Abstract 329: Blood Pressure Variability during High Salt Intake Is Associated with Cardiovascular Events in Patients with Essential Hypertension

Introduction: Accumulating evidence suggests that blood pressure variability (BPV) is a strong predictor of cardiovascular events in patients with hypertension. However, it is unknown whether high salt intake may affect BPV and its predictive value. Method: We analyzed the prevalence of cardiovascular events in 47 patients with essential hypertension in whom systolic BPV was determined during three different 7 day salt intake diets: regular (10g/day NaCl diet), low (3g), and high (20g). Supine blood pressures were measured every hour from 6:00 through 23:00. Mean and standard deviation (SD) in the supine systolic blood pressure (SBP) was used to calculate BPV. Results: SDs in SBP during the regular salt (12.5 ± 4.8 mm Hg) and high salt (12.8 ± 5.4 mm Hg) diets were significantly increased compared with the low salt (10.2 ± 4.0 mm Hg). Coefficients of variation (CV) in SBP for the regular, low, and high salt diets were 8 ± 3%, 7 ± 2% and 8 ± 3%, respectively. Salt loading significantly increased both SD and CV (p < 0.05). During a 22 ± 6 year follow-up period, 25 cardiovascular events were observed including 9 fatal events. ROC analyses revealed SD of SBP during regular salt diet had an AUC = 0.66 (95% CI, 0.53 - 0.74) and high salt diet of AUC = 0.72 (0.58 - 0.79), but the low salt diet was not associated with adverse events. CV of SBP during high salt diet, AUC = 0.72 (0.60 - 0.79), was also significantly associated with events. Kaplan Meier analysis also showed that patients with CV of SBP larger than 8% had significantly greater number of cardiovascular events (p < 0.05). Conclusion: These results suggest that high salt diet increased BPV, thereby leading to increased incidence of cardiovascular diseases.