Supplementary materials of

A potential linkage between mitochondrial function of the heart and leg muscles in patients with heart failure

include supplementary methods, 2 figures, and 4 tables.

Supplementary methods

Calculation of 99mTc-MIBI washout

A region of interest was manually drawn around the heart and in the region of the mediastinum between the upper limbs (supplementary figure 1). The myocardial 99mTc-MIBI washout rate (percentage) was calculated using the following equation: [(early heart count)-(early mediastinum count)] - [(delayed heart count)-(delayed mediastinum count)] / [(early heart count)-(early mediastinum count)} × 100 (%). [1][ In the legs, we traced the upper thigh and the lesion outside of the legs (background). The leg 99mTc-MIBI washout rate (percentage) was calculated using the following equation: {[(early leg count)-(early background count)] - [(delayed leg count)-(delayed background count)] / [(early leg count)-(early background count)} × 100 (%).

Cardio-pulmonary exercise testing (CPX)

CPX was performed in the upright position on a bicycle ergometer with an initial workload of 0 watt (W) and subsequent increments of 20 W (male) or 15 W (female) every minute until exhaustion was reached. A 12-lead electrocardiogram was used to monitor heart rate throughout the test using the Stress test system (ML-6500, Fukuda Denshi). Oxygen consumption and carbon dioxide production were measured with a metabolic cart (AE310s, MINATO). The exercise test variables analyzed in the study included oxygen consumption at aerobic threshold and peak oxygen uptake (peakVO2). AT was determined from the gas exchange data by the V-slope method. [2]

References

1. S. Matsuo, I. Nakae, T. Tsutamoto, N. Okamoto, M. Horie, A novel clinical indicator using tc-99m sestamibi for evaluating cardiac mitochondrial function in patients with cardiomyopathies, J. Nucl. Cardiol. 14 (2007) 215–220.

2.W. Beaver, K. Wasserman, B.J. Whipp, A new method for detecting anaerobic threshold by gas exchange, J. Appl. Physiol. (1985). 60 (1986) 2020–2027.

Supplementary Figure 1. Representative images of the calculation of washout ratio. (A) hearts, (B) leg muscles.

Supplementary Figure 2. A schema of the subgroup analysis.

Supplementary Table 1. Patient characteristics

Total number / 45 / Mean / SD
Sex / Male / 28 / (62.2%) / Age / 68 / 15.2
Female / 17 / (37.8%) / BMI (kg/m2) / 23.3 / 3.4
Aetiology / DCM / 17 / (37.3%) / EF (%) / 41.1 / 14.0
IHD / 10 / (22.2%) / WR of heart (%) / 46.8 / 9.1
Tachycardia-induced / 8 / (17.7%) / WR of leg muscles (%) / 30.7 / 7.2
HFpEF / 6 / (13.3%) / BNP (pg/mL) / 370.9 / 200.1
Valvular / 2 / (4.4%) / CRP (mg/dL) / 1.09 / 1.75
Others / 2 / (4.4%)
Comorbidities / Hypertension / 25 / (55.5%)
Diabetes / 11 / (24.4%)

BMI, body mass index; BNP, brain natriuretic peptide; CRP, C-reactive protein; DCM, dilated cardiomyopathy; HFpEF, heart failure with preserved ejection fraction; IHD, ischemic heart disease; EF, ejection fraction; SD, standard deviation; WR, washout rate.

Supplementary Table 2. Determinants of washout rate of the heart using a general linear model with a Poisson distribution by the likelihood-ratio chi-squared test

the likelihood-ratio chi-squared / P value
WR of leg / 4.5137 / 0.0336*
BMI / 1.2236 / 0.2686
Age / 0.0645 / 0.7995
EF / 1.8749 / 0.1709
BNP / 15.9580 / <0.0001*

BMI, body mass index; BNP, brain natriuretic peptide; EF, ejection fraction; WR, washout rate. *P <0.005

Supplementary Table 3. Characteristics of patients with or without CPX.

CPX group (mean, SD) / Non-CPX (mean, SD) / P
Age / 59.2, 2.6 / 76.1, 2.3 / 0.003
BNP (pg/ml) / 400.7, 62 / 342.0, 60 / 0.88
EF (%) / 37.6, 3.0 / 44.5, 3.0 / 0.10
WR (heart; %) / 45.4, 1.9 / 48.2, 1.9 / 0.26
WR (leg muscles; %) / 30.1, 1.6 / 31.2, 1.5 / 0.69

Supplementary Table 4. Determinants of peak oxygen consumption in the subgroup using general linear model in Poisson distribution by the likelihood-ratio chi-square test.

the likelihood-ratio chi-squared / P value
WR of heart / 2.2061 / 0.1375
WR of leg / 5.1281 / 0.0235*
BMI / 1.9755 / 0.1599
Age / 1.9091 / 0.1671
Circumflex / 0.4838 / 0.4867
EF / 10.5784 / 0.0011*
BNP / 1.2444 / 0.2646