Renin-angiotensin system inhibitor exerts prognostic effects in HFpEF patients with low baseline chloride level.

BACKGROUND:Few interventions have shown improved prognosis in patients with heart failure and preserved ejection fraction (HFpEF). Serum chloride levels, which are affected by serum renin secretion, are associated with the prognosis of HFpEF patients. However, the relationship between serum chloride levels and the effects of renin-angiotensin system inhibitors (RASi) in HFpEF patients remains unclear. We investigated whether the prognostic benefit of RASi depends on baseline serum chloride levels in HFpEF patients. METHODS:This observational study included 506 hospitalized patients with HFpEF (ejection fraction ≥50%) who were discharged. They were divided into two categories based on serum chloride levels at admission (cutoff level: 101 mEq/L) according to previous reports. In each chloride category, all-cause mortality, the primary endpoint, was compared between patients who received RASi and those who did not. RESULTS:Patients who received RASi had a significantly lower mortality rate after discharge than those who did not, but only in the lower chloride category (log-rank, P = 0.001). Multivariable Cox regression analysis confirmed the effect of risk reduction by RASi on all-cause mortality in the lower chloride category (adjusted hazard ratio: 0.31, 95% confidence interval: 0.11-0.84). The prognostic advantages of RASi were evident in the lower chloride category, but not in the higher chloride category, at admission (P for interaction = 0.027). CONCLUSION:RASi administration was associated with an improved prognosis only in HFpEF patients with a low baseline serum chloride level. Clinicians should consider RASi administration if patients' serum chloride levels are low, to improve the long-term prognosis of HFpEF patients.