ABSTRACT
BACKGROUND: Increased QT dispersion (QTd) has been implicated as a marker of arrhythmogenesis and cardiac death. Paucity of literature on QTd in Nigeria necessitated an inquiry into QTd in adult hypertensive population. This study sought to: (i) compare the QTd values of adult hypertensive subjects with age and sex matched normotensive subjects and (ii)examine the relationship between QTd and left ventricular hypertrophy (LVH). STUDY DESIGN: One hundred and fifty-one hypertensive patients and 101 age and sex-matched controls were recruited into this study. A resting 12- lead ECG was obtained from all subjects for determination of QTd and ECG LVH using Sokolow Lyon (SL) and Araoye's codes. Echocardiographic LVH was determined for 60 hypertensive subjects and 60 age/sex matched controls. RESULTS: Hypertensive subjects had higher mean QTd than the controls (65.6 ± 28.1 ms vs 38.7 ± 11.3 ms, p< 0.0001). QTd of hypertensives with ECG LVH was significantly higher than those without ECG LVH (Araoye: 71.5 ± 22.0 ms vs 62.2 ± 24.1 ms, p = 0.02, SL; 72.0 ± 24.4 ms vs 61.6 ± 23.1 ms p = 0.009). Similarly the QTd of hypertensives with echocardiographic LVH (72.6 ± 21.3 ms) was higher than those without (60.1 ± 22.2 ms) but did not achieve statistical significance (p = 0.085). CONCLUSIONS: Hypertension with or without ECG LVH is associated with significantly increased QTd. Echo-cardiographic LVH is associated with a non significant increase in QTd in hypertensive subjects.
Subject(s)
Electrocardiography , Hypertension/complications , Hypertension/physiopathology , Hypertrophy, Left Ventricular/complications , Adult , Aged , Case-Control Studies , Echocardiography , Female , Humans , Hypertrophy, Left Ventricular/diagnostic imaging , Male , Middle Aged , Nigeria , Risk FactorsABSTRACT
BACKGROUND: Prehypertension has been associated with target-organ damage. This study sought to determine the impact of prehypertension (PHT) on QT dispersion and left ventricular hypertrophy (LVH) in adult black Nigerians. METHODS: One hundred and one subjects with office blood pressure (BP) < 140/90 mmHg were categorised according to their office BP into normotensive (normal BP < 120/80 mmHg, n = 57) and prehypertensive (prehypertensive BP 120-139/80-89 mmHg, n = 44) groups. Echocardiography and electrocardiography (ECG) were performed on the subjects. RESULTS: Thirty-four males aged 53.65 ± 16.33 years and 67 females aged 52.42 ± 12.00 years were studied. The mean QT interval dispersion (QT(d)) of the normotensive (38.96 ± 11.06 ms) and prehypertensive (38.41 ± 11.81 ms) groups were similar (p = 0.81). Prehypertensive subjects had higher left ventricular mass (LVM) (165.75 ± 33.21 vs 144.54 ± 35.55 g, p = 0.024), left ventricular mass index 1 (LVMI-1) (91.65 ± 16.84 vs 80.45 ± 18.65 g/m(2), p = 0.021) and left ventricular mass index 2 (LVMI-2) (54.96 ± 10.84 vs 47.51 ± 12.00 g/m(2.7), p = 0.017). QT(d) was independent of echocardiographic and electrocardiographic LVH (p > 0.05). CONCLUSIONS: Compared with normotension, prehypertension is associated with higher LVM but similar QT(d). This suggests that structural remodelling precedes electrical remodelling in prehypertension.
Subject(s)
Blood Pressure/physiology , Hypertrophy, Left Ventricular/etiology , Prehypertension/complications , Adult , Aged , Aged, 80 and over , Blood Pressure Determination/methods , Echocardiography/methods , Electrocardiography/methods , Female , Humans , Male , Middle Aged , Nigeria , Prehypertension/physiopathologyABSTRACT
BACKGROUND: Increase in QT dispersion (QTd) is associated with an increased risk of cardiovascular morbidity and mortality. OBJECTIVES: This study sought to (i) determine the mean QTd and (ii) characterise QTd in a healthy Nigerian population. METHODS: One hundred healthy Nigerian adults were studied. Healthy status of the subjects was determined by history and physical examination. A resting 12- lead ECG was obtained from all subjects for determination of QTc, QTd and ECG left ventricular hypertrophy (LVH) using Sokolow Lyon (SL) and Araoye's codes. Echocardiography was used to determine LV systolic function, LVM and LVMI for 60 subjects. RESULTS: The QTd ranged from 15-70ms with a mean value of 38.5 ± 11.2ms. QTd was independent of age (p = 0.86), sex (p = 0.97), heart rate (p = 0.22), blood pressure (p > 0.05), BMI (p = 0.81), QTc (p = 0.41), LVH (ECG and echo) and LV systolic function (p > 0.05). CONCLUSION: QT dispersion is independent of demographic parameters, LV systolic function and LV hypertrophy in healthy adult Nigerians.