CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 2, May – August 2024 AFRICA 97 Permission was granted by the local ethics committee for the study protocol (2022/3652) and every patient provided written informed consent. The study was completed according to the principles of the Declaration of Helsinki. Four groups were identified according to the valve type used in the operation. These were mechanical valve, bovine bioprosthetic (pericardial) valve, porcine bioprosthetic valve and sutureless valve. The pre-operative transthoracic echocardiography findings of patients (LVM, LVMI, LVEDD, LVESD, PPM, PAP, EF and gradient) were compared with the one-year (from 10 to 15 months) postoperative transthoracic echocardiography results. The LVM and LVMI values of patients were calculated with the commonly used formula based on echocardiographic parameters developed by Devereux and Reichek. The body surface area (BSA) of patients was calculated by measuring their height and weight. LVM was calculated with the following formula: LVM (g) = 0.8 × [1.04 (LVEDD + PWt + IVSt)³ – (LVEDD)³] + 0.6 where IVSt is interventricular septum thickness, PWt is posterior wall thickness, 1.04 is the myocardial specific weight and 0.8 is the correction factor. LVMI was calculated with the following formula: LVMI (g/m²) = LVM/BSA Patients were classified in terms of PPM as severe, moderate and normal according to the indexed effective orifice area (IEOA) (severe: IEOA < 0.65 cm²/m², moderate: 0.65 ≤ IEOA ≤ 0.85 cm²/ m², normal: IEOA > 0.85 cm²/m²). The predicted effective orifice area (EOA) of the implanted prosthetic valve was calculated using the previously published EOA measurements for each valve type and size.10-12 IEOA was calculated with the following formula: IEOA (cm²/m²) = EOA/BSA Statistical analysis We used the SPSS 21.0 (IBM Inc, Chicago, IL, USA) program for statistical analysis. Numerical parameters are given as mean ± standard deviation, while categorical variables are given as frequency and percentage. Fit to normal distribution was examined with the Kolmogorov–Smirnov test. Analysis of homogeneity of numerical parameters was done with the Levene test. Comparison of independent groups was done with the independent samples t-test or one-way analysis of variance (ANOVA). Comparison of pre-operative–postoperative dependent parameters was done with the paired t-test. Binary logistic regression analysis was used for identification of predictive factors. Model regression fit was tested with the Box– Tidwell test. The fit of binary logistic regression models was confirmed with the Hosmer and Hemeshow test. Analysis of categorical groups was done with the chi-squared test. Suitable parameters were analysed with receiver operating characteristic (ROC) curves and diagnostic data were determined. For the whole study, the type-I error rate was 5% and p < 0.05 was accepted as significant. Results The mean age of the 199 patients included in the study was 64.4 ± 13.0 years, and the gender distribution was 41.7% women (n = 83) and 58.3% men (n = 116). Mean body mass index was 28.8 ± 5.4 kg/m² and mean BSA was 1.84 ± 0.19 m². Mean cardiopulmonary bypass duration was 85.21 ± 27.53 minutes with a mean cross-clamp duration of 59.12 ± 22.14 minutes. Demographic data are given in Table 1. According to the New York Heart Association (NYHA) heart failure classification, the class I patient rate was 9.5% (n = 19), class II was 74.9% (n = 149), class III was 15.6% (n = 31) and class IV was 0%. When the types of valves used were investigated, 78 patients had mechanical valves (39.2%), 36 had porcine valves (18.1%), 17 had bovine pericardial valves (8.5%) and 68 had sutureless valves (34.2%). The use of biological valves was higher in the group over 64 years (76.3%; n = 98), while selection of mechanic valves was higher in the 50–65-year age group (76.4%; n = 42). The mean valve dimension was 22.89 ± 2.41 mm. The distribution of valve brands used is given in Fig. 1. According to the four valve groups, echocardiographic findings for surviving patients in the first year postoperatively (n = 176) showed significant statistical changes in maximum gradient, mean gradient and PAP. The mean maximum gradient value was highest in the porcine valve group (27.79 ± 11.60 mmHg) and lowest in the sutureless valve group (19.87 ± 7.67 mmHg) (p = 0.001). The mean gradient value was highest in the porcine valve group (15.67 ± 7.89 mmHg) and lowest in the sutureless valve group (11.04 ± 4.79 mmHg) (p = 0.007). The postoperative mean PAP values were observed to be highest in the bovine pericardial valve group (35.20 ± 7.99 mmHg) and lowest in the mechanical valve group (30.63 ± 5.54 mmHg) (p = 0.013) (Table 2). Thepre-operativeandone-yearpostoperative echo-cardiography findings for patients were compared in general without dividing into valve groups. From this investigation, LVEDD, LVESD, maximum gradient, mean gradient, PAP, LVM and LVMI values were statistically significantly reduced in the postoperative period Table 1. Demographic data and related descriptive statistics Patient characteristics Frequency (n) Percentage (%) Age group, years 19–49 23 11.6 50–65 65 32.7 > 65 111 55.7 Gender Women 83 41.7 Men 116 58.3 Demographic data Diabetes mellitus 50 25.1 Hypertension 163 81.9 Chronic obstructive pulmonary disease 55 27.6 Peripheral vascular disease 12 6.0 Coronary artery disease 64 32.1 Atrial fibrillation 36 18.0 Cerebrovascular disease 9 4.5 Cardiac pacing device 2 1.0 Pulmonary embolism 1 0.5 Epilepsy 2 1.0 Congenital hearing loss 1 0.5 Bipolar disorder 1 0.5 History of malignancy 3 1.5
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