QRS-amplitudes during antihypertensive treatment: a comparison between beta-blocker and thiazide diuretic regimens.

QRS-amplitudes and other ECG variables have been studied in 168 middle-aged men with uncomplicated, mild-to-moderate untreated primary hypertension. They were randomized to treatment with either the beta-adrenoceptor blocker metoprolol (n = 88) or the thiazide diuretic hydrochlorothiazide (n = 80). Significant reductions in combined precordial voltages (S1 + R5-6, S2 + R4, Smax + Rmax) were achieved on both regimens, probably reflecting a regression of hypertensive cardiac involvement. In the group treated with beta-blockers the reduction in all three combined voltage measurements was significant after one year's treatment. A longer period of treatment seemed to be necessary to achieve equal reductions with hydrochlorothiazide although a non-significant reduction was observed after the first year of follow-up in this group. A small increase in 1st degree AV-block was observed on both regimens, but no 2nd degree or total AV-block was recorded.