How Should Muscle Mass Be Measured in Heart Failure?

In patients with heart failure, mid-upper arm circumference (MUAC) and arm muscle circumference (AMC) are more significantly associated with prognosis than guideline-recommended skeletal muscle mass index (SMI) or calf circumference (CC) measurements, research suggests.

In a single-center, retrospective study that included more than 800 patients, high MUAC (hazard ratio [HR], for combined events, 0.590) and high AMC (HR for combined events, 0.529) were associated with significantly better prognoses than low MUAC and low AMC.

The findings were “surprising,” Kentaro Kamiya, PT, PhD, and Shota Uchida, PT, PhD, of Kitasato University School of Allied Health Sciences in Kanagawa, Japan, told Medscape Medical News.

“These findings challenge the current recommendations found in sarcopenia guidelines,” they noted. The European Working Group on Sarcopenia in Older People and the Asian Working Group for Sarcopenia recommend SMI, as measured by the bioelectrical impedance analysis (BIA), and CC as methods for screening skeletal muscle mass.

The study was published online August 11 in the Canadian Journal of Cardiology.

Arm Measures Prognostic

Sarcopenia, which is marked by a loss of skeletal muscle mass and strength, is associated with risks of adverse outcomes. Patients with heart failure have a high rate of sarcopenia, but assessing skeletal muscle mass in these patients is difficult because of the fluid retention they often have.

The investigators examined the association between skeletal muscle mass metrics, measured using bioelectrical impedance analysis (BIA), and anthropometric measures and prognosis in patients with heart failure.

SMI was calculated using the BIA by dividing appendicular skeletal muscle mass by height squared. MUAC and CC were measured to the nearest 1 mm using a plastic tape measure. AMC was calculated as follows: MUAC (cm) − (0.314 × triceps skinfold [TSF]). The TSF was measured to the nearest 2 mm with a skinfold caliper. The measuring spot for TSF was same measuring spot for MUAC. MUAC, CC, and TSF were measured by trained physiotherapists or nurses.

The investigators identified 1930 consecutive patients with heart failure who underwent cardiac rehabilitation during their hospitalization. They excluded from their analysis 1013 patients who did not undergo a skeletal mass metrics evaluation and 48 who could not be followed up.

The analysis included 869 patients (median age, 73 years; 62% men). Patients were separated into three groups on the basis of the sex-specific tertiles of skeletal muscle mass. The study endpoint was all-cause death or readmission due to heart failure, and the median follow-up period was 1.24 years.

After the investigators adjusted the data for age, sex, New York Heart Association functional class III or IV, left ventricular ejection fraction (LVEF), ischemic etiology, prior heart failure, diabetes, chronic obstructive pulmonary disease, log-transformed B-type natriuretic peptide (BNP), and estimated glomerular filtration rate (eGFR), the high MUAC and high AMC groups were associated with significantly better prognoses than their respective low groups. By contrast, high SMI and high CC were not associated with better prognoses.

Subgroup analyses showed no interactions between MUAC and age, sex, LVEF, BNP, eGFR, prior heart failure, beta-blocker use, and angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker use. However, diuretic agents significantly interacted with AMC (P = .03).

“These results support the use of MUAC and AMC to determine the risk stratification of sarcopenia and a poor prognosis in patients with heart failure and suggest that they may be useful in developing treatment strategies in patients with heart failure,” wrote the authors.

“When caring for patients with heart failure, it seems that the often overlooked and simple measure of arm circumference might carry significant prognostic value,” said Kamiya and Uchida. “So, as you cuff the arm for routine blood pressure measurement, it might be worthwhile to also pay attention to arm girth.”

Although the findings provide valuable insights, they should be approached with caution, Kamiya and Uchida added. “Before considering them practice-changing, further research is needed to validate these results in diverse patient cohorts.”

Prospective Study Needed

Commenting on the study for Medscape, Jonathan H. Whiteson, MD, vice chair of clinical operations and medical director of cardiac and pulmonary rehabilitation at NYU Langone Health’s Rusk Rehabilitation in New York City, expressed concerns about the study methodology.

Methodologic weaknesses include the retrospective, observational nature of the study and the fact that incomplete data collection led to the exclusion of more than half of the potential participants, he said. In addition, “anthropometric measurements are prone to inter-rater error. It is not clear if the same or different researchers conducted these measurements.

“Furthermore, hospitalized patients may not be clinically stable when discharged,” said Whiteson. “It is recommended that biometrics for muscle mass and fluid retention be done when patients are at an optimized clinical state: that is, stabilized outpatients.”

For now, Whiteson concluded, the findings should be considered “interesting and suggestive of further study.” What’s needed is “a prospective study including all patients admitted with heart failure, but measurements done when the patient is stabilized as an outpatient.”

The study was partially supported by the Japan Society for the Promotion of Science KAKENHI. Kamiya, Uchida, and Whiteson reported no conflicts of interest.

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