Relations of stroke volume and cardiac output to body composition: the strong heart study.

BACKGROUND: Although cardiac output (CO) plays the vital role of delivering nutrients to body tissues, few data are available concerning the relations of stroke volume (SV) and CO to body composition in large population samples. METHODS AND RESULTS: Doppler and 2D echocardiography and bioelectric impedance in 2744 Strong Heart Study participants were used to calculate SV and CO and to relate them to fat-free body mass (FFM), adipose mass, and demographic variables. Both SV and CO were higher in men than women and in overweight than normal-weight individuals, but these differences were diminished or even reversed by normalization for FFM or body surface area. In both sexes, SV and CO were more strongly related to FFM than adipose mass, other body habitus measures, arterial pressure, diabetes, or age. In multivariate analyses using the average of Doppler and left ventricular SV to minimize measurement variability, FFM was the strongest correlate of SV and CO; other independent correlates were adipose mass, systolic pressure, diabetes, age, and use of digoxin and calcium channel and beta-blockers. CONCLUSIONS: In a population-based sample, SV and CO are more strongly related to FFM than other variables; increased FFM may be the primary determinant of increased SV and CO in obesity.

Impact of diabetes on cardiac structure and function: the strong heart study.

BACKGROUND: Whether diabetes mellitus (DM) adversely affects left ventricular (LV) structure and function independently of increases in body mass index (BMI) and blood pressure is controversial. METHODS AND RESULTS: Echocardiography was used in the Strong Heart Study, a study of cardiovascular disease in American Indians, to compare LV measurements between 1810 participants with DM and 944 with normal glucose tolerance. Participants with DM were older (mean age, 60 versus 59 years), had higher BMI (32.4 versus 28.9 kg/m(2)) and systolic blood pressure (133 versus 124 mm Hg), and were more likely to be female, to be on antihypertensive treatment, and to live in Arizona (all P<0.001). In analyses adjusted for covariates, women and men with DM had higher LV mass and wall thicknesses and lower LV fractional shortening, midwall shortening, and stress-corrected midwall shortening (all P<0.002). Pulse pressure/stroke volume, a measure of arterial stiffness, was higher in participants with DM (P<0.001 independent of confounders). CONCLUSIONS: Non-insulin-dependent DM has independent adverse cardiac effects, including increased LV mass and wall thicknesses, reduced LV systolic chamber and myocardial function, and increased arterial stiffness. These findings identify adverse cardiovascular effects of DM, independent of associated increases in BMI and arterial pressure, that may contribute to cardiovascular events in diabetic individuals.

Rising tide of cardiovascular disease in American Indians. The Strong Heart Study.

BACKGROUND: Although cardiovascular disease (CVD) used to be rare among American Indians, Indian Health Service data suggest that CVD mortality rates vary greatly among American Indian communities and appear to be increasing. The Strong Heart Study was initiated to investigate CVD and its risk factors in American Indians in 13 communities in Arizona, Oklahoma, and South/North Dakota. METHODS AND RESULTS: A total of 4549 participants (1846 men and 2703 women 45 to 74 years old) who were seen at the baseline (1989 to 1991) examination were subjected to surveillance (average 4.2 years, 1991 to 1995), and 88% of those remaining alive underwent a second examination (1993 to 1995). The medical records of all participants were exhaustively reviewed to ascertain nonfatal cardiovascular events that occurred since the baseline examination or to definitively determine cause of death. CVD morbidity and mortality rates were higher in men than in women and were similar in the 3 geographic areas. Coronary heart disease (CHD) incidence rates among American Indian men and women were almost 2-fold higher than those in the Atherosclerosis Risk in Communities Study. Significant independent predictors of CVD in women were diabetes, age, obesity (inverse), LDL cholesterol, albuminuria, triglycerides, and hypertension. In men, diabetes, age, LDL cholesterol, albuminuria, and hypertension were independent predictors of CVD. CONCLUSIONS: At present, CHD rates in American Indians exceed rates in other US populations and may more often be fatal. Unlike other ethnic groups, American Indians appear to have an increasing incidence of CHD, possibly related to the high prevalence of diabetes. In the general US population, the rising prevalence of obesity and diabetes may reverse the decline in CVD death rates. Therefore, aggressive programs to control diabetes and its risk factors are needed.

Diabetes and coronary heart disease in American Indians: The Strong Heart Study.

Coronary heart disease (CHD) is the leading cause of death among American Indians. However, information on the prevalence of CHD and its association with known risk factors is limited. The purpose of the Strong Heart Study is to quantify CHD and its risk factors among three geographically diverse groups of American Indians. The population consists of 4,549 adults between 45 and 74 years of age in 13 Indian communities in Arizona, Oklahoma, and South and North Dakota. The phase I examination (1989-1991) revealed very high prevalence rates of diabetes that ranged from 33 to 72% in men and women in the three centers. Prevalence rates of definite myocardial infarction (MI) and definite CHD were higher in men than in women in all three centers (P < 0.0001) and in those with diabetes (P = 0.002 and P = 0.0003 in women and men respectively). Diabetes was associated with a relatively greater increase in prevalence of MI (prevalence rate = 3.8 vs. 1.9) and CHD (prevalence rate = 4.6 vs. 1.8) in women than in men. Logistic regression analysis indicated that the prevalence of CHD among American Indians was significantly related to age, diabetes, hypertension, albuminuria, percentage of body fat, smoking, high concentrations of plasma insulin, and low concentrations of HDL cholesterol. Lower prevalence rates of CHD were found in Arizona despite higher rates of diabetes, obesity, hypertension, and albuminuria; these lower rates may be in part related to lower smoking frequency and lower concentrations of total and LDL cholesterol. These findings from the baseline Strong Heart Study examination emphasize the relative importance of diabetes and its associated variables as risk factors for CHD among American Indian populations.

Risk factors for coronary heart disease in diabetic and nondiabetic Native Americans. The Strong Heart Study.

The Strong Heart Study is a study of cardiovascular disease and its risk factors among diabetic and nondiabetic Native Americans. The study includes 12 tribes in Arizona, Oklahoma, and North and South Dakota. Phase I, initiated in October 1988, included a mortality survey to determine CVD death rates in individuals 35-74 yr old between 1984 and 1988, and a medical record review to determine rates of myocardial infarction and stroke for individuals ages 45-74 during the same time. In addition, a physical examination was performed on persons 45-74 yr old to measure the prevalence of cardiovascular and peripheral vascular diseases and known and suspected risk factors. In Phase II, CVD mortality and morbidity rates will be determined in the examined cohort by surveillance. CVD risk factors, changes in risk factors over time, and the relationship between risk factors and CVD incidence will be assessed longitudinally. This study provides data on the relative importance of cardiovascular risk factors in nondiabetic and diabetic Native Americans and will provide insight into possible variations in the quantitative or qualitative importance of CVD risk factors among diverse population groups.

The impact of diabetes on left ventricular filling pattern in normotensive and hypertensive adults: the Strong Heart Study.

OBJECTIVES: We sought to determine the effect of diabetes mellitus (DM) on left ventricular (LV) filling pattern in normotensive (NT) and hypertensive (HTN) individuals. BACKGROUND: Diastolic abnormalities have been extensively described in HTN but are less well characterized in DM, which frequently coexists with HTN. METHODS: We analyzed the transmitral inflow velocity profile at the mitral annulus in four groups from the Strong Heart Study: NT-non-DM (n = 730), HTN-non-DM (n = 394), NT-DM (n = 616) and HTN-DM (n = 671). The DM subjects were further divided into those with normal filling pattern (n = 107) and those with abnormal relaxation (AbnREL) (n = 447). RESULTS: The peak E velocity was lowest in HTN-DM, intermediate in NT-DM and HT-non-DM and highest in the NT-non-DM group (p < 0.001), with a reverse trend seen for peak A velocity (p < 0.001). In multivariate analysis, E/A ratio was lowest in HTN-DM and highest in NT-non-DM, with no difference between NT-DM and HTN-non DM (p < 0.001). Likewise, mean atrial filling fraction and deceleration time were highest in HTN-DM, followed by HTN-non-DM or NT-DM and lowest in NT-non-DM (both p < 0.05). Among DM subjects, those with AbnREL had higher fasting glucose (p = 0.03) and hemoglobin A1C (p = 0.04). CONCLUSIONS: Diabetes mellitus, especially with worse glycemic control, is independently associated with abnormal LV relaxation. The severity of abnormal LV relaxation is similar to the well-known impaired relaxation associated with HTN. The combination of DM and HTN has more severe abnormal LV relaxation than groups with either condition alone. In addition, AbnREL in DM is associated with worse glycemic control.

Prevalence and correlates of aortic regurgitation in American Indians: the Strong Heart Study.

OBJECTIVES: We sought to determine the prevalence and correlates of aortic regurgitation (AR) in a population-based sample group. BACKGROUND: Concern over induction of AR by weight loss medication highlights the importance of assessing the prevalence and correlates of AR in unselected patient groups. METHODS: Aortic regurgitation was assessed by color flow Doppler echocardiography in 3,501 American Indian participants age 47 to 81 years during the second Strong Heart Study. RESULTS: Mild (1+) AR was present in 7.3%, 2+ AR in 2.4% and 3+ to 4+ AR in 0.3% of participants, more frequently in those > or =60 years old than in those <60 years old (14.4% vs. 5.8%, p<0.001); AR was unrelated to gender. Compared with participants without AR, those with mild AR had a lower body mass index (p<0.004) and higher systolic pressure (p<0.003). Participants with AR had larger aortic root diameters (3.6+/-0.4 vs. 3.4+/-0.4 cm, p<0.001), higher creatinine levels (1.3+/-1.3 vs. 1.0+/-1.0 mg/dl, p<0.001) and higher urine albumin/creatinine levels (3.6+/-2.3 vs. 3.3+/-2.0 log, p<0.001), as well as higher prevalences of aortic stenosis (AS) or mitral stenosis (MS) (p<0.001). Regression analysis showed that AR was independently related to older age and larger aortic roots (p<0.0001), AS and absence of diabetes (p = 0.002), MS (p = 0.003) and higher log urine albumin/creatinine (p = 0.005). CONCLUSIONS: Aortic regurgitation occurred in 10% of a sample group of middle-aged to older adults and was related to older age, larger aortic root diameter, aortic and mitral stenosis and albuminuria. There was no association of AR with being overweight and a negative association of AR with diabetes.

The benefits of isoniazid chemoprophylaxis and risk factors for tuberculosis among Oglala Sioux Indians.

In a case-control study of 92 Indian patients, 46 with active tuberculosis (cases) and 46 tuberculin reactors without the disease (control subjects), significantly more control subjects than patients had prior adequate isoniazid chemoprophylaxis. While the Indian Health Service recommends treating all tuberculin reactors with isoniazid prophylaxis, most (75%) of our tuberculosis (TB) cases could have been prevented if the guidelines of the American Thoracic Society had been followed. Diabetes, alcohol abuse, and chronic renal failure were risk factors for active TB. Despite marked reductions in TB morbidity and mortality rates among American Indians and Alaska Natives over the past 30 years, their TB rates are still two to three times higher than overall United States and white rates. Enhanced TB control programs with an emphasis on preventive therapy for patients at risk for developing active disease, especially those with diabetes and chronic renal failure, could decrease the incidence and eventually eliminate TB among American Indians and Alaska Natives.

Cardiovascular disease among American Indians and Alaska Natives.

OBJECTIVE: To compare the regional differences in cardiovascular disease in AI/AN with the U.S. general population and determine the parity gap and preventable proportion of cardiovascular mortality. RESEARCH DESIGN AND METHODS: Age-adjusted cardiovascular disease mortality rates for 1981-1983 and hospital discharge rates for 1982-1984 reported by the IHS were compared with U.S. data for 1982 and 1983, respectively. RESULTS: Rates of ischemic heart disease and atherosclerosis were found to be generally low among AI/AN although those in the 25- to 44-yr age-group have higher death rates from cardiovascular disease than in the U.S. population. Although the mortality rate from cardiovascular disease in AI/AN is 19% lower than the rate for the general U.S. population, the parity gap in individual regions of the U.S. ranges from favorable to extremely unfavorable. There were also wide variations in the preventable gap theoretically possible by reduction of the three major risk factors. CONCLUSIONS: Changing nutrition and exercise patterns and the increasing prevalence of diabetes in many Indian tribes may have adverse effects in the future, possibly increasing the prevalence of heart disease. Regional differences in the prevalence of some major cardiovascular risk factors (smoking, hypertension, hypercholesterolemia, and diabetes) are the probable explanation for these differences in cardiovascular morbidity and mortality rates. Prevention and treatment of these risk factors will have the greatest impact in attempts to reduce cardiovascular disease among AI/AN. In addition, moderation in the use of alcohol, or abstinence, may prevent sudden deaths resulting from acute intoxication.

Type II diabetes and cognitive function. A population-based study of Native Americans.

OBJECTIVE: To explore the relationship between type II diabetes and cognitive function in older Native Americans and to assess the effects of other selected risk factors for cognitive dysfunction on this relationship. RESEARCH DESIGN AND METHODS: Cognitive function was assessed in 80 diabetic and 81 nondiabetic Native Americans who were 45-76 years of age in a cross-sectional population-based sub-study of the Strong Heart Study. Thirteen cognitive function tests were administered during a personal interview. Information about six other risk factors for cognitive dysfunction, including depressive symptoms, physical function, alcoholism, current alcohol use, hypertension, and myocardial infarction, was ascertained from interviews and from abstraction of medical records. RESULTS: Diabetes was associated with impairment on only two tests of cognitive function: verbal fluency (P = 0.004) and similarities (P = 0.010). Depressive symptoms were related to verbal fluency (P = 0.004), but did not explain the diabetes-related difference in performance. The effects of hypertension, depressive symptoms, and current alcohol use explained the diabetes-related performance difference on similarities. Cognitive function was not related to metabolic control (HbA1c level). CONCLUSIONS: We found little evidence that type II diabetes in this population of Native Americans is associated with decrement in cognitive function. Some of the cognitive impairment previously attributed to diabetes may be related, at least in part, to the influence of other risk factors. This should be considered in the design of future studies in other populations.

The prevalence of diabetic retinopathy and associated risk factors among Sioux Indians.

OBJECTIVE: To estimate the prevalence of and risk factors for diabetic retinopathy among Sioux Indians of South Dakota. RESEARCH DESIGN AND METHODS: Strong Heart Study (SHS) participants with diabetes who are members of the Cheyenne River Sioux Tribe and the Oglala Sioux Tribe were invited to have ophthalmological examinations in 1991. A total of 417 people had eye examinations out of the 488 diabetic SHS participants of the two tribes (85% participation rate). Fundus photographs were obtained of each eye and graded for severity of retinopathy using the modified Airlie House Classification Scheme. Risk factors for retinopathy were determined from the SHS database. RESULTS: The prevalence of diabetic retinopathy among participants from these tribes was 45.3%. Risk factors associated with severity of retinopathy include mean fasting glucose, level. HbA1c, systolic blood pressure, urinary albumin-to-creatinine ratio, renal dialysis, and duration of diabetes. CONCLUSIONS: The prevalence of diabetic retinopathy among diabetic Sioux Indians is similar to or higher than the prevalence in other diabetic Indian and non-Indian populations. Aggressive glycemic and blood pressure control is urgently needed to reduce this high rate, and annual eye examinations to detect and treat diabetic retinopathy should be emphasized.

Adverse effects of diabetes on multiple cardiovascular disease risk factors in women. The Strong Heart Study.

OBJECTIVE: Many studies have shown that diabetes increases the risk of cardiovascular disease (CVD) in women to a greater extent than in men. One explanation could be that diabetes has more adverse effects on CVD risk factors in women than in men. We compared diabetes-associated differences in CVD risk factors in men and women in the Strong Heart Study, a population-based study of CVD and its risk factors in American Indians. RESEARCH DESIGN AND METHODS: A total of 1,846 men and 2,703 women between the ages of 45 and 74 years from 13 American Indian communities in three geographic areas underwent an examination that included a medical history; an electrocardiogram; anthropometric and blood pressure measurements; an oral glucose tolerance test; and measurements of fasting plasma lipoproteins, fibrinogen, insulin, HbA1c, and urinary albumin. RESULTS: Statistically significantly greater adverse differences in those with diabetes versus those without diabetes were observed in women than in men for waist-to-hip ratio, HDL cholesterol, apolipoprotein (apo)B, apoA1, fibrinogen, and LDL size. In multiple linear regression models adjusting for age, center, sex, and diabetes, the diabetes by sex interaction terms were statistically significant for waist-to-hip ratio, LDL cholesterol, HDL cholesterol, apoB, apoA1, fibrinogen, and LDL size. CONCLUSIONS: Compared with diabetes-associated differences in men, diabetes in women was related to greater adverse differences in levels of several CVD risk factors. Although the magnitude of the individual diabetes-related differences between men and women was not large, the combined effects of these risk factor differences in diabetic women may be substantial. The apparent greater negative impact of diabetes on CVD risk factors in women may explain, in part, the greater risk for CVD in diabetic women.

Glycemic control in diabetic American Indians. Longitudinal data from the Strong Heart Study.

OBJECTIVE: To describe glycemic control and identify correlates of elevated HbA1c levels in diabetic American Indians participating in the Strong Heart Study, which is a longitudinal study of cardiovascular disease in American Indians in Arizona, Oklahoma, South Dakota, and North Dakota. RESEARCH DESIGN AND METHODS: This analysis is based on data from the baseline (1989-1992) and first follow-up (1994-1995) examinations of the Strong Heart Study. The 1,581 diabetic participants included in this analysis were aged 45-74 years at baseline, were diagnosed with diabetes before and at baseline, and had their HbA1c levels measured at follow-up. HbA1c was used as the index of glycemic control. Characteristics that may affect glycemic control were evaluated for cross-sectional and longitudinal relationships by analysis of covariance and multiple regression. RESULTS: There was no significant difference between median HbA1c at baseline (8.4%) and at follow-up (8.5%). Sex, age (inversely), and insulin and oral hypoglycemic agent therapy were significantly related to HbA1c levels in both the cross-sectional and longitudinal analyses. Current smoking, prior use of alcohol, and duration of diabetes were significant only for the cross-sectional data. Baseline HbA1c significantly and positively predicted HbA1c levels at follow-up. Comparison of HbA1c by therapy type shows that insulin therapy produced a significant decrease in HbA1c between the baseline and follow-up examinations. CONCLUSIONS: Glycemic control was poor among diabetic American Indians participating in the Strong Heart Study. Women, patients taking insulin or oral hypoglycemic agents, and younger individuals had the worst control of all the participants. Baseline HbA1c, and weight loss predicted worsening of control, whereas insulin therapy predicted improvement in control. Additional therapies and/or approaches are needed to improve glycemic control in this population.

Prevalence of undiagnosed diabetes in three American Indian populations. A comparison of the 1997 American Diabetes Association diagnostic criteria and the 1985 World Health Organization diagnostic criteria: the Strong Heart Study.

OBJECTIVE: In 1997, the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus of the American Diabetes Association (ADA) recommended three new sets of criteria for the diagnosis of diabetes that were different from those established by the World Health Organization (WHO) in 1985. One of these three methods was based on a fasting plasma glucose value only. This article compares ADA criteria with WHO criteria by applying them to three subgroups of American Indians in the Strong Heart Study who had no known diabetes. RESEARCH DESIGN AND METHODS: The Strong Heart Study is a prospective epidemiological study of vascular disease in three American Indian populations aged 45-74 years. During the baseline examination from 1988 to 1991, participants without diagnosed diabetes underwent a fasting glucose test and a 2-h oral glucose tolerance test. These values were used to compare the ADA and WHO diagnostic criteria. RESULTS: By using fasting and 2-h glucose values, prevalence rates of undiagnosed diabetes were 15.9% according to WHO criteria and 14.4% according to ADA criteria. The overall agreement rate was 65%, and the weighted kappa statistic was 0.474, which indicates moderate agreement. The age-specific analysis showed that, among participants between 45 and 54 years of age, the prevalence rates of undiagnosed diabetes were 13.4% according to WHO criteria and 12.7% according to ADA criteria. Among those aged 55-74 years, the rates were 18.7% according to WHO criteria and 16.3% according to ADA criteria. Thus, the difference in the prevalence rates when using WHO and ADA criteria, although generally small in this population, was three times higher in the older group (2.4%) than the difference in the younger group (0.7%). CONCLUSIONS: The Strong Heart Study found that prevalence rates of undiagnosed diabetes determined by ADA criteria and WHO criteria were similar in its American Indian population. The data suggest that the difference between the two criteria may increase as age increases. Longitudinal data will be needed to evaluate further the utility of the two criteria.

Diabetes and impaired glucose tolerance in three American Indian populations aged 45-74 years. The Strong Heart Study.

OBJECTIVE: To estimate prevalence rates of diabetes and impaired glucose tolerance (IGT) in three American Indian populations, using standardized diagnostic criteria, and to assess the association of diabetes with the following selected possible risk factors: age, obesity, family history of diabetes, and amount of Indian ancestry. RESEARCH DESIGN AND METHODS: This cross-sectional study involved enrolled members, men and women aged 45-74 years, of 13 American Indian tribes or communities in Arizona, Oklahoma, and South and North Dakota. Eligible participants were invited to the clinic for a personal interview and a physical examination. Diabetes and IGT status were defined by the World Health Organization criteria and were based on fasting plasma glucose and oral glucose tolerance test results. Data on age, family history of diabetes, and amount of Indian ancestry were obtained from the personal interview, and measures of obesity included body mass index, percentage body fat, and waist-to-hip ratio. RESULTS: A total of 4,549 eligible participants were examined, and diabetes status was determined for 4,304 (1,446 in Arizona, 1,449 in Oklahoma, and 1,409 in the Dakotas). In all three centers, diabetes was more prevalent in women than in men. Arizona had the highest age-adjusted rates of diabetes: 65% in men and 72% in women. Diabetes rates in Oklahoma (38% in men and 42% in women) and South and North Dakota (33% in men and 40% in women), although considerably lower than in Arizona, were several times higher than those reported for the U.S. population. Rates of IGT among the three populations (14-17%) were similar to those in the U.S. population. Diabetes rates were positively associated with age, level of obesity, amount of Indian ancestry, and parental diabetes status. CONCLUSIONS: Diabetes is found in epidemic proportions in Native American populations. Prevention programs and periodic screening should be implemented among American Indians. Standards of care and intervention have been developed by the Indian Health Service for individuals in whom diabetes is diagnosed. These programs should be expanded to include those with IGT to improve glycemic control or to reduce the risk of development of diabetes as well as to reduce the risk of diabetic complications.

Hypertension in adult American Indians. The Strong Heart Study.

Hypertension is a primary risk factor for cardiovascular disease in the United States. Although cardiovascular disease is the leading cause of death among American Indians, the prevalence of hypertension, its awareness and control, and its association with other cardiovascular disease risk factors and physiological variables have not been well studied in this population. The Strong Heart Study is a longitudinal study of cardiovascular disease and its risk factors in American Indians. Participants (2703 women and 1846 men) were members of 13 tribes in central Arizona, southwestern Oklahoma, and regions of South and North Dakota. At least 1500 individuals between 45 and 74 years of age participated from each center in a baseline clinical examination conducted between July 1989 and January 1992. The examination consisted of a personal interview and physical examination that included an oral glucose tolerance test and three consecutive blood pressure measurements. This study reports data from the baseline examination on the prevalence of hypertension and correlates of blood pressure. Results indicated that despite the high frequency of diabetes and obesity, prevalence rates of hypertension in Arizona and Oklahoma were similar to those in the US population in the Third National Health and Nutrition Examination Survey (NHANES III), and rates among South/North Dakota participants were significantly lower (P < .0001). Blood pressure was higher in individuals with diabetes (P < .0001) and was significantly correlated with age (P < .0001) and albuminuria (P < .0001) but only weakly related to obesity. There was no independent relation between blood pressure and insulin. Blood pressure seems to be less affected by obesity and hyperinsulinemia in American Indians compared with other populations. Nevertheless, hypertension should be aggressively treated and controlled in American Indians because it is a known precursor to morbidity and mortality associated with diabetes and cardiovascular disease.

Health implications of obesity in American Indians and Alaska Natives.

American Indians and Alaska Natives (AI/ANs) are experiencing an epidemic of diabetes, increasing rates of coronary artery disease and hypertension, and poor survival rates for breast cancer that are likely partially attributable to the increasing prevalence of obesity over the past generation. Obesity may also contribute to the high rates of gallstones and to adverse outcomes of pregnancy in AI/ANs. Although overall mortality was not associated with obesity in Pima Indians (except in the most obese men), the relationship of obesity to longevity in other AI/AN groups is not known. Further study of the specific health effects of obesity in various groups of AI/ANs are needed. In the meantime, community-based programs to prevent obesity and its sequelae should be implemented in all AI/AN communities.

Prevalence and correlates of mitral valve prolapse in a population-based sample of American Indians: the Strong Heart Study.

PURPOSE: Mitral valve prolapse is heritable and occurs frequently in the general population despite associations with mitral regurgitation and infective endocarditis, suggesting that selective advantages might be associated with mitral valve prolapse. SUBJECTS AND METHODS: Clinical examination and 2-dimensional and color Doppler echocardiography were performed in 3340 American Indian participants in the Strong Heart Study. RESULTS: Mitral valve prolapse (clear-cut billowing of one or both mitral leaflets across the mitral anular plane in 2-dimensional parasternal long-axis recordings or >2-mm late systolic posterior displacement of mitral leaflets by M mode) occurred in 37 (1.8%) of 2077 women and 20 (1.6%) of 1263 men (P = 0.88); 32 (3.5%) of 907 patients with normal glucose tolerance, 11 (2.3%) of 486 patients with impaired glucose tolerance, and 13 (0.7%) of 1735 patients with diabetes (P <0.0001). Participants with mitral valve prolapse had lower mean (+/- SD) body mass index (28 +/- 5 kg/m(2) vs. 31 +/- 6 kg/m(2), P = 0.001) and blood pressure (124/71 +/- 19/10 mm Hg vs. 130/75 +/- 21/10 mm Hg, P <0.05), as well as lower levels of fasting glucose, triglycerides, serum creatinine, and log urine albumin/creatinine ratio (all P <0.001), than did those without mitral valve prolapse, although all subjects were similar in age (60 +/- 8 years). Participants with mitral valve prolapse had lower ventricular septal (0.87 +/- 0.08 cm vs. 0.93 +/- 0.13 cm) and posterior wall thicknesses (0.82 +/- 0.08 cm vs. 0.87 +/- 0.10 cm), mass (38 +/- 7 g/m(2.7) vs. 42 +/- 11 g/m(2.7)), and relative wall thickness (0.33 +/- 0.04 vs. 0.35 +/- 0.05), and increased stress-corrected midwall shortening (all P <0.01). Mitral valve prolapse was associated with a higher prevalence of mild (16 of 57 [28%] vs. 614 of 3283 [19%]) and more severe mitral regurgitation (5 of 57 [9%] vs. 48 of 3283 [1%], P <0.0001). Regression analyses showed prolapse was associated with low ventricular relative wall thickness, high midwall function, and low urine albumin/creatinine ratio, independent of age, sex, body mass index, and diabetes. CONCLUSIONS: Mitral valve prolapse is fairly common and is strongly associated with mitral regurgitation in the general population. However, it is also associated with lower body weight, blood pressure, and prevalence of diabetes; a more favorable metabolic profile and ventricular geometry; and better myocardial and renal function.

Gasoline sniffing and lead toxicity in Navajo adolescents.

During a 6-year period, 23 Navajo adolescents were hospitalized 47 times for presumed lead intoxication secondary to gasoline sniffing. Most patients were male (87%) and sniffed gasoline as a social activity, more frequently in spring and summer. Sixty-five percent of the patients first presented with toxic encephalopathy. Of total episodes, 31% involved asymptomatic lead overload; 31% involved tremor, ataxia, and other neurologic signs; and 38% involved encephalopathy with disorientation and hallucinations. Free erythrocyte protoporphyrin levels were not consistently high, although blood lead levels were all elevated. One death occurred. Approximately 11% of 537 Navajo adolescents said they inhaled gasoline for enjoyment at least occasionally. Among 147 junior high school students, blood lead levels averaged 18 +/- 6 micrograms/dL with no values greater than 40 micrograms/dL. Three of these students had elevated zinc protoporphyrin levels and all three were anemic. No correlation was found between levels of blood lead or zinc protoporphyrin and whether or not the youth reported sniffing gasoline. However, sniffing gasoline was associated with poor school performance and delinquent behavior. Although apparently many Navajo adolescents experiment with gasoline inhalation, only a few engage in this activity frequently enough to develop either asymptomatic or symptomatic lead overload.

Congestive heart failure despite normal left ventricular systolic function in a population-based sample: the Strong Heart Study.

In selected clinical series, > or = 50% of adults with congestive heart failure (CHF) do not have left ventricular (LV) systolic dysfunction. Little is known of the prevalence of this phenomenon in population samples. Therefore, clinical examination and echocardiography were used in the second examination of the Strong Heart Study (3,184 men and women, 47 to 81 years old) to identify 95 participants with CHF, 50 of whom had normal LV ejection fraction (EF) (> 54%), 19 of whom had mildly reduced EF (40% to 54%), and 26 of whom had EF < or = 40%. Compared with those with no CHF, participants with CHF and no, mild, or severe decrease in EF had higher creatinine levels (2.34 to 2.85 vs 1.01 mg/dl, p < 0.001) and higher prevalences of diabetes (60% to 70% vs 50%) and hypertension (75% to 96% vs 46%, p < 0.05). Compared with those with no CHF, participants with CHF and normal EF had prolonged deceleration time (233 vs 204 ms, p < 0.05) and a reduced E/A, whereas those with CHF and EF < or = 40% had short deceleration time (158 ms, p < 0.05) and high E/A (1.70, p < 0.001); patients with CHF and normal EF had higher LV mass (98 vs 84 g/m2, p < 0.001) and relative wall thickness (0.37 vs 0.35, p < 0.05) than those without CHF. Patients with CHF with normal EF were, compared with those without CHF or with CHF and EF < or = 40%, disproportionately women (mean 84% vs 63% and 42%, p < 0.001), older (mean 64 vs 60 years and 63 years, respectively, p < 0.01), had higher body mass index (mean 33.1 vs 31.0 and 27.7 kg/m2, p < 0.05), and higher systolic blood pressure (mean 137 vs 130 and 128 mm Hg, both p < 0.05). Thus, in a population-based sample, patients with CHF and normal LV EF were older and overweight, more often women, had renal dysfunction, impaired early diastolic LV relaxation, and concentric LV geometry, whereas patients with CHF and severe LV dysfunction were more often men, had lower body mass index, a restrictive pattern of LV filling, and eccentric LV hypertrophy.