Effect of daily sodium consumption on hemodynamics in patients with hypertrophic cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Patients with hypertrophic cardiomyopathy (HCM) are advised to avoid dehydration and drink enough fluids to maintain circulating blood volume (BV) when LV volume is reduced. Salt (NaCl) intake is one of the main factors affecting BV and hemodynamics. At the same time, there have been no studies to find the optimal level of salt intake and identify its effect on hemodynamics in HCM patients. Purpouse To estimate the effect of salt (NaCl) intake on the clinical course and hemodynamics in hypertrophic cardiomyopathy patients (HCM). Material and methods: 54 HCM patients aged between 18 and 81 (average age 60.1 ± 15.2 years), were examined. Medical history and complaints were mainly focused on the shortness of breath, dizziness, and nonarrhythmogenic syncope. ECG, Holter ECG monitoring and EchoCG were performed. The NT-proBNP level and the 24-hour urine sodium tests were taken. Results The average level of Na+ in the 24-hour urine sample was 128.2 ± 84.1 mmol/day; an inverse correlation was found between this parameter and syncope (r=-0.4, p = 0.03) and also with LV outflow tract obstruction (r=-0.3, p = 0.04). NT-proBNP level was found to be 1449 [444; 3807] ng/L, with a positive relationship between NT-proBNP and functional class of chronic heart failure by NYHA (r = 0.4; p = 0.009). In patients with daily natriuresis <50 mmol/day, syncope was more common (60% vs 8%, p = 0.01), a lower LV stroke volume index (LV SVI) was revealed (19.8 ± 3.6 vs 27.1 ± 4, 8 ml/m², p = 0.006); daily natriuresis >65 mmol/day corresponded to a higher right atrium volume index (21.7 ± 7.3 vs 29.1 ± 11.1 ml/m², p = 0.01), higher left atrium volume index (36.0 ± 13.8 vs 47.6 ± 13.8 ml/m², p = 0.01) and higher systolic pulmonary artery pressure (28.4 ± 6.3 vs 35.1 ± 7.9 mm Hg, p = 0.02). An increase in natriuresis > 100 mmol/day was followed by a decrease in the frequency of obstruction (52% vs 22%, р=0.04), which persisted at natriuresis > 110 mmol/day (58% vs 29%, р=0.03). Daily natriuresis <50 mmol/day folowed by increased of syncope with OR 16.9 (95% CI: 2.2-132.5, p = 0.007), and <65 mmol/day - OR 7.6 (95% CI: 1.4-41.7; p = 0.02). Obstruction frequency decreased with natriuresis > 90 mmol/day - OR 3.7 (95% CI: 1.2-12.1, p = 0.03), with natriuresis >100 mmol/day OR 3.9 (95% CI: 1.3-12.3, p = 0.02), with natriuresis >110 mmol/day OR 5.2 (95% CI: 1.6-16.9, p = 0.007). Conclusions Low salt intake in the observed cohort of HCM patients was accompanied by a lower LV SVI and higher incidents of syncope. As salt intake in patients with HCM increases, the atria volume and the pressure in the pulmonary artery increase also. Frequency of obstruction was reduced with sodium levels in daily natriuresis > 90 mmol/day.