Impact of prehypertension on left ventricular mass and QT dispersion in adult black Nigerians

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.