Acute myocardial infarction quality of care: the Strong Heart Study.

OBJECTIVES: Evaluate the quality of care provided patients with acute myocardial infarction and compare with similar national and regional data. DESIGN: Case series. SETTING: The Strong Heart Study has extensive population-based data related to cardiovascular events among American Indians living in three rural regions of the United States. PARTICIPANTS: Acute myocardial infarction cases (72) occurring between 1/1/2001 and 12/31/2006 were identified from a cohort of 4549 participants. OUTCOME MEASURES: The proportion of cases that were provided standard quality of care therapy, as defined by the Healthcare Financing Administration and other national organizations. RESULTS: The provision of quality services, such as administration of aspirin on admission and at discharge, reperfusion therapy within 24 hours, prescription of beta blocker medication at discharge, and smoking cessation counseling were found to be 94%, 91%, 92%, 86% and 71%, respectively. The unadjusted, 30 day mortality rate was 17%. CONCLUSION: Despite considerable challenges posed by geographic isolation and small facilities, process measures of the quality of acute myocardial infarction care for participants in this American Indian cohort were comparable to that reported for Medicare beneficiaries nationally and within the resident states of this cohort.

Diabetes and incident heart failure in hypertensive and normotensive participants of the Strong Heart Study.

OBJECTIVES: Type 2 diabetes is accepted as a cause of heart failure, but direct cause-effect evidence independent of incident myocardial infarction (MI), hypertension and other coexisting risk factors is less well studied. We tested the hypothesis that diabetes predisposes to heart failure independently of hypertension and intercurrent MI. METHODS: We evaluated 12-year incident heart failure in 2740 participants (1781 women) without prevalent cardiovascular or severe kidney disease, at the time of the first exam of the Strong Heart Study cohort. Intercurrent MI was censored as a competing risk event. RESULTS: Diabetes was present in 1206 individuals (44%), and impaired fasting glucose (IFG) in 391 (14%). Diabetic participants more frequently had hypertension and/or central obesity (both P < 0.0001). Incident heart failure was ascertained in 64 participants with normal fasting glucose (NFG; 6%), 26 (7%) with IFG and 201 with diabetes (17%, hazard ratio = 4.04 vs. NFG, P < 0.0001). In Cox analysis adjusting for age, sex, obesity, central fat distribution, hypertension, antihypertensive medications, prevalent atrial fibrillation, glomerular filtration rate, urinary albumin/creatinine ratio, plasma cholesterol, Hb1Ac, smoking habit, alcohol use, educational level and physical activity, diabetes was associated with a two-fold greater risk of incident heart failure than NFG (hazard ratio = 2.45, P < 0.0001). Diabetes maintained 1.5-fold greater risk of heart failure than NFG (P < 0.03) even when intercurrent MI (n = 221) was censored as a competing risk event, similar to the adjusted hazard ratio for heart failure in hypertension. CONCLUSION: Type 2 diabetes is a potent, independent risk factor for heart failure. Risk of heart failure in diabetic patients cannot be fully explained by incident MI and coexisting cardiovascular risk factors. Mechanisms directly related to diabetes and impairing cardiac function should be studied and identified.

Incidence and risk factors for stroke in American Indians: the Strong Heart Study.

BACKGROUND: There are few published data on the incidence of fatal and nonfatal stroke in American Indians. The aims of this observational study were to determine the incidence of stroke and to elucidate stroke risk factors among American Indians. METHODS AND RESULTS: This report is based on 4549 participants aged 45 to 74 years at enrollment in the Strong Heart Study, the largest longitudinal, population-based study of cardiovascular disease and its risk factors in a diverse group of American Indians. At baseline examination in 1989 to 1992, 42 participants (age- and sex-adjusted prevalence proportion 1132/100 000, adjusted to the age and sex distribution of the US adult population in 1990) had prevalent stroke. Through December 2004, 306 (6.8%) of 4507 participants without prior stroke suffered a first stroke at a mean age of 66.5 years. The age- and sex-adjusted incidence was 679/100 000 person-years. Nonhemorrhagic cerebral infarction occurred in 86% of participants with incident strokes; 14% had hemorrhagic stroke. The overall age-adjusted 30-day case-fatality rate from first stroke was 18%, with a 1-year case-fatality rate of 32%. Age, diastolic blood pressure, fasting glucose, hemoglobin A(1c,) smoking, albuminuria, hypertension, prehypertension, and diabetes mellitus were risk factors for incident stroke. CONCLUSIONS: Compared with US white and black populations, American Indians have a higher incidence of stroke. The case-fatality rate for first stroke is also higher in American Indians than in the US white or black population in the same age range. Our findings suggest that blood pressure and glucose control and smoking avoidance may be important avenues for stroke prevention in this population.

Central pressure more strongly relates to vascular disease and outcome than does brachial pressure: the Strong Heart Study.

Brachial blood pressure is predictive of cardiovascular outcome; however central pressure may better represent the load imposed on the coronary and cerebral arteries and thereby bear a stronger relationship to vascular damage and prognosis. Relations of brachial and central pressures to carotid artery hypertrophy (intimal-medial thickness and vascular mass), extent of atherosclerosis (plaque score), and incident cardiovascular events were examined in the Strong Heart Study. Central pressures were calculated using radial applanation tonometry. Among 3520 participants, central and brachial pulse pressures were more strongly related to vascular hypertrophy and extent of atherosclerosis than were systolic pressures. Central pulse pressure was more strongly related to all 3 arterial measures than was brachial pulse pressure (r=0.364 versus 0.309 for plaque score; P<0.001 for comparison of Spearman correlation coefficient; r=0.293 versus 0.249 for intimal-medial thickness; P<0.002; r=0.320 versus 0.289 for vascular mass; P<0.05). Among the 2403 participants free of clinical cardiovascular disease at baseline, 319 suffered fatal or nonfatal cardiovascular events during mean follow-up of 4.8+/-1.3 years. After adjustment for age, gender, current smoking, body mass index, cholesterol:HDL ratio, creatinine, fibrinogen, diabetes, and heart rate, central pulse pressure predicted cardiovascular events more strongly than brachial pulse pressure (hazards ratio=1.15 per 10 mm Hg, chi(2)=13.4, P<0.001 versus hazards ratio=1.10, chi(2)=6.9, P=0.008). In conclusion, noninvasively-determined central pulse pressure is more strongly related to vascular hypertrophy, extent of atherosclerosis, and cardiovascular events than is brachial blood pressure. These findings support prospective examination of use of central blood pressure as a treatment target in future trials.

Prediction of coronary heart disease in a population with high prevalence of diabetes and albuminuria: the Strong Heart Study.

BACKGROUND: The present article presents equations for the prediction of coronary heart disease (CHD) in a population with high rates of diabetes and albuminuria, derived from data collected in the Strong Heart Study, a longitudinal study of cardiovascular disease in 13 American Indian tribes and communities in Arizona, North and South Dakota, and Oklahoma. METHODS AND RESULTS: Participants of the Strong Heart Study were examined initially in 1989-1991 and were monitored with additional examinations and mortality and morbidity surveillance. CHD outcome data through December 2001 showed that age, gender, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein cholesterol, smoking, diabetes, hypertension, and albuminuria were significant CHD risk factors. Hazard ratios for ages 65 to 75 years, hypertension, LDL cholesterol > or = 160 mg/dL, diabetes, and macroalbuminuria were 2.58, 2.01, 2.44, 1.66, and 2.11 in men and 2.03, 1.69, 2.17, 2.26, and 2.69 in women, compared with ages 45 to 54 years, normal blood pressure, LDL cholesterol <100 mg/dL, no diabetes, and no albuminuria. Prediction equations for CHD and a risk calculator were derived by gender with the use of Cox proportional hazards model and the significant risk factors. The equations provided good discrimination ability, as indicated by a c statistic of 0.70 for men and 0.73 for women. Results from bootstrapping methods indicated good internal validation and calibration. CONCLUSIONS: A "risk calculator" has been developed and placed on the Strong Heart Study Web site, which provides predicted risk of CHD in 10 years with input of these risk factors. This may be valuable for diverse populations with high rates of diabetes and albuminuria.

Cardiac procedure use following acute myocardial infarction among American Indians.

BACKGROUND: The prevalence of coronary heart disease is rising among American Indians (AIs), but there is limited evidence describing processes of care for AI with acute myocardial infarction (AMI). We compared rates of cardiac catheterization, percutaneous coronary intervention (PCI), and coronary artery bypass graft (CABG) surgery between AI and whites with AMI. METHODS: Using data from the Nationwide Inpatient Sample and the Indian Health Service National Patient Information Reporting System, we identified 2511 AI and 316,526 whites older than 30 years admitted with AMI during 1998 to 2001. Comparisons of cardiac procedure use between AI and whites were performed after adjusting for comorbid conditions and after stratifying by geographic region. RESULTS: American Indians were less likely than whites to undergo cardiac catheterization and PCI in 3 of 4 geographic regions, with the largest difference occurring in the West South Central region (OR 0.32, 95% CI 0.24 to 0.43 for catheterization; OR 0.43, 95% CI 0.31 to 0.57 for PCI). American Indians were less likely than whites to undergo CABG surgery among diabetic patients (OR 0.48, 95% CI 0.32-0.73), but not among nondiabetic patients (OR 0.90, 95% CI 0.72-1.12). There were no differences in rates of PCI and CABG surgery between AIs and whites among those receiving cardiac catheterization. CONCLUSIONS: Differences in the performance of coronary procedures are concentrated in western regions of the United States and are especially related to access to cardiac catheterization. Future studies are indicated to elucidate the mechanisms of these differences in care and their impact on clinical outcomes.

Mitral annular calcification, aortic valve sclerosis, and incident stroke in adults free of clinical cardiovascular disease: the Strong Heart Study.

BACKGROUND AND PURPOSE: Mitral annular calcification (MAC) and aortic valve (AV) sclerosis have each been linked to cardiovascular disease. Whether MAC and AV sclerosis are risk factors for stroke independent of other echocardiographic or laboratory predictors has not been established. We evaluated the relationship between MAC, AV sclerosis, and first stroke events in a population-based cohort. METHODS: Our study cohort consisted of 2723 American Indians participating in the Strong Heart Study who were free of prevalent cardiovascular disease. Participants underwent standardized clinical, echocardiographic, and laboratory evaluation, and incident stroke was ascertained using validated methods. RESULTS: During a median follow-up of 7 years, 86 strokes occurred. Age- and sex-adjusted incidence rates of stroke were significantly increased for MAC (rate ratio [RR], 3.12; 95% CI, 1.77 to 5.25) but not for AV sclerosis (RR, 1.15; 95% CI, 0.45 to 2.49). MAC was also associated with a reduced time to first stroke events after adjustment for clinical variables and the inflammatory markers C-reactive protein and fibrinogen (hazard ratio [HR], 2.42; 95% CI, 1.39 to 4.21) or the echocardiographic covariates left ventricular hypertrophy and left atrial enlargement (HR, 1.89; 95% CI, 1.04 to 3.41). Individuals with and without AV sclerosis showed no significant difference in stroke-free survival in unadjusted analyses (P=0.698). Crossing of the survival curves precluded multivariable analysis using Cox models. CONCLUSIONS: In this cohort of American Indians without clinical cardiovascular disease, the presence of MAC, but not AV sclerosis, proved to be a strong risk factor for incident stroke after extensive adjustment for other predictors. Individuals exhibiting MAC may benefit from aggressive risk factor modification, but this will require further investigation.

Cardiovascular health among American Indians and Alaska Natives: successes, challenges, and potentials.

With low rates of the risk factors for cardiovascular disease as recently as 40 years ago, the rates of cardiovascular disease (CVD) in American Indians and Alaska Natives were exceedingly low. Despite recent large-scale efforts to eliminate health disparities in ethnic and minority populations, the impact among American Indian and Alaska Natives to date has been relatively limited. Indeed, over the past several decades the incidence and prevalence of cardiovascular risk factors has risen significantly, including the development of an epidemic of diabetes. Evidence suggests that these higher rates of cardiovascular risk factors, including tobacco abuse, diabetes, high blood pressure, and elevated cholesterol levels, may be placing an inordinate burden of cardiovascular disease on the American Indian and Alaska Native population. The rates of heart disease and stroke among American Indians and Alaska Natives are now higher than in the general U.S. population as well as in U.S. whites. Recent evaluations suggest that these rates are also higher than among other ethnic or racial populations in the United States. Additionally, American Indians and Alaska Natives have been found to have a substantially higher proportion of premature death from heart disease when compared with other ethnic and racial populations. A number of recent prevention initiatives and focused clinical efforts are making promising strides toward reduced disparities in cardiovascular health with primordial, primary, and secondary cardiovascular prevention efforts along with enhanced early identification and therapeutic intervention for more favorable cardiovascular outcomes in the future. In order to reach our goals of heart-healthy and stroke-free American Indians and Alaska Natives, implementation of an aggressive, reasonably resourced, systemic plan of coordinated health promotion, risk reduction, and disease control efforts are necessary, with appropriate policy and legislative support.

The epidemiology of atherosclerosis and its risk factors among Native Americans.

In the past, the rates of risk factors for atherosclerosis and cardiovascular disease (CVD) as well as the manifestations of coronary heart disease, stroke, and peripheral vascular disease in Native Americans have been relatively low compared to the general United States population. However, over the past several decades the rates of these CVD-associated risk factors have markedly increased with the concomitant development of a significant and alarming rise in the manifestations of atherosclerosis.