It is controversial whether high salt intake is directly associated with cardiovascular (CV) events and how far this relation is independent of blood pressure (BP). As Portugal has higher salt consumption and higher mortality by stroke than other European countries, we examined whether salt intake could predict the development of stroke and CV events in a hypertensive population.Methods
In a longitudinal retrospective study of a cohort of 608 adult treated hypertensive patients 54.1±14.3 years of age, BMI 29.3±8.3 kg/m2, 56.3% women and 17.1% diabetics, we evaluate the long-term prognostic significance of urinary sodium (UNa) excretion measured in 24 h valid samples within the first 3 months after admission along with 24 h ambulatory blood pressure monitoring and pulse wave velocity [(PWV), complior)] measurements.Results
The mean follow-up duration was 7.2 years (0.5–11.1 years), during which 122 CV events occurred including 80 strokes and 36 coronary events. In 608 patients (group A=507 without events and group B=101 with events: 69 strokes, 26 coronary events, six others), the mean 24 h UNa was 208±79 mmol/day, corresponding to a salt intake of 12.1±4.6 g/day. Twenty-four hours UNa correlated positively with BMI, PWV and systolic blood pressure (SBP) particularly with night-time SBP. Group B versus A showed higher UNa (260+98 vs. 198+71 mmol/day, P<0.001) and higher PWV, BP office, 24 h, daytime and night-time SBP. Logistic regression analysis identified age, night-time SBP and 24 h UNa+ [HR=1.09 (95% CI, 1.06–1.12, P<0.001)] for each 10 mmol increase of UNa+ as the only independent predictors of CV events. UNa+ above the median (189 mmol sodium/day) predicted CV events with HR=2.99 (95% CI, 1.75–5.13, P<0.001) with worse CV event-free survival rates (log rank statistics of 17.44, P<0.001).Conclusion
In a cohort of hypertensive patients, high salt intake independently predicts the occurrence of CV events, particularly of stroke.