Mean arterial pressure: a better marker of stroke in patients with uncontrolled hypertension in rural areas of China

Association of mean arterial pressure with non-alcoholic fatty liver disease: results from the NAGALA study

Objective

Several recent reports have suggested the use of mean arterial blood pressure (MAP) to assess/predict the risk of developing atherosclerosis, chronic kidney disease, diabetes, metabolic syndrome, and poor prognosis in a variety of cardiovascular and cerebrovascular diseases. The current study aimed to investigate the association of MAP with non-alcoholic fatty liver disease (NAFLD) and to explore the differences in this association across populations.

Methods

This study used data from the NAGALA study from 1994 to 2016. MAP was calculated as 1/3 systolic blood pressure (SBP) + 2/3 diastolic blood pressure (DBP). Restricted cubic spline (RCS) and logistic regression models were used to examine the correlation of MAP with NAFLD.

Results

The study population was 14,251 general people undergoing health screening, with a median (interquartile range) age of 42 (36-50) years; among them, 48% were women, and 2,507 (17.59%) were diagnosed with NAFLD. After fully controlling for confounders in the current dataset, MAP was positively and non-linearly associated with NAFLD [(odds ratios (ORs): 1.39, 95% confidence intervals (CIs): 1.15, 1.68); P for non-linearity = 0.024]; the dose-response curve showed that there was a transient saturation effect interval when MAP was between 85 and 95 mmHg, where the risk of NAFLD was neither increased nor decreased. The results of the stratified analysis showed that the risk of NAFLD associated with MAP appeared to be influenced only by age (P-interaction = 0.002), but not by sex, body mass index (BMI), habits of exercise, drinking status, or smoking status (P-interaction > 0.05); further age-stratified RCS analysis showed that the non-linear association between MAP and NAFLD in the young and middle-aged and the middle-aged and elderly populations was consistent with the results of the whole population, whereas, in the elderly population, a U-shaped curve association between MAP and NAFLD was observed, with both low and high MAP increasing the risk of NAFLD.

Conclusion

In the general population, MAP was positively and non-linearly associated with NAFLD, and this association only differed significantly by age, but not by sex, BMI, habits of exercise, drinking status, and smoking status.

Mean arterial pressure values calculated using seven different methods and their associations with target organ deterioration in a single-center study of 1878 individuals

To assess the differences among seven different methods for the calculation of mean arterial pressure (MAP) and to identify the formula that provides MAP values that are more closely associated with target organ deterioration as expressed by the carotid cross-sectional area (CSA), carotid-to-femoral pulse-wave velocity (cf-PWV) and left ventricular mass (LVM). The study population consisted of 1878 subjects who underwent noninvasive cardiovascular risk assessment. Blood pressure (BP) was assessed in all subjects, and MAP was calculated by direct oscillometry and six different formulas. Carotid artery ultrasound imaging was performed in 1628 subjects. The CSA of the right and left common carotid artery (CCA) were calculated and used as surrogates of arterial wall mass and hypertrophy. Aortic stiffness was evaluated in 1763 subjects by measuring the cf-PWV. Finally, 218 subjects underwent echocardiographic examination for the assessment of LVM. Among the examined methods of MAP calculation, the formula MAP1=[diastolic BP]+0.412 × [pulse pressure] yielded the strongest correlations with the LVM, cf-PWV and CSA of the right and left CCA, even after adjusting for age and gender. The MAP calculation using the 0.412 was superior compared with the traditional formula that uses the 0.33 for the discrimination of subjects with left ventricular and carotid wall hypertrophy, as well as subjects with increased aortic stiffness. MAP estimated with the 0.412 is better correlated with target organ deterioration compared with other formulas. Future studies are needed to explore the accuracy of these formulas for MAP estimation compared with direct intra-arterial BP measurement.

Smoking, heart rate, and ischemic stroke: a population-based prospective cohort study among Inner Mongolians in China

BACKGROUND AND PURPOSE

Smoking is a major public health challenge and an important risk factor for cardiovascular diseases. No previous studies have evaluated the association among smoking, heart rate, and ischemic stroke in an Inner Mongolian population. We aim to evaluate the cumulative effect of smoking and heart rate on ischemic stroke incidence in this population.

METHODS

A prospective cohort study from June 2003 through July 2012 was conducted among 2530 people ≥20 years of age from Inner Mongolia, China. We categorized the participants into 4 subgroups according to smoking status and heart rate. Cox proportional hazards models and receiver operating characteristic curves were used to evaluate the association among smoking, heart rate, and ischemic stroke.

RESULTS

The multivariate-adjusted hazard ratios (95% confidence intervals) of ischemic stroke incidence for nonsmokers with heart rate ≥80 bpm, smokers with heart rate <80 bpm, and smokers with heart rate ≥80 bpm were 1.42 (0.62-3.28), 2.11 (1.06-4.23), and 2.86 (1.33-6.14), respectively, compared with nonsmokers with heart rate <80 bpm. The area under receiver operating characteristic curve (area under the curve) for a model containing smoking status and heart rate, along with conventional factors (area under the curve=0.755), was significantly (P=0.018) larger than the one containing only conventional factors (area under the curve=0.739).

CONCLUSIONS

Our study indicated that smoking was an independent risk factor of ischemic stroke, and smokers with faster heart rate had the highest risk of ischemic stroke among Inner Mongolians. These findings suggest that smoking status and heart rate may be valuable in predicting ischemic stroke incidence.

Coexistence of hyperlipidemia and acute cerebral ischemia/reperfusion induces severe liver damage in a rat model

AIM: To investigate the correlation of hyperlipemia (HL) and acute cerebral ischemia/reperfusion (I/R) injury on liver damage and its mechanism.

METHODS: Rats were divided into 4 groups: control, HL, I/R and HL+I/R. After the induction of HL via a high-fat diet for 18 wk, middle cerebral artery occlusion was followed by 24 h of reperfusion to capture I/R. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) were analyzed as part of liver function tests and liver damage was further assessed by histological examination. Hepatocyte apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. The expression of genes related to apoptosis (caspase-3, bcl-2) was assayed by immunohistochemistry and Western blotting. Serum tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1) and liver mitochondrial superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and Ca²⁺ levels were measured to determine inflammatory and oxidative/antioxidative status respectively. Microsomal hydroxylase activity of the cytochrome P450 2E1 (CYP2E1)-containing enzyme was measured with aniline as the substrate, and CYP2E1 expression in the liver tissue and microsome was determined by immunohistochemistry and Western blotting respectively.

RESULTS: HL alone induced by high-fat diet for 18 wk resulted in liver damage, indicated by histopathological analysis, and a considerable increase in serum ALT (25.13 ± 16.90 vs 9.56 ± 1.99, P < 0.01) and AST levels (18.01 ± 10.00 vs 11.33 ± 4.17, P < 0.05) compared with control. Moreover, HL alone induced hepatocyte apoptosis, which was determined by increased TUNEL-positive cells (4.47 ± 0.45 vs 1.5 ± 0.22, P < 0.01), higher caspase-3 and lower bcl-2 expression. Interestingly, compared with those in control, HL or I/R groups, massive increases of serum ALT (93.62 ± 24.00 vs 9.56 ± 1.99, 25.13 ± 16.90 or 12.93 ± 6.14, P < 0.01) and AST (82.32 ± 26.92 vs 11.33 ± 4.17, 18.01 ± 10.00 or 14.00 ± 6.19, P < 0.01) levels in HL+I/R group were observed suggesting severe liver damage, which was confirmed by liver histology. In addition, HL combined with I/R also caused significantly increased hepatocyte apoptosis, as evidenced by increased TUNEL-positive cells (6.20 ± 0.29 vs 1.5 ± 0.22, 4.47 ± 0.45 or 1.97 ± 0.47, P < 0.01), elevated expression of caspase-3 and lower expression of bcl-2. Furthermore, when compared to HL or I/R alone, HL plus I/R enhanced serum TNF-α, IL-1, liver mitochondrial MDA and Ca²⁺ levels, suppressed SOD and GSH-Px in liver mitochondria, and markedly up-regulated the activity (11.76 ± 2.36 vs 4.77 ± 2.31 or 3.11 ± 1.35, P < 0.01) and expression (3.24 ± 0.38 vs 1.98 ± 0.88 or 1.72 ± 0.58, P < 0.01) of CYP2E1 in liver.

CONCLUSION: The coexistence of HL and acute cerebral I/R induces severe liver damage, suggesting that cerebral ischemic stroke would exaggerate the damage of liver caused by HL. This effect is possibly due to enhanced CYP2E1 induction which further promotes oxidative damage, inflammation and hepatocyte apoptosis.

Relation of blood pressure components and categories and all-cause, stroke and coronary heart disease mortality in urban Chinese women: a population-based prospective study

OBJECTIVE

To determine whether various levels of blood pressure (BP), particularly normal and high normal BP or prehypertension, predict cardiovascular mortality among urban Chinese women.

METHODS

We evaluated the impact of all measures of BP on total mortality and stroke and coronary heart disease (CHD)-specific mortality in a population-based cohort study, the Shanghai Women's Health Study. Included in this analysis were 68 438 women aged 40-70 years at baseline for whom BP was assessed.

RESULTS

During an average of 5 years of follow-up, we identified 1574 deaths from all causes, 247 from stroke and 91 from CHD. Hypertension and higher levels of individual BP parameters including systolic BP, diastolic BP, pulse pressure, and mean arterial pressure were positively associated with all-cause, stroke, and CHD mortality (Ptrend < 0.05 for all except for DBP and CHD mortality). Prehypertension [adjusted hazard ratio (HRadj) = 1.65; 95% confidence interval, 0.98-2.78], particularly high normal BP (HRadj = 2.34; 95% confidence interval, 1.32-4.12), was associated with an increased risk of mortality from stroke. Hypertension accounted for 9.3% of mortality from all causes, 25.5% of mortality from stroke, and 21.7% mortality from CHD. High normal BP accounted for 10.8% of mortality from stroke. Isolated systolic BP also predicted stroke and mortality from CHD.

CONCLUSION

Hypertension is a significant contributor to mortality, particularly stroke and CHD mortality, among women in Shanghai. High normal BP is associated with high stroke mortality.