In Cardiac Amyloidosis, Waning Muscle Predicts Death

TOPLINE:

Lower skeletal muscle mass was associated with an increased risk for short- and long-term mortality in patients with cardiac amyloidosis (CA). This association was particularly strong with transthyretin CA, where both low muscle mass and low subcutaneous fat predicted worse outcomes.

METHODOLOGY:

• Researchers investigated the impact of body composition parameters on the risk for mortality using CT-derived measurements in patients with CA.
• They included 160 patients (mean age, 79 years; 78.1% men) diagnosed with either transthyretin or light-chain CA who had chest CT within 1 year of diagnosis.
• CT axial images were analyzed for body composition measurements, including skeletal muscle, intermuscular adipose tissue percentage, and subcutaneous adipose tissue index (SATI), at the 12th vertebral level.
• Patients were categorized into sex-stratified tertiles of low, medium, and high for each body composition parameter, resulting in 33.8% of patients each in low muscle, low intermuscular adipose percentage, and low SATI groups.
• The primary outcome was all-cause mortality, with median follow-up durations of 12, 21.5, and 21.5 months for 1-, 5-, and 10-year mortality, respectively.

TAKEAWAY:

• Compared with high skeletal muscle, low muscle was associated with a twofold to 2.5-fold higher risk for 1-year mortality (adjusted hazard ratio [aHR], 2.53; P = .022), 5-year mortality (aHR, 2.03; P = .013), and 10-year mortality (aHR, 2.01; P = .012).
• Skeletal muscle was the only independent predictor of 10-year mortality, with each SD increase in skeletal muscle being associated with a 31% decrease in the risk for 10-year mortality (aHR, 0.69; P = .010).
• Medium intermuscular adipose tissue percentage and medium SATI were associated with higher risks for 5-year and 10-year mortality than high intermuscular adipose tissue percentage and high SATI, respectively (P < .05 for all).
• Low skeletal muscle and low SATI were associated with increased risks for 5-year and 10-year mortality in patients with transthyretin CA, while the association between body composition parameters and mortality was not significant in patients with light-chain CA.

IN PRACTICE:

“Our findings imply that body composition parameters, especially muscle mass and SATI [subcutaneous adipose tissue index], may have important prognostic value in CA [cardiac amyloidosis],” wrote the study authors.

“These findings also emphasize the recognition of muscle mass for risk stratification and declining muscle mass as a potentially important therapeutic target in the cardiac amyloidosis population,” they added.

SOURCE:

This study was led by Joshua Longinow, DO, and Saeid Mirzai, DO, MS, both from the Cleveland Clinic in Cleveland. It was published online on February 19, 2025, in the European Journal of Heart Failure.

LIMITATIONS:

This single-center study used registry data from a large quaternary referral center that limited the generalizability of the findings and introduced potential referral bias. CT imaging of the chest limited the quantification below the 12th vertebral level. Data on functional testing, including quality-of-life scores, the 6-minute walk test, and the grip strength test, were unavailable for most patients.

DISCLOSURES:

Three authors were supported by grants from sources including Pfizer; Cleveland Clinic Philanthropy Institute’s Caregiver Catalyst; Musculoskeletal Research Center’s Pilot Project Program; the National Heart, Lung, and Blood Institute; and the National Institutes of Health. Two authors reported serving on advisory boards or serving as a consultant or receiving an honorarium from several pharmaceutical, biotechnology, and publishing companies.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.