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Biomedical subjects

R R Fabsitz

Publications and source records attributed to R R Fabsitz.

At least 37 records · Page 2Linked to original sources

Relation of generalized and central obesity to cardiovascular risk factors and prevalent coronary heart disease in a sample of American Indians: the Strong Heart Study.

OBJECTIVE: To examine the hypothesis linking measures of obesity including body mass index (BMI), waist circumference (waist) and percentage body fat to coronary heart disease (CHD) prevalence and its risk factors in American Indians. DESIGN: The Strong Heart Study assesses the prevalence of CHD and its risk factors in American Indians in Arizona, Oklahoma and South/North Dakota. Participants underwent a physical examination and an electrocardiogram; anthropometric and blood pressure measurements were taken, as were measurements of glucose, lipoproteins, fibrinogen, insulin, hemoglobin A1c and urinary albumin. PARTICIPANTS: Data were available for 4549 men and women between 45 and 74 y of age. MEASUREMENTS: Obesity, measured using body mass index, waist circumference and percentage body fat, was correlated with prevalent CHD and its risk factors. RESULTS: More than 75% of participants were overweight (BMI>25 kg/m2). Measures of obesity were greater in women than in men, in younger than in older participants, and in participants with diabetes than in nondiabetic participants. CHD risk factors were associated with measures of obesity but, except for insulin concentration, changes in metabolic variables with increasing obesity were small. Associations were not stronger with waist than with BMI. The prevalence of CHD in those whose BMI and/or waist measurements lay in the lowest and highest quintiles, by gender and diabetic status, was similar. CONCLUSIONS: Although CHD risk factors are associated with obesity in American Indians, distribution of obesity (ie waist) is no more closely related to risk factors than is generalized obesity (ie BMI), and changes in CHD risk factors with obesity were small. Thus, the relations among obesity, body fat distribution and CHD risk may differ in this population.

Age Factors↗

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.

Aged↗

Respondent bias in the collection of alcohol and tobacco data in American Indians: the Strong Heart Study.

This study addresses the impact of assessment method (interviewer-administered questionnaire vs. self-administered questionnaire) and interviewers demographic characteristics (gender, ethnicity, and residency) on responses to alcohol and tobacco questions. The study population included 1,522 men and women aged 45 to 74 from the Dakota Center of the Strong Heart Study (SHS), a multi-center study of cardiovascular disease in American Indians. Assessment method effects were greater for alcohol than tobacco but did not differ by interviewer characteristics.

Adult↗

Recruitment of American Indians in epidemiologic research: the Strong Heart Study.

This paper describes the methods used to recruit American Indian (AI) populations for the Strong Heart Study (SHS), a community-based study of cardiovascular disease (CVD) and its risk factors in AI men and women. Recruitment strategies included personal contact by recruiters and drivers/recruiters in remote areas, SHS staff participation in community activities, and mass media. A total of 4,549 participants aged 45-74 years were recruited from 13 American Indian tribes and communities. Overall participation rates were 72&percnt, 55&percnt, and 62&percnt, respectively, for the three study centers (Arizona, the Dakotas, and Oklahoma). Participant feedback and educational material related to risk factor reduction and promoting a healthy lifestyle were emphasized. Participants were likely to be female, young, and nonsmokers. Barriers to recruitment included lack of telephones in a large proportion of households, conflicting beliefs about health/health care/research, fears, taboos, and occasional rumors about study examination procedures. Participants were referred for follow-up of health problems detected by the study. The strong commitment of the participating communities helped to insure the success of the SHS, which can be considered a model for recruitment in future American Indian population-based studies. Success was facilitated by the use of a variety of recruitment techniques.

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Prevalence of peripheral arterial disease and associated risk factors in American Indians: the Strong Heart Study.

Studies of peripheral arterial disease (PAD) in minority populations provide researchers with an opportunity to evaluate PAD risk factors and disease severity under different types of conditions. Examination 1 of the Strong Heart Study (1989-1992) provided data on the prevalence of PAD and its risk factors in a sample of American Indians. Participants (N = 4,549) represented 13 tribes located in three geographically diverse centers in the Dakotas, Oklahoma, and Arizona. Participants in this epidemiologic study were aged 45-74 years; 60% were women. Using the single criterion of an ankle brachial index less than 0.9 to define PAD, the prevalence of PAD was approximately 5.3% across centers, with women having slightly higher rates than men. Factors significantly associated with PAD in univariate analyses for both men and women included age, systolic blood pressure, hemoglobin A1c level, albuminuria, fibrinogen level, fasting glucose level, prevalence of diabetes mellitus, and duration of diabetes. Multiple logistic regression analyses were used to predict PAD for women and men combined. Age, systolic blood pressure, current cigarette smoking, pack-years of smoking, albuminuria (micro- and macro-), low density lipoprotein cholesterol level, and fibrinogen level were significantly positively associated with PAD. Current alcohol consumption was significantly negatively associated with PAD. In American Indians, the association of albuminuria with PAD may equal or exceed the association of cigarette smoking with PAD.

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Coronary heart disease. At the interface of molecular genetics and preventive medicine.

BACKGROUND: Susceptibility to common chronic diseases such as coronary heart disease (CHD) appears to be influenced by "context-dependent effects," which include interactions among genes (genetic epistasis) and among genes and environmental factors (gene-environment interactions). METHODS: A synthesis of current knowledge and research findings demonstrates the importance of integrating genetic research on cardiovascular disease with preventive medicine and public health initiatives. RESULTS: A variety of candidate genes have been implicated in risk for CHD, but only limited examples of context-dependent effects have been described. Interactions between genetic and environmental factors appear to influence lipid metabolism, plasma homocysteine levels, and pharmacologic response to many commonly prescribed medications. Quantification of genetic effects associated with increased disease risk that are modifiable by interventions such as diet, exercise, and smoking cessation is an important interface between molecular genetics and preventive medicine. CONCLUSIONS: As a primary focus of preventive medicine expands to encompass early detection and treatment of asymptomatic individuals at risk for disease, the ability to quantify the influence of context-dependent effects on disease risk will be critical for determining drug safety and effectiveness in diverse patient populations and for implementing effective prevention and treatment programs.

Coronary Disease↗

The epidemic of obesity in American Indian communities and the need for childhood obesity-prevention programs.

American Indians of all ages and both sexes have a high prevalence of obesity. The high prevalence of diabetes mellitus in American Indians shows the adverse effects that obesity has in these communities. Obesity has become a major health problem in American Indians only in the past 1-2 generations and is believed to be associated with the relative abundance of high-fat foods and the rapid change from active to sedentary lifestyles. Intervention studies are urgently needed in American Indian communities to develop and test effective strategies for weight reduction. The poor success rate of adult obesity treatment programs in the general population points to the need to develop prevention approaches aimed toward children. Because eating and physical activity practices are formed early in life and may be carried into adulthood, prevention programs that encourage increased physical activity and healthful eating habits targeted toward young people need to be developed and tested. To be most effective, interventions must be developed with full participation of the American Indian communities.

Adolescent↗

Design and statistical analysis for the Pathways study.

We report the design, rationale, and statistical procedures used in Pathways, a randomized, school-based intervention for the primary prevention of obesity in American Indian children. The intervention, which is now being implemented in 7 American Indian communities around the country, includes a health-promotion curriculum, a physical education program, a school meal program, and a family involvement component. Forty-one schools serving American Indian children were randomly assigned to be either intervention or control groups. The intervention will begin in the third grade and continue through the end of the fifth grade. Efficacy of intervention will be assessed by differences in mean percentage body fat, calculated by a prediction equation, between intervention and control schools at the end of the fifth grade. Power computations indicate that the study has power to detect a mean difference of 2.8% in body fat. Data analysis will use intention-to-treat concepts and the mixed linear model. The study will be completed in 2000.

Analysis of Variance↗

Relations of left ventricular mass to fat-free and adipose body mass: the strong heart study. The Strong Heart Study Investigators.

BACKGROUND: It is unclear whether increased left ventricular (LV) mass in overweight individuals is related to their adiposity or to greater fat-free mass (FFM). METHODS AND RESULTS: We compared echocardiographic LV mass to FFM and adipose body mass by bioelectric impedance and to anthropometric measurements in 3107 American Indian participants in the Strong Heart Study. In men and women, the relations of LV mass and FFM (r=0.37 and 0.38, P<0.001) were closer (P<0.05 to <0.001) than they were with adipose mass, waist/hip ratio, body mass index, systolic blood pressure, height, or height2.7. Regression analyses showed that in men LV mass had the strongest independent relation with FFM, followed by systolic blood pressure and age (all P<0.001); in women, LV mass was related to FFM more strongly than it was to systolic blood pressure, age (all P<0. 001), and diabetes (P=0.012). Adipose mass had no independent relation to LV mass. When waist/hip ratio or body mass index were substituted for adipose mass, LV mass was independently related to FFM (P<0.001) and body mass index (P=0.02) but not to waist/hip ratio in men and was independently related to FFM and waist/hip ratio (both P<0.001) but not to body mass index in women. Using 97.5 percentile gender-specific partitions for LV mass/FFM in reference individuals, we found that LV hypertrophy occurred in 20.8% of Strong Heart Study participants with hypertension, overweight, or diabetes compared with 10.5% and 16.7% by LV mass indexed for body surface area or height2.7. CONCLUSIONS: LV mass is more strongly related to FFM than to adipose mass, waist/hip ratio, body mass index, or height-based surrogates for lean body weight; LV mass/FFM criteria may increase sensitivity to detect LV hypertrophy.

Adipose Tissue↗

Risk factor clustering in the insulin resistance syndrome. The Strong Heart Study.

The objective of this study was to examine how the major components of the insulin resistance syndrome relate to each other and to macrovascular disease in American Indians in the Strong Heart Study. The study cohort (4,228 resident tribal members 45-74 years old) underwent a personal interview and a physical examination between July 1989 and January 1992 at three centers: Arizona, Oklahoma, and North and South Dakota; blood samples were drawn and a 75-g oral glucose tolerance test was performed. Factor analysis was used to assess the clustering and interdependence of groups of insulin resistance syndrome variables. Within both diabetic and nondiabetic groups, three factors emerged. In nondiabetic participants, a cluster of glucose, body mass index, and insulin accounted for 35% (male) and 32% (female) of the total variance in all variables considered, and a cluster of systolic blood pressure and diastolic blood pressure accounted for 25% and 22% in men and women, respectively. Both clusters were positively associated with coronary heart disease but not peripheral vascular disease. In diabetic participants, the combination of systolic and diastolic blood pressures was the most important factor, but the cluster was not associated with coronary heart disease or peripheral vascular disease. A component containing high density lipoprotein cholesterol, triglycerides, and glucose had a positive association with coronary heart disease in diabetic women and with peripheral vascular disease in both sexes. The association of clusters of risk factors and their relations with coronary heart disease provide important clues that may be used in understanding the metabolic disorders associated with insulin resistance and diabetes.

Aged↗

All-cause mortality and cardiovascular disease mortality in three American Indian populations, aged 45-74 years, 1984-1988. The Strong Heart Study.

Community mortality surveillance for 1984-1988 was conducted by researchers of the Strong Heart Study, which examined the incidence, prevalence, and risk factors of cardiovascular disease in three American Indian populations, aged 45-74 years, in Arizona, Oklahoma, and South/North Dakota. All-cause and cardiovascular disease mortality rates were determined through the use of death certificate data. Cardiovascular disease deaths were confirmed by independent systematic review of medical records. In all three populations, men had higher all-cause and cardiovascular disease mortality rates than did women. Oklahoma exhibited slightly lower 5-year, age-adjusted, all-cause mortality (96/1,000) than did Arizona (107/1,000) and South/North Dakota (114/1,000). The leading cause of death among both sexes in Oklahoma and in South/North Dakota was cardiovascular disease. Diabetes mellitus led among Arizona women. The other major causes of death were cancer, liver disease including cirrhosis, and injury. When compared with the rates in each state, average annual all-cause mortality rates were higher for the American Indian populations in almost every age group. The all-cause annual mortality rates in the three Indian populations were close to rates in the US black population and higher than the rates of the entire US population and of US whites. This trend was amplified in the 45- to 64-year age group. Only in the 65- to 74-year age group did mortality rates in the Indian population approach those of the US population. Cardiovascular disease mortality rates were close to the US averages in Arizona and Oklahoma, but they were more than two times higher in South/North Dakota among those between 45 and 64 years of age. Thus, American Indians in Arizona, Oklahoma, and South/North Dakota exhibit high all-cause mortality rates. In particular, the South/North Dakota population cardiovascular disease death rate appears to present a potential target for community-based programs to intervene on known risk factors to promote healthy lifestyles.

Aged↗

Heritability of ECG measurements in adult male twins.

To assess the genetic contribution to electrocardiographic (ECG) measurements, heritability analysis was performed on ECG data collected on 251 pairs of adult male twins during the second examination of the National Heart, Lung and Blood Institute twin study, a multicenter study of cardiovascular risk factors. Resting 12-lead ECGs were obtained on each twin, pair and, the R-R, QRS, QT, and JT intervals were measured. Both the R-R and QT intervals demonstrated significant heritable components, accounting for 77% and 36%, respectively, of the variability. No significant heritable component of the QRS complex could be identified. Although the MZ intraclass correlation was higher than the DZ intraclass correlation, the JT interval did not demonstrate significant heritability. Therefore, in adult males both heart rate and the duration of ventricular repolarization have significant heritable components. These heritable components may need to be considered when using ECG measurements to screen for patients at risk for cardiovascular disorders or sudden cardiac death.

Adult↗

Relations of left ventricular mass to demographic and hemodynamic variables in American Indians: the Strong Heart Study.

BACKGROUND: Previous studies have identified associations of left ventricular (LV) mass with demographic (body habitus and sex) and hemodynamic variables (blood pressure, stroke volume [SV], and myocardial contractility), but the relative strength and independence of these associations remain unknown. METHODS AND RESULTS: We examined the relations of echocardiographically determined LV mass to demographic variables, blood pressure, Doppler SV, and measures of contractility (end-systolic stress [ESS]/end-systolic volume index and midwall fractional shortening [MFS] as a percentage of predicted for circumferential end-systolic stress [stress-independent shortening]) in 1935 American Indian participants in the Strong Heart Study phase 2 examination without mitral regurgitation or segmental wall motion abnormalities. Weak positive relations of LV mass with systolic and diastolic pressures (r=.22 and r=.20) were exceeded by positive relations with height (r=.30), weight (r=.47), body mass index (r=.31), body surface area (r=.49), and Doppler SV (r=.50) and negative relations with ESS/volume index ratios (r= -.33 and -.29) and stress-independent MFS (r= -.26, all P<.0001). In multivariate analyses that included blood pressure, SV, and a different contractility measure in each model, systolic pressure, stroke volume, and the contractility measure were independent correlates of LV mass (multiple R=.60 to .66, all P<.0001). When demographic variables were added, LV mass was more strongly predicted by higher SV and lower afterload-independent MFS than by greater systolic pressure, height, and body mass index (each P<.00001, multiple R=.71). CONCLUSIONS: Additional characterization of volume load and contractile efficiency improves hemodynamic prediction of LV mass (R(2)=.30 to .44) over the use of systolic blood pressure alone (R(2)=.05), with a further increase in R(2) to .51 when demographic variables are also considered. However, nearly half of the ventricular mass variability remains unexplained.

Aged↗

Relations of Doppler stroke volume and its components to left ventricular stroke volume in normotensive and hypertensive American Indians: the Strong Heart Study.

Doppler echocardiographic measurement of time-velocity integral of blood flow across the aortic annulus ("stroke distance") or of stroke volume (SV) have been proposed as noninvasive measures of cardiac pump performance that could elucidate the hemodynamics of hypertension. To evaluate the performance of these measures of hemodynamic volume load in a population with a wide range of body build and other characteristics, we obtained technically adequate imaging and Doppler echocardiograms in 1,935 of 2,212 (87%) American Indian Strong Heart Study participants, without mitral regurgitation or segmental left ventricular (LV) dysfunction, in Arizona, Oklahoma, and South/North Dakota. The subjects ranged widely in age (48 to 81 years) and body mass index (17.0 to 62.6 kg/m2); 65% were women; 1,161 were normotensive and 774 were hypertensive. As a reference standard, LV and stroke volumes were calculated from LV internal dimensions by the Teichholz method. Doppler SVs were moderately related to LV SVs (r = 0.63), but Doppler SV was slightly lower in both normotensive (mean = 69.8 and 72.9 mL, respectively) and hypertensive subjects (71.1 v 73.6 mL). Aortic stroke distance was less closely related than was aortic annular area to LV SV (r = 0.34 v 0.40, P < .001). Aortic annular area (r = 0.44) but not stroke distance (r = 0.04) was moderately correlated with body surface area. Stroke distance was inversely related to annular area (r = -0.29) and in subjects stratified by aortic annular diameter 1.6 to 1.9, 2.0 to 2.1, and 2.3 to 2.9 cm, mean LV SV increased from 67 to 74 to 80 mL, but average stroke distance fell from 22.8 to 21.6 to 20.1 cm. Stroke distance also failed to identify gender differences in LV SV but did identify that due to obesity. Thus Doppler SV closely parallels independently measured LV SV but slightly underestimates SV in both normotensive and hypertensive adults, whereas aortic stroke distance yields misleading comparisons between genders or individuals of different body sizes.

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Correlates of sleep problems among men: the Vietnam Era Twin Registry.

The Vietnam Era Twin (VET) Registry includes 14,800 male twins born 1939-55 and in military service in 1964-75. A mailed health survey including the Jenkins Sleep Questionnaire was sent to 11,959 members and 8,870 (74.2%) provided responses on the frequency of sleep problems in the previous month. Prevalence of those experiencing conditions at least 1 day per month was 67.2% for waking often, 61.5% for waking tired/worn out, 48.1% for trouble falling asleep and 48.6% for awakening early. Ordinal logistic regression analysis was used to estimate sleep problems from demographic, behaviour and lifestyle characteristics, and morbid conditions. Black (vs. white) race, older age, church/religious group participation, social support, employment, cigarette smoking, light physical activity, and strenuous physical activity were associated with lower risk of one or more sleep problems. Eleven morbid conditions with a prevalence of 1% or more, coffee consumption, heavy alcohol consumption, and Framingham Type A behaviour pattern were associated with a higher risk of sleep problems. These analyses suggest that sleep problems may be one of the mechanisms relating reduced quality of life to many physical and behavioural characteristics. Fortunately, a number of the risk factors associated with sleep problems are lifestyle characteristics which, if modified, may reduce sleep problems.

Adult↗

Parity, postmenopausal estrogen use, and cardiovascular disease risk factors in American Indian women: the Strong Heart Study.

Studies have suggested that high parity is related to an increased risk of cardiovascular disease (CVD). Reasons for an increased risk are unclear but may include influences of child-bearing on levels of CVD risk factors. The present study examined the associations of parity and CVD risk factors in American Indian women, among whom large families are common. Estrogen use and CVD risk factors also were assessed. The study included 1982 ever-married, postmenopausal women aged 45 through 74 years who participated in the Strong Heart Study (SHS), a large study of American Indians in three geographic areas of the United States. Information was obtained during a physical examination and interview. Parity ranged from 0 to 18 (median 5). Current estrogen use varied from 5% in Arizona to 21% in Oklahoma. Multivariable analyses found a statistically significant, inverse association between parity and high-density lipoprotein (HDL) cholesterol, although the difference with increasing parity was small (-0.26 mg/dl per additional live birth). Estrogen users had significantly lower levels of low-density lipoprotein cholesterol (-6.4 mg/dl) and fibrinogen (-26.2 mg/dl) and a lower waist/hip ratio (-0.02), and higher values of HDL (5 mg/dl) and logarithm (ln) triglyceride (0.13 mg/dl). Current users were slightly more likely to be hypertensive (prevalence odds ratio, 1.56). Relations between parity and CVD risk factors in American Indian women with high parity suggested only small differences with increasing parity. Associations with estrogen use are much stronger and are similar to those observed in other groups of women.

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Relation of LDL size to the insulin resistance syndrome and coronary heart disease in American Indians. The Strong Heart Study.

Small, dense LDL has been shown to be associated with the insulin resistance syndrome and coronary heart disease (CHD). We examined the distribution of LDL size and phenotype within a population-based sample of American Indians to determine the relationships with prevalent CHD and to examine associations with hyperinsulinemia and other components of the insulin resistance syndrome. Data were available for 4505 men and women between 45 and 74 years of age who are members of 13 American Indian communities in three geographic areas. Diabetes, CHD, and CHD risk factors were assessed by standardized techniques, and LDL size was measured by gradient gel electrophoresis. LDL size was smaller in men than in women and in individuals with diabetes than in those without diabetes. In multivariate analysis, LDL size was significantly related to several components of the insulin resistance syndrome, including triglycerides (inversely) and HDL cholesterol (positively). Although univariate relations were positive, LDL size was not significantly related to fasting insulin concentrations or body mass index in the multivariate model. LDL size also showed no relationship to apolipoprotein E phenotype. When LDL size was compared in individuals with and without CHD, no significant differences were observed, either in nondiabetic or diabetic individuals. We conclude that LDL size is most strongly related to lipoprotein components of the insulin resistance syndrome, especially plasma triglycerides. However, in this population with low LDL, it is not related to cardiovascular disease.

Aged↗

Major electrocardiographic abnormalities among American Indians aged 45 to 74 years (the Strong Heart Study).

As part of the Strong Heart Study assessment of prevalent cardiovascular disease in middle-aged to elderly American Indians, the prevalence of major Minnesota code electrocardiographic (ECG) abnormalities was assessed in 4,531 participants aged 45 to 74 years (59% women) in selected tribal communities in Arizona, South and North Dakota, and Oklahoma. The overall prevalence of major ECG abnormalities was lowest in Arizona participants, (e.g., definite ECG myocardial infarction in 0.3% vs 1.8% in the other centers), although nearly two thirds of them had diabetes. One or more major ECG abnormality occurred in progressively more women (10.4% to 21.2%) and men (13.3% to 32%) (both p < 0.0001) from 45- to 54- to 55- to 64- and 65- to 74-year age groups, with the latter prevalence rates exceeding those in predominately white age peers in the Cardiovascular Health Study. Diabetes in women, but not in men, and hypertension in both genders showed positive associations with prevalence rates of major ECG abnormalities compatible with coronary artery disease or hypertensive cardiac hypertrophy. Hypercholesterolemia was not associated with ECG abnormalities except for definite myocardial infarction in women. In conclusion, major ECG abnormalities are common in middle-aged to elderly American Indians ,consistent with recent documentation of higher cardiovascular mortality in this population than in similar aged U.S. whites.

Adult↗