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

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 6, November/December 2021 314 AFRICA Relationship between P-wave dispersion, left ventricular mass index and function in Nigerian hypertensive patients Francisca O Inofomoh, Oluranti B Familoni, Casmir E Amadi Abstract Hypertension is the most prevalent cardiovascular disor- der in the world. It is associated with target-organ damage in various organs and ECG changes. P-wave dispersion (PWD), which represents inhomogeneous atrial conduction and discontinuation of impulses, has been observed, when prolonged, to predict atrial fibrillation, particularly in the setting of hypertension. This study of PWD in 150 hyperten- sive patients and controls sought to determine the prevalence of PWD in Nigerian hypertensives and its relationship to left ventricular mass index and left ventricular function. Mean PWD in normal subjects was 32.14 ± 4.72 ms and was significantly shorter than that in hypertensive patients at 38.29 ± 8.02 ms. In the total population, 51.3% had prolonged PWD ( > 33.46 ms); 70% in the hypertensives and 32.7% of controls. The only significant difference in hyper- tensives with prolonged and normal PWD was the waist circumference. There was a negative correlation between PWD and ejection fraction ( r = –0.17, p = 0.03), but not with diastolic function. Keywords: P-wave dispersion, hypertension, Nigeria Submitted 20/2/20, accepted 11/2/21 Published online 4/5/21 Cardiovasc J Afr 2021; 32 : 314–319 www.cvja.co.za DOI: 10.5830/CVJA-2021-003 Non-communicable diseases, including cardiovascular diseases (CVD) such as congestive cardiac failure, coronary heart disease, transient ischaemic attack (TIA), stroke, diabetes, cancers and chronic respiratory diseases, constitute a global problem. 1 CVD-related deaths have become very prevalent and about half are attributable to hypertension. 2 The global prevalence of hypertension [defined as systolic (SBP)/diastolic blood pressure (DBP) ≥ 140/90 mmHg] in adults aged 18 years and over was around 22% in 2014, 1 and was recently estimated at 30 to 35%. 3 Hypertension is the single most important cardiovascular risk factor affecting adults of low- to middle-income countries. 4 Studies in Nigeria have reported a prevalence of hypertension from eight to 46.4%, with a higher prevalence in urban than rural areas. The pooled prevalence increased from 8.6% in 1970–1979 to 22.5% in 2000–2011, 5 and in 2015 to 28.9%. 6 In a review of target-organ damage and cardiovascular complications in hypertensives aged 18 to 64 years, 7 prevalence of left ventricular hypertrophy (LVH) was 27.9% of the subjects, atrial fibrillation 16.4%, micro-albuminuria 12.3% and overt proteinuria 15.3%. Stroke was present in 6.3%, heart failure in 4.6%, retinopathy in 2.2%, ischaemic heart disease in 1.7% and peripheral vascular disease in 3.6%. P-wave dispersion (PWD) is defined as the difference between maximum and minimum P-wave duration on the surface ECG. It is believed to represent an inhomogeneous atrial conduction and discontinuous propagation of impulses. It also measures heterogeneity of atrial depolarisation on a 12-lead ECG. 8 PWD has been studied in a wide range of populations, in healthy adults and in various clinical conditions, including both cardiovascular and non-cardiac diseases, especially in hypertension-related disorders and arrhythmias. It has also been proposed as a useful marker of target-organ damage in the hypertensive population. 8 PWD has been found to be a useful predictor of paroxysmal atrial fibrillation, 8-11 as well as predicting the transition from paroxysmal to persistent atrial fibrillation. 9 PWD and left ventricular mass index (LVMI) have been shown to increase in children with hypertension. 10 PWD tends to be longer in boys than girls 11 and is generally longer in trained athletes than in sedentary individuals. 11 Some antihypertensives have been shown to reduce PWD and P-wave duration. Such drugs include quinapril, irbesartan, 12 nebivolol and atenolol. 13 These drug effects may, in addition to controlling blood pressure, help in reducing the risk of atrial fibrillation in hypertensives. It has also been observed that PWD is increased in patients with left ventricular diastolic dysfunction and has a weak correlation with left ventricular ejection fraction (LVEF). 14 We therefore set out to determine the pattern and relationship between PWD, LVMI, left ventricular systolic and diastolic function and blood pressure in a population of hypertensives attending the medical out-patient clinics of the Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, Nigeria. Methods This was a cross-sectional, comparative study involving consecutive consenting hypertensive subjects and normotensive controls. Patients were recruited from those attending the cardiology out-patient clinic and the general out-patient department of OOUTH. Cardiology Unit, Department of Medicine, Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria Francisca O Inofomoh, MB ChB, FMCP Oluranti B Familoni, MB BS, FMCP, FACC, drrantifamiloni@yahoo.com Department of Medicine, College of Medicine, University of Lagos Nigeria Casmir E Amadi, BMed Sci, MB BS, MSc, FMCP