CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 1, January – April 2024 46 AFRICA variables at presentation [age, gender, BMI, body surface area (BSA) and RV parameters]. Independent variables were selected a priori for multivariate analyses. All clinically relevant and/or statistically significant variables on univariate analysis with a p-value ≤ 0.1 were included in the multivariate analysis. Results Baseline characteristics of the overall population of the study are presented in Table 1. A total of 100 participants were included, with a median age of 37.5 years [interquartile range (IQR) 26−46] with 60% female, and 24% of participants were above 50 years of age. Weight differed by age group (p = 0.049) and the median BMI was 28.0 (24.0−34.9) kg/m2. A greater percentage of female participants were overweight and obese (50%). There was an age-related increase in BMI of all participants, but it was not statistically significant (p = 0.089). Two-dimensional echocardiography parameters according to age groups are depicted in Table 2. There were no statistically significant differences with regard to age-related RA volumetric measurements (p = 0.271). RALS had a trend towards decreasing with age but did not achieve statistical significance (p = 0.362). RA volume indexed (RAVI) andRALS had a negative correlation with age but did not reach statistical significance (r = –0.060, p = 0.526; r = –0.153, p = 0.129, respectively) (Fig. 3). Regarding traditional RV functional parameters such as tricuspid annular plane systolic excursion (TAPSE), RV E′, RV A′, and RV S′) there were no statistically significant differences. RV diastolic function declined with age, with RV E′/A′ showing a decrease with age (p = 0.002). Left ventricular (LV) diastolic function parameters showed a decrease with age but remained within ASE guideline-specified normal limits (p < 0.001). Echocardiographic parameters according to gender are depicted in Table 3. Males had a tendency towards higher RAVI and RALS measurements compared to females (20.8 ± 6.3 and 18.7 ± 5.2 ml/m2, p = 0.07; 34.6 ± 9.6 and 31.4 ± 10.9%, p = 0.141, respectively). There were no statistically significant differences in RV measurements and functional parameters between males and females. All participants had LV diastolic pulsed-wave (transmitral E and A waves) and tissue Doppler measurements within the normal accepted guideline range except for A wave and A′ lateral, which were higher in females compared to males (p = 0.001 and p = 0.004, respectively). Male participants had higher LV end-diastolic and end-systolic dimensions and volumes, as well as LA volume indexed to BSA. Clinical and echocardiographic indices according to BMI are depicted in Table 4. Twenty-three per cent of participants were overweight and 44% were obese. Obese participants had higher heart rates than non-obese participants (p = 0.002) There were no statistically significant differences with regard to RA volumetric measurements, but RALS had a tendency to decrease with increasing BMI (35.7 ± 9.3%, < 25 kg/m2; 34.6 ± 11.4%, < 30 kg/m2; and 29.9 ± 10.1%, > 30 kg/m2, respectively, p = 0.571). RV E′/A′ ratio decreased with increasing BMI (p = 0.020), suggestive of worsening RV diastolic dysfunction with increasing BMI. Left atrial (LA) volume and size increased with an increasing BMI (p = 0.010 and p < 0.001, respectively). Similar to RV diastolic parameters, there was worsening of LV diastolic function with an increase in BMI. Determinants of RA longitudinal strain are depicted in Table 5. BMI was an independent predictor of RALS (BMI was a statistically significant variable on both univariate and multivariate analyses). BMI negatively correlated with RALS (r = –0.43, p = 0.003). For example, in the adjusted analyses, a unit increase in BMI resulted in a 0.72 decline in RALS. The intraobserver coefficient of variation for peak RALS was 4.6% and the inter-observer variability was 9%. Discussion This is the first study to provide normative age-related data for RALS in a sub-Saharan African population. Additionally, we have also provided complementary data regarding RAVI according to age and gender in this population. RALS had a tendency to decrease with age concurrent with a decline in RV diastolic function despite no alteration in RAVI, and BMI was an important independent predictor of RALS. Even though there was a tendency of RAVI to be higher in males, RAVI and RALS were not influenced significantly by gender. Previous studies using 2DE by Wang et al. in 1984, and Kou et al. from the Normal Reference Ranges for Echocardiography (NORRE) study in 2013, were focused on Caucasians populations, andwere in linewith theASEandESC2015 chamber quantification guideline document, which states that RAVI should be < 33 ml/m2 (or < 35 ml/m2 in men and < 31 ml/m2 in women).23,24 In our study, we found that while the lower limits were similar to those of ASE and ESC guidelines, the upper margins were much lower (20.8 ± 6.3 ml/m2 in male and 18.7 ± 5.2 ml/m2 in Table 1. Demographic and clinical characteristics of the study population according to age categories Clinical parameters Total (20–62 years) (n = 100) Group 1 (18–29 years) (n = 27) Group 2 (30–39 years) (n = 28) Group 3 (40–49 years) (n = 21) Group 4 (≥ 50 years) (n = 24) p-value* (ANOVA)# Age (years) 37.5 (29.0–48.0) 25.0 (23.0–28.0) 34.0 (33.0–37.0) 45.0 (42.0–47.0) 54.0 (51.0–57.5) < 0.001 Height (cm) 160.7 ± 7.3 161.6 ± 8.2 160.6 ± 6.5 162.0 ± 6.4 158.8 ± 7.9 0.499 Weight (kg) 73.0 (65.0–85.0) 67.0 (59.0–75.0) 73.0 (65.0–86.5) 80.0 (64.0–87.0) 78.3 (69.3–84.5) 0.049 Female, n (%) 60 (60.0) 13 (48.2) 18 (64.3) 10 (47.6) 19 (79.2) 0.078 Body mass index (kg/m2) 28.0 (24.0–34.9) 24.0 (22.5–29.3) 29.1 (24.2–35.4) 29.0 (26.6–34.3) 30.8 (27.1–36.6) 0.089 Body surface area (m2) 1.8 ± 0.2 1.7 ± 0.2 1.8 ± 0.2 1.8 ± 0.2 1.8 ± 0.1 0.168 Systolic blood pressure (mmHg) 126.8 ± 12.4 123 ± 11.6 126 ± 14.0 127 ± 9.1 130.8 ± 13.2 0.205 Diastolic blood pressure (mmHg) 79.3 ± 10.3 76.9 ± 10.9 79.2 ± 11.6 80.5 ± 9.3 80.9 ± 9.0 0.498 Heart rate (bpm) 72.0 (62.5–82.0) 67.0 (57.0–81.0) 75.5 (67.0–85.5) 70.0 (61.0–82.0) 71.0 (62.5–81.5) 0.217 Data reported as means ± SD or median (IQR). SD, standard deviation; IQR, interquartile range. #Kruskall–Wallis p-value for non-normally distributed variables. *Statistical significance denoted by p < 0.05.
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