Humberto Zea-Diaz

Endogenous Nitric Oxide Synthase Inhibitors, Arterial Hemodynamics, and Subclinical Vascular Disease: The PREVENCION Study

Endogenous NO synthase inhibitors (end-NOSIs) have been associated with cardiovascular risk factors and atherosclerosis. In addition, end-NOSIs may directly cause hypertension through hemodynamic effects. We aimed to examine the association between end-NOSI asymmetrical dimethylarginine (ADMA) and N-guanidino-monomethyl-arginine (NMMA), subclinical atherosclerosis, and arterial hemodynamics. We studied 922 adults participating in a population-based study (PREVENCION Study) and examined the correlation between end-NOSI/l-arginine and arterial hemodynamics, carotid-femoral pulse wave velocity, and carotid intima-media thickness using linear regression. ADMA, NMMA, and l-arginine were found to be differentially associated with various classic cardiovascular risk factors. ADMA and NMMA (but not l-arginine) were significant predictors of carotid intima-media thickness, even after adjustment for cardiovascular risk factors, C-reactive protein, and renal function. In contrast, ADMA and NMMA did not predict carotid-femoral pulse wave velocity, blood pressure, or hemodynamic abnormalities. Higher l-arginine independently predicted systolic hypertension, higher central pulse pressure, incident wave amplitude, central augmented pressure, and lower total arterial compliance but not systemic vascular resistance or cardiac output. We conclude that ADMA and NMMA are differentially associated with cardiovascular risk factors, but both end-NOSIs are independent predictors of carotid atherosclerosis. In contrast, they are not associated with large artery stiffness, hypertension, or hemodynamic abnormalities. Our findings are consistent with a role for asymmetrical arginine methylation in atherosclerosis but not in large artery stiffening, hypertension, or long-term hemodynamic regulation. l-Arginine is independently associated with abnormal pulsatile (but not resistive) arterial hemodynamic indices, which may reflect abnormal l-arginine transport, leading to decreased intracellular bioavailability for NO synthesis.

Prevalence of lifestyle-related cardiovascular risk factors in Peru: the PREVENCION study

OBJECTIVES To estimate the prevalence of lifestyle-related cardiovascular risk factors in the adult population of Arequipa, the second largest city in Peru. METHODS The prevalence and patterns of smoking, alcohol drinking, lack of physical activity, high-fat diet, and low fruit and vegetable intake were evaluated among 1 878 subjects (867 men and 1 011 women) in a population-based study. RESULTS The age-standardized prevalence of current smoking, former smoking, and never smoking were 21.6%, 14.3%, and 64.1%, respectively. The prevalence of current smoking was significantly higher in men than women (31.1% vs. 12.1%; P < 0.01). The prevalence of current alcohol use was 37.7% and significantly higher in men than women (55.5% vs. 19.7%; P < 0.01). Similarly, the prevalence of binge drinking was 21.2%, and the percentage of men who binge drink (36.1%) was significantly higher than for women (6.4%; P < 0.01). The vast majority of alcohol drinkers reported a pattern of alcohol consumption mainly on weekends and holidays rather than regular drinking with meals during the week. The proportion of insufficiently active people was 57.6% and was significantly higher in women than men (63.3% vs. 51.9%; P < 0.01). Overall, 42.0% of adults reported consuming high-fat diets, 34.5% reported low fruit intake, and 33.3% reported low vegetable intake. CONCLUSIONS The high prevalence of lifestyle-related cardiovascular risk factors found in this Andean population is of concern. Preventive programs are urgently needed to deal with this growing problem.

Optimal Definitions for Abdominal Obesity and the Metabolic Syndrome in Andean Hispanics: The PREVENCION Study

OBJECTIVE We aimed to establish optimal definitions for abdominal obesity and metabolic syndrome (MetS) among Andean adults. RESEARCH DESIGN AND METHODS Among 1,448 Andean adults, we assessed the relationship between waist circumference and subclinical vascular disease assessed by carotid intima-media thickness (cIMT) and manifest cardiovascular disease (M-CVD). RESULTS Optimal waist circumference cutoffs to classify individuals with abnormal cIMT or M-CVD were >97 and >87 cm in men and women, respectively. With these cutoffs, there was substantial disagreement between the original American Heart Association/National Heart, Lung and Blood Institute (AHA/NHLBI) and the recently updated MetS definition, particularly among men (κ = 0.85). Subjects with MetS identified by the updated definition but not meeting the original AHA/NHLBI MetS criteria demonstrated significantly increased cIMT (P < 0.001) compared with subjects who did not meet the MetS criteria by either definition. CONCLUSIONS Our findings support the use of ethnic-specific waist circumference cutoffs and the updated MetS definition in Andean adults.

Normative values and correlates of carotid artery intima-media thickness and carotid atherosclerosis in Andean-Hispanics: The Prevencion Study

OBJECTIVES Carotid intima-media thickness (cIMT) is an independent predictor of cardiovascular risk. Furthermore, ethnicity and gender-specific normative data are required to assess cIMT, which are not available for Andean-Hispanics. In addition, data regarding correlates of subclinical atherosclerosis in ethnic population are needed. METHODS We studied 1448 adults enrolled in a population-based study in Peru. cIMT and carotid plaque were measured with high-resolution ultrasonography. A healthy reference sample (n=472) with no cardiovascular disease, normal weight and normal metabolic parameters was selected to establish normative cIMT values. Correlates of abnormal cIMT and carotid plaque were assessed in the entire population. RESULTS In the reference sample, 95th-percentile cIMT values were both age and gender-dependent. In stepwise regression, selected predictors of increasing cIMT were: older age, impaired fasting glucose, diabetes mellitus, higher systolic blood pressure, higher LDL-cholesterol, smoking and male gender. Predictors of carotid plaque included older age, male gender, higher systolic blood pressure, lower diastolic blood pressure and higher LDL-cholesterol. HDL-cholesterol and C-reactive protein were not associated with cIMT or carotid plaque. The lack of association with HDL-cholesterol was confirmed using high performance liquid chromatography. CONCLUSIONS We present ethnic-specific cut-offs for abnormal cIMT applicable to Andean-Hispanics and correlates of subclinical atherosclerosis in this population. Pending longitudinal studies, our data supports several risk associations seen in other populations and can be used to identify Andean-Hispanics at increased risk for atherosclerotic cardiovascular disease. The lack of association between HDL-C and cIMT or carotid plaque in this population requires further investigation.

Prevalence and patterns of hypertension in Peruvian Andean Hispanics: the PREVENCION study

Cardiovascular disease is emerging as a leading cause of morbidity and mortality in Latin America. Population-based data regarding the prevalence of hypertension and hypertension subtypes in Andean Hispanic populations are scarce. The authors performed a population-based study that included 1878 Peruvian Andean adults to determine: (1) the prevalence, awareness, and control of hypertension and (2) the relative frequency of hypertension subtypes (systolic vs. diastolic). The prevalence of hypertension was 15.7% (95% confidence interval [CI], 14.0%-17.4%), did not differ by gender, and increased steeply with age, particularly in women. Awareness, treatment, and control rates were 47.9%, 39.5%, and 14%, respectively. Diastolic blood pressure increased until age 50 years and reached a plateau thereafter, whereas mean arterial pressure continued to increase with age even after age 50 years. Furthermore, in sharp contrast with the United States population, the predominant type of hypertension was systodiastolic (41.7%; 95% CI, 35.1%-48.5%). Isolated systolic hypertension accounted for only 29.3% of cases (95% CI, 23.9%-35.4%) and was responsible for a minority of cases in all age groups before age 70 years. Hypertension subtypes in this Andean population seem to differ significantly from those present in the United States population, with a much larger proportion of systodiastolic and diastolic hypertension even with advanced age. These differences result from interactions between hemodynamic and structural factors, and further studies aimed at characterizing their genetic and environmental determinants and implications in end-organ damage and prognosis in this population may contribute to understanding the pathophysiology of hypertension.