The influence of the daily salt-intake on the antihypertensive action and atrial natriuretic peptide level in patietns with angiotensin receptor neprilysin inhibition

Abstract Background The angiotensin receptor–neprilysin inhibitor (ARNI) is a drug which acts through angiotensin receptor blocking effect and the increase in atrail natriuretic peptide (ANP) through neprilysin inhibitor in hypertension (HT). These combined effects result in a reduced risk of hospitalization for heart failure or death from cardiovascular causes. ANP is also known for its various cardioprotective effects including vasodilator and natriuretic action. Acording to Guyton's pressure-natriuresis curve, the efficacy of angiotensin receptor blocker drugs is diminished in HT cases with high daily salt inatke. However, whether the effect of ARNI on HT is attenuated in patients with high daily salt intake remains unclear. Purpose The present study investigated the influence of a daily salt intake on the antihypertensive action and ANP level in patients with ARNI. Methods Fourty-four consecutive essential HT patients on ARNI were enrolled. Blood pressure and ANP level were measured at baseline (before taking ARNI) and 3 weeks later. ARNI (200mg) was prescribed and maintained during the study. In addtion, the daily salt intake was calculated using creatinine and natrium levels in urine, age, and body weight according to Japanese hypertensive guideline at baseline and 3 weeks later. Results The average age was 70±8 years old. About 50% (N=23) was male. The mean sytolic and diastolic blood pressure was 148±14mmHg and 89±10mmHg, respectively. The mean daily salt intake was 9.5±2.2 g/day at baseline. The mean ANP level was 529±300pg/ml. At follow up (3 weeks later), the mean systolic and diastolic blood pressure significanly went down to 132± 18 mmHg and 70± 9 mmHg, respectively (p=0.03). ANP level also increased from 529±300pg/ml to 793±580pg/ml. However, the mean daily salt intake was almost same as the baseline at 9.4±3.2 g/day. The patients were divided into 2 groups; high daily salt intake (N=20 with mean daily salt intake 10.5±1.7g/day)) and low daily salt intake (N=24 with 8.4±3.1g/day) groups compared to the baseline. The absolute and percentage changes in systolic blood pressure were almost same in the high and low daily salt intake groups (-12.7±15.8mmHg vs -13.7±14.2mmHg, p=0.75; -5.8±6.5% vs.-7.0±9.6%, p=0.58, respectively). However, the change rate in ANP level was significantly higer in the high daily salt intake group than in the low daily salt intake group (155±63 vs. 12±16%, p=0.01). Conclusion ARNI demonstrates effectiveness in lowering the blood pressure even in patients with higher salt intake, unlike angiotensin receptor blocker. In cases with high salt intake, the notable increase in ANP levels may contribute to decreasing blood pressure through vasodilator and natriuretic action.