COMMENTARY

Questions Remain on Tricuspid Repair at Time of Mitral Surgery

John Mandrola, MD

Disclosures

November 13, 2021

The idea of add-on tricuspid valve repair at the time of mitral valve surgery makes sense because severe tricuspid regurgitation (TR) is associated with a poor prognosis, and reoperation on the tricuspid valve has a high perioperative death rate.

Guidelines therefore recommend concomitant repair of mild or moderate tricuspid regurgitation with annular dilatation of 4.0 cm or more. But the recommendation is based on observational data, and there remains controversy over the best approach—as evidenced by rates of concomitant tricuspid repair in U.S. surgery programs that range from under 10% to more than 75%.

Medicine is replete with examples of things that makes sense but do not pass muster when subjected to the tough test of randomization. 

At the American Heart Association (AHA) Scientific Sessions 2021, James Gammie, MD, from the Cardiothoracic Surgical Trials Network (CTSN), presented results of a trial that randomly assigned 401 patients undergoing surgery for degenerative mitral regurgitation to add-on tricuspid valve annuloplasty or no tricuspid valve repair. The New England Journal of Medicine published the study along with an accompanying editorial.  

Enrolled patients were young (age 67 to 68 years), were mostly male (75%), and had to have moderate TR or, for lesser degrees of TR, an annular dilation above 4 cm. 

The researchers chose a composite primary endpoint of death, reoperation for TR, or progression of TR (severe TR or two grades worse than baseline): in essence, two binary clinical endpoints and a surrogate endpoint judged from an ultrasound image. 

Results

The primary endpoint occurred in 10.2% of the mitral surgery alone group vs 3.9% of the add-on tricuspid repair group (hazard ratio, 0.37; 95% CI, 0.16 - 0.86; P = .02).

There were no reoperations for TR in either group and low mortality rates, so a lower rate of TR progression (6.1% vs 0.6%) drove the primary endpoint.

Other secondary endpoints of all-cause death, major adverse cardiac events, readmissions, quality of life, and functional status did not significantly differ between the treatment groups at 2 years.

The rate of pacemaker implants was more than 5-fold higher in the tricuspid repair group (14.1% vs 2.5%).

Comments

The official results of this trial were quite positive; the active arm had a statistically significant 63% reduction in the primary endpoint. But I agree with the circumspect wording of the authors in which they acknowledge the nuance of these results.

The authors highlight the 2 main reasons for not calling this a "positive" study. First, the reduction in the primary endpoint was driven by progression of tricuspid regurgitation, which is not a robust endpoint. It is susceptible to measurement error, dependent on pre- and after-load and … I've never heard a patient complain of their TR jet.

The second core problem with the results is that even if you believe that reducing progression of TR at 2 years was clinically relevant, the cost for this more favorable ultrasound measurement was a 5-fold higher need for permanent pacing.

I implant pacemakers and love what they do for people, but I would argue that avoiding a pacemaker at a young age is a far better outcome than avoiding an unfavorable Doppler signal on an ultrasound. Imagine, as the editorialists did, if the composite endpoint included pacemaker implantation. This clearly would not favor add-on tricuspid valve repair.

Proponents of add-on tricuspid repair will argue that even though there were no differences in functional status or quality of life, having worse TR may lead to problems in the future. Indeed, that is the question. But the only way to know that is to recruit many more patients, follow them longer than 2 years, and measure clinical outcomes, not surrogate endpoints.

There was discussion during the session and in the editorial that surgical trials are more difficult to conduct than drug trials, and that is why we need surrogate endpoints such as TR progression. I would agree that surgical (and procedural) trials create more challenges relative to drug trials, but I disagree that proper surgical trials cannot be done.

In fact, the CTSN group has shown that it is possible to do larger trials. They recruited 2100 patients in a multicenter trial of rate vs rhythm control after cardiac surgery. And the recent LAAOS III trial recruited more than 2300 patients to study add-on left atrial appendage closure. The latter study measured the hard endpoint of stroke and went out to 4 years.
 

Conclusion

This latest CTSN trial confirms that tricuspid repair at the time of mitral valve surgery increases the risk for pacemakers in young patients with mild-to-moderate TR. Whether that harm will be outweighed by fewer adverse clinical outcomes in the future remains unknown.

Sadly, despite a high-profile presentation at a big medical meeting and a publication in the New England Journal of Medicine, patients, cardiologists and surgeons still do not know whether doing more rather than less at the time of mitral surgery is worth it.  

John Mandrola practices cardiac electrophysiology in Louisville, Kentucky, and is a writer and podcaster for Medscape. He espouses a conservative approach to medical practice. He participates in clinical research and writes often about the state of medical evidence.

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