Development and Validation of Risk Prediction Models for Cardiovascular Events in Black Adults: The Jackson Heart Study Cohort

IMPORTANCE

Cardiovascular risk assessment is a fundamental component of prevention of cardiovascular disease (CVD). However, commonly used prediction models have been formulated in primarily or exclusively white populations. Whether risk assessment in black adults is dissimilar to that in white adults is uncertain.

OBJECTIVES

To develop and validate risk prediction models for CVD incidence in black adults, incorporating standard risk factors, biomarkers, and subclinical disease.

DESIGN, SETTING, AND PARTICIPANTS

The Jackson Heart Study (JHS), a longitudinal community-based study of 5301 black adults in Jackson, Mississippi. Inclusive study dates were the date of a participant's first visit (September 2000 to March 2004) to December 31, 2011. The median (75th percentile) follow-up was 9.1 (9.7) years. The dates of the analysis were August 2013 to May 2015. Measurements included standard risk factors, including age, sex, body mass index, systolic and diastolic blood pressure, ratio of fasting total cholesterol to high-density lipoprotein cholesterol, estimated glomerular filtration rate, antihypertensive therapy, diabetes mellitus, and smoking; blood biomarkers; and subclinical disease measures, including ankle-brachial index, carotid intimal-medial thickness, and echocardiographic left ventricular hypertrophy and systolic dysfunction.

MAIN OUTCOMES AND MEASURES

Incident CVD event was defined as the first occurrence of myocardial infarction, coronary heart disease death, congestive heart failure, stroke, incident angina, or intermittent claudication. Model performance was compared with the American College of Cardiology/American Heart Association (ACC/AHA) CVD risk algorithm and the Framingham Risk Score (FHS) refitted to the JHS data and evaluated in the Atherosclerosis Risk in Communities (ARIC) and Multi-Ethnic Study of Atherosclerosis cohorts.

RESULTS

The study cohort comprised 3689 participants with mean (SD) age at baseline was 53 (11) years, and 64.8% (n = 2390) were female. Over a median of 9.1 years, 270 participants (166 women) experienced a first CVD event. A simple combination of standard CVD risk factors, B-type natriuretic peptide, and ankle-brachial index (model 6) yielded modest improvement over a model without B-type natriuretic peptide and ankle-brachial index (C statistic, 0.79; 95% CI, 0.75-0.83 [relative integrated discrimination improvement, 0.22; 95% CI, 0.15-0.30]). However, the reclassification improvement was not substantially different between model 6 and the ACC/AHA CVD Pooled Cohort risk equations or between model 6 and the FHS. The models discriminated reasonably well in the ARIC and Multi-Ethnic Study of Atherosclerosis data (C statistic range, 0.70-0.77).

CONCLUSIONS AND RELEVANCE

Our findings using the JHS data in the present study are valuable because they confirm that current FHS and ACC/AHA risk algorithms work well in black individuals and are not easily improved on. A unique risk calculator for black adults may not be necessary.

Increased Proximal Aortic Diameter is Associated With Risk of Cardiovascular Events and All-Cause Mortality in Blacks The Jackson Heart Study

BACKGROUND

Enlargement of the proximal aorta is associated with aortic wall tissue remodeling, including fragmentation of the elastin fibers, increased synthesis of collagen, and calcification, all of which are associated with aortic wall stiffening. We hypothesized that the proximal aortic diameter (AoD) is associated with cardiovascular events in a community-based cohort of blacks.

METHODS AND RESULTS

We investigated the associations between AoD and cardiovascular events among 3018 black participants (mean age, 55.9 years; 69% women) without past history of cardiovascular disease in the Jackson Heart Study. AoD was measured using echocardiography at the level of the sinuses of Valsalva at end diastole. Cardiovascular event was defined as incident myocardial infarction, fatal coronary artery disease, stroke, or heart failure hospitalization. Cox proportional hazards regression models were used to evaluate the association between baseline AoD and cardiovascular events. Over a median follow-up of 8.3 years, there were 258 cardiovascular events (incident rate, 10.5 per 1000 person-years). After adjustment for traditional risk factors, increased AoD was significantly associated with cardiovascular events (hazard ratio per 1-cm increase, 1.72; 95% CI, 1.10-2.69; P<0.05). Participants in the top AoD quintile had a higher incidence of cardiovascular events compared to those not in the top quintile (hazard ratio, 1.47; 95% CI, 1.11-1.94; P<0.005) after adjustment for risk factors.

CONCLUSIONS

Greater AoD was associated with an increased risk of cardiovascular events in a community-based cohort of blacks. AoD may be useful as a predictor of incident cardiovascular events and further investigation is warranted.

Large-scale genome-wide analysis identifies genetic variants associated with cardiac structure and function

BACKGROUND

Understanding the genetic architecture of cardiac structure and function may help to prevent and treat heart disease. This investigation sought to identify common genetic variations associated with inter-individual variability in cardiac structure and function.

METHODS

A GWAS meta-analysis of echocardiographic traits was performed, including 46,533 individuals from 30 studies (EchoGen consortium). The analysis included 16 traits of left ventricular (LV) structure, and systolic and diastolic function.

RESULTS

The discovery analysis included 21 cohorts for structural and systolic function traits (n = 32,212) and 17 cohorts for diastolic function traits (n = 21,852). Replication was performed in 5 cohorts (n = 14,321) and 6 cohorts (n = 16,308), respectively. Besides 5 previously reported loci, the combined meta-analysis identified 10 additional genome-wide significant SNPs: rs12541595 near MTSS1 and rs10774625 in ATXN2 for LV end-diastolic internal dimension; rs806322 near KCNRG, rs4765663 in CACNA1C, rs6702619 near PALMD, rs7127129 in TMEM16A, rs11207426 near FGGY, rs17608766 in GOSR2, and rs17696696 in CFDP1 for aortic root diameter; and rs12440869 in IQCH for Doppler transmitral A-wave peak velocity. Findings were in part validated in other cohorts and in GWAS of related disease traits. The genetic loci showed associations with putative signaling pathways, and with gene expression in whole blood, monocytes, and myocardial tissue.

CONCLUSION

The additional genetic loci identified in this large meta-analysis of cardiac structure and function provide insights into the underlying genetic architecture of cardiac structure and warrant follow-up in future functional studies.

FUNDING

For detailed information per study, see Acknowledgments.

Relations between subclinical disease markers and type 2 diabetes, metabolic syndrome, and incident cardiovascular disease: the Jackson Heart Study

OBJECTIVE

The presence of subclinical disease measures has been directly associated with the development of cardiovascular disease (CVD) in whites. African Americans (AAs) in the U.S. are at higher risk of CVD compared with non-Hispanic whites; however, data on the prevalence of subclinical disease measures in AAs and their association to CVD remain unclear and may explain the higher CVD risk in this group.

RESEARCH DESIGN AND METHODS

We evaluated 4,416 participants attending the first examination of the Jackson Heart Study (mean age 54 years; 64% women) with available subclinical disease measures.

RESULTS

There were 1,155 participants (26%) with subclinical disease, defined as the presence of one or more of the following: peripheral arterial disease, left ventricular hypertrophy, microalbuminuria, high coronary artery calcium (CAC) score, and low left ventricular ejection fraction. In cross-sectional analyses using multivariable-adjusted logistic regression, participants with metabolic syndrome (MetS) or diabetes (DM) had higher odds of subclinical disease compared with those without MetS and DM (odds ratios 1.55 [95% CI 1.30-1.85] and 2.86 [95% CI 2.32-3.53], respectively). Furthermore, the presence of a high CAC score and left ventricular hypertrophy were directly associated with the incidence of CVD (265 events) in multivariable-adjusted Cox proportional hazards regression models (P < 0.05). In prospective analyses, having MetS or DM significantly increased the hazard of incident CVD, independent of the presence of subclinical disease (P < 0.001).

CONCLUSIONS

In our community-based sample of AAs, we observed a moderately high prevalence of subclinical disease, which in turn translated into a greater risk of CVD, especially in people with MetS and DM.

Clinical correlates and prognostic significance of change in standardized left ventricular mass in a community-based cohort of African Americans

Background

Though left ventricular mass (LVM) predicts cardiovascular events (CVD) and mortality in African Americans, limited data exists on factors contributing to change in LVM and its prognostic significance. We hypothesized that baseline blood pressure (BP) and body mass index (BMI) and change in these variables over time are associated with longitudinal increases in LVM and that such increase is associated with greater incidence of CVD.

Methods and Results

We investigated the clinical correlates of change in standardized logarithmically transformed‐LVM indexed to height2.7 (log‐LVMI) and its association with incident CVD in 606 African Americans (mean age 58±6 years, 66% women) who attended serial examinations 8 years apart. Log‐LVMI and clinical covariates were standardized within sex to obtain z scores for both visits. Standardized log‐LVMI was modeled using linear regression (correlates of change in standardized log‐LVMI) and Cox proportional hazards regression (incidence of CVD [defined as coronary heart disease, stroke, heart failure and intermittent claudication]). Baseline clinical correlates (standardized log‐LVM, BMI, systolic BP) and change in systolic BP over time were significantly associated with 8‐year change in standardized log‐LVMI. In prospective analysis, change in standardized LVM was significantly (P=0.0011) associated with incident CVD (hazards ratio per unit standard deviation change log‐LVMI 1.51, 95% CI 1.18 to 1.93).

Conclusions

In our community‐based sample of African Americans, baseline BMI and BP, and change in BP on follow‐up were key determinants of increase in standardized log‐LVMI, which in turn carried an adverse prognosis, underscoring the need for greater control of BP and weight in this group.

C-reactive protein and subclinical cardiovascular disease among African-Americans: (the Jackson Heart Study)

OBJECTIVE

Systemic inflammation has been implicated as an early marker for subclinical cardiovascular disease; however, findings have been inconsistent in the African-American population.

METHODS

We examined the relation of C-reactive protein (CRP) to subclinical disease in African-American participants of the Jackson Heart Study first examination. Subclinical disease evaluated included aortic valve calcification (AVC), carotid intima-medial thickness (IMT) and peripheral arterial disease (PAD). We assessed the relation of CRP to subclinical disease, adjusting for age, BMI, sex, SBP and DBP, diabetes, total/high-density lipoprotein cholesterol, triglycerides, smoking, antihypertensive therapy, lipid-lowering therapy and hormone replacement therapy.

RESULTS

In the study population approximately, 5.1% of participants had AVC and 6.7% had PAD. In the age-adjusted and sex-adjusted model, CRP was significantly related to AVC (P = 0.02) and carotid IMT (P = 0.02). However, in the multivariable-adjusted logistic regression analysis, CRP was significantly related to AVC (P = 0.02) and to PAD (P = 0.04) but not to carotid IMT (P = 0.18).

CONCLUSION

We describe significant associations between CRP and AVC and PAD in a population-based cohort of African-Americans.

Incidence and survival of hospitalized acute decompensated heart failure in four US communities (from the Atherosclerosis Risk in Communities Study)

Most population-based estimates of incident hospitalized heart failure (HF) have not differentiated acute decompensated heart failure (ADHF) from chronic stable HF nor included racially diverse populations. The Atherosclerosis Risk in Communities Study conducted surveillance of hospitalized HF events (age ≥55 years) in 4 US communities. We estimated hospitalized ADHF incidence and survival by race and gender. Potential 2005 to 2009 HF hospitalizations were identified by International Classification of Diseases, Ninth Revision, Clinical Modification, codes; 6,168 records were reviewed to validate ADHF cases. Population estimates were derived from US Census data; 50% of eligible hospitalizations were classified as ADHF, of which 63.6% were incident ADHF and 36.4% were recurrent ADHF. The average incidence of hospitalized ADHF was 11.6 per 1,000 persons, aged ≥55 years, per year, and recurrent hospitalized ADHF was 6.6 per 1,000 persons/yr. Age-adjusted annual ADHF incidence was highest for black men (15.7 per 1,000), followed by black women (13.3 per 1,000), white men (12.3 per 1,000), and white women (9.9 per 1,000). Of incident ADHF events with heart function assessment (89%), 53% had reduced the ejection fraction (heart failure with reduced ejection fraction [HFrEF]) and 47% had preserved ejection fraction (heart failure with preserved ejection fraction [HFpEF]). Black men had the highest proportion of acute HFrEF events (70%); white women had the highest proportion of acute HFpEF (59%). Age-adjusted 28-day and 1-year case fatality after an incident ADHF was 10.4% and 29.5%, respectively. Survival did not differ by race or gender. In conclusion, ADHF hospitalization and HF type varied by both race and gender, but case fatality rates did not. Further studies are needed to explain why black men are at higher risk of hospitalized ADHF and HFrEF.

Aldosterone, C-reactive protein, and plasma B-type natriuretic peptide are associated with the development of metabolic syndrome and longitudinal changes in metabolic syndrome components: findings from the Jackson Heart Study

OBJECTIVE

Several pathomechanisms are implicated in the pathogenesis of metabolic syndrome (MetS), most of which have not been investigated in African Americans (AAs). We examined the contribution of a selected panel of biomarkers to the development of MetS in Jackson Heart Study (JHS) participants in this investigation.

RESEARCH DESIGN AND METHODS

We evaluated 3,019 JHS participants (mean age, 54 years; 64% women) with measurements for seven biomarkers representing inflammation (high-sensitivity C-reactive protein [CRP]), adiposity (leptin), natriuretic pathway (B-natriuretic peptide [BNP]), adrenal pathway (cortisol and aldosterone), and endothelial function (endothelin and homocysteine). We related the biomarker panel to the development of MetS on follow-up and to longitudinal changes in MetS components.

RESULTS

There were 278 (22.9%) of 1,215 participants without MetS at baseline who had development of new-onset MetS at follow-up. The incidence of MetS was significantly associated with serum aldosterone (P=0.004), CRP (P=0.03), and BNP (P for trend=0.005). The multivariable-adjusted odds ratios (95% CI) per SD increment of log biomarker were as follows: 1.25 (1.07-1.45) for aldosterone, 1.20 (1.02-1.43) for CRP, and 1.54 (1.07-2.23) and 1.91 (1.31-2.80) for low and high BNP quartiles, respectively. Aldosterone was positively associated with change in all MetS risk components, except low HDL cholesterol and waist circumference. CRP concentration was significantly and directly associated with change in systolic blood pressure (SBP) and waist circumference but inversely associated with HDL cholesterol. For BNP, we observed a U-shape relation with SBP and triglycerides.

CONCLUSIONS

Our analysis confirms that, in AAs, higher circulating aldosterone and CRP concentrations predict incident MetS. The nonlinear U-shape relation of BNP with MetS and its components has not been reported before and thus warrants replication.

Associations of adiponectin and leptin with incident coronary heart disease and ischemic stroke in african americans: the jackson heart study

Background: Because the predictive significance of previously reported racial differences in leptin and adiponectin levels remains unclear, we assessed the prospective association of these adipokines with the risk of cardiovascular disease (CVD) events in African Americans, a population with a high prevalence of cardiometabolic risk factors.

Methods: Serum specimens from 4,571 Jackson Heart Study participants without prevalent CVD at baseline examination (2000–2004) were analyzed for adiponectin and leptin levels. Cox proportional hazard regression models were used to estimate the associations of the two adipokines with incident coronary heart disease (CHD) and incident ischemic stroke.

Results: During 6.2 years average of follow-up, 98 incident CHD and 87 incident ischemic stroke events were documented. Among study participants (64% women; mean age 54 ± 13 years), the mean (standard deviation, SD) was 6.04 (4.32) μg/mL in women and 4.03 (3.14) μg/mL in men for adiponectin and 37.35 (23.90) ng/mL in women and 11.03 (10.05) ng/mL in men for leptin. After multivariable adjustment that included age, body mass index, high-density lipoprotein cholesterol, triglycerides, C-reactive protein, insulin resistance by homeostasis model assessment for insulin resistance, systolic blood pressure, hypertension medication, smoking, and physical activity, adiponectin was directly associated in women with incident stroke, HR = 1.41 (1.04–1.91) per one SD increase (p = 0.03), but not in men (p = 0.42). It was not associated with incident CHD in women or men. Leptin was not associated with incident CHD or incident stroke.

Conclusion: In the largest community-based African American cohort, adiponectin was associated among women with a higher risk of incident stroke. Whether adiponectin harbors harmful properties, or it is produced in response to vascular inflammation to counter the atherosclerotic process, or the putative “adiponectin resistance” phenomenon acts, should be further assessed.

Genome-wide association study of cardiac structure and systolic function in African Americans: the Candidate Gene Association Resource (CARe) study

BACKGROUND

Using data from 4 community-based cohorts of African Americans, we tested the association between genome-wide markers (single-nucleotide polymorphisms) and cardiac phenotypes in the Candidate-gene Association Resource study.

METHODS AND RESULTS

Among 6765 African Americans, we related age, sex, height, and weight-adjusted residuals for 9 cardiac phenotypes (assessed by echocardiogram or magnetic resonance imaging) to 2.5 million single-nucleotide polymorphisms genotyped using Genome-wide Affymetrix Human SNP Array 6.0 (Affy6.0) and the remainder imputed. Within the cohort, genome-wide association analysis was conducted, followed by meta-analysis across cohorts using inverse variance weights (genome-wide significance threshold=4.0 ×10(-7)). Supplementary pathway analysis was performed. We attempted replication in 3 smaller cohorts of African ancestry and tested lookups in 1 consortium of European ancestry (EchoGEN). Across the 9 phenotypes, variants in 4 genetic loci reached genome-wide significance: rs4552931 in UBE2V2 (P=1.43×10(-7)) for left ventricular mass, rs7213314 in WIPI1 (P=1.68×10(-7)) for left ventricular internal diastolic diameter, rs1571099 in PPAPDC1A (P=2.57×10(-8)) for interventricular septal wall thickness, and rs9530176 in KLF5 (P=4.02×10(-7)) for ejection fraction. Associated variants were enriched in 3 signaling pathways involved in cardiac remodeling. None of the 4 loci replicated in cohorts of African ancestry was confirmed in lookups in EchoGEN.

CONCLUSIONS

In the largest genome-wide association study of cardiac structure and function to date in African Americans, we identified 4 genetic loci related to left ventricular mass, interventricular septal wall thickness, left ventricular internal diastolic diameter, and ejection fraction, which reached genome-wide significance. Replication results suggest that these loci may be unique to individuals of African ancestry. Additional large-scale studies are warranted for these complex phenotypes.

Association of plasma B-type natriuretic peptide concentrations with longitudinal blood pressure tracking in African Americans: findings from the Jackson Heart Study

Water and sodium retention precedes the development of high blood pressure (BP) and explains a compensatory rise in B-type natriuretic peptide (BNP) concentrations. It is unclear whether BNP concentrations antedate the BP progression. We hypothesized that higher BNP concentrations in our African American cohort will be associated with longitudinal increases in BP, progression of BP stage, and incident hypertension. Our study sample consisted of 888 normotensive (based on BP at examination 1 [2000-2004]) participants of the Jackson Heart Study (mean age, 47±12 years; 61% women). We examined the relation of BNP concentrations at the baseline examination to change in systolic and diastolic BPs, BP progression (an increase by 1 BP stage as defined by THE sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure) and incident hypertension by examination 2 (2005-2008) adjusting for baseline BP stages, systolic and diastolic BPS, traditional risk factors, and echocardiographic left ventricular mass. Over a median follow-up period of 5.0±0.8 years, 36.9% progressed to a higher BP stage and 19.3% developed hypertension. In multivariable regression models, higher log-BNP concentrations at examination 1 were significantly and positively associated with changes in systolic and diastolic BPs (P<0.05 for both). Baseline log-BNP was significantly associated with BP progression (P=0.046). Every SD increase in baseline log BNP was associated with a 12% increased risk of BP progression. Log-BNP was not significantly associated with incident hypertension (P=0.12). In our community-based sample of African Americans, higher BNP concentrations predicted a longitudinal increase in systolic and diastolic BPs and progression of BP stage.

Common genetic variation near the connexin-43 gene is associated with resting heart rate in African Americans: a genome-wide association study of 13,372 participants

BACKGROUND

Genome-wide association studies have identified several genetic loci associated with variation in resting heart rate in European and Asian populations. No study has evaluated genetic variants associated with heart rate in African Americans.

OBJECTIVE

To identify novel genetic variants associated with resting heart rate in African Americans.

METHODS

Ten cohort studies participating in the Candidate-gene Association Resource and Continental Origins and Genetic Epidemiology Network consortia performed genome-wide genotyping of single nucleotide polymorphisms (SNPs) and imputed 2,954,965 SNPs using HapMap YRI and CEU panels in 13,372 participants of African ancestry. Each study measured the RR interval (ms) from 10-second resting 12-lead electrocardiograms and estimated RR-SNP associations using covariate-adjusted linear regression. Random-effects meta-analysis was used to combine cohort-specific measures of association and identify genome-wide significant loci (P≤2.5×10(-8)).

RESULTS

Fourteen SNPs on chromosome 6q22 exceeded the genome-wide significance threshold. The most significant association was for rs9320841 (+13 ms per minor allele; P = 4.98×10(-15)). This SNP was approximately 350 kb downstream of GJA1, a locus previously identified as harboring SNPs associated with heart rate in Europeans. Adjustment for rs9320841 also attenuated the association between the remaining 13 SNPs in this region and heart rate. In addition, SNPs in MYH6, which have been identified in European genome-wide association study, were associated with similar changes in the resting heart rate as this population of African Americans.

CONCLUSIONS

An intergenic region downstream of GJA1 (the gene encoding connexin 43, the major protein of the human myocardial gap junction) and an intragenic region within MYH6 are associated with variation in resting heart rate in African Americans as well as in populations of European and Asian origin.

Abstract P42: Health Professional Shortage Areas, Insurance Status, and Cardiovascular Disease Prevention in the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Background: Uninsured individuals and those living in federally designated Health Professional Shortage Areas (HPSA) face considerable access barriers and, consequently, may receive less cardiovascular disease (CVD) preventive care.

Methods: REGARDS is a national cohort of 30,239 African American (AA) and White community dwelling individuals >45 years of age recruited between 2003 and 2007. We investigated 5 CVD prevention guidelines: 1) aspirin in those with coronary heart disease (CHD), 2) beta-blockers (BB) following myocardial infarction, 3) angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers in those with diabetes or CVD and either hypertension or chronic kidney disease, 4) statins in those with diabetes or CHD, and 5) warfarin for atrial fibrillation. We compared use of these medications by insurance status and HPSA county residence, adjusting for sociodemographics, health behaviors, and health status. Counties with partial HPSA status were excluded.

Results: Mean age of participants was 64±9 years, 42% were AA, 55% were women, 93% were insured; 2,548 participants resided in complete HPSA counties and 17,441 in non-HPSA counties, representing 340 of 842 complete HPSA and 1,145 of 1,792 non-HPSA counties nationally. The odds of receiving aspirin, BBs, and ACEI by were similar by HPSA county type and insurance status. However, the odds of receiving statin therapy were lower among uninsured participants, regardless of county type (Table).

Conclusions: Residence in HPSA counties was not associated with less CVD prevention. However, a combination of lack of insurance and residence in a HPSA county defined those with the lowest recommended statin use, suggesting lack of access to newer, more expensive therapies among those with both financial and geographic barriers to primary care.

Health Professional Shortage Areas, insurance status, and cardiovascular disease prevention in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

Individuals with cardiovascular disease (CVD) living in Health Professional Shortage Areas (HPSA) may receive less preventive care than others. The Reasons for Geographic And Racial Differences in Stroke Study (REGARDS) surveyed 30,239 African American (AA) and White individuals older than 45 years of age between 2003-2007. We compared medication use for CVD prevention by HPSA and insurance status, adjusting for sociodemographic factors, health behaviors, and health status. Individuals residing in partial HPSA counties were excluded. Mean age was 64±9 years, 42% were AA, 55% were women, and 93% had health insurance; 2,545 resided in 340 complete HPSA counties and 17,427 in 1,145 non-HPSA counties. Aspirin, beta-blocker, and ACE-inhibitor use were similar by HPSA and insurance status. Compared with insured individuals living in non-HPSA counties, statin use was lower among uninsured participants living in non-HPSA and HPSA counties. Less medication use for CVD prevention was not associated with HPSA status, but less statin use was associated with lack of insurance.

Association of adiponectin with left ventricular mass in blacks: the Jackson Heart Study

BACKGROUND

Blacks have a higher prevalence of left ventricular hypertrophy than whites. Several population-based studies have reported an inverse association between adiponectin and left ventricular mass (LVM); however, the relationship between adiponectin levels and LVM has yet to be defined in blacks. The Jackson Heart Study cohort provides an opportunity to test the hypothesis that the inverse association between adiponectin and LVM may be modified by risk factors common among blacks.

METHODS AND RESULTS

The study population included 2649 black Jackson Heart Study participants (mean age 51±12 years, 63% women, 51% obese, 54% with hypertension, and 16% with diabetes). Multiple linear and spline regression was used to assess the association, with adjustment for demographic, clinical, and behavioral covariates. Among all the participants, there was a statistically significant but modest inverse association between adiponectin and LVM index. Hypertension and insulin resistance emerged as statistically significant effect modifiers of this relationship. The inverse association present among the normotensive participants was explained by obesity measures such as the body mass index. Among participants with both hypertension and insulin resistance, there was a significant direct association between adiponectin and the LVM index after multivariable adjustment (β=1.55, P=0.04, per 1-SD increment in the adiponectin log value).

CONCLUSIONS

The association between serum adiponectin and LVM among blacks in the Jackson Heart Study cohort was dependent on hypertension and insulin resistance status. Normotensive blacks exhibited an inverse adiponectin-LVM association, whereas participants with hypertension and insulin resistance had a direct association.

Relation of obesity to circulating B-type natriuretic peptide concentrations in blacks: the Jackson Heart Study

BACKGROUND

Lower plasma B-type natriuretic peptide (BNP) concentrations in obese individuals ("natriuretic handicap") may play a role in the pathogenesis of obesity-related hypertension. Whether this phenomenon may contribute to hypertension in blacks is unknown. We tested the hypothesis that body mass index is inversely related to BNP concentrations in blacks.

METHODS AND RESULTS

We examined the relation of plasma BNP to body mass index in 3742 Jackson Heart Study participants (mean age, 55 ± 13; 62% women) without heart failure using multivariable linear and logistic regression, adjusting for clinical and echocardiographic covariates. The multivariable-adjusted mean BNP was higher for lean participants compared with obese participants in both normotensive (P<0.0001) and hypertensive (P<0.0012) groups. In sex-specific analyses, the adjusted mean BNP was higher in lean hypertensive individuals compared with obese hypertensive individuals for both men (20.5 versus 10.9 pg/mL, respectively; P=0.0009) and women (20.0 versus 13.8 pg/mL; P=0.011). The differences between lean and obese participants were more pronounced in normotensive participants (men, 9.0 versus 4.4 pg/mL; P<0.0001; women, 12.8 versus 8.4 pg/mL; P=0.0005). For both hypertensive and normotensive individuals in the pooled sample, multivariable-adjusted BNP was significantly related to both continuous body mass index (P<0.05 and P<0.0001, respectively) and categorical body mass index (P for trend <0.006 and <0.0001, respectively).

CONCLUSION

Our cross-sectional study of a large community-based sample of blacks demonstrates that higher body mass index is associated with lower circulating BNP concentrations, thereby extending the concept of a natriuretic handicap in obese individuals observed in non-Hispanic whites to this high-risk population.

The relation of diabetes, impaired fasting blood glucose, and insulin resistance to left ventricular structure and function in African Americans: the Jackson Heart Study

OBJECTIVE

We assessed the relation of diabetes and insulin resistance (IR) on left ventricular (LV) structure and function in African Americans.

RESEARCH DESIGN AND METHODS

Among those receiving echocardiograms in cycle 1 of the Jackson Heart Study, we assessed the sex-specific relation of fasting blood glucose (FBG), diabetes, and IR to LV structure and function, adjusting for age, systolic blood pressure, antihypertensive medications, and BMI.

RESULTS

Among 2,399 participants, LV mass index (P(women) = 0.0002 and P(men) = 0.02), posterior wall thickness (P(women) = 0.01 and P(men) = 0.05), and interventricular septal wall thickness (P(women) = 0.01) were related to FBG categories. Among those with normal FBG and no diabetes, concentric remodeling and low ejection fraction in women and LV mass index and posterior wall thickness in men were related to IR.

CONCLUSIONS

In the largest study of its kind in a community-based cohort of African Americans, we found a relation of FBG category and IR to LV structure and function.

Epidemiology, heritability, and genetic linkage of C-reactive protein in African Americans (from the Jackson Heart Study)

C-reactive protein (CRP) has been studied largely in white non-Hispanic cohorts. There is limited information on CRP's range of values, heritability, and relation to cardiovascular disease risk factors in African Americans. The aim of this study was to evaluate the distribution, clinical correlates, heritability, and genetic linkage of log-transformed CRP in participants in the middle-aged to elderly African American cohort in the community-based Jackson Heart Study. The distribution and correlates of CRP were analyzed for the entire study cohort who underwent the first examination (2001 to 2004). Heritability was estimated for the family cohort nested within the larger Jackson Heart Study (246 families, n = 1,317). The relation between CRP and cardiovascular disease risk factors was tested with multivariable stepwise regression analyses. Heritability was estimated using a variance-components method. Linkage analysis was performed using the multipoint variance-components approach. The study sample consisted of 4,919 participants (mean age 55 +/- 13 years, 63% women); the median CRP concentration was 2.7 mg/L. In stepwise models, traditional risk factors explained 23.8% of CRP's variability, with body mass index (partial R(2) = 13.6%) explaining 57.1% of the variability of CRP due to traditional risk factors. The heritability of CRP (adjusted for age, gender, and body mass index) was 0.45. The strongest linkage evidence for CRP was observed on chromosome 11 (11p13 to 11p11.2), with a logarithm of odds score of 2.72. In conclusion, in this large population-based cohort of African Americans, circulating CRP concentration was heritable and associated with several traditional cardiovascular risk factors, particularly body mass index.

The predictive value of left atrial size for incident ischemic stroke and all-cause mortality in African Americans: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND AND PURPOSE

The association between left atrial (LA) size, ischemic stroke, and death has not been well established in African Americans despite their disproportionately higher rates of stroke and cardiovascular mortality compared to non-Hispanic whites.

METHODS

For the analysis, participants in the Jackson cohort of the Atherosclerosis Risk in Communities Study were followed from the date of the echocardiogram in cycle three to the date of the first ischemic stroke event (or death) or to December 31, 2004 if no ischemic stroke event (or death) was detected.

RESULTS

There were 1886 participants in the study population (mean age 58.9 years, 65% women). Participants in the top quintile of LA diameter indexed to height (LA diameter/height; 2.57 to 3.55 cm/m) were more likely women, hypertensive, diabetic, and obese compared to those not in the top quintile. Over a median follow-up of 9.8 years for ischemic stroke and 9.9 years for all-cause mortality, there were 106 strokes and 242 deaths. In a multivariable model adjusting for traditional clinical risk factors, the top quintile of LA diameter/height was significantly related to ischemic stroke (HR 1.7; 95% CI: 1.1, 2.7) and all-cause mortality (HR 2.0; 95% CI: 1.5, 2.7). After further adjustment for left ventricular (LV) hypertrophy and low LV ejection fraction, the top quintile remained significantly related to all-cause mortality (HR 1.8; 95% CI: 1.3, 2.5).

CONCLUSIONS

In this population-based cohort of African Americans, LA size was a predictor of all-cause mortality after adjusting for traditional cardiovascular risk factors, LV hypertrophy, and low LV ejection fraction.

Echocardiographic left ventricular mass in African-Americans: the Jackson cohort of the Atherosclerosis Risk in Communities Study

Characterization of target organ damage from hypertension is of particular interest in African-Americans, and evidence from electrocardiographic studies suggests that left ventricular hypertrophy is a frequent clinical finding of considerable prognostic importance. Echocardiographic studies may permit more precise characterization of the pathologic impact of hypertension on cardiac structure and function. The objective of this study is to characterize left ventricular (LV) structure including measures of wall thickness, septal thickness, internal dimension, and mass in a middle-aged sample of African-Americans using echocardiography. This study is a cohort (cross-sectional) study in which 2445 middle-aged African-American study participants from a population-based sample initially enrolled by the Atherosclerosis Risk in Communities, Jackson, Mississippi Examination Center in 1987-1989 underwent an M-mode echocardiograpic examination at their third or fourth clinic visit in 1993-1996. Measures of LV mass, even where indexed by size were conspicuously greater in men compared to women, and men exhibited a demonstrably steeper gradient of LV mass across the rather restricted age range of the study. However, when gender specific thresholds for LV hypertrophy were utilized, African-American men appear to have lower prevalence of LV hypertrophy than women. The lowest prevalence of LV hypertrophy was observed in African-American men who did not have hypertension (28.4%). The findings confirm previous suggestions from electrocardiographic investigations that cardiac hypertrophy is common, if not epidemic in middle-aged African-American men and women, whether or not they have hypertension.

Vegetation biopsy using transesophageal echocardiography guidance: a technique to aid in diagnosis of culture-negative endocarditis

A method of obtaining a vegetation sample in a culture-negative endocarditis is described. A combination of fluoroscopy and transesophageal echocardiography was utilized to obtain the sample. The results positively influenced the diagnosis and treatment in this 16-yr-old male with complex congenital heart disease.

Fetal echocardiography in gravidas with historic risk factors for congenital heart disease

All fetal echocardiograms performed at our institution between January 1, 1986, and June 1, 1991, were reviewed. The echocardiogram referral indication and results were verified for all women studied. Historic risk factors under consideration were pregestational diabetes, anticonvulsant or lithium ingestion in the first trimester, and a family history of congenital heart disease. Women with historic risk factors who had either a fetal abnormality on antenatal sonography or a known aneuploid fetus prior to the fetal echocardiograph were excluded. Of the 994 women who had a fetal echocardiogram performed during this study period, 486 (48.9%) were evaluated solely on the basis of a historic risk factor. Four of the 486 women (0.8%) were diagnosed as having a significant fetal structural cardiac malformation. Two of the four fetuses succumbed to obstetric complications. The remaining two infants were delivered at term and are doing well after postnatal cardiac surgery. In this select group of women with risk factors but no recognized fetal abnormality, the incidence of significant cardiac lesions was low. Although indications for fetal echocardiography must be evaluated on an individual basis, our data do not support a recommendation for the routine use of fetal echocardiography as a screening test in all women with historic risk factors.

Transesophageal echocardiographic diagnosis of multicentric left ventricular myxomas mimicking a left atrial tumor

We report a case of multicentric left ventricular myxomas with prolapse of one myxoma into the left atrium during ventricular systole that mimicked a left atrial tumor. The transthoracic echocardiogram showed large masses in the region of the mitral valve leaflets consistent with vegetations or tumors. A computed tomographic scan of the chest demonstrated two distinct left atrial masses, one of which appeared to prolapse from the left atrium into the left ventricle. Intraoperative transesophageal echocardiography showed a large pedunculated mass moving between the two left-sided cardiac chambers with intermittent trapping of the mass in the left atrium. The mass was attached to the left ventricular posteromedial papillary muscle by a long stalk. Another adjacent large ventricular mass was also noted in the left ventricle. These findings were confirmed at operation, which also demonstrated a third small tumor arising from the atrial aspect of the posterior mitral leaflet.

Usefulness and limitations of transesophageal echocardiography in the assessment of proximal coronary artery stenosis

To assess the usefulness of transesophageal echocardiography in the evaluation of proximal coronary artery stenosis, 111 consecutive patients (mean age 61 years) who had intraoperative transesophageal echocardiography and coronary angiography within 1 week of surgery were studied. Transesophageal echocardiography visualized the entire length of the left main artery (0.2 to 2.2 cm, mean 0.93), 0.2 to 2.2 cm of the proximal left anterior descending artery and 0.1 to 3.4 cm of the proximal left circumflex artery in 103 patients (93%) and 0.1 to 4.6 cm of the proximal right coronary artery in 55 patients (49%). In the coronary artery segments visualized by echocardiography and compared with the corresponding angiographic segments, transesophageal echocardiography correctly identified 23 (96%) of 24 left main stenoses, 11 (78%) of 14 stenoses involving the left anterior descending artery, 6 (75%) of 8 left circumflex stenoses and all 7 stenoses (100%) of the right coronary artery. In all seven patients with ostial stenosis (left main artery in five and right coronary artery in two), the condition was correctly diagnosed by this technique. The sensitivity and specificity of transesophageal echocardiography in the overall evaluation of proximal coronary artery stenosis as customarily defined by angiography were 96% and 99% for the left main artery, 48% and 99% for the left anterior descending artery, 67% and 100% for the left circumflex artery and 37% and 100% for the right coronary artery, respectively. The distance of the stenotic lesion from the origin of the vessel by transesophageal echocardiography also correlated well with that measured by angiography (r = 0.63 to 0.99).(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of transesophageal echocardiography in assessment of aortic dissection

BACKGROUND

The value of transesophageal echocardiography in the assessment of patients with aortic dissection was studied.

METHODS AND RESULTS

Group 1 (34 patients) represented all patients studied at our institution with this technique in whom aortic dissection was proven by aortography, surgery, or autopsy. Group 2 (27 patients) represented all patients studied with this technique at our institution in whom aortic dissection was excluded by aortography. Transesophageal echocardiography made a correct diagnosis of aortic dissection in 33 of 34 patients (sensitivity, 97%; specificity, 100%). It also correctly demonstrated the type of dissection in all 29 patients with aortographic or surgical proof. On the other hand, computed tomography scanning, performed in 24 of 34 patients in group 1, made a correct diagnosis in only 67% of patients and misclassified the type of dissection in 33%. Transesophageal echocardiography correctly identified involvement of the coronary arteries by aortic dissection in six of seven patients as well as absence of both left and right coronary artery involvement in 10 patients with aortic dissection. This technique was also useful in detecting communications between the true and false lumens, presence of thrombi in the false lumen, and, in two patients, localized dissection rupture with formation of a false aneurysm. In both groups 1 and 2, transesophageal echocardiography correctly identified patients with moderate to severe aortic regurgitation.

CONCLUSIONS

Transesophageal echocardiography is very useful in the assessment of aortic dissection.

Transesophageal echocardiography in aortopulmonary communications

The assessment of congenital aortopulmonary communications by transthoracic echocardiography may be suboptimal, particularly postoperatively, due to limited acoustic windows. We performed intraoperative transesophageal echocardiograms in six patients with eight proven systemic-pulmonary communications. Diagnosis included truncus arteriosus (1), aortopulmonary window (1), Waterston anastomosis (3), central Gore-Tex shunt (1), and modified left Blalock-Taussig shunt (2). All communications were accurately demonstrated by transesophageal echocardiography (TEE). The transesophageal technique also provided an assessment of the size of the aortopulmonary communications and the proximal pulmonary arteries. In addition, the gradient across some of the communications could be accurately estimated utilizing the high pulse repetition frequency Doppler. On the other hand, only two of the seven aortopulmonary communications were detected by transthoracic echocardiography. Postoperatively, transesophageal imaging demonstrated unobstructed conduit in five of five patients who underwent conduit repair, as well as intact closure of aortopulmonary communications and concomitant closure of ventricular septal defects.

Uses and limitations of transthoracic echocardiography in the assessment of atrial septal defect in the adult

Two-dimensional and color Doppler echocardiography accurately detected the presence of an atrial septal defect (ASD) in 47 of 50 adults (mean age 40 years) confirmed by surgery or cardiac catheterization, or both. It correctly categorized all patients with ostium secundum and ostium primum ASD but misdiagnosed 3 of 5 patients with surgically proven sinus venosus ASD. The shunt flow volume across the ASD was calculated with the standard Doppler equation, and assuming the ASD to be circular correlated with shunt flow volume obtained by cardiac catheterization (r = 0.74). The maximum width of the color flow signals moving across the ASD was taken as its diameter. Mean flow velocity was determined either by placing a pulsed Doppler sample volume parallel to the flow across the ASD as visualized by color Doppler or by color M-mode examination, which allowed determination of flow velocities using a previously validated method that incorporates a computer analysis of pixel color intensity. The pulmonary to systemic blood flow ratio obtained by color-guided conventional Doppler interrogation of the left and right ventricular outflow tracts correlated poorly with cardiac catheterization results (r = 0.38). In patients with associated tricuspid regurgitation, the peak systolic pulmonary artery pressure obtained by color Doppler-guided continuous-wave Doppler correlated well with that obtained at cardiac catheterization (r = 0.89). The maximum color Doppler jet width of the flow across the ASD poorly correlated with ASD size estimated at surgery (r = 0.50).

Echocardiographic and electrocardiographic correlation in cases of congestive cardiomyopathy

Echocardiographically diagnosed sixty cases of congestive cardiomyopathy were electrocardiographically analysed. None of the cases had normal electrocardiogram. The commonest rhythm disorder was premature ventricular contractions (P.V.C.-26.6%), and the commonest conduction disorder was left anterior hemi block (LAHB-17%). Nonspecific ST-T changes in the anterolateral leads was the most common electrocardiographic finding. No correlation was seen between electrocardiographic evidence of hypertrophy and echocardiographic evidence of cardiac enlargement.