because the surgery is so safe and the results are so good, that you end up needing an echo endpoint to power the trial." But, she argued, the echo endpoint is clinically meaningful: "We know that [severe tricuspid regurgitation] eventually leads to liver failure, right heart failure, increased chances of death."

Gammie noted that "these patients tend to be very difficult to manage in the office with severe TR without mechanical intervention."

As to whether the trial will change the sometimes "fierce opinions in the cardiac community around this issue" that has led to the range of concomitant tricuspid repair rates from 5% to 75% across U.S. cardiac surgery programs, Gammie added: "It's going to be interesting. A lot of folks will probably take away from this that moderate TR should be fixed; that putting that tricuspid annuloplasty in arrests the progression of TR very, very effectively."

On the other hand, he pointed out, "I do think it calls into question the guidelines around tricuspid annular dilation, since we found in that subgroup of patients that progression was very rare with or without tricuspid annuloplasty."

The trial enrolled patients getting mitral valve surgery for degenerative mitral regurgitation at centers in the U.S., Canada, and Germany who had moderate TR (37%) or who had no worse than mild TR with annular dilatation. The tricuspid surgery was standardized to undersized (26-30) rigid nonplanar annuloplasty.

For patients enrolled based on moderate TR, the advantage of combined surgery was clear, with a primary composite endpoint rate of 4.5% versus 18.1% among controls (RR 0.25, 95% CI 0.07-0.83).

In the patients enrolled based on TR diameter instead, that rate was 3.4% versus 6.1%, with only about 1% in both groups having TR progression.

"The very dynamic nature of tricuspid regurgitation and wide variability in assessing tricuspid annular dilatation are additional compelling reasons to leave lesser regurgitation alone," Chikwe added in an NEJM accompanying with Mario Gaudino, MD, of Weill Cornell Medicine in New York City. "The most appropriate strategy for the treatment of milder tricuspid regurgitation may emerge from longer follow-up."

Follow-up out to 5 years is planned, although Chikwe noted that it can take up to 10 years to see net clinical benefit to patients with surgeries like this.

Gammie agreed that impact on a young patient population like in this trial (mean age 67-68) can still be felt out to 10 to 20 years.

A subanalysis of pacemaker implantation is planned to look at risk factors, since some sites had rates as low as 3%, Gammie noted at the late-breaking clinical trial session. "There may be both management issues and technical issues that we may come up that will allow us to achieve the benefit of locking that tricuspid valve in place and preventing progression TR without the risk of a pacemaker."