Effect of salt intake on clinical course and hemodynamics in patients with hypertrophic cardiomyopathy

Aim. To evaluate the relationship between the salt intake (NaCl) and the clinical and hemodynamic parameters in patients with hypertrophic cardiomyopathy (HCM).

Material and methods. Forty four patients with HCM (mean age, 60,4±15,3 years) were examined. Particular attention was paid to intraventricular obstruction and hypovolemic syncope. NaCl consumption was estimated by 24-hour urine sodium test.

Results. An inverse correlation was found between syncope and 24-hour natriuresis (r=-0,3, p=0,04). At 24-hour natriuresis <50 mmol/day,  syncope was more common (p=0,02): odds ratio (OR), 12,3 (95% confidence interval (CI): 1,3-121,3, p=0,03), as well as <65 mmol/day (p=0,04): OR, 8,3 (95% CI: 1,13-60,3; p=0,04). At higher 24-hour urine sodium values, no reduction in syncope risk was recorded. A correlation was found between low values of left ventricular (LV) stroke volume index (SVI) (<26 ml/m2) and 24-hour urine sodium (<50 mmol/day) (r=0,5, p=0,01). An inverse correlation was observed between LV SVI and syncope at 24-hour natriuresis <50 mmol/day (r=-0,9; p=0,05). An inverse relationship was found between the intraventricular obstruction and 24-hour urine sodium (r=-0,4, p=0,01). The prevalence of obstruction increased as natriuresis decreased: at 120 mmol/day, OR was 4,3 (95% CI: 1,01-18,6, p=0,048), at 110 mmol/day, OR — 4,6 (95% CI: 1,218,1, p=0,03), and at 100 mmol/day, OR — 4,0 (95% CI: 1,1-11,7, p=0,04). An increase in 24-hour urine sodium >130 mmol/day was not followed by a further decrease in obstruction prevalence.

Conclusion. To reduce the obstruction risk, the optimal 24-hour urine sodium level is ≥130 mmol/day (NaCl, 7,5 g/day). To reduce the syncope risk, regardless of obstruction presence, the optimal level of 24-hour natriuresis is ≥65 mmol/day (NaCl, 3,8 g/day).

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