HDCN Article Review/Hyperlink

Alderman MH, Ooi WL, Madhavan S, Sealey JE, Laragh JH

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

Am J Hypertens (Jan) 10:1-8 1997

Well established cardiovascular risk factors include hypertension, dyslipidemia, age, gender, smoking status, diabetic status and family history. Other risk factors studied include uric acid, plasma homocysteine levels and plasma renin activity (PRA). Over 25 years ago a putative link between PRA profile and myocardial infarction was suggested, and this association has been confirmed and extended in the last few years. One difficulty with the use of PRA profiling is, that in its original formulation, there has been the requirement for a 24 hour urinary sodium (to determine if the PRA level measured is inappropriately altered. The same group has now re-examined the concept of linking PRA to cardiovascular risk using PRA level only (in the absence of sodium excretion information as the dependent variable and myocardial infarction as an endpoint.

The patient population studied was from a worksite hypertension control program. All patients had untreated BP of > 160/95 mmHg. A total of 2902 subjects who had adequate BP readings, PRA and at least two months of follow-up were included. Treatment of these subjects was based on a step-care protocol. Treatment decisions were not based on PRA. Most of the subjects were treated with diuretics and beta-blockers. White males had the highest PRA levels whereas blacks and women had lower levels. All groups appeared to receive equal BP control with time. The overall group was divided into high normal and low renin groups.

All cause mortality and cardiovascular disease rates were higher in the high renin compared to the low renin group. In the Cox proportional hazard model, PRA was significantly associated to time to first MI along with LVH, cholesterol, age, sex, and smoking. The PRA level was most strongly associated with MI risk in white men. The authors suggest that PRA can be used to refine cardiovascular risk stratification. The relationship between PRA and cardiovascular risk was strongly influenced by the blood pressure, and in fact disappeared in subjects with diastolic BP < 95mmHg.

Comment: This study confirms the relationship of PRA (without sodium correction) to myocardial infarction in white moderately hypertensive older men. The relationship of PRA in other groups remains very weak. The incorporation of PRA in the evaluation of all hypertensive subjects will likely lead to considerable increases in health care costs. The prognostic and therapeutic benefit of the knowledge of the PRA is yet to be determined in clinical practice. (George Mansoor, M.D., University of Connecticut)