Plasma renin activity: a risk factor for myocardial infarction in hypertensive patients.

To determine whether pretreatment plasma renin activity (PRA), without accompanying 24-h urine sodium, can predict myocardial infarction (MI), the PRA levels of 2,902 hypertensive patients [white (38%), male (65%), median age 55 years], with mean entry blood pressure (BP) of 150/97 mm Hg were examined. During an average 3.6 years follow-up (87% > or = 9 months), there were 55 MIs, 21 strokes, and 16 other cardiovascular disease (CVD) deaths. Classification of PRA levels into 3 renin strata [high (H) PRA > or = 4.5 (n = 354), normal (N) 0.75 to 4.49 (n = 1,622), and low (L) < 0.75 (n = 926) ng/mL/h] yielded subgroups that did not differ in LVH (9% v 11%) or smoking prevalence (26% v 25%) but high versus low PRA subjects included more aged < 55 years (64% v 53%); white (49% v 25%); men (79% v 52%); cholesterol > or = 6.3 mmol/L (33% v 25%); all P values < .01. MI rates per 1,000/year were H: 9.3, N: 5.5, L: 2.5 (H v L, RR = 3.8, 95% CI: 1.7 to 8.4). A similar relationship was seen with total CVD (H: 12.5, N: 9.3, L: 5.2; RR = 2.4, 95% CI: 1.3 to 4.5) and all-cause mortality (H: 7.0, N: 6.2, L: 2.5; RR = 2.8, 95% CI: 1.2 to 6.8) but not CVA (H: 1.6, N: 2.0, L: 1.9). In a Cox survival analysis only renin, age, sex, smoking, LVH, and cholesterol were significantly (P < .02) related to MI occurrence. There was, for every 2 unit increase in PRA, an overall 25% increase in MI incidence. Among hypertensive subjects, PRA level (without urine sodium), is independently and directly associated with the incidence of MI.