CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 4, September/October 2023 AFRICA 225 Association between salt sensitivity and blood pressure variability in patients with essential hypertension and predictive value for cardiovascular events Biao Zhang, Dexuan Zhao, Xiaohua Dai, Dengyue Pan Abstract We aimed to explore the association between salt sensitivity and blood pressure variability in patients with essential hypertension. A total of 730 patients with essential hypertension treated from 2016 to 2019 were subjected to salt-sensitivity risk stratification according to 24-hour ambulatory blood pressure monitoring. Their clinical data were compared among groups with different grades of salt-sensitivity risk, and the association between salt sensitivity and blood pressure variability was analysed. The influencing factors for cardiovascular events in patients with essential hypertension were analysed through multivariate regression analysis, and their predictive value was detected using receiver operating characteristic (ROC) curves. Salt sensitivity was positively correlated with night-time and 24-hour systolic standard deviation and 24-hour systolic blood pressure coefficient of variation. Age ≥ 55 years, family history of cardiovascular diseases, high risk of salt sensitivity, night-time systolic standard deviation ≥ 14 mmHg, 24-hour systolic standard deviation ≥ 20 mmHg and 24-hour systolic blood pressure coefficient of variation ≥ 13.5% were all independent risk factors for cardiovascular diseases in patients with essential hypertension (p < 0.05). The area under the ROC curve of the prediction model was 0.837. There was a positive correlation between salt sensitivity and blood pressure variability, which has predictive value for cardiovascular events in patients with essential hypertension. Keywords: salt sensitivity, blood pressure variability, essential hypertension Submitted 12/5/22, accepted 2/9/22 Published online 22/3/23 Cardiovasc J Afr 2023; 34: 225–230 www.cvja.co.za DOI: 10.5830/CVJA-2022-048 Essential hypertension is a complex disease caused by both genetic and environmental factors, and patients have a risk of damage to target organs such as the heart, brain and kidney, dominated by cardiovascular diseases.1 In the late 1970s, Luft et al.2 and Kawasaki et al.3 verified the existence of salt sensitivity in humans through long-term observation of blood pressure changes and degree of sodium retention under high-salt conditions. Salt sensitivity refers to the different responses of an individual’s blood pressure to salt load or salt restriction.4 In the case of changes in sodium intake, blood pressure changes by at least 5–10% or 5 mmHg.5 Salt sensitivity is the genetic basis for the link between salt intake and hypertension, manifested as elevation of blood pressure due to relatively high salt intake, and differences and genetic tendencies among individuals, which is an intermediate genetic phenotype of essential hypertension.6 Patients with salt-sensitive hypertension suffer from early damage to target organs such as the heart, brain and kidney, often accompanied by impaired vascular endothelial function.7 Blood pressure varies with physiological and environmental changes. Blood pressure variability refers to fluctuation of blood pressure, expressed as the standard deviation of the change in blood pressure within a certain time period. Clinically, the individual’s fluctuation of blood pressure is generally exhibited using blood pressure curves, and the normal blood pressure curve displays double peaks and one valley.8 Blood pressure variability is primarily detected clinically by 24-hour ambulatory blood pressure monitoring, and it has been applied in the diagnosis and treatment of hypertension.9,10 The risk of cardiovascular diseases and target organ damage rises with increasing blood pressure variability, and blood pressure variability is a predictor for cardiovascular diseases.11 In the present study, the association between salt sensitivity and blood pressure variability in patients with essential hypertension was explored, and its predictive value for cardiovascular diseases was also investigated. Detecting salt sensitivity-related indices can help clinicians to timeously adjust the treatment regimens to reduce the incidence rate of adverse cardiovascular events. Methods A total of 730 patients with essential hypertension treated in our hospital from 2016 to 2019 were selected as the subjects, and their baseline data were collected. Inclusion criteria were as follows: patients meeting the diagnostic criteria for essential hypertension, and those aged 18–75 years old. Exclusion criteria were as follows: patients with organic heart diseases, such as myocarditis, cardiomyopathy or valvular disease; those with severe liver or kidney insufficiency; patients with severe infections in the lungs or other sites; and those with severe malignancies Fuyang Second People’s Hospital, Fuyang, Anhui Province, China Biao Zhang, MD Dengyue Pan, MD, marvinlynchxwb@yahoo.com Fuyang Sixth People’s Hospital, Fuyang, Anhui Province, China Dexuan Zhao, MD First Affiliated Hospital of Anhui University of Chinese Medicine, Hefei, China Xiaohua Dai, MD
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