Reported Weight Change in Older Adults and Presence of Frailty.

OBJECTIVE: A 5% change in weight is a significant predictor for frailty and obesity. We ascertained how self-reported weight change over the lifespan impacts rates of frailty in older adults. METHODS: We identified 4,984 subjects ≥60 years with body composition measures from the National Health and Nutrition Examination Survey. An adapted version of Fried's frailty criteria was used as the primary outcome. Self-reported weight was assessed at time current,1 and 10 years earlier and at age 25. Weight changes between each time point were categorized as ≥ 5%, ≤5% or neutral. Logistic regression assessed the impact of weight change on the outcome of frailty. RESULTS: Among 4,984 participants, 56.5% were female, mean age was 71.1 years, and mean BMI was 28.2kg/m2. A weight loss of ≥ 5% had a higher association with frailty compared to current weight, age 25 (OR 2.94 [1.72,5.02]), 10 years ago (OR 1.68 [1.05,2.69]), and 1 year ago (OR 1.55 [1.02,2.36]). Weight gain in the last year was associated with increased rate of frailty (1.59 [1.09,2.32]). CONCLUSION: There is an association between frailty and reported weight loss over time while only weight gain in the last year has an association with frailty.

Association of Obesity and Frailty in Older Adults: NHANES 1999-2004.

OBJECTIVES: Body composition changes with aging can increase rates of obesity, frailty and impact function. Measuring adiposity using body fat (%BF) or central adiposity using waist circumference (WC) have greater diagnostic accuracy than traditional measures such as body mass index (BMI). DESIGN: This is an observational study. SETTING: This study focused on older community-dwelling participants. PARTICIPANTS: We identified individuals age ≥ 60 years old using the 1999-2004 cross-sectional National Health and Nutrition Survey (NHANES). INTERVENTION: The primary analysis evaluated the association between frailty and %BF or WC. Frailty was the primary predictor (robust=referent) and %BF and WC were considered continuous outcomes. Multiple imputation analyses accounted for missing characteristics. MEASUREMENT: Dual energy x-ray absorptiometry was used to assess %BF and WC was objectively measured. Frailty was defined using an adapted version of Fried's criteria that was self-reported: (low BMI<18.5kg/m2; slow walking speed [<0.8m/s]; weakness [unable to lift 10lbs]; exhaustion [difficulty walking between rooms on same floor] and low physical activity [compared to others]). Robust, pre-frail and frail persons met zero, 1 or 2, and ≥3 criteria, respectively. RESULTS: Of the 4,984 participants, the mean age was 71.1±0.2 (SE) years and 56.5% were females. We classified 2,246 (50.4%), 2,195 (40.3%), and 541 (9.2%) individuals as robust, pre-frail and frail, respectively. Percent BF was 35.9±0.13, 38.3±0.20 and 40.0±0.46 in the robust, pre-frail and frail individuals, respectively. WC was 99.5±0.32 in the robust, 100.1±0.43 in pre-frail, 104.7±1.17 in frail individuals. Compared to robust individuals, only frail individuals had greater %BF on average (ß=0.97±0.43,p=0.03); however, pre-frail and frail individuals had 2.18 and 4.80 greater WC, respectively (ß=2.18±0.64,p=0.002, and ß=4.80±1.1,p<0.001). CONCLUSION: Our results demonstrate that in older adults, frailty and pre-frailty are associated with a greater likelihood of high WC (as dichotomized) and a greater average WC (continuous).

Continuing Colorado plateau uplift by delamination-style convective lithospheric downwelling.

The Colorado plateau is a large, tectonically intact, physiographic province in the southwestern North American Cordillera that stands at ∼1,800-2,000 m elevation and has long been thought to be in isostatic equilibrium. The origin of these high elevations is unclear because unlike the surrounding provinces, which have undergone significant Cretaceous-Palaeogene compressional deformation followed by Neogene extensional deformation, the Colorado plateau is largely internally undeformed. Here we combine new seismic tomography and receiver function images to resolve a vertical high-seismic-velocity anomaly beneath the west-central plateau that extends more than 200 km in depth. The upper surface of this anomaly is seismically defined by a dipping interface extending from the lower crust to depths of 70-90 km. The base of the continental crust above the anomaly has a similar shape, with an elevated Moho. We interpret these seismic structures as a continuing regional, delamination-style foundering of lower crust and continental lithosphere. This implies that Pliocene (2.6-5.3 Myr ago) uplift of the plateau and the magmatism on its margins are intimately tied to continuing deep lithospheric processes. Petrologic and geochemical observations indicate that late Cretaceous-Palaeogene (∼90-40 Myr ago) low-angle subduction hydrated and probably weakened much of the Proterozoic tectospheric mantle beneath the Colorado plateau. We suggest that mid-Cenozoic (∼35-25 Myr ago) to Recent magmatic infiltration subsequently imparted negative compositional buoyancy to the base and sides of the Colorado plateau upper mantle, triggering downwelling. The patterns of magmatic activity suggest that previous such events have progressively removed the Colorado plateau lithosphere inward from its margins, and have driven uplift. Using Grand Canyon incision rates and Pliocene basaltic volcanism patterns, we suggest that this particular event has been active over the past ∼6 Myr.

Adverse effects of left ventricular hypertrophy in the reduction of endpoints in NIDDM with the angiotensin II antagonist losartan (RENAAL) study.

AIMS/HYPOTHESIS: We explored the impact of baseline left ventricular hypertrophy (LVH) and losartan treatment on renal and cardiovascular (CV) events in 1,513 patients from the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) trial, which studied the effects of losartan on the progression of renal disease and/or death in patients with type 2 diabetes and nephropathy. MATERIALS AND METHODS: LVH was assessed using ECG criteria (Cornell product and/or Sokolow-Lyon voltage). The risk of renal or CV events was determined by a proportional hazards model fit with treatment allocation and presence of LVH. Covariates at baseline included age, sex, systolic BP, mean arterial pressure, pulse, proteinuria, serum creatinine, albumin and haemoglobin. RESULTS: A total of 187 subjects (12%) had LVH at baseline. Treatment with losartan resulted in a significant decrease in the Cornell product (-6.2%) and Sokolow-Lyon voltage (-6.3%). LVH was shown to be significantly associated with the primary endpoint, which was a composite of doubling of serum creatinine (DSCR), endstage renal disease (ESRD) or death (hazard ratio [HR]=1.44, p=0.011), as well as with the composite renal endpoint of DSCR/ESRD (HR=1.42, p=0.031) and CV events (HR=1.68, p=0.001). Losartan treatment of patients with LVH decreased the CV as well as renal risk to a level similar to that of patients without LVH. CONCLUSIONS/INTERPRETATION: In patients with type 2 diabetes and nephropathy, LVH is associated with significantly increased risk of CV events and the progression of kidney disease. Importantly, in patients with LVH, losartan reduced the CV as well as the renal risk to a level similar to that seen in subjects without LVH.

Computerized ST depression analysis improves prediction of all-cause and cardiovascular mortality: the strong heart study.

BACKGROUND: Nonspecific ST depression assessed by standard visual Minnesota coding (MC) has been demonstrated to predict risk. Although computer analysis has been applied to digital ECGs for MC, the prognostic value of computerized MC and computerized ST depression analyses have not been examined in relation to standard visual MC. METHODS: The predictive value of nonspecific ST depression as determined by visual and computerized MC codes 4.2 or 4.3 was compared with computer-measured ST depression >or= 50 microV in 2,127 American Indian participants in the first Strong Heart Study examination. Computerized MC and ST depression were determined using separate computerized-ECG analysis programs and visual MC was performed by an experienced ECG core laboratory. RESULTS: The prevalence of MC 4.2 or 4.3 by computer was higher than by visual analysis (6.4 vs 4.4%, P < 0.001). After mean follow-up of 3.7 +/- 0.9 years, there were 73 cardiovascular deaths and 227 deaths from all causes. In univariate Cox analyses, visual MC (relative risk [RR] 4.8, 95% confidence interval [CI] 2.6-9.1), computerized MC (RR 6.0, 95% CI 3.5-10.3), and computer-measured ST depression (RR 7.6, 95% CI 4.5-12.9) were all significant predictors of cardiovascular death. In separate multivariate Cox regression analyses that included age, sex, diabetes, HDL and LDL cholesterol, body mass index, systolic and diastolic blood pressure, microalbuminuria, smoking, and the presence of coronary heart disease, computerized MC (RR 3.0, 95% CI 1.6-5.6) and computer-measured ST depression (RR 3.1, 95% CI 1.7-5.7), but not visual MC, remained significant predictors of cardiovascular mortality. When both computerized MC and computer-measured ST depression were entered into the multivariate Cox regression, each variable provided independent risk stratification (RR 2.1, 95% CI 1.0-4.4, and RR 2.1, 95% CI 1.0-4.4, respectively). Similarly, computerized MC and computer-measured ST depression, but not visual MC, were independent predictors of all-cause mortality after controlling for standard risk factors. CONCLUSIONS: Computer analysis of the ECG, using computerized MC and computer-measured ST depression, provides independent and additive risk stratification for cardiovascular and all-cause mortality, and improves risk stratification compared with visual MC. These findings support the use of routine computer analysis of ST depression on the rest ECG for assessment of risk and suggest that computerized MC can replace visual MC for this purpose.

Association of ventricular premature complexes with electrocardiographic-estimated left ventricular mass in a population of African-American and white men and women (The Atherosclerosis Risk in Communities.

Increased left ventricular (LV) mass is often found in adults and is a powerful predictor of cardiovascular mortality. To test the hypothesis that an electrocardiographic estimate of LV mass--the Cornell voltage--is associated with ventricular premature complexes (VPCs) in free-living adults, a cross-sectional analysis of the predictors of VPCs on a 2-minute rhythm strip in a population-based sample of 13,606 middle-aged, African-American and white men and women from 4 US communities in the Atherosclerosis Risk in Communities Study baseline examinations was performed. In adults without known coronary artery disease, the prevalence of VPCs increases monotonically with increasd Cornell voltages within ethnicity and gender groups. Independent of systemic hypertension, serum electrolytes, age, heart rate, educational attainment, gender, and ethnicity, a millivolt increase in Cornell voltage was associated with a 20% to 30% increase in the prevalence odds ratio of VPCs on the 2-minute electrocardiogram. Thus, Cornell voltage is associated with VPCs on a 2-minute electrocardiogram. The association is consistent in African-Americans, whites, men, and women.

Assessment of QT dispersion as a prognostic marker for sudden death in a regional nonreferred hypertrophic cardiomyopathy cohort.

In a consecutive, prospectively assessed and unselected hypertrophic cardiomyopathy (HC) cohort closely resembling the true disease state, QTc dispersion (and QTc) on the 12-lead electrocardiogram did not prove to be a reliable predictor of HC-related sudden death. Therefore, QT dispersion would not appear to be useful in devising future risk stratification strategies for predicting sudden death in HC.

Low heart rate variability in a 2-minute rhythm strip predicts risk of coronary heart disease and mortality from several causes: the ARIC Study. Atherosclerosis Risk In Communities.

BACKGROUND: Low heart rate variability (HRV) is associated with a higher risk of death in patients with heart disease and in elderly subjects and with a higher incidence of coronary heart disease (CHD) in the general population. METHODS AND RESULTS: We studied the predictive value of HRV for CHD and death from several causes in a population study of 14 672 men and women without CHD, aged 45 to 65, by using the case-cohort design. At baseline, in 1987 to 1989, 2-minute rhythm strips were recorded. Time-domain measures of HRV were determined in a random sample of 900 subjects, for all subjects with incident CHD (395 subjects), and for all deaths (443 subjects) that occurred through 1993. Relative rates of incident CHD and cause-specific death in tertiles of HRV were computed with Poisson regression for the case-cohort design. Subjects with low HRV had an adverse cardiovascular risk profile and an elevated risk of incident CHD and death. The increased risk of death could not be attributed to a specific cause and could not be explained by other risk factors. CONCLUSIONS: Low HRV was associated with increased risk of CHD and death from several causes. It is hypothesized that low HRV is a marker of less favorable health.

Comparison of computer-assigned Minnesota Codes with the visual standard method for new coronary heart disease events.

The Minnesota Code is the most widely used electrocardiogram (ECG) classification system for epidemiologic studies and has been incorporated into several Computer algorithms. The authors compared the Modular ECG Analysis System (MC-MEANS) and NOVACODE computer ECG findings with the Visual coding standard for agreement and prognostic associations with coronary heart disease (CHD) events occurring during follow-up from 1987 to 1995 in 2,116 individuals participating in the Atherosclerosis Risk in Communities (ARIC) Study. The exact agreement between Visual and computer findings was greater than 90% for all Minnesota Code categories except Q-code, which was 77% for MC-MEANS and 81% for NOVACODE. Approximately 60% of all Q-codes were assigned by computer methods only. Among the 2,116 participants, there were 246 (11.6%) new coronary events. Unadjusted relative risks for codes assigned by the three methods were similar. When computer methods disagreed on code severity, the CHD occurrence rates for MC-MEANS-detected severer code versus NOVACODE-detected severer code were 21% and 7%, respectively. This study provides clear evidence that computers assign more and severer Minnesota Codes with similar prognostic importance as does the Visual method; it also alerts researchers to potential problems in pooling Minnesota Code data read by different methods.

Agreement and coding reliability of the Minnesota and Mayo electrocardiographic coding systems.

PROBLEM: To determine whether diagnoses of myocardial infarction assigned by a system that uses Marquette 12SL electrocardiographic (ECG) codes with manual over-reading agree with diagnoses assigned by Minnesota ECG codes. STUDIES UNDERTAKEN: Agreement and recode reliability of Minnesota and Mayo coding systems based on 768 ECGs plus chest pain history and serum enzyme values were analyzed for a stratified random sample of 141 patients with an event in 1990 or 1991 coded as HICDA 410.x, 411, 413 or 796.9. The population was reconstructed from the stratified random sample so that population-based inferences could be made from the analysis. RESULTS: For the stratified random sample, exact agreement on 4 categories (evolving diagnostic, diagnostic, equivocal, or other ECG) between Mayo and Minnesota ECG coding was 53.9% (kappa = 0.37 +/- 0.05). Code-recode agreement was higher for Minnesota coding (83.0%; kappa = 0.74 +/- 0.05) compared with Mayo coding (73.8%; kappa = 0.64 +/- 0.05). The same pattern was present for the reconstructed population. For coding myocardial infarction based on the ECG, serum enzyme levels, and the presence or absence of ischemic chest pain, agreement between Mayo and Minnesota coding was 84.4% (kappa = 0.72 +/- 0.05) based on the stratified random sample and 81.7% (kappa = 0.67 +/- 0.06) based on the reconstructed population. For the stratified random sample, reliability of diagnosis of myocardial infarction was 93.6% (kappa = 0.88 +/- 0.04) for the Minnesota system and 94.3% (kappa = 0.90 +/- 0.03) for the Mayo system. CONCLUSION: ECG interpretation by the Mayo and Minnesota coding systems differs significantly, and Mayo ECG coding is less reliable than Minnesota ECG coding. Coding of myocardial infarction on the basis of ECGs, serum enzymes, and ischemic chest pain, however, is equally reliable for both systems.

Validation of death certificate diagnosis of out-of-hospital sudden cardiac death.

The validity of death certificate diagnosis of out-of-hospital sudden cardiac death (OOH-SCD) was studied among 108,676 30- to 74-year-old residents in 5 Minnesota communities using 6-year mortality data (1985 to 1990). Among 4,244 total deaths, location of death was listed on the certificate as out of hospital in 2,035 cases. Of those, 911 were judged not to have OOH-SCD because they had actually been admitted to the hospital or were noncardiovascular deaths. Among the remaining 1,124, 254 were diagnosed as OOH-SCD using a thorough, physician-based procedure that used clinical records, autopsy reports, and an informant (next-of-kin) interview. We used only death certificate information to define OOH-SCD simply and inexpensively as ICD-9 code 427.5 (cardiac arrest) plus location of death listed as out-of-hospital. Compared with the physician diagnosis, sensitivity was only 24%, whereas specificity was 85%. When the definition of OOH-SCD was expanded to include ICD codes 410-414 (acute myocardial infarction and chronic coronary artery disease), sensitivity improved to 87%, whereas specificity became 66%. However, even with this higher sensitivity and specificity, only 27% of the cases labeled OOH-SCD by death certificate agreed with the physician diagnosis. Death certificate diagnosis of OOH-SCD included many erroneous cases, and may not have been suitable for study of etiologic factors, such as cardiac dysrhythmias. Death certificate diagnosis may be useful to assess population time trends in OOH-SCD, provided that misclassification (false-positive rate) remains constant over time.

Seven-year change in graded exercise treadmill test performance in young adults in the CARDIA study. Cardiovascular Risk Factors in Young Adults.

PURPOSE: Most studies of physical fitness change have been relatively small, not population-based, and lacking in women and nonwhites. The purpose of this analysis was to evaluate the 7-yr change in physical fitness in a biracial (black and white) population of young men and women. METHODS: We evaluated change in exercise treadmill test performance in a biracial (black and white) population of 1,962 young adults, ages 18-30 yr at baseline, who completed symptom-limited graded exercise treadmill tests at the baseline (1985-1986) and year 7 (1992-1993) examinations of the CARDIA study. RESULTS: Mean test duration decreased 58 s (9.5%) over 7 yr (black men, 13.6% decrease, white men, 7.4%; black women, 11.1%; white women, 7.0%). Mean time to heart rate 130 (WL130), a measure of submaximal performance, decreased 31 s (11.3%) (black men, 16.9%; white men, 10.0%; black women, 12.3%; white women, 6.1%). Baseline body mass index (BMI) and physical activity were not statistically significant predictors of test duration change in any race-gender group, but change in BMI and activity were. Seven-year weight gain >20 lbs (31% of cohort) was associated with a large decrease in fitness (18.5% decrease in mean duration, 21.8% decrease in WL130). CONCLUSION: These data suggest that fitness declines during young adulthood in blacks and whites and that fitness changes are related to changes in weight and physical activity.

Electrocardiographic findings in a healthy biracial population. Atherosclerosis Risk in Communities (ARIC) Study Investigators.

It has been well documented that the prevalence of certain electrocardiographic (ECG) findings among individuals free of coronary heart disease (CHD) differs by race. However, it is not known whether these differences exist independently of CHD risk factors (e.g., hypertension). We examined the ECG tracings of 2,686 apparently healthy, middle-aged African-American and white men and women who participated in the Atherosclerosis Risk in Communities Study and were at low risk of CHD. Using the Minnesota Code, among men, 46% of African-Americans, but only 25% of whites, had a minor ECG finding (p < 0.001). In women, 32% of African-Americans and 23% of whites had a minor ECG finding (p < 0.01). Specifically, the age-adjusted prevalences of high-amplitude R wave, ST elevation, T-wave findings, and prolonged P-R interval were statistically significantly higher in African-Americans. As for continuous ECG measurements, the R wave in leads V5 and V6, the S wave in V1, the J-point amplitude in leads V2 and V5, the P-R interval, and the Cornell voltage (¿S V3¿ + R aVL) for left ventricular hypertrophy were all significantly greater in African-Americans than in whites. However, in both men and women, the heart rate corrected QT interval was shorter in African-Americans than in whites. All of these findings remained statistically significant after further adjustment for traditional CHD risk factors. These results suggest that racial differences in electrocardiograms may not be explained entirely by differences in established CHD risk factors, and because current diagnostic ECG criteria are largely based on data from middle-aged white men and women, race should be considered in the interpretation of ECG findings.

Heart rate adjustment of exercise-induced ST-segment depression identifies men who benefit from a risk factor reduction program.

BACKGROUND: Whether subjects identified as being at increased risk of coronary heart disease (CHD) death by heart rate adjustment of exercise-induced ST-segment depression will benefit from therapy aimed at reducing risk factors has not been examined. METHODS AND RESULTS: Exercise ECGs were performed in 11,880 men from the Usual Care (UC) and Special Intervention (SI) groups of the Multiple Risk Factor Intervention Trial. UC men were referred to customary sources of care in the community; SI men received counseling on smoking cessation and dietary reduction of cholesterol, and stepped-care therapy for hypertension. An abnormal ST-segment response to exercise was defined according to standard criteria as > or = 100 microV of additional horizontal or downsloping ST-segment depression and by an ST-segment/heart rate (ST/HR) index >1.60 microV/bpm. After 7 years of follow-up, CHD mortality was significantly lower in SI than UC men with an abnormal ST/HR index (2.4%, 19/786 versus 5.3%, 39/729, P=.005) but was comparable in SI and UC men with a normal ST/HR index (1.6%, 84/5154 versus 1.3%, 70/5211, P=NS). Risk reduction in SI men with an abnormal ST/HR index was independent of age and other cardiac risk factors. In contrast, there was no significant difference in CHD death rate between the smaller groups of SI and UC men with an abnormal test by standard criteria (3.6%, 7/192 versus 2.7%, 5/186, P=NS). CONCLUSIONS: An abnormal ST/HR index identifies men in whom therapy aimed at reducing CHD risk factors reduces the risk of CHD death by 61%. These findings support the application of heart rate adjustment of ST depression for screening of asymptomatic subjects at increased risk of CHD to identify those who will benefit most from risk factor-reduction programs.

Hyperinsulinemia and the development of ST-T electrocardiographic abnormalities. An 11-year follow-up study.

OBJECTIVE: It has been suggested that insulin resistance and consequent hyperinsulinemia promote atherosclerosis, but few prospective studies have reported the relationships between hyperinsulinemia and the development of ST-T abnormalities in the 12-lead resting electrocardiogram (ECG) in populations in which atherosclerosis is rare. RESEARCH DESIGN AND METHODS: A total of 304 Japanese men and women, aged 20-69 years, selected for having high blood glucose or more than a trace-positive urine glucose from a population-based health examination in 1981, were followed for 11 years. Of these, 33 died, 1 from myocardial infarction, while 260/271 living were reexamined in 1992. The 237 subjects with a normal ECG at the baseline examination were analyzed. RESULTS: Incident ST-T abnormalities occurred in 13/237 people. Insulin concentrations were positively associated with the development of ST-T abnormalities (relative risk approximately 8, comparing those in the highest versus lowest quartile of insulin values). Adjustment for age, sex, and systolic blood pressure or other risk factors had little effect on this relationship. CONCLUSIONS: Hyperinsulinemia was related to the development of ST-T abnormalities in ECGs in the absence of the development of clinical signs of atherosclerosis, independent of blood pressure and other risk factors in men and women with mild glucose intolerance.

Prognostic associations of Minnesota Code serial electrocardiographic change classification with coronary heart disease mortality in the Multiple Risk Factor Intervention Trial.

A central requirement for epidemiologic studies and clinical trials is a bias-free, objective determination of cardiac incidence rates between comparison groups. Epidemiologic studies and clinical trials frequently use changes in the Minnesota Code to document incident ischemic events. An electrocardiographic (ECG) classification system was developed to document significant ECG pattern change using objective comparison rules for side-by-side annual ECG comparison. Previously, we showed that major evolving Q waves were strongly and independently associated with total and coronary disease mortality. Using baseline-to-annual ECG comparisons in the Multiple Risk Factor Intervention Trial, we evaluated major evolving Q waves, minor evolving Q waves combined with major evolving ST-T waves and major evolving ST-T waves alone for their prognostic associations with coronary, cardiovascular, and total mortality during 16 years of follow-up. The 16-year coronary mortality rate in men with evolving minor Q waves plus evolving ST-T waves had an average adjusted relative risk of 4, equivalent to that of a major evolving Q wave. These risk ratios held whether a clinical infarction had occurred. Silent evolving ST-T waves without Q-wave change had an average adjusted relative coronary mortality risk of 1.6. Serial comparison methodology documents additional incident ischemic ECG events beyond the traditional major Minnesota Q-code change used in older epidemiologic studies. The procedure is standardized, quantitative, and repeatable. It is applicable for any study, present or past, that used Minnesota coding. The method is also well suited for incorporation in computer analysis programs.

Prognostic value of heart rate adjustment of exercise-induced ST segment depression in the multiple risk factor intervention trial.

OBJECTIVES: We sought to assess the effect of heart rate adjustment of ST segment depression on risk stratification for the prediction of death from coronary artery disease. BACKGROUND: Standard analysis of the ST segment response to exercise based on a fixed magnitude of horizontal or downsloping ST segment depression has demonstrated only limited diagnostic sensitivity for the detection of coronary artery disease and has variable test performance in predicting coronary artery disease mortality. Heart rate adjustment of the magnitude of ST segment depression has been proposed as an alternative approach to increase the diagnostic and prognostic accuracy of the exercise electrocardiogram (ECG). METHODS: Exercise ECGs were performed in 5,940 men from the Usual Care Group of the Multiple Risk Factor Intervention Trial at entry into the study. An abnormal ST segment response to exercise was defined according to standard criteria as > or = 100 micro V of additional horizontal or downsloping ST segment depression at peak exercise. The ST segment/heart rate index was calculated by dividing the change in ST segment depression from rest to peak exercise by the exercise-induced change in heart rate. An abnormal ST segment/heart rate index was defined as >1.60 micro V/beats per min. RESULTS: After a mean follow-up of 7 years there were 109 coronary artery disease deaths. Using a Cox proportional hazards model, a positive exercise ECG by standard criteria was not predictive of coronary mortality (age-adjusted relative risk [RR] 1.5, 95% confidence interval [CI] 0.6 to 3.6, p = 0.39). In contrast, an abnormal ST segment/heart rate index significantly increased the risk of death from coronary artery disease (age-adjusted RR 4.1, 95% CI 2.7 to 6.0, p < 0.0001). Excess risk of death was confined to the highest quintile of ST segment/heart rate index values, and within this quintile, risk was directly related to the magnitude of test abnormality. After multivariate adjustment for age, diastolic blood pressure, serum cholesterol and cigarettes smoked per day, the ST segment/heart rate index remained a significant independent predictor of coronary death (RR 3.6, 95% CI 2.4 to 5.4, p < 0.001). CONCLUSIONS: Simple heart rate adjustment of the magnitude of ST segment depression improves the prediction of death from coronary artery disease in relatively high risk, asymptomatic men. These findings strongly support the use of heart rate-adjusted indexes of ST segment depression to improve the predictive value of the exercise ECG.

Is the echocardiogram an appropriate ECG validity standard for the detection and change in left ventricular size?

The echocardiogram (Echo) is the validity standard for left ventricular mass (LVM) and LV hypertrophy (LVH). Numerous studies have confirmed modest correlations between the electrocardiogram (ECG) and Echo for LVM and low ECG sensitivity for Echo-LVH. In spite of this, investigators continue modeling ECG parameters to optimize their relation with the Echo. The authors studied the association between eight ECG criteria and Echo-LVM estimates in a biracial population of men and women with mild hypertension. The Echo-LVM was determined by the Penn convention and expressed in grams, g/m, g/m2, and g/m2.7. The ECGs and Echos were recorded at baseline, 3 months, and annually for 4 years. The ECGs were computer processed to define the following criteria: (1) Casale/Devereux, (2) Cornell product, (3) Cornell voltage, (4) 12-lead voltage product, (5) sum of the 12-lead, (6) Rautaharju, (7) Sokolow-Lyon, and (8) Romhilt-Estes point score. The major findings were: (1) correlations between the ECG and Echo were modest for level and minimal for change, (2) Echo indexing did not alter correlations with ECG criteria, (3) white men and women show higher correlations for level and change than blacks, (4) repeatability of the Echo-LVM index was 0.7, making it a "moving" validity standard for the ECG, (5) further ECG modeling to predict Echo-LVH, especially in whites, is not a productive approach, and (6) ECG measurements should be combined with other non-ECG characteristics when detecting LVH, and future ECG-LVM studies should investigate the prognostic value of ECG characteristics and use disease outcome as the validity standard.

Relation between electrocardiography and echocardiography for left ventricular mass in mild systemic hypertension (results from Treatment of Mild Hypertension Study).

Clinical recognition of hypertensive cardiac involvement depends primarily on use of noninvasive methods. The performance of 8 electrocardiographic (ECG) criteria sets were compared with an echocardiographic standard in the treatment of Mild Hypertension Study. Electrocardiograms were computer processed to define the following ECG criteria sets: (1) Casale/Devereux, (2) Cornell product, (3) Cornell voltage, (4) 12-lead voltage product, (5) sum of 12-lead voltage, (6) Rautaharju, (7) Sokolow-Lyon, and (8) Romhilt-Estes. Echocardiographic left ventricular (LV) mass index was calculated by using the Penn convention on a biracial population of 834 men and women. Correlations between ECG and echocardiographic LV mass index were modest (<0.40). ECG-LV hypertrophy sensitivity at 95% specificity was < 34%. The Casale/Devereux ECG criteria showed the highest average sensitivity (17%) at 95% specificity for all race-sex groups. Whites had significantly higher correlation values than blacks. ECG correlations with LV mass index were consistently improved by including systolic blood pressure and body mass index. ECG criteria sets appear to be optimized for white men. The study findings confirm the poor ECG sensitivity and correlation with echocardiographic LV mass and suggest: (1) further refinement of ECG criteria alone in white men is unlikely to improve its relationship with LV mass; and (2) combining the electrocardiogram with other non-ECG variables or noninvasive measurements offers the best strategy for improving ECG sensitivity and its prognostic value.