Aldosterone-to-Renin Ratio as a Predictor of Stroke Under Conditions of High Sodium Intake: The Ohasama Study

BACKGROUND Aldosterone is thought to have deleterious effects on the cardiovascular system. The aldosterone-to-renin ratio (ARR) is more reproducible than aldosterone levels alone and could be an index for inappropriate aldosterone secretion or activity. We previously reported the apparent relation between ARR and hypertension in subjects with high sodium intake. This prospective study investigated the risk of ARR for a first stroke in a general population stratified by sodium intake. METHODS We obtained plasma renin activity (PRA) and plasma aldosterone concentrations (PAC) for 883 participants aged >= 35 years not receiving antihypertensive treatment in the general population of Ohasama (mean age: 59.0 +/- 11.3 years; 65.6% women). RESULTS Over a mean of 10.9 follow-up years, 45 strokes occurred. The median PRA, PAC, and ARR were 1.2 ng/ml/h, 6.4 ng/dl, and 5.3 ng/dl per ng/ml/h, respectively. Using Cox regression, we computed hazard ratios adjusted for sex, age, body mass index (BMI), and systolic blood pressure. No association between logARR and stroke was observed in subjects overall. However, in subjects with high sodium intake (>= median of 4,058 mg/day (salt equivalent, 10.5 g/day)), each 1 s.d. increase in logARR was associated with an increased hazard ratio for stroke (hazard ratio: 1.49, P = 0.04). No significant association was observed in subjects with low sodium intake (P = 0.7). When we repeated all the analyses using logPRA or logPAC, no significant associations were found. CONCLUSION These results suggest that high ARR, that is, relative aldosterone excess, is a predictor for stroke under conditions of high sodium intake.