CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 3, September – October 2024 148 AFRICA Methods This was a cross-sectional study conducted in the Centre Médical de Kinshasa (CMK) between January and December 2019. The CMK is a reference clinic with a cardiology centre named Pôle de Cardiologie, where cardiovascular explorations such as Doppler echocardiography, coronary scanning and cardiopulmonary exercise testing are performed. It operates with highly qualified, regularly retrained personnel. This research was conducted in strict compliance with the recommendations of the Helsinki Declaration III. Approval to conduct the study was obtained from the ethics committee of the University of Kinshasa Public Health School prior to its commencement. Each participant provided written, informed consent to participate in the study. All respondents were debriefed on the results of the study. Two hundred and twenty asymptomatic hypertensive patients (133 men, 60.4%), aged 51.5 ± 9.7 years, were consecutively enrolled during out-patient consultations at the Pôle de Cardiologie of the CMK between January and December 2019. The inclusion criteria were age of 20 years and above and absence of clinical or laboratory evidence of secondary hypertension, renal or hepatic disease. Patients with heart disease unrelated to high blood pressure were excluded from participation. Demographic data (age, gender), lifestyle habits (heavy alcohol consumption, current smoking, sedentary behaviour), medical history including cardiovascular risk factors (age at diagnosis of high blood pressure, history of diabetes mellitus, dyslipidaemia, hyperuricaemia, menopause), previous cardiovascular events (stroke, ischaemic heart disease, heart failure, chronic kidney disease, cardiovascular surgery), and current medication use for chronic disease (antihypertensive treatment, antidiabetic treatment and other treatments including statins, antiplatelet agents, hypo-uricaemics, oral contraception and hormone replacement therapy) were collected during an in-person directed interview using an ad hoc questionnaire. Anthropometric parameters measured by a trained observer consisted of measurements of body weight, height, and waist and hip circumference according to WHO recommendations. Body weight was measured in kilograms using a validated electronic balance on a stable and flat surface, with participants in light clothing and shoes. The reading was taken to the nearest 100 g. Height was measured with a measuring rod, to the nearest centimetre, with participants standing barefoot and bareheaded. Body mass index (BMI) was obtained by dividing the weight (kg) by the height (m) squared. Waist circumference was measured to the nearest 0.1 cm, using a measuring tape applied directly to the skin along the horizontal line passing through the umbilicus. Body surface area (BSA) was calculated using the DuBois formula,14 as follows: BSA = height 0.725 × weight 0.425 × 0.007184. Blood pressure was measured non-invasively by 24-hour ambulatory blood pressure monitoring using a Tonoport V (GE Healthcare, Freiburg, Germany) type recorder. During this recording, the participant was asked to maintain his usual way of life. LV measurements were obtained according to the updated 2015 American Society of Echocardiography and European Association of Cardiovascular Imaging guidelines for cardiac chamber quantification,15 using a Vivid T8 (GE) type ultrasound system equipped with 3.5-MHz transducers. Two-dimensionally guided M-mode echocardiography was performed in the parasternal long-axis view. IVS, LVED and PWT were measured at end-diastole at a level just below the mitral valve leaflets. Simultaneous ECG was used to correlate measurements with the cardiac cycle. Diastolic wall thickness was measured at the onset of the QRS wave. LVMwas calculated according to the American Society of Echocardiography simplified cubed equation linear method using the equation of Devereux (see above).13 LVM was indexed by BSA and by height2.7. The relative wall thickness (RWT) of the left ventricle was calculated as (2 × PWT)/LVED. In accordance with international recommendations,16 the parameters of LV diastolic function were measured by recording transmitral flow velocity using conventional Doppler echocardiography. With pulsed-wave (PW) Doppler, transmitral flow velocity was recorded from the apical transducer position with the sample volume situated between the mitral leaflet tips. E (peak E-wave velocity), A (peak A-wave velocity) and deceleration time of early filling (DT) were recorded in the apical four-chamber view with colour-flow imaging for optimal alignment of PW Doppler with blood flow. PW Doppler sample volume (1–3 mm axial size) was placed between the mitral leaflet tips using low wall filter setting (100–200 MHz) and low signal gain, so that the optimal spectral waveforms would not display spikes. E, A and DT were measured as the averages of five consecutive cardiac cycles. The E/A ratio was calculated. Tissue Doppler echocardiography, which measures the velocity of the regional cardiac wall, was performed by activating the tissue Doppler echocardiographic function as for two-dimensional and M-mode echocardiography. Mitral annular velocities were recorded from the apical window. Sample volumes were located at the lateral site of the mitral annulus. Peak early diastolic mitral annular velocity (E′, cm/s) was measured over five cardiac cycles and the mean was calculated. The ratio E/e′ was used as a parameter of left atrial pressure, which is elevated with progression of LV diastolic dysfunction. These parameters, obtained by tissue Doppler echocardiography, were also used as parameters of LV diastolic function. For all analyses, a blood sample was taken between 7:00 and 9:00 from the cubital vein of the patient who had been fasting since 22:00 the previous day. All analyses were carried out at the CMK laboratory. For the determination of serum uric acid, total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides, blood was collected in a dry tube and the assay was performed by colorimetric spectrophotometer (Helios Epsilon, Milwaukee, USA). The blood glucose test was performed on plasma oxalate by colorimetric method using standard reagents (Biolabs) and was measured by the Helios Epsilon spectrophotometer. The dosage of insulin was performed on EDTA plasma by ELISA. Reading the optical density was done on a string read from the firm Humareader Human (Germany). Hyperinsulinaemia was defined as a fasting insulin level > 90 mmol/l and IR was defined by a HOMAIR ≥ 2.5.17 Normal LVM was defined as ≤ 115 g/m2 or ≤ 48 g/m2.7 in males and ≤ 95 g/m2 or ≤ 44 g/m2.7 in females, with LVH defined as LVM exceeding those values.18 Four LV geometric patterns were defined as follows:18,19 normal geometry (normal LVM and RWT ≤ 0.42); concentric remodelling (normal LVM and RWT > 0.42); concentric
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