Cardiovascular Journal of Africa: Vol 32 No 6 (NOVEMBER/DECEMBER 2021)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 6, November/December 2021 AFRICA 315 Inclusion criteria were adults aged 18 years and older, self- reported history of hypertension or use of antihypertensives, bloodpressure ≥ 140/90mmHgor onantihypertensivemedication. Hypertensive patients on drugs known to alter P-wave duration (e.g. irebesartan, quinapril, valsartan, ramipril) 12,15 were excluded from the study. Age- and gender-matched non-hypertensive controls were recruited from the general population, staff and relatives of patients who gave consent. They were healthy with no obvious organ disease, such as liver pathology, thyroid dysfunction, adrenal disorders, or chronic kidney disease. All subjects gave informed consent. Approval for the study was obtained from the institution Health Research and Ethics Committee. Eligible participants had a complete history taken and physical examination done. Information collected from each participant included socio-demographic data, past medical history of congenital heart disease, diabetes, any evidence of endocrine dysfunction, chronic kidney disease, any past hospitalisation and surgical history, family history of hypertension and detailed drug history. Examination included weight and height to calculate body mass index (BMI). Hip and waist circumference (WC) were recorded to determine the waist/hip ratio. Blood pressure (BP) was measured using appropriate cuff sizes connected to an Accoson branded mercury sphygmomanometer. Readings were taken with the arm positioned at the level of the heart, after participants had been seated and rested for at least five minutes. A standard 12-lead ECG was done for all participants using the Schiller AT-1 ECG machine in the cardiac laboratory; a hard copy was printed, scanned and saved for measurements. The Mindray BeneHeart R3 ECG machine was also used; with its added advantage of auto-saving all ECG tracings, this was stored for onward enlargement and digital measurement for better accuracy. Measurement of P-wave maximum and PWD: on the ECG, the P wave was identified in all leads as the first positive, negative or isophasic deflection before the QRS complex, and its duration was measured manually with ECG callipers. Its duration was taken at the onset; at the beginning of its deflection (positive or negative) in the isoelectric line-up to its termination in the same line. The P-wave duration was measured on all leads in at least three consecutive cycles, and the mean recorded P-wave maximum was taken as the longest measured P wave. 16 The minimum P-wave value was taken as the lowest measured value and PWD was calculated as the difference between the maximum and minimum P-wave duration. To qualify for analysis, there had to be visible P-wave amplitude in at least eight out of the 12 standard ECG leads, including leads II and V1, 17 and absence of any arrhythmias on the ECG. All readings in the 12 leads were considered. However measurements in leads where the P-wave amplitude was either too small or indistinct were discarded. Measurements were taken over three consecutive cycles. 17 In this study, participants with PWD > 33.46 ms were deemed to have prolonged PWD; this was based on a meta- analysis of PWD studies done among healthy individuals. 18 Echocardiography was performed using the Philips Clearvue echo-machine and a 3.5-MHz linear array transducer in the cardiac laboratory. Measurements were obtained according to the American Society of Echocardiography (ASE) leading- edge to leading-edge criteria. 19 Left ventricular systolic function (LVSF) and diastolic function (LVDF) were assessed according to the guidelines of the ASE recommendations. 19,20 In this study, indices for assessing abnormal LVSF was taken as EF < 50% for both male and female. We used transmitral Doppler velocities and tissue Doppler, as recommended by the ASE, 20 of the septal, lateral mitral annulus. However for those with normal or preserved EFs, more parameters than mitral inflow were needed. Pulsed-wave tissue Doppler imaging was performed in the apical four-chamber view to acquire septal and lateral mitral annular velocities. Septal e ′ and lateral e ′ were acquired and E/e ′ was calculated. All these parameters were combined together to further help make a conclusion on diastolic dysfunction. Septal e ′ < 7 cm/s and E/e ′ > 15 were considered to be diastolic dysfunction. 20 Statistical analysis Data obtained were coded and entered into a computer for analysis. Statistical analysis was done using the Statistical Package for Social Sciences Software (SPSS) version 21. Continuous variables are expressed as mean ± standard deviation (SD) and categorical variables as percentages, frequency tables and charts, as appropriate. Differences in categorical variables were assessed with chi-squared analysis while the student’s t -test was used for continuous variables that were normally distributed. The unpaired t -test was used for comparison of continuous variables between groups. Pearson’s linear correlation was used for normally distributed numerical data. This was used to assess the relationship of PWD and LVMI, EF, LVSF, LVDF (using E/ septal e ′ ), systolic and diastolic blood pressures. A value of p < 0.05 was considered statistically significant. Results This study comprised 150 subjects and 150 controls. Of the subjects, 72 (48.0%) were males while among the controls, 76 (50.6%) were males. The mean age of subjects was 49.38 ± 11.31 years while that of the controls was 47.14 ± 11.72 years ( p = 0.09). The median of hypertension duration among subjects was 48 months, the range being one to 360 months (Table 1). The mean BMI of subjects (26.84 ± 3.64 kg/m 2 ) was significantly higher than that of the controls (25.32 ± 3.22) ( p ≤ 0.001. And the mean WC of the subjects was also more (95.74 ± 11.08 vs 92.24 ± 9.62 cm) ( p = 0.004). The mean P-wave maximum duration (P max ) of the subjects was significantly longer than that of the controls (114.62 ± 16.28 vs 107.16 ± 15.50 ms; p ≤ 0.001).The mean P-wave minimum duration (P min ) of the subjects was 82.31 ± 14.87, significantly longer than that of the controls (76.96 ± 14.90 ms; p = 0.003). The mean PWD of the subjects was also longer (38.29 ± 8.02 vs 32.11 ± 4.72 ms, p ≤ 0.001). In this study all participants with PWD > 33.46 ms were deemed to have prolonged PWD; the prevalence of prolonged PWD among subjects was more than that of the controls (70.0 vs 32.6%; p ≤ 0.001). Furthermore, in the 105 subjects with prolonged PWD, their mean PWD was 42.06 ± 6.31 ms compared with the 49 controls with prolonged PWD whose