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Doppler quantification of functional tricuspid regurgitation (TR) predicted 5-year mortality in heart failure with reduced ejection fraction (HFrEF), with even milder regurgitation by volume linked to a 50% increase in death risk, researchers found.

Among 382 consecutive HFrEF patients on guideline-directed medical therapy who were treated at the outpatient heart failure clinic of the Vienna General Hospital, three echocardiographic metrics had strong ties to all-cause mortality over 5 years:

• Effective regurgitant orifice area (EROA; HR 1.009 per 0.01 cm² increase, 95% CI 1.004-1.013)
• Regurgitant volume (HR 1.013 per 1 ml increase, 95% CI 1.007-1.020)
• Vena contracta width (HR 1.109 per 1 mm increase, 95% CI 1.066-1.154)

There was a clear excess in deaths above Doppler thresholds that "fall within current ranges defining non-severe TR," according to Georg Goliasch, MD, PhD, of Austria's Medical University of Vienna, and colleagues reporting online in .

These thresholds were EROA 0.2 cm² or higher (typically indicative of moderate tricuspid regurgitation), regurgitant volume 20 mL or greater (mild regurgitation), and vena contracta width 5 mm or wider (moderate regurgitation).

For example, mortality risk was 1.5-fold higher for both a patient with a vena contracta width of 4 mm (or an EROA of 0.3 cm²) but with moderate tricuspid regurgitation, based on current guidelines, and one with a regurgitant volume of 20 mL and so-called "mild" tricuspid regurgitation.

"The volume of TR, whether or not it is quantitatively assessed, may not fully capture the prognostic importance of the TR. As with any valve lesion, TR needs to be considered within the context of the entire patient," commented Judy Hung, MD, and Sammy Elmariah, MD, MPH, both of Massachusetts General Hospital in Boston.

Yet taking quantitative measures is no easy technical task, they emphasized in an accompanying editorial.

"The inherent underestimation of EROA using a hemispherical assumption for proximal flow convergence surface area and lack of reproducibility due to technically difficult measurement of flow convergence radius hinder assessment and application of EROA and RV in grading TR," Hung and Elmariah said.

By Doppler echocardiography, 69% of the study cohort had moderate-or-worse tricuspid regurgitation. The group had a median age of 68 years, and 78% were men. Median left ventricular ejection fraction was 26%, while median NT-proBNP was 3,144 pg/mL. Half of patients were in New York Heart Association functional class III or IV.

"The significance of TR in chronic heart failure is controversial. Earlier studies have shown an independent impact of TR on mortality, whereas more recent evidence suggests myocardial impairment to be the driving force of mortality rather than TR itself," Goliasch's group noted.

"In patients with HFrEF, TR is usually left untreated in the majority of patients due to unacceptable high perioperative mortality even in Heart Valve Centers of Excellence (up to 10%) giving rise to a clinical management dilemma of decision for surgical intervention and timing of surgery," they said.

In their study, the greater the tricuspid regurgitation severity, the more symptoms the patient typically had, and the greater the neurohumoral activation progression in right ventricular dilatation and functional impairment.

"However, the complex nature of HFrEF with competing and interacting risks between heart failure and tricuspid regurgitation and mortality highlights the need for prospective controlled trials," the investigators said.

They also cautioned that their study was limited to secondary tricuspid regurgitation and acknowledged that they couldn't be sure if the presence of permanent endocardial device leads impacted the accuracy of Doppler measurements.

Whether tricuspid regurgitation is a marker or driver of risk remains uncertain, Hung and Elmariah wrote, adding that reducing regurgitation has yet to be shown to affect hard clinical outcomes.

"As effective transcatheter tricuspid valve repair comes to fruition, it will be critical to investigate the clinical impact of earlier interventions given the reported observation that even mild TR may limit survival," the editorialists said.