IJCS | Volume 32, Nº2, May/June 2019

257 Table 3 - Correlations between the thickness of the adductor pollicis muscle and variables of interest Total sample (n = 74) Men (n = 49) Women (n = 25) Variables R p value R p value r p value BMI 0.28* 0.015 0.29* 0.046 0.34* 0.92 AMC 0.35† 0.003 0.20* 0.16 0.45* 0.02 AMA 0.34† 0.003 0.15† 0.29 0.44† 0.03 LM 0.31* 0.009 0.14* 0.92 0.41* 0.04 PA 0.49* < 0.001 0.41* 0.003 0.46* 0.02 SPA 0.31† 0.008 0.34† 0.016 0.33† 0.09 *Pearson's correlation coefficient; † Spearman's correlation coefficient. BMI: body mass index; AMC: arm muscle circumference; AMA: arm muscle area; LM: lean mass; PA: phase angle; SPA: standard phase angle. Rosário et al. Adductor pollicis muscle in heart failure Int J Cardiovasc Sci. 2019;32(3)253-260 Original Article The APM thickness has been related to mortality and risk of complications in different clinical conditions. Bragagnolo et al. 25 observed that the APM thickness was associated with a higher risk of death and postoperative complications in patients undergoing gastrointestinal surgery. In patients undergoing dialysis, APM thickness was demonstrated to be associated with a higher risk of hospitalization during 6 months of follow-up. 26 When assessed before cardiac surgery, APMwas able to predict clinical outcomes, such as septic complications, length of hospital stay, and mortality. 9 Although the association between APM and mortality/morbidity has not yet been established for the HF population, the present study demonstrated a direct relationship between APM thickness and PA. PA is generated from the storage of part of the electric current by the cell membrane, 27 and decreased PA values are suggestive of death or reduced cellular integrity, while increased values are suggestive of a greater amount of intact cell membranes. This result is useful even in patients with fluid alteration or in those in whom body weight cannot be measured. In addition, PA values have the advantage of not requiring regression equations, unlike other EBI parameters, such as lean body mass. 28 For a healthy population, the mean PA values vary between 4° and 10°, depending on gender and age. Low PA values are related to decreased cellular integrity, reduced lean mass, and increased morbidity and mortality. 29 As for an unhealthy population, the cutoff values differ among pathologies. In patients with liver cirrhosis, PA values ≤ 5.4° are associated with greater mortality when compared with patients with PA values greater than these. 30 In the same context, studies have identified PA as being a strong prognostic indicator and an important tool to assess clinical signs and monitor disease progression in patients on peritoneal dialysis (PA = 6.0°), 31 HIV-positive (PA = 5.4°), 32 or with lung cancer (PA = 4.5°). 33 Collin-Ramírez et al. 23 also observed in patients with HF that a PA below 4.2° was an independent predictor of mortality. In parallel, patients with PA below this cutoff value (1 st distribution quartile) presented lower values of hemoglobin, BMI, and manual dynamometry. Malnutrition can be detected early by changes in cell membrane and fluid imbalance, which precede anthropometric or biochemical alterations. According to Barbosa-Silva et al., 34 the first level to be affected during the process of malnutritionwould be related tometabolic changes, such as alterations in cell membranes detected by PA. Functional muscle changes would be the next affected level, and only after that would anthropometric parameters be modified. In general, studies show a good correlation between APMthickness and classic anthropometric parameters. 19,35 Bragagnolo et al. 25 observed a positive correlation of APM thickness with BMI, AMC, and TSF in surgical patients. Oliveira et al., 36 when assessing patients on hemodialysis, also found a positive correlation of APM thickness with BMI, AMC, AMA, and PA. An important correlation between APM and lean mass estimated by EBI has also been observed in patients with stroke. 35 The present study corroborates these findings, since it showed a correlation