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Health status, exercise capacity help predict outcomes in heart failure with mitral regurgitation

JACC: Heart Failure
Reuters Health - 03/09/2021 - In patients with heart failure (HF) and severe secondary mitral regurgitation, disease-specific health status and exercise capacity provide complementary information that's useful for prognosis, researchers have found.

This prognostic information is valuable both before and after transcatheter mitral-valve replacement (TMVr), as well as if a patient receives medical treatment only, they note in JACC: Heart Failure.

"At baseline, health status is more closely associated with risk of HF hospitalization, whereas exercise capacity is a stronger predictor of late mortality," Dr. Suzanne V. Arnold of Saint Luke's Mid America Heart Institute, in Kansas City, Missouri, and colleagues report.

"While improvements in both measures are associated with better outcomes over time, health status may be a better assessment of response to treatment with TMVr, given its increased sensitivity to change," they say.

The study was a secondary analysis of the COAPT study, an open-label trial of TMVr with the MitraClip device from Abbott in 614 patients with HF and severe secondary mitral regurgitation (MR) who were randomized to maximally tolerated guideline-directed medical therapy alone or with TMVr. Participants were followed through two years for clinical events.

The mean age for the 604 participants included in the new analysis was 72, their mean left ventricular ejection fraction was 31% and their mean BMI 27. About two-thirds were men and three-quarters were white.

Heart failure-specific health status was assessed with the Kansas City Cardiomyopathy Questionnaire (KCCQ), and functional capacity was measured using 6-minute walk distance (6MWD).

"In models including both measures, greater baseline 6MWD (but not KCCQ-OS) was associated with reduced 2-year mortality," with a hazard ratio per 125 m of 0.75 (95% confidence interval, 0.61 to 0.92), the researchers report.

Mortality was highest in the groups with low 6MWD; among these, the two-year mortality was 45% regardless of baseline KCCQ scores.

Among patients with high 6MWD at baseline, mortality was only slightly greater in the low-KCCQ group compared with the high-KCCQ group (29% vs. 25%).

In contrast, the highest annualized HF-hospitalization rate was seen in patients with low KCCQ and low 6MWD at baseline (64.5%), followed by those with low KCCQ and high 6MWD (52.5%), those with high KCCQ and low 6MWD (49.2%), and finally those with high KCCQ and high 6MWD (36.3%).

Among patients treated with TMVr, baseline KCCQ score was significantly associated with reduced risk of HF hospitalization, but 6MWD was not. Both measures were associated with risk of HF hospitalization among patients receiving medical therapy only.

"Understanding how exercise capacity and heart failure-specific health status relate to different outcomes and how to interpret them around the time of these procedures is really important, both for clinical care and the design of trials," Dr. Arnold told Reuters Health by email.

She explained that the KCCQ is "disease-specific, quantifying HF symptoms, functional limitations, and quality of life" and as such is "most sensitive to change after TMVr."

"So," Dr. Arnold said, "the KCCQ is particularly good at assessing success of the procedure, at least in terms of symptoms and heart failure-related issues." On the other hand, "Exercise capacity, no matter what condition, will always be an important marker of mortality, regardless of procedures."

Dr. Siddhartha Angadi, a cardiovascular exercise physiologist at the University of Virginia, in Charlottesville, told Reuters Health by email that the KCCQ is only modestly correlated with exercise capacity and provides information beyond it - for example, on such symptoms as swelling in the feet due to peripheral edema.

Overall, he said the new study is "Interesting work in a population that has very high rates of morbidity and mortality, so finding markers that can be easily used for risk prediction or surveillance has value. There's a reasonable case to be made for including both the KCCQ and the 6MWD in surveillance efforts to identify patients at higher risk." Dr. Angadi was not involved in the research.

The COAPT trial was sponsored by Abbott.

SOURCE: https://bit.ly/3gYupNA JACC: Heart Failure, online August 11, 2021.

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