A019: Effects of antihypertensive therapy on QT dispersion in essential hypertensive patients

We assessed the relationship between blood pressure (BP) level and QT dispersion in patients with essential hypertension. 40 untreated essential hypertensive subjects were treated with antihypertensive drugs for 8 weeks. 21 were treated with ACE inhibitor (imidapril, 10 mg, s.i.d.; group I). 11 were treated with alpha 1 blocker (bunazosin, 3, 6 or 9 mg, s.i.d.; group B). 8 were treated with beta blocker (metoprolol, 120 mg, s.i.d.; group M). BP and heart rate were measured for 48 hours every 30 minutes by ambulatory BP monitoring device (TM-2425, A&D Co.) before and after treatment. Standard 12-lead electrocardiogram (ECG) and echocardiography (UCG) was performed before and after treatment. QT dispersion (the difference between the maximum and minimum QT interval in different leads) was measured. Left ventricular hypertrophy (LVH) was assessed by ECG and UCG. Diurnal and nocturnal BP were decreased, and maximum QT interval and QT dispersion were shortened in group I. Diurnal BP was decreased, but QT dispersion did not change in group B. Diurnal BP was decreased, and maximum and minimum QT interval and QT dispersion prolonged in group M. Antihypertensive therapy with imidapril reduced QT dispersion and left ventricular mass index. We conclude that long-term imidapril treatment of hypertensive patients with LVH improves LVH and reduces the dispersions of QT. This effect may be important in preventing sudden cardiac death in hypertensive subjects.