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Traditional procedures for establishment of normal limits failed because of proportional scaling, assumption of normal QT distribution, or omission of regression intercept. Percentile distributions of linearly scaled adjusted QT produced regularized rate invariant normal limits within normal sinus rates.

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A US national sample of 20,962 participants (57% women, 44% blacks) from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study provided general population estimates for ECG abnormalities among black and white men and women. Participants were recruited during 2003–2007 by random selection from a commercially available nationwide list, with oversampling of blacks and persons from the stroke belt for a cooperation rate of 49%. Measurement of risk factors and 12-lead ECGs (centrally coded using Minnesota Code criteria) showed 28% had at least one major ECG abnormality. Prevalence of abnormalities was higher (35%+) for those 65 years and older with no differences between blacks and whites. However, among men less than 65 years, blacks had more major abnormalities than whites, most notably for atrial fibrillation, major Q waves and left ventricular hypertrophy (LVH). Men generally had more ECG abnormalities than women. The most common ECG abnormalities were T-wave abnormalities. Average heart rate corrected QT interval was longer in women than men, similar in whites and blacks and increased with age, whereas the average heart rate was higher in women than men and in blacks than whites and decreased with age. The prevalence of ECG abnormalities was related to hypertension, diabetes, blood pressure level and age. In conclusion, black men and women in the US have a significantly higher prevalence of ECG abnormalities than whites at ages 45–64 but these proportions, although larger, tend to equalize or reverse after age 65.

Background The same electrocardiographic (ECG) criteria that have been used for detection of left ventricular hypertrophy (LVH) have recently been recognized as predictors of adverse clinical outcomes, but this predictive ability is inadequately explored and understood. Methods A total of 14,984 participants from the Atherosclerosis Risk in Communities (ARIC) study were included in this analysis. Romhilt-Estes (R-E) LVH score was measured from the automatically processed baseline (1987-1989) ECG data. All-cause mortality was ascertained up to December 2010. Cox proportional hazard models were used to examine the association between baseline R-E score, overall and each of its six individual components separately, with all-cause mortality. The associations between change in R-E score between baseline and first follow up visit with mortality was also examined. Results During a median follow up of 21.7 years, 4549 all-cause mortality events occurred during follow up. In multivariable adjusted models, increasing levels of the R-E score was associated with increasing risk of mortality both as a baseline finding and as a change between the baseline and the first follow-up visit. Four of the six ECG components of the score were predictive of all-cause mortality [P-terminal force, QRS amplitude, LV strain, and intrinsicoid deflection], while two of the components were not [left axis deviation and prolonged QRS duration]. Differences in the strengths of the associations between the individual components of the score and mortality were observed. Conclusions The R-E score, traditionally used for detection of LVH, could be used as a useful tool for predication of adverse outcomes.

Background: Atrial fibrillation (AF) has been shown to be independently associated with an increased risk of myocardial infarction (MI) in a predominantly middle-aged population; however, this association has not been examined in older populations. Hypothesis: AF is associated with MI in older adults. Methods: A total of 4608 participants (85% white, 40% male) from the Cardiovascular Health Study without evidence of baseline coronary heart disease were included in this analysis. AF cases were identified during the yearly study electrocardiogram, a self-reported history of a physician diagnosis, or by hospitalization data. Incident MI was identified using medical records with local and central adjudication. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AF and incident MI. Results: A total of 434 (9.4%) participants had evidence of AF before incident MI. Over a median follow-up of 12.2 years, a total of 797 (17.3%) participants developed MI. In a multivariable Cox proportional hazards analysis adjusted for socio-demographics, cardiovascular risk factors, and potential confounders, AF was associated with an increased risk of MI (HR: 1.7, 95% CI: 1.4-2.2). A significant interaction was detected by race, with black (HR: 3.1, 95% CI: 1.7-5.6) AF participants having an increased risk of MI compared with whites (HR: 1.6, 95% CI: 1.2-2.1; P interaction = 0.030). Conclusions: AF is associated with an increased risk of MI in a population of older adults.

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