Race- and sex-specific ECG models for left ventricular mass in older populations. Factors influencing overestimation of left ventricular hypertrophy prevalence by ECG criteria in African-Americans

Black-white Differences in Left Ventricular Hypertrophy Rates Among Young Adults with Ischemic Stroke

OBJECTIVES

Few studies have addressed Black-White differences in left ventricular hypertrophy (LVH) in young stroke patients without a history of hypertension.

METHODS

A case-only cross-sectional analysis performed in 2019 of data from the Stroke Prevention in Young Adults Study, a population-based case-control study of ischemic stroke patients ages 15-49. The main outcomes were hypertension indicators at the time of stroke hospitalization: self-reported history of hypertension, LVH by echocardiography (Echo-LVH) and LVH by electrocardiogram (ECG-LVH). The prevalence of Echo-LVH was further determined in those with and without a history of hypertension. Adjusted odds ratios and 95% confidence intervals comparing blacks and whites were calculated by logistic regression.

RESULTS

The study population included 1028 early-onset ischemic stroke patients, 48% Black cases, 54% men, median age 43 years (interquartile range, 38-46 years). Overall, the prevalence of hypertension history, Echo-LVH and ECG-LVH were 41.3%, 34.1% and 17.5%, respectively. Each of the hypertension indicators were more frequent in men than in women and in Black cases than in White cases. Black patients without a history of hypertension had higher rates of Echo-LVH than their white counterparts, 40.3% vs 27.7% (age and obesity adjusted OR 1.8; 95% CI 1.02-3.4) among men and 20.9% vs 7.6% (adjusted OR 2.7; 95% CI 1.2-6.2) among women.

CONCLUSIONS

LVH was common in young patients with ischemic stroke, regardless of self-reported history of hypertension. These findings emphasize the need for earlier screening and more effective treatment of hypertension in young adults, particularly in the Black population.

Automated ECG Interpretation—A Brief History from High Expectations to Deepest Networks

This article traces the development of automated electrocardiography from its beginnings in Washington, DC around 1960 through to its current widespread application worldwide. Changes in the methodology of recording ECGs in analogue form using sizeable equipment through to digital recording, even in wearables, are included. Methods of analysis are considered from single lead to three leads to twelve leads. Some of the influential figures are mentioned while work undertaken locally is used to outline the progress of the technique mirrored in other centres. Applications of artificial intelligence are also considered so that the reader can find out how the field has been constantly evolving over the past 50 years.

Myorelaxation, respiratory depression and electrocardiographic changes caused by the administration of extract of açai (Euterpe oleracea Mart.) stone in rats

The biological and pharmacological properties of natural polyphenols of the extract of Euterpe oleracea stone (EEOS) are associated with the central nervous system (CNS). To investigate the sedative and myorelaxant activity of EEOS in vivo, this study aimed to present the myorelaxant and sedative effects of EEOS in Wistar rats using spontaneous locomotor activity and motor electrophysiology. A total of 108 animals were used in the following experiments: a) behavioral tests (n = 27); b) electromyographic recordings of skeletal muscle (n = 27); c) respiratory muscle activity recordings (n = 27); d) cardiac muscle activity recordings (n = 27). The behavioral characteristics were measured according to the latency time of onset, the transient loss of posture reflex and maximum muscle relaxation. Electrodes were implanted in the gastrocnemius muscle and in the tenth intercostal space for electromyographic (EMG) signal capture to record muscle contraction, and in the D2 lead for electrocardiogram acquisition. After using the 300 mg/kg dose of EEOS intraperitoneally, a myorelaxant activity exhibited a lower frequency of contractility with an amplitude pattern of low and short duration at gastrocnemius muscle and intercostal muscle, which clearly describes a myorelaxant activity and changes in cardiac activity. The present report is so far the first study to demonstrate the myorelaxant activity of this extract, indicating an alternative route for açai stone valorization and its application in pharmaceutical fields.

Detection of Left Ventricular Hypertrophy Using Bayesian Additive Regression Trees: The MESA

Background

We developed a new left ventricular hypertrophy (LVH) criterion using a machine‐learning technique called Bayesian Additive Regression Trees (BART).

Methods and Results

This analysis included 4714 participants from MESA (Multi‐Ethnic Study of Atherosclerosis) free of clinically apparent cardiovascular disease at enrollment. We used BART to predict LV mass from ECG and participant characteristics using cardiac magnetic resonance imaging as the standard. Participants were randomly divided into a training set (n=3774) and a validation set (n=940). We compared the diagnostic/prognostic performance of our new BART‐LVH criteria with traditional ECG‐LVH criteria and cardiac magnetic resonance imaging–LVH. In the validation set, BART‐LVH showed the highest sensitivity (29.0%; 95% CI, 18.3%–39.7%), followed by Sokolow‐Lyon‐LVH (21.7%; 95% CI, 12.0%–31.5%), Peguero–Lo Presti (14.5%; 95% CI, 6.2%–22.8%), Cornell voltage product (10.1%; 95% CI, 3.0%–17.3%), and Cornell voltage (5.8%; 95% CI, 0.3%–11.3%). The specificity was >93% for all criteria. During a median follow‐up of 12.3 years, 591 deaths, 492 cardiovascular disease events, and 332 coronary heart disease events were observed. In adjusted Cox models, both BART‐LVH and cardiac magnetic resonance imaging–LVH were associated with mortality (hazard ratio [95% CI], 1.88 [1.45–2.44] and 2.21 [1.74–2.81], respectively), cardiovascular disease events (hazard ratio [95% CI], 1.46 [1.08–1.98] and 1.91 [1.46–2.51], respectively), and coronary heart disease events (hazard ratio [95% CI], 1.72 [1.20–2.47] and 1.96 [1.41–2.73], respectively). These associations were stronger than associations observed with traditional ECG‐LVH criteria.

Conclusions

Our new BART‐LVH criteria have superior diagnostic/prognostic ability to traditional ECG‐LVH criteria and similar performance to cardiac magnetic resonance imaging–LVH for predicting events.

Assessing and Mitigating Bias in Medical Artificial Intelligence: The Effects of Race and Ethnicity on a Deep Learning Model for ECG Analysis

BACKGROUND

Deep learning algorithms derived in homogeneous populations may be poorly generalizable and have the potential to reflect, perpetuate, and even exacerbate racial/ethnic disparities in health and health care. In this study, we aimed to (1) assess whether the performance of a deep learning algorithm designed to detect low left ventricular ejection fraction using the 12-lead ECG varies by race/ethnicity and to (2) determine whether its performance is determined by the derivation population or by racial variation in the ECG.

METHODS

We performed a retrospective cohort analysis that included 97 829 patients with paired ECGs and echocardiograms. We tested the model performance by race/ethnicity for convolutional neural network designed to identify patients with a left ventricular ejection fraction ≤35% from the 12-lead ECG.

RESULTS

The convolutional neural network that was previously derived in a homogeneous population (derivation cohort, n=44 959; 96.2% non-Hispanic white) demonstrated consistent performance to detect low left ventricular ejection fraction across a range of racial/ethnic subgroups in a separate testing cohort (n=52 870): non-Hispanic white (n=44 524; area under the curve [AUC], 0.931), Asian (n=557; AUC, 0.961), black/African American (n=651; AUC, 0.937), Hispanic/Latino (n=331; AUC, 0.937), and American Indian/Native Alaskan (n=223; AUC, 0.938). In secondary analyses, a separate neural network was able to discern racial subgroup category (black/African American [AUC, 0.84], and white, non-Hispanic [AUC, 0.76] in a 5-class classifier), and a network trained only in non-Hispanic whites from the original derivation cohort performed similarly well across a range of racial/ethnic subgroups in the testing cohort with an AUC of at least 0.930 in all racial/ethnic subgroups.

CONCLUSIONS

Our study demonstrates that while ECG characteristics vary by race, this did not impact the ability of a convolutional neural network to predict low left ventricular ejection fraction from the ECG. We recommend reporting of performance among diverse ethnic, racial, age, and sex groups for all new artificial intelligence tools to ensure responsible use of artificial intelligence in medicine.

Bringing Critical Race Praxis Into the Study of Electrophysiological Substrate of Sudden Cardiac Death: The ARIC Study

Background Race is an established risk factor for sudden cardiac death (SCD). We sought to determine whether the association of electrophysiological substrate with SCD varies between black and white individuals. Methods and Results Participants from the ARIC (Atherosclerosis Risk in Communities) study with analyzable ECGs (n=14 408; age, 54±6 years; 74% white) were included. Electrophysiological substrate was characterized by ECG metrics. Two competing outcomes were adjudicated: SCD and non-SCD. Interaction of ECG metrics with race was studied in Cox proportional hazards and Fine-Gray competing risk models, adjusted for prevalent cardiovascular disease, risk factors, and incident nonfatal cardiovascular disease. At the baseline visit, adjusted for age, sex, and study center, blacks had larger spatial ventricular gradient magnitude (0.30 mV; 95% CI, 0.25-0.34 mV), sum absolute QRST integral (18.4 mV*ms; 95% CI, 13.7-23.0 mV*ms), and Cornell voltage (0.30 mV; 95% CI, 0.25-0.35 mV) than whites. Over a median follow-up of 24.4 years, SCD incidence was higher in blacks (2.86 per 1000 person-years; 95% CI, 2.50-3.28 per 1000 person-years) than whites (1.37 per 1000 person-years; 95% CI, 1.22-1.53 per 1000 person-years). Blacks with hypertension had the highest rate of SCD: 4.26 (95% CI, 3.66-4.96) per 1000 person-years. Race did not modify an association of ECG variables with SCD, except QRS-T angle. Spatial QRS-T angle was associated with SCD in whites (hazard ratio, 1.38; 95% CI, 1.25-1.53) and hypertension-free blacks (hazard ratio, 1.52; 95% CI, 1.09-2.12), but not in blacks with hypertension (hazard ratio, 1.15; 95% CI, 0.99-1.32) (P-interaction=0.004). Conclusions Race did not modify associations of electrophysiological substrate with SCD and non-SCD. Electrophysiological substrate does not explain racial disparities in SCD rate.

Diagnostic performance of electrocardiographic criteria in echocardiographic diagnosis of different patterns of left ventricular hypertrophy

Background

Electrocardiogram (ECG) is considered the initial screening method for the detection of left ventricular hypertrophy (LVH) despite its low sensitivity. However, there are no data on how ECG criteria for LVH perform in patients with concentric (cLVH) and eccentric LVH (eLVH).

Methods

In the setting of the Corinthia cross‐sectional study, ECGs were analyzed in 1,570 participants of the study. Seven ECG LVH criteria were calculated (Sokolow–Lyon voltage, index, and product, sex‐specific Cornell voltage and product, Lewis voltage, and the Framingham), whereas LVH was defined, based on echocardiographic data, as left ventricular mass indexed for body surface area (BSA) of at least 125 g/m² in men and at least 110 g/m² in women.

Results

Regarding the frequency encountered for each ECG LVH criterion, there was no difference between eLVH and cLVH. However, when ECG criteria were compared as continuous variables between LVH groups, Cornell voltage and product were higher in cLVH individuals, with a value of Cornell voltage >13.95 mV having 61% sensitivity and 62% specificity to differentiate cLVH from eLVH (p = .05). Even after adjustment for age, sex, body mass index, and hypertension, the occurrence of Cornell voltage or product increased the odds of cLVH by 1.6 times (p = .001).

Conclusion

Cornell voltage and product criteria disclosed a superior discriminative ability for the detection of LVH via ECG. When further categorizing LVH as concentric and eccentric, Cornell product depicted the higher discriminative ability for cLVH.

Marked variation in heritability estimates of left ventricular mass depending on modality of measurement

Left ventricular (LV) hypertrophy is a strong risk factor for heart failure and cardiovascular death. ECG measures of LV mass are estimated as heritable in twin and family-based analyses and heritability estimates of LV mass measured by echocardiography are lower. We hypothesised that CMR-derived measurements, being more precise than echocardiographic measurements, would advance our understanding of heritable LV traits. We phenotyped 116 British families (427 individuals) by CMR and ECG, and undertook heritability analyses using variance-components (QTDT) and GWAS SNP-based (GCTA-GREML) methods. ECG-based traits such as LV mass and Sokolow-Lyon duration showed substantial estimates of heritability (60%), whereas CMR-derived LV mass was only modestly heritable (20%). However, the ECG LV mass was positively correlated with the lateral diameter of the chest (rho = 0.67), and adjustment for this attenuated the heritability estimate (42%). Finally, CMR-derived right ventricular mass showed considerable heritability (44%). Heritability estimates of LV phenotypes show substantial variation depending on the modality of measurement, being greater when measured by ECG than CMR. This may reflect the differences between electrophysiological as opposed to anatomical hypertrophy. However, ECG LV hypertrophy traits are likely to be influenced by genetic association with anthropometric measures, inflating their overall measured heritability.

Distribution and determinants of QRS rotation of black and white persons in the general population

BACKGROUND

The prevalence and determinants of QRS transition zones are not well established.

METHODS

We examined the distributions of Normal, clockwise (CW) and counterclockwise (CCW)) QRS transition zones and their relations to disease, body size and demographics in 4624 black and white men and women free of cardiovascular disease and major ECG abnormalities enrolled in the NHANES-III survey.

RESULTS

CW transition zones were least observed (6.2%) and CCW were most prevalent (60.1%) with Normal in an intermediate position (33.7%). In multivariable logistic regression analysis, the adjusted, significant predictors for CCW compared to Normal were a greater proportion of blacks and women, fewer thin people (BMI<20, thin), a greater ratio of chest depth to chest width, and an LVMass index <80g. By contrast, CW persons were older, had larger QRS/T angles, smaller ratio of chest depth to chest width, had a greater proportion of subjects with low voltage QRS, more pulmonary disease, a greater proportion with high heart rates, shorter QRS duration and were more obese (BMI≥30).

CONCLUSIONS

Normal rather than being the most prevalent transition zone was intermediate in frequency between the most frequently encountered CCW and the least frequently encountered transition zone CW. Differences in the predictors of CW and CCW exist. This requires further investigation to examine how far these differences explain the differences in the published prognostic differences between CW and CCW.

Cohort Study of ECG Left Ventricular Hypertrophy Trajectories: Ethnic Disparities, Associations With Cardiovascular Outcomes, and Clinical Utility

Background

ECG left ventricular hypertrophy (LVH) is a well‐known predictor of cardiovascular disease. However, no prior study has characterized patterns of presence/absence of ECG LVH (“ECG LVH trajectories”) across the adult lifespan in both sexes and across ethnicities. We examined: (1) correlates of ECG LVH trajectories; (2) the association of ECG LVH trajectories with incident coronary heart disease, transient ischemic attack, ischemic stroke, hemorrhagic stroke, and heart failure; and (3) reclassification of cardiovascular disease risk using ECG LVH trajectories.

Methods and Results

We performed a cohort study among 75 412 men and 107 954 women in the Northern California Kaiser Permanente Medical Care Program who had available longitudinal exposures of ECG LVH and covariates, followed for a median of 4.8 (range <1–9.3) years. ECG LVH was measured by Cornell voltage‐duration product. Adverse trajectories of ECG LVH (persistent, new development, or variable pattern) were more common among blacks and Native American men and were independently related to incident cardiovascular disease with hazard ratios ranging from 1.2 for ECG LVH variable pattern and transient ischemic attack in women to 2.8 for persistent ECG LVH and heart failure in men. ECG LVH trajectories reclassified 4% and 7% of men and women with intermediate coronary heart disease risk, respectively.

Conclusions

ECG LVH trajectories were significant indicators of coronary heart disease, stroke, and heart failure risk, independently of level and change in cardiovascular disease risk factors, and may have clinical utility.

Black-White Differences in Incident Fatal, Nonfatal, and Total Coronary Heart Disease

BACKGROUND

Blacks have higher coronary heart disease (CHD) mortality compared with whites. However, a previous study suggests that nonfatal CHD risk may be lower for black versus white men.

METHODS

We compared fatal and nonfatal CHD incidence and CHD case-fatality among blacks and whites in the Atherosclerosis Risk in Communities study (ARIC), the Cardiovascular Health Study (CHS), and the Reasons for Geographic and Racial Differences in Stroke study (REGARDS) by sex. Participants 45 to 64 years of age in ARIC (men=6479, women=8488) and REGARDS (men=5296, women=7822), and ≥65 years of age in CHS (men=1836, women=2790) and REGARDS (men=3381, women=4112), all without a history of CHD, were analyzed. Fatal and nonfatal CHD incidence was assessed from baseline (ARIC=1987-1989, CHS=1989-1990, REGARDS=2003-2007) through up to 11 years of follow-up.

RESULTS

Age-adjusted hazard ratios comparing black versus white men 45 to 64 years of age in ARIC and REGARDS were 2.09 (95% confidence interval, 1.42-3.06) and 2.11 (1.32-3.38), respectively, for fatal CHD, and 0.82 (0.64-1.05) and 0.94 (0.69-1.28), respectively, for nonfatal CHD. After adjustment for social determinants of health and cardiovascular risk factors, hazard ratios in ARIC and REGARDS were 1.19 (95% confidence interval, 0.74-1.92) and 1.09 (0.62-1.93), respectively, for fatal CHD, and 0.64 (0.47-0.86) and 0.67 (0.48-0.95), respectively, for nonfatal CHD. Similar patterns were present among men ≥65 years of age in CHS and REGARDS. Among women 45 to 64 years of age in ARIC and REGARDS, age-adjusted hazard ratios comparing blacks versus whites were 2.61 (95% confidence interval, 1.57-4.34) and 1.79 (1.06-3.03), respectively, for fatal CHD, and 1.47 (1.13-1.91) and 1.29 (0.91-1.83), respectively, for nonfatal CHD. After multivariable adjustment, hazard ratios in ARIC and REGARDS were 0.67 (95% confidence interval, 0.36-1.24) and 1.00 (0.54-1.85), respectively, for fatal CHD, and 0.70 (0.51-0.97) and 0.70 (0.46-1.06), respectively, for nonfatal CHD. Racial differences in CHD incidence were attenuated among older women. CHD case fatality was higher among black versus white men and women, and the difference remained similar after multivariable adjustment.

CONCLUSIONS

After accounting for social determinants of health and risk factors, black men and women have similar risk for fatal CHD compared with white men and women, respectively. However, the risk for nonfatal CHD is consistently lower for black versus white men and women.

Usefulness of Left Ventricular Mass and Geometry for Determining 10-Year Prediction of Cardiovascular Disease in Adults Aged >65 Years (from the Cardiovascular Health Study)

Left ventricular (LV) mass and geometry are associated with risk of cardiovascular disease (CVD). We sought to determine whether LV mass and geometry contribute to risk prediction for CVD in adults aged ≥65 years of the Cardiovascular Health Study. We indexed LV mass to body size, denoted as LV mass index (echo-LVMI), and we defined LV geometry as normal, concentric remodeling, and eccentric or concentric LV hypertrophy. We added echo-LVMI and LV geometry to separate 10-year risk prediction models containing traditional risk factors and determined the net reclassification improvement (NRI) for incident coronary heart disease (CHD), CVD (CHD, heart failure [HF], and stroke), and HF alone. Over 10 years of follow-up in 2,577 participants (64% women, 15% black, mean age 72 years) for CHD and CVD, the adjusted hazards ratios for a 1-SD higher echo-LVMI were 1.25 (95% CI 1.14 to 1.37), 1.24 (1.15 to 1.33), and 1.51 (1.40 to 1.62), respectively. Addition of echo-LVMI to the standard model for CHD resulted in an event NRI of -0.011 (95% CI -0.037 to 0.028) and nonevent NRI of 0.034 (95% CI 0.008 to 0.076). Addition of echo-LVMI and LV geometry to the standard model for CVD resulted in an event NRI of 0.013 (95% CI -0.0335 to 0.0311) and a nonevent NRI of 0.043 (95% CI 0.011 to 0.09). The nonevent NRI was also significant with addition of echo-LVMI for HF risk prediction (0.10, 95% CI 0.057 to 0.16). In conclusion, in adults aged ≥65 years, echo-LVMI improved risk prediction for CHD, CVD, and HF, driven primarily by improved reclassification of nonevents.

Electrocardiographic and Echocardiographic Left Ventricular Hypertrophy in the Prediction of Stroke in the Elderly

INTRODUCTION

It is unclear whether left ventricular hypertrophy (LVH) detected by electrocardiography (ECG-LVH) is equally predictive of heart failure as LVH detected by echocardiography (echo-LVH).

METHODS

This analysis included 4,008 white participants (41% men) aged 65 years or older from the Cardiovascular Health Study who were free of stroke and major intraventricular conduction defects. ECG-LVH was defined by the Cornell criteria from baseline ECG data and echo-LVH was calculated from baseline echocardiography measurements. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between ECG-LVH and echo-LVH and adjudicated incident stroke events, separately. Harrell's concordance indices (C-index) were calculated for the Framingham Stroke Risk Score with inclusion of ECG-LVH and echo-LVH, separately.

RESULTS

ECG-LVH was detected in 136 (3.4%) participants and echo-LVH was present in 208 (5.2%) participants. Over a median follow-up of 13 years, a total of 769 (19%; incidence rate = 15.4 per 1000 person-years) strokes occurred. In a multivariable Cox regression analysis adjusted for stroke risk factors and potential confounders, ECG-LVH (HR = 1.68; 95% CI = 1.23, 2.28) and echo-LVH (HR = 1.58; 95% CI = 1.17, 2.14) were associated with an increased risk of stroke. Similar values were obtained for the C-index when either ECG-LVH (C-index = .786) or echo-LVH (C-index = .786) were included in the Framingham Stroke Risk Score.

CONCLUSION

ECG-LVH and echo-LVH are able to be used interchangeably in stroke risk scores.

Association of electrocardiographic and imaging surrogates of left ventricular hypertrophy with incident atrial fibrillation: MESA (Multi-Ethnic Study of Atherosclerosis)

OBJECTIVES

This study sought to examine the association between left ventricular hypertrophy (LVH), defined by cardiac magnetic resonance (CMR) and electrocardiography (ECG), with incident atrial fibrillation (AF).

BACKGROUND

Previous studies of the association between AF and LVH were based primarily on echocardiographic measures of LVH.

METHODS

The MESA (Multi-Ethnic Study of Atherosclerosis) enrolled 4,942 participants free of clinically recognized cardiovascular disease. Incident AF was based on MESA-ascertained hospital-discharge International Classification of Diseases codes and Centers for Medicare and Medicaid Services inpatient hospital claims. CMR-LVH was defined as left ventricular mass ≥95th percentile of the MESA population distribution. Eleven ECG-LVH criteria were assessed. The association of LVH with incident AF was evaluated using multivariable Cox proportional hazards models adjusted for CVD risk factors.

RESULTS

During a median follow-up of 6.9 years, 214 incident AF events were documented. Participants with AF were more likely to be older, hypertensive, and overweight. The risk of AF was greater in participants with CMR-derived LVH (hazard ratio [HR]: 2.04, 95% confidence interval [CI]: 1.15 to 3.62). AF was associated with ECG-derived LVH measure of Sokolow-Lyon voltage product after adjusting for CMR-LVH (HR: 1.83, 95% CI: 1.06 to 3.14, p = 0.02). The associations with AF for CMR-LVH and Sokolow-Lyon voltage product were attenuated when adjusted for CMR left atrial volumes.

CONCLUSIONS

In a multiethnic cohort of participants without clinically detected cardiovascular disease, both CMR and ECG-derived LVH were associated with incident AF. ECG-LVH showed prognostic significance independent of CMR-LVH. The association was attenuated when adjusted for CMR left atrial volumes.

Fibroblast growth factor 23, left ventricular mass, and left ventricular hypertrophy in community-dwelling older adults

OBJECTIVES

In chronic kidney disease (CKD), high FGF23 concentrations are associated with left ventricular hypertrophy (LVH), cardiovascular events, and death. The associations of FGF23 with left ventricular mass (LVM) and LVH in the general population and the influence of CKD remains uncertain.

METHODS

C-terminal plasma FGF23 concentrations were measured, and LVM and LVH evaluated by echocardiogram among 2255 individuals ≥65 years in the Cardiovascular Health Study. Linear regression analysis adjusting for demographics, cardiovascular, and kidney related risk factors examined the associations of FGF23 concentrations with LVM. Analyses were stratified by CKD status and adjusted linear and logistic regression analysis explored the associations of FGF23 with LVM and LVH.

RESULTS

Among the entire cohort, higher FGF23 concentrations were associated with greater LVM in adjusted analyses (β = 6.71 [95% CI 4.35-9.01] g per doubling of FGF23). 32% (n = 624) had CKD (eGFR <60 mL/min/1.73 m(2) and/or urine albumin-to-creatinine ratio >30 mg/g). Associations were stronger among participants with CKD (p interaction = 0.006): LVM β = 9.71 [95% CI 5.86-13.56] g per doubling of FGF23 compared to those without CKD (β = 3.44 [95% CI 0.77, 6.11] g per doubling of FGF23). While there was no significant interaction between FGF23 and CKD for LVH (p interaction = 0.25), the OR (1.46 95% CI [1.20-1.77]) in the CKD group was statistically significant and of larger magnitude than the OR for in the no CKD group (1.12 [95% CI 0.97-1.48]).

CONCLUSION

In a large cohort of older community-dwelling adults, higher FGF23 concentrations were associated with greater LVM and LVH with stronger relationships in participants with CKD.

Association of electrocardiographically determined left ventricular mass with incident diabetes, 1985-1986 to 2010-2011: Coronary Artery Risk Development in Young Adults (CARDIA) study

OBJECTIVE

Electrocardiographic indices reflecting left ventricular hypertrophy are associated with incident diabetes in clinical populations at risk for coronary heart disease. We tested whether electrocardiographically determined left ventricular mass was positively associated with incident diabetes in a population sample.

RESEARCH DESIGN AND METHODS

Coronary Artery Risk Development in Young Adults (CARDIA) study participants (n = 4,739) were followed from 1985-1986 to 2010-2011 for incident diabetes. Validated sex- and race-specific formulas were applied to standard electrocardiograms to determine left ventricular mass.

RESULTS

Over 25 years, 444 participants developed diabetes (9.4%). After adjustment for demographic, behavioral, and clinical covariates, participants in the highest quartile of left ventricular mass index (LVMI) were twice as likely to develop diabetes than participants in the lower three quartiles (hazard ratio 2.61 [95% CI 2.16-3.17]). Neither Cornell voltage nor Cornell voltage product was associated with incident diabetes in fully adjusted models.

CONCLUSIONS

Electrocardiographically determined LVMI may be a useful noninvasive marker for identifying adults at risk for diabetes.

Prevalence, prospective risk markers, and prognosis associated with the presence of left ventricular diastolic dysfunction in young adults: the coronary artery risk development in young adults study

The authors sought to determine the prevalence, prospective risk markers, and prognosis associated with diastolic dysfunction in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. The CARDIA Study cohort includes approximately equal proportions of white and black men and women. The authors collected data on risk markers at year 0 (1985-1986), and echocardiography was done at year 5 when the participants were 23-35 years of age. Participants were followed for 20 years (through 2010) for a composite endpoint of all-cause mortality, myocardial infarction, heart failure, and stroke. Diastolic function was defined according to a validated hierarchical classification algorithm. In the 2,952 participants included in the primary analysis, severe diastolic dysfunction was present in 1.1% and abnormal relaxation was present in 9.3%. Systolic blood pressure at year 0 was associated with both severe diastolic dysfunction and abnormal relaxation 5 years later, whereas exercise capacity and pulmonary function abnormalities were associated only with abnormal relaxation 5 years later. After multivariate adjustment, the hazard ratios for the composite endpoint in participants with severe diastolic dysfunction and abnormal relaxation were 4.3 (95% confidence interval: 2.0, 9.3) and 1.6 (95% confidence interval: 1.1, 2.5), respectively. Diastolic dysfunction in young adults is associated with increased morbidity and mortality, and the identification of prospective risk markers associated with diastolic dysfunction could allow for targeted primary prevention efforts.

Factors associated with development of prolonged QRS duration over 20 years in healthy young adults: the Coronary Artery Risk Development in Young Adults study

BACKGROUND

Data describing factors associated with the development of a prolonged QRS duration (QRSd) from young adulthood to middle age are sparse.

METHODS

We analyzed 12-lead electrocardiograms (ECGs) from the Coronary Artery Risk Development in Young Adults study over 20 years. We performed logistic regression to examine the associations of baseline (year 0) or average (years 0-20) risk factors with incident prolonged QRSd (QRS >100 milliseconds).

RESULTS

We included 2537 participants (57.2% women, 44.7% black; mean age, 25 years); 292 (11.5%) developed incident QRSd greater than 100 milliseconds by year 20. In univariate analyses, baseline covariates associated with incident QRSd prolongation included white race, male sex, ECG-left ventricular mass index, and baseline QRSd. Similar results were observed after multivariable adjustment.

CONCLUSION

We found no long-term associations of modifiable risk factors with incident QRSd >100 milliseconds. Men, whites, and those with higher ECG-left ventricular mass index and QRSd in young adulthood are at an increased risk for incident prolonged QRSd by middle age.

Long-term effects of chlorthalidone versus hydrochlorothiazide on electrocardiographic left ventricular hypertrophy in the multiple risk factor intervention trial

Chlorthalidone (CTD) reduces 24-hour blood pressure more effectively than hydrochlorothiazide (HCTZ), but whether this influences electrocardiographic left ventricular hypertrophy is uncertain. One source of comparative data is the Multiple Risk Factor Intervention Trial, which randomly assigned 8012 hypertensive men to special intervention (SI) or usual care. SI participants could use CTD or HCTZ initially; previous analyses have grouped clinics by their main diuretic used (C-clinics: CTD; H-clinics: HCTZ). After 48 months, SI participants receiving HCTZ were recommended to switch to CTD, in part because higher mortality was observed for SI compared with usual care participants in H-clinics, whereas the opposite was found in C-clinics. In this analysis, we examined change in continuous measures of electrocardiographic left ventricular hypertrophy using both an ecological analysis by previously reported C- or H-clinic groupings and an individual participant analysis where use of CTD or HCTZ by SI participants was considered and updated annually. Through 48 months, differences between SI and usual care in left ventricular hypertrophy were larger for C-clinics compared with H-clinics (Sokolow-Lyon: -93.9 versus -54.9 μV, P=0.049; Cornell voltage: -68.1 versus -35.9 μV, P=0.019; Cornell voltage product: -4.6 versus -2.2 μV/ms, P=0.071; left ventricular mass: -4.4 versus -2.8 g, P=0.002). At the individual participant level, Sokolow-Lyon and left ventricular mass were significantly lower for SI men receiving CTD compared with HCTZ through 48 months and 84 months of follow-up. Our findings on left ventricular hypertrophy support the idea that greater blood pressure reduction with CTD than HCTZ may have led to differences in mortality observed in the Multiple Risk Factor Intervention Trial.

Electrocardiographic and clinical predictors separating atherosclerotic sudden cardiac death from incident coronary heart disease

OBJECTIVE

To identify specific ECG and clinical predictors that separate atherosclerotic sudden cardiac death (SCD) from incident coronary heart disease (CHD) (non-fatal events and non-sudden death) in the combined cohorts of the Atherosclerosis Risk in Communities study and the Cardiovascular Health Study.

METHODS

This analysis included 18,497 participants (58% females, 24% black individuals, mean age 58 years) who were initially free of clinical CHD. A competing risk analysis was conducted to examine the prognostic significance of baseline clinical characteristics and an extensive electronic database of ECG measurements for prediction of 229 cases of SCD as a first event versus 2297 incident CHD cases (2122 non-fatal events and 175 non-sudden death) that occurred during a median follow-up time of 13 years in the Cardiovascular Health Study and 14 years in the Atherosclerosis Risk in Communities study.

RESULTS

After adjusting for common CHD risk factors, a number of clinical characteristics and ECG measurements were independently predictive of SCD and CHD. However, the risk of SCD versus incident CHD was significantly different for race/ethnicity, hypertension, body mass index (BMI), heart rate, QTc, abnormally inverted T wave in any ECG lead group and level of ST elevation in V2. Black race/ethnicity (compared to non-black) was predictive of high SCD risk but less risk of incident CHD (p value for differences in the risk (HR) for SCD versus CHD <0.0001). Hypertension, increased heart rate, prolongation of QTc and abnormally inverted T wave were stronger predictors of high SCD risk compared to CHD (p value=0.0460, 0.0398, 0.0158 and 0.0265, respectively). BMI was not predictive of incident CHD but was predictive of high SCD risk in a quadratic fashion (p value=0.0220). On the other hand, elevated ST height as measured at the J point and that measured at 60 ms after the J point in V2 were not predictive of SCD but were predictive of high incident CHD risk (p value=0.0251 and 0.0155, respectively).

CONCLUSIONS

SCD and CHD have many risk factors in common. Hypertension, race/ethnicity, BMI, heart rate, QTc, abnormally inverted T wave in any ECG lead group and level of ST elevation in V2 have the potential to separate between the risks of SCD and CHD. These results need to be validated in another cohort.

Prevalence of electrocardiographic abnormalities in a middle-aged, biracial population: Coronary Artery Risk Development in Young Adults study

BACKGROUND

Few studies to date have described the prevalence of electrocardiographic (ECG) abnormalities in a biracial middle-aged cohort.

METHODS AND RESULTS

Participants underwent measurement of traditional risk factors and 12-lead ECGs coded using both Minnesota Code and Novacode criteria. Among 2585 participants, of whom 57% were women and 44% were black (mean age 45 years), the prevalence of major and minor abnormalities was significantly higher (all P < .001) among black men and women compared to whites. These differences were primarily due to higher QRS voltage and ST/T-wave abnormalities among blacks. There was also a higher prevalence of Q waves (Minnesota Code 1-1, 1-2, 1-3) than described by previous studies. These racial differences remained after multivariate adjustment for traditional cardiovascular (CV) risk factors.

CONCLUSIONS

Black men and women have a significantly higher prevalence of ECG abnormalities, independent of traditional cardiovascular risk factors, than whites in a contemporary cohort of middle-aged participants.

Diagnostic and prognostic utility of electrocardiography for left ventricular hypertrophy defined by magnetic resonance imaging in relationship to ethnicity: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Left ventricular mass is a strong predictor of cardiovascular disease (CVD), and magnetic resonance imaging (MRI) of the heart is a standard of reference for left ventricular mass measurement. Ethnicity is believed to affect electrocardiographic (ECG) performance. We evaluated the diagnostic and prognostic performance of ECG for left ventricular hypertrophy (LVH) as defined by MRI in relationship to ethnicity.

METHODS

Data were analyzed from 4,967 participants (48% men, mean age 62 +/- 10 years; 39% white, 13% Chinese, 26% African American, 22% Hispanic) enrolled in the Multi-Ethic Study of Atherosclerosis (MESA) who were followed for a median of 4.8 years for incident CVD.

RESULTS

Thirteen traditional ECG-LVH criteria were assessed, and showed overall and ethnicity-specific low sensitivity (10%-26%) and high specificity (88%-99%) in diagnosing MRI-defined LVH. Ten of 13 ECG-LVH criteria showed superior sensitivity and diagnostic performance in African Americans as compared with whites (P = .02-.001). The sum of amplitudes of S wave in V(1), S wave in V(2), and R wave in V(5) (a MESA-specific ECG-LVH criterion) offered higher sensitivity (40.4%) compared with prior ECG-LVH criteria while maintaining good specificity (90%) and diagnostic performance (receiver operating characteristic area = 0.65). In fully adjusted models, only the MESA-specific ECG-LVH criterion, Romhilt-Estes score, Framingham score, Cornell voltage, Cornell duration product, and Framingham-adjusted Cornell voltage predicted increased CVD risk (P < .05).

CONCLUSIONS

Electrocardiography has low sensitivity but high specificity for detecting MRI-defined LVH. The performance of ECG for LVH detection varies by ethnicity, with African Americans showing higher sensitivity and overall performance compared with other ethnic groups.

Genetic influences on resting electrocardiographic variables in older women: a twin study

BACKGROUND

Previous studies in young and middle-aged men and women have shown that resting electrocardiographic (ECG) variables are influenced by genetic factors. However, the extent to which resting ECG variables are influenced by genetic factors in older women is unknown. Thus, the aim of this study was to estimate the relative contribution of genetic and environmental influences to individual differences in resting ECG variables among older female twins without overt cardiac diseases.

METHODS

Resting ECG recordings were obtained from 186 monozygotic and 203 dizygotic twin individuals, aged 63-76 years. Quantitative genetic modeling was used to decompose the phenotypic variance in each resting ECG variable into additive genetic, dominance genetic, shared environmental, and unique environmental influences.

RESULTS

The results showed that individual differences in the majority of the resting ECG variables were moderately to highly explained by additive genetic influences, ranging from 32% for T axis to 72% for TV(5). The results also suggested dominance genetic influences on QRS duration, TV(1), and Sokolow-Lyon voltage (36%, 53%, and 57%, respectively). Unique environmental influences were important for each resting ECG variable, whereas shared environmental influences were detected only for QT interval and QTc.

CONCLUSION

In older women without overt cardiac diseases, genetic influences explain a moderate to high proportion of individual differences in the majority of the resting ECG variables. Genetic influences are especially strong for T-wave amplitudes, left ventricular mass, and hypertrophy indices, whereas other variables, including heart rate, intervals, and axes, are more affected by environmental influences.

Electrocardiographic (ECG) criteria for determining left ventricular mass in young healthy men; data from the LARGE Heart study

BACKGROUND

Doubts remain over the use of the ECG in identifying those with increased left ventricular (LV) mass. This is especially so in young individuals, despite their high prevalence of ECG criteria for LV hypertrophy. We performed a study using cardiovascular magnetic resonance (CMR), which provides an in vivo non-invasive gold standard method of measuring LV mass, allowing accurate assessment of electrocardiography as a tool for defining LV hypertrophy in the young.

METHODS AND RESULTS

Standard 12-lead ECGs were obtained from 101 Caucasian male army recruits aged (mean +/- SEM) 19.7 +/- 0.2 years. LV mass was measured using CMR. LV mass indexed to body surface area demonstrated no significant correlation with the Cornell Amplitude criteria or Cornell Product for LV hypertrophy. Moderate correlations were seen with the Sokolow-Lyon Amplitude (0.28) and Sokolow-Lyon Product (0.284). Defining LV hypertrophy as a body surface area indexed left ventricular mass of 93 g/m(2), calculated sensitivities [and specificities] were as follows; 38.7% [74.3%] for the Sokolow-Lyon criteria, 43.4% [61.4%] for the Sokolow-Lyon Product, 19.4% [91.4%] for Cornell Amplitude, and 22.6% [85.7%] for Cornell Product. These values are substantially less than those reported for older age groups.

CONCLUSION

ECG criteria for LV hypertrophy may have little value in determining LV mass or the presence of LV hypertrophy in young fit males.

The relationship of left ventricular mass and geometry to incident cardiovascular events: the MESA (Multi-Ethnic Study of Atherosclerosis) study

OBJECTIVE

The purpose of this study was to evaluate the relationship of left ventricular (LV) mass and geometry measured with cardiac magnetic resonance imaging (MRI) to incident cardiovascular events in the MESA (Multi-Ethnic Study of Atherosclerosis) study.

BACKGROUND

MRI is highly accurate for evaluation of heart size and structure and has not previously been used in a large epidemiologic study to predict cardiovascular events.

METHODS

A total of 5,098 participants in the MESA study underwent cardiac MRI at the baseline examination and were followed up for a median of 4 years. Cox proportional hazard models were constructed to predict the end points of coronary heart disease (CHD), stroke, and heart failure (HF) after adjustment for cardiovascular risk factors.

RESULTS

A total of 216 incident events were observed during the follow-up period. In adjusted models, the end points of incident CHD and stroke were positively associated with increased LV mass-to-volume ratio (CHD, hazard ratio [HR]: 2.1 per g/ml, p = 0.02; stroke, HR: 4.2 per g/ml, p = 0.005). In contrast, LV mass showed the strongest association with incident HF events (HR: 1.4 per 10% increment, p < 0.0001). The HF events occurred primarily in participants with LV hypertrophy, that is, >or=95th percentile of LV mass (HR: 8.6, 95% confidence interval: 3.7 to 19.9, reference group <50th percentile of LV mass).

CONCLUSIONS

The LV size was related to incident HF, stroke, and CHD in this multiethnic cohort. Whereas body size-adjusted LV mass alone predicted incident HF, concentric ventricular remodeling predicted incident stroke and CHD.

Thresholds in the relationship between mortality and left ventricular hypertrophy defined by electrocardiography

BACKGROUND

Electrocardiographic criteria for the diagnosis of left ventricular hypertrophy in current use were defined using autopsy results or echocardiography; criteria defined using mortality might be more clinically meaningful.

METHODS

Using data from Third National Health and Nutrition Examination Survey (NHANES III), we selected electrocardiographic measures that best differentiated those surviving at 5 years from those who did not. We identified voltage thresholds using regression techniques and then compared survival for subjects above and below the thresholds.

RESULTS

Cornell voltage, Cornell product, and Novacode estimate of left ventricular mass index were discriminative for mortality and had identifiable thresholds present in their relationships with mortality. Independent of systolic blood pressure, there were significant associations with 5-year mortality for Novacode index above threshold; hazard ratios were 1.58 for women and 1.27 for men, and for 5-year cardiovascular mortality were 1.78 for women and 2.34 for men.

CONCLUSIONS

Electrocardiographic criteria for left ventricular hypertrophy validated against mortality might be clinically useful.

Subclinical disease detection: advanced imaging applications

Coronary events are the leading cause of death in the United States, and sudden coronary death is often the first presenting symptom. Because there is such a large population at risk for coronary events and because many of these patients go undetected before presenting with a significant cardiovascular event or sudden death, there is great interest in better detection and characterization of subclinical disease before it causes morbidity and mortality. This chapter will focus on promising imaging-based methods for the evaluation of subclinical cardiovascular disease. Several imaging methods that are most likely to be useful for future screening and intervention studies for characterizing risk among asymptomatic persons will be presented.

Increased prevalence of concentric left ventricular hypertrophy in African-Americans: will an epidemic of heart failure follow?

Left ventricular hypertrophy (LVH), used in this review to denote abnormally increased left ventricular (LV) mass, is an important cardiac trait because of its association with numerous adverse cardiovascular outcomes including myocardial infarction and heart failure. LV mass is typically assessed by noninvasive cardiac imaging (echocardiography or MRI); electrocardiography is an insensitive measure. There are two predominant types of hypertrophy: concentric, where LV wall thickness is increased relative to cavity dimensions, and eccentric, where LV wall thickness is not increased relative to cavity dimensions. Several large studies indicate that the prevalence of concentric LVH is higher in African-Americans versus whites. Although there are data to suggest that concentric LVH results in systolic heart failure in animal models, such data are lacking in humans. How concentric LVH affects the prevalence of systolic and diastolic heart failure in African-Americans needs further study. Given the large burden of LVH among African-Americans, such data are needed to estimate the expected burden and type of heart failure which will occur in the future in this population.

Is Electrocardiography Still Useful in the Diagnosis of Cardiac Chamber Hypertrophy and Dilatation?

The echocardiogram undoubtedly is part of the cardiologist's armamentarium in the diagnosis and elucidation of cardiac abnormalities, but the ECG still continues to be the most frequently recorded noninvasive test in medicine. For many patients, particularly those who have newly diagnosed hypertension, a 12-lead ECG recording may be the only test that is required as a baseline measure. For those who have possible heart failure, an ECG and B-type natriuretic peptide measurement may be sufficient to obviate the need for an echocardiogram. Electrocardiography and echocardiography will continue to live side-by-side for the foreseeable future.

Electrocardiographic findings and incident coronary heart disease among participants in the Atherosclerosis Risk in Communities (ARIC) study

The associations of many electrocardiographic (ECG) abnormalities at rest with incident coronary heart disease (CHD) are not completely established, and whether individual ECG abnormalities convey similar risk across gender and race is uncertain. We studied the independent association of several ECG findings with incident CHD, testing for effect modification by gender and race, in a large, population-based, prospective cohort study. Findings from the baseline 12-lead electrocardiograms in 1987 to 1989 were classified according to the Minnesota Code in 12,987 black and white men and women, aged 45 to 64 years, who were initially free of CHD and the use of specific cardiac medications. The incidence of CHD was ascertained through 2000. After adjustment for multiple cardiovascular risk factors, the ECG findings that had the highest hazard rate ratios (HRRs) for incident CHD, when considered singly, were left ventricular hypertrophy with ST-T strain pattern in white men (HRR 6.50) and in black women (HRR 2.31) and, in the whole cohort, major (HRR 2.27) and minor (HRR 2.47) ST depression and major T-wave abnormalities (HRR 2.12). Statistically significant associations were also found in the whole cohort for minor Q waves and left ventricular hypertrophy by the Cornell definition, but not for a prolonged QTc interval, major ventricular conduction defects, or ST elevation. In conclusion, several 12-lead ECG findings were independently associated with incident CHD in middle-aged adults. With only a few exceptions, the associations were similar for blacks and whites.

Prevalence and determinants of electrocardiographic left ventricular hypertrophy among a multiethnic population of postmenopausal women (The Women's Health Initiative)

Our objectives were to determine the prevalence and factors related to left ventricular hypertrophy (LVH) among older women for commonly used electrocardiographic criteria. LVH is a potent risk factor for cardiovascular disease, especially among women. However, its value has been limited, in part, by the use of different electrocardiographic criteria and the lack of a clearly defined standard for the general population. A total of 3,613 eligible women, aged 50 to 79 years, underwent medical history, physical measurements, and biochemical determinations and had behavioral factors recorded at baseline. Three LVH indexes were derived from computer measurement of the electrocardiogram: hypertrophied left ventricular mass > or =171.04 g (HLVM); Cornell voltage > or =2,200 microV; and Minnesota Code items. The prevalence of LVH ranged from <1% to 13% when stratified by age, ethnicity, and scoring technique. Baseline traits differed significantly for those meeting the LVH criteria. Predictors (p <0.01) of HLVM were age (odds ratio 0.66), height (odds ratio 1.47), waist/hip ratio (odds ratio 1.30), systolic blood pressure (odds ratio 1.18); low-density lipoprotein cholesterol (odds ratio 0.97), log insulin (odds ratio 2.10), dietary kilocalories (odds ratio 1.16), weekly energy expenditure (odds ratio 0.53), hypertension (odds ratio 1.61), current estrogen use (odds ratio 0.60), and current smoker (odds ratio 0.47). The presence of the metabolic syndrome was related to all LVH indexes, with odds ratios of 4.95, 2.24, and 2.35, respectively, for HLVM, Cornell voltage, and Minnesota Code. In conclusion, the prevalence of LVH varied by ethnicity and the electrocardiographic index used. However, the baseline traits, especially the factors associated with the metabolic syndrome, were consistently and strongly related to all LVH indexes, particularly HLVM. Intervention on these factors may provide strategies for reducing LVH, a strong independent risk factor for cardiovascular morbidity and mortality among women.

Comparison of mortality risk for electrocardiographic abnormalities in men and women with and without coronary heart disease (from the Cardiovascular Health Study)

Mortality risk associated with electrocardiographic (ECG) abnormalities has been commonly reported to be lower in women than in men. We compared coronary heart disease (CHD) and all-cause mortality risk for ECG variables during a mean 9.1-year follow-up in 4,912 participants in the Cardiovascular Health Study who were > or = 65 years of age. The hypothesis was that mortality risk for ECG abnormalities is not lower in women than in men. Five ECG variables were significant mortality predictors in Cox regression models that were adjusted for demographic, clinical, and medication variables. Gender differences were significant and mortality risk was higher in women for ECG estimates of left ventricular mass for both end points and for nondipolar QRS voltage for all-cause mortality. When evaluated simultaneously in multiple ECG variable risk models in subgroups that were stratified by baseline CHD status, no gender difference was significant. In the latter models, ST depression was a strong predictor of CHD mortality in groups with and without previous CHD. Other significant ECG predictors were previous myocardial infarction in the previous CHD group and nondipolar QRS voltage in the CHD-free group. Four ECG abnormalities were significant predictors of all-cause mortality in the CHD-free group, with risk increases of 18% to 50%. The risk of all-cause mortality in the previous CHD group was significantly increased for ST depression (by 64%), the ECG estimate of left ventricular mass (by 48%), and previous myocardial infarction (by 34%). In conclusion, we found no evidence that the relative risk of mortality for ECG abnormalities is lower in women than in men.

Left ventricular hypertrophy is more prevalent in blacks than whites in the general population: the Dallas Heart Study

Although recent studies have suggested that blacks compared with whites have an increased prevalence of left ventricular hypertrophy, it remains uncertain whether this is true despite adjustment for body composition (fat mass and fat-free mass) and when assessed by cardiac MRI in the general population. The Dallas Heart Study is a population-based study of Dallas County in which 1335 black and 858 white participants 30 to 67 years of age underwent detailed assessment including dual-energy x-ray absorptiometry scan to measure body composition and cardiac MRI. Left ventricular hypertrophy, whether defined by indexation to body surface area (P<0.001), fat-free mass (P=0.002), or height2.7 (P<0.001) was 2- to 3-fold more common in black versus white women. Similar results were seen when comparing black and white men (P<0.001 when left ventricular hypertrophy was indexed to body surface area or height2.7 and P=0.05 when indexed to fat-free mass). Ethnic disparities in left ventricular mass persisted in multivariable models despite adjustment for fat mass, fat-free mass, systolic blood pressure, age, gender, and measures of socioeconomic status. We conclude that blacks compared with whites have increased left ventricular mass and a 2- to 3-fold higher prevalence of left ventricular hypertrophy in the general population, as assessed by cardiac MRI. The ethnic differences in left ventricular mass are independent of differences in body composition.

Distance correction in the electrocardiographic estimation of left ventricular mass

Assessment of the left ventricular mass (LVM) from electrocardiograms may be improved by the addition of clinical variables into a multivariate equation. As the heart-thorax distance may affect the results, its relationships with electrocardiographic and clinical data have been evaluated in a group of 220 subjects (53 +/- 15 years, 126 female, 175 without demonstrated heart disease) who were assessed for echocardiographic LVM and heart-thorax distance. Sokolow, Cornell, and total QRS voltage indexes were obtained. Multiple regression equations with LVM as the dependent variable were fit, with an ECG index, body mass index (BMI), age, and gender as the independent predictors. Each of the 3 ECG indexes, BMI, age, and sex was shown to be independent predictors of LVM, with the ECG and BMI contributing with most of the explanatory power. When added to the model, the distance from the interventricular septum to the precordium (septal-LVD) was not a predictor of LVM, but when BMI was withdrawn, septal-LVD became an independent predictor of LVM (P < .001). This was not observed when septal-LVD was substituted for any other clinical or ECG variable, thus suggesting that septal-LVD accounts for information contained in BMI but not in the remaining variables. In addition, the distance from the center of LV to the precordium (mid-LVD) achieved significance as an independent LVM predictor, although the coefficient of multiple determination (R) practically did not change. Almost identical results are obtained when LVM is indexed for body surface area. Body mass index supplies virtually all the information contained in the heart-thorax distance.

Optimal threshold value for left ventricular hypertrophy in blacks: the Atherosclerosis Risk in Communities study

The distribution of echocardiographic left ventricular (LV) mass differs among ethnicities. Because ethnic-specific echocardiographic criteria for LV hypertrophy (LVH) are not established, we determined whether threshold values derived from overwhelmingly white populations are appropriate for blacks, a subgroup having more LVH. Between 1992 and 1994, LV mass was measured echocardiographically in the Jackson, Mississippi, black cohort of the Atherosclerosis Risk in Communities study. Participants free of prevalent cardiovascular disease (CVD) (n=1616; mean+/-SD, age 59+/-5.7; 65% women and 57% with hypertension) were included. The optimal LVH threshold value was selected from the continuum of LV mass index (LVMI=LV mass/height(2.7)) using 3 methods: (1) the best operating point from the area under the resulting receiver-operating characteristic (ROC) curve predicting incident CVD; (2) the value with the smallest probability value associated with incident CVD; and (3) visual inspection of functions of LVMI and CVD in the general additive model (GAM) plot. At a median follow-up of 6.8 years, there were 192 events (coronary heart disease=87, stroke=62, and congestive heart failure=43; incidence=17.6/1000 person-years). The best operating point from the resulting ROC analysis was 51.2 g/m(2.7) for sensitivity (53.4%) and specificity (61.5%). The Cox and GAM models adjusted for age, gender, systolic blood pressure, hypertension, diabetes, smoking, total cholesterol-to-high-density lipoprotein ratio, LVH by ECG criterion, and socioeconomic status found 50 to 51 g/m(2.7) as the optimal threshold for LVH in middle-aged blacks, corresponding to a minimum probability value and to a log-hazard ratio of zero, respectively. Because these values are close to the 51 g/m(2.7) established from predominantly white populations, this cutpoint is appropriate for both groups.

The determinants of left ventricular hypertrophy defined by Sokolow-Lyon criteria in untreated hypertensive patients

Left ventricular hypertrophy (LVH) measured by electrocardiography (ECG LVH) in hypertensive patients has been shown to be associated with an increased risk of cardiovascular sequelae. Analysis of the determinants predisposing to ECG LVH may be helpful in the prevention of LVH. The Department of Health and Social Security Hypertension Care Computer Project studied 2994 hypertensive patients in whom an electrocardiogram was recorded while not on treatment. LVH was determined as the voltage sum SV1+RV5 or RV6>or=35 mm using Sokolow-Lyon voltage criteria. The relations were determined between the presence of LVH or voltage sum and different variables. Untreated systolic (SBP) and diastolic (DBP) blood pressure and pulse pressure were positively related to the increasing ECG voltage, while body mass index (BMI) and serum cholesterol were inversely related. Blood glucose and age did not correlate significantly. Patients with the presence of ECG LVH were more often men, black people, smokers and users of alcohol. In multiple logistic regression analyses, SBP, DBP, male gender and black race were positively, whereas BMI was negatively related to the presence of LVH. The positive relation of smoking and negative relation of serum cholesterol concentration to the presence of ECG LVH were apparent in men but not in women. This study confirms the adverse association between ECG LVH and SBP and DBP, male gender, black race and decreased BMI. It also addresses the less well-known associations of blood glucose, cholesterol, smoking and alcohol consumption.

Ethnic differences in electrocardiographic criteria for left ventricular hypertrophy: the LIFE study. Losartan Intervention For Endpoint

BACKGROUND

African Americans have greater precordial QRS voltages than whites, with concomitant higher prevalences of electrocardiographic (ECG) left ventricular hypertrophy (LVH) and lower specificity of ECG LVH criteria for the identification of anatomic hypertrophy. However, the high mortality associated with LVH in African American patients makes more accurate ECG detection of LVH in these patients a clinical priority.

METHODS

Electrocardiograms and echocardiograms were obtained at study baseline in 120 African American and 751 white hypertensive patients enrolled in the Losartan Intervention For Endpoint (LIFE) echocardiographic substudy. The ECG LVH was determined using Sokolow-Lyon, 12-lead sum, and Cornell voltage criteria. Echocardiographic LVH was defined by LV mass indexed to height(2.7) >46.7 g/m(2.7) in women and >49.1 g/m(2.7) in men.

RESULTS

After adjusting for ethnic differences in LV mass, body mass index, sex, and prevalence of diabetes, mean Sokolow-Lyon and 12-lead sum of voltage were significantly higher, but Cornell voltage was lower, in African Americans than in whites. As a consequence of these differences, when identical partition values were used in both ethnic groups, Sokolow-Lyon and 12-lead voltage criteria had lower specificity in African Americans than whites (44% v 69%, P = .007 and 44% v 59%, P = .10) but had greater sensitivity in African Americans (51% v 27%, P < .001 and 62% v 45%, P = .003). In contrast, Cornell voltage specificity was higher (78% v 62%, P = .09) but sensitivity was slightly lower (49% v 57%, P = 0.16) in African Americans. However, when overall test performance was compared using receiver operating curve analyses that were independent of partition value selection, ethnic differences in test performance disappeared, with no differences in accuracy of any of the ECG voltage criteria for the identification of LVH between African American and white hypertensive individuals.

CONCLUSIONS

When standard, non-ethnicity-specific thresholds for the identification of LVH are used, Sokolow-Lyon and 12-lead voltage overestimate and Cornell voltage underestimates the presence and severity of LVH in African American relative to white individuals. However, these apparent ethnic differences in test performance disappear when ethnic differences in the distribution of ECG LVH criteria are taken into account. These findings demonstrate that ethnicity-specific ECG criteria can equalize detection of anatomic LVH in African American and white patients.

Usefulness of T-axis deviation as an independent risk indicator for incident cardiac events in older men and women free from coronary heart disease (the Cardiovascular Health Study)

T-axis shift has been reported to be an indicator of increased mortality risk. We evaluated the association of spatial T-axis deviation with incident coronary heart disease (CHD) events in older men and women free from clinically overt CHD. Spatial T-axis deviation was measured from the standard 12-lead electrocardiogram of a subgroup of 4,173 subjects considered free of CHD at baseline in the Cardiovascular Health Study, a prospective cohort study of risk factors for CHD and stroke in older men and women. Cox regression analysis was used to evaluate the association of altered repolarization with the risk of incident CHD events. The prevalence of marked T-axis deviation (> or =45 degrees ) was 12%. During the median follow-up of 7.4 years, there were 161 CHD deaths, 743 deaths from all causes, and 679 incident CHD events. Adjusting for demographic and clinical risk factors, including other electrocardiographic abnormalities, there was a nearly twofold excess risk of CHD death, and approximately a 50% excess risk of incident CHD and all-cause mortality for those with marked T-axis deviation. From other electrocardiographic abnormalities, only QT prolongation was associated with excess risk for incident CHD comparable to that for abnormal T-axis deviation. These results suggest that T-axis deviation is an easily quantified marker for subclinical disease and an independent indicator for the risk of incident CHD events in older men and women free of CHD.