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Involuntary unemployment due to job loss has been associated with increased risk of cardiovascular events. Whether it also is associated with increased risk of atrial fibrillation (AF) is currently unknown. Therefore, we examined this association in 8,812 participants residing mainly in the Southeastern United States (mean age 58.1 ± 7.8 years; 63.2%; women; 43.2% black) with data on employment status who were enrolled in the REasons for Geographic And Racial Differences in Stroke study between 2003 and 2007 after excluding those with voluntary unemployment (retiree, homemakers, and students). AF was identified by electrocardiogram and past medical history at the same period. The cross-sectional association between status and type of unemployment with AF was examined in multivariable logistic regression models. Additional analysis in 4,273 participants without baseline AF and with data on incident AF collected in a follow-up visit occurred after a median of 9.4 years from baseline was also conducted. In a model adjusted for socio-demographics, health insurance, income, perceived stress, and cardiovascular risk factors, unemployment was associated with 60% increased odds of AF (odds ratio [95% confidence interval] 1.60 (1.24, 2.07)). This association was consistent in subgroups stratified by median age, gender, race, education, income, and health insurance status. Similarly, unemployment was associated with AF in those without AF at baseline who developed incident AF (odds ratio [95% confidence interval] 1.54 (1.04, 2.37)). In conclusion, involuntary unemployment is associated with increased risk of AF. This may call for considering socioeconomic determinants such as unemployment as part of the preventive strategies for AF., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Higher resting heart rate (RHR) is associated with increased risk of all-cause and cardiovascular mortality, with some reports showing the magnitude of association with all-cause mortality being stronger than that with cardiovascular mortality. This suggests that RHR association with mortality may not be limited to cardiovascular death. We compared the association between RHR with cardiovascular and noncardiovascular mortality in 6,743 participants (mean age 58.7 years, 52% women, 48% non-Hispanic whites) from the Third National Health and Nutrition Examination Survey (NHANES-III) after excluding those on antiarrhythmic drugs or with missing data. RHR data were obtained from standard 12-lead electrocardiogram recorded on the NHANES participants during a physical examination. National Death Index was used to identify the date and cause of death. Multivariable Cox proportional hazards analysis was used to calculate the hazard ratios (HRs) and 95% CIs for cardiovascular mortality and noncardiovascular mortality, separately, associated with 10 beats/min increase in RHR. During a median follow-up of 13.9 years, 906 cardiovascular deaths and 1,306 noncardiovascular deaths occurred. In models adjusted for age, gender, race, hypertension, diabetes, obesity, dyslipidemia, previous cardiovascular disease, smoking, cancer, chronic obstructive airway disease, thyroid disease, and serum creatinine, higher RHR was associated with increased risk of both cardiovascular mortality and noncardiovascular mortality with a relatively similar magnitude of risk (HR 1.19, 95% CI 1.12 to 1.26 and HR 1.23, 95% CI 1.17 to 1.29, respectively). In conclusion, higher RHR is associated with both cardiovascular mortality and noncardiovascular mortality suggesting that RHR is probably a marker of overall well-being rather than a marker of cardiovascular health., (Copyright © 2017 Elsevier Inc. All rights reserved.)

We hypothesized that maintaining a normal electrocardiogram (ECG) status over time is associated with low cardiovascular (CV) disease in a dose-response fashion and subsequently could be used to monitor programs aimed at promoting CV health. This analysis included 4,856 CV disease-free participants from the Atherosclerosis Risk in Communities study who had a normal ECG at baseline (1987 to 1989) and complete electrocardiographic data in subsequent 3 visits (1990 to 1992, 1993 to 1995, and 1996 to 1998). Participants were classified based on maintaining their normal ECG status during these 4 visits into "maintained," "not maintained," or "inconsistent" normal ECG status as defined by the Minnesota ECG classification. CV disease events (coronary heart disease, heart failure, and stroke) were adjudicated from Atherosclerosis Risk in Communities visit-4 through 2010. Over a median follow-up of 13.2 years, 885 CV disease events occurred. The incidence rate of CV disease events was lowest among study participants who maintained a normal ECG status, followed by those with an inconsistent pattern, and then those who did not maintain their normal ECG status (trend p value <0.001). Similarly, the greater the number of visits with a normal ECG status, the lower was the incidence rate of CV disease events (trend p value <0.001). Maintaining (vs not maintaining) a normal ECG status was associated with a lower risk of CV disease, which was lower than that observed in those with inconsistent normal ECG pattern (trend p value <0.01). In conclusion, maintaining a normal ECG status over time is associated with low risk of CV disease in a dose-response fashion, suggesting its potential use as a monitoring tool for programs promoting CV health., Competing Interests: None., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The association between the J wave, a key component of the early repolarization pattern, and adverse cardiovascular outcomes remains unclear. Inconsistencies have stemmed from the different methods used to measure the J wave. We examined the association between the J wave, detected by an automated method, and adverse cardiovascular outcomes in 14,592 (mean age = 54 ± 5.8 years; 56% women; 26% black) participants from the Atherosclerosis Risk In Communities (ARIC) study. The J wave was detected at baseline (1987 to 1989) and during follow-up study visits (1990 to 1992, 1993 to 1995, and 1996 to 1998) using a fully automated method. Sudden cardiac death, coronary heart disease death, and cardiovascular mortality were ascertained from hospital discharge records, death certificates, and autopsy data through December 31, 2010. A total of 278 participants (1.9%) had evidence of a J wave. Over a median follow-up of 22 years, 4,376 of the participants (30%) died. In a multivariable Cox regression analysis adjusted for demographics, cardiovascular risk factors, and potential confounders, the J wave was not associated with an increased risk of sudden cardiac death (hazard ratio [HR] 0.74, 95% CI 0.36 to 1.50), coronary heart disease death (HR 0.72, 95% CI 0.40 to 1.32), or cardiovascular mortality (HR 1.16, 95% CI 0.87 to 1.56). An interaction was detected for cardiovascular mortality by gender with men (HR 1.54, 95% CI 1.09 to 2.19) having a stronger association than women (HR 0.74, 95% CI 0.43 to 1.25; P-interaction = 0.030). In conclusion, our findings suggest that the J wave is a benign entity that is not associated with an increased risk for sudden cardiac arrest in middle-aged adults in the United States., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Although advanced interatrial block (aIAB) is an established electrocardiographic phenotype, its prevalence, incidence, and prognostic significance in the general population are unclear. We examined the prevalence, incidence, and prognostic significance of aIAB in 14,625 (mean age = 54 ± 5.8 years; 26% black; 55% female) participants from the Atherosclerosis Risk in Communities (ARIC) study. aIAB was detected from digital electrocardiograms recorded during 4 study visits (1987 to 1989, 1990 to 1992, 1993 to 1995, and 1996 to 1998). Risk factors for the development of aIAB were examined using multivariable Poisson regression models with robust variance estimates. Cox regression was used to compute hazard ratios and 95% CIs for the association between aIAB, as a time-dependent variable, and atrial fibrillation (AF). AF was ascertained from study electrocardiogram data, hospital discharge records, and death certificates thorough 2010. A total of 69 participants (0.5%) had aIAB at baseline, and 193 (1.3%) developed aIAB during follow-up. The incidence for aIAB was 2.27 (95% CI 1.97 to 2.61) per 1,000 person-years. Risk factors for aIAB development included age, male gender, white race, antihypertensive medication use, low-density lipoprotein cholesterol, body mass index, and systolic blood pressure. In a Cox regression analysis adjusted for sociodemographics, cardiovascular risk factors, and potential confounders, aIAB was associated with an increased risk for AF (hazard ratio 3.09, 95% CI 2.51 to 3.79). In conclusion, aIAB is not uncommon in the general population. Risk factors for developing aIAB are similar to those for AF, and the presence of aIAB is associated with an increased risk for AF., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Repolarization abnormalities in the setting of bundle branch blocks (BBB) are generally ignored. We used Cox regression models to determine hazard ratios (HRs) with 95% confidence intervals (CIs) for incident heart failure (HF) associated with wide spatial and frontal QRS/T angle (upper twenty-fifth percentile of each) in men and women with and without BBB. This analysis included 14,478 participants (54.6% women, 26.4% blacks, 377 [2.6%] with BBB) from the Atherosclerosis Risk in Communities Study who were free of HF at baseline. Using No-BBB with normal spatial QRS/T angle as the reference group, the risk for HF in multivariable adjusted models was increased 51% for No-BBB with wide spatial QRS/T angle (HR 1.51, 95% CI 1.37 to 1.66), 48% for BBB with normal spatial QRS/T angle (HR 1.48, 95% CI 1.17 to 1.88), and the risk for incident HF was increased more than threefold for BBB with wide spatial QRS/T angle (HR 3.37, 95% CI 2.47 to 4.60). The results were consistent across subgroups by gender. Similar results were observed for the frontal plane QRS/T angle. In the pooled BBB group excluding right BBB, a positive T wave in lead aVR and heart rate 70 bpm and higher were also potent predictors of incident HF similar to the QRS/T angles. In conclusion, both BBB and wide QRS/T angles are predictive of HF, and concomitant presence of both carries a much higher risk than for either predictor alone. These findings suggest that repolarization abnormalities in the setting of BBB should not be considered benign or an expected consequence of BBB., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The association of electrocardiographic (ECG) abnormalities with cardiovascular disease and risk factors has been extensively studied in whites and African-Americans. Comparable data have not been reported in Hispanics/Latinos. The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a multicenter, community-based, prospective cohort study of men and women of diverse backgrounds aged 18 to 74 years who self-identified as Hispanic/Latinos. Participants (n = 16,415) enrolled from March 2008 to June 2011. We describe the prevalence of minor and major ECG abnormalities and examined their cross-sectional associations with cardiovascular disease and risk factors. The Minnesota code criteria were used to define minor and major ECG abnormalities. Previous cardiovascular disease and risk factors were based on data obtained at baseline examination. Significant differences in prevalent ECG findings were found between men and women. Major ECG abnormalities were present in 9.2% (95% confidence interval 8.3 to 10.1) of men and 6.6% (95% confidence interval 5.8 to 7.3) of women (p <0.0001). The odds of having major ECG abnormalities significantly increased with age, presence of ≥3 cardiovascular risk factors, and prevalent cardiovascular disease, in both men and women. Significant differences in major ECG abnormalities were found among the varying groups; Puerto Ricans and Dominicans had more major abnormalities compared with Mexican men and women. In conclusion, in a large cohort of Hispanic/Latino men and women, prevalence of major abnormalities was low, yet strong associations of major ECG abnormalities with cardiovascular disease and risk factors were observed in both men and women., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The risk of incident hospitalized heart failure (HF) was evaluated for 23 electrocardiographic (ECG) variables in men and women free from cardiovascular disease. The hazard ratios with 95% confidence intervals were determined from Cox regression analysis for 13,428 participants 45 to 65 years old in the Atherosclerosis Risk in Communities (ARIC) study. New-onset HF during a 14-year follow-up period occurred in 695 men (11.9%) and 721 women (9.5%). Several ECG variables were significant predictors of incident HF when evaluated as single ECG variables. Predominant among them were spatial angles, reflecting deviations of the direction of the repolarization sequence from the normal reference direction. After controlling for collinearity among the ECG variables, the spatial angle between T peak and normal T reference vectors, Ө(Tp|Tref), was a significant independent predictor in men (HF risk increased 31%) and women (HF risk increased 46%). Other independent predictors in men included epicardial repolarization time (62% increased risk) and T wave peak to T wave end (TpTe) interval, reflecting global dispersion of repolarization (27% increased risk). The independent predictors in women, in addition to Ө(Tp|Tref), were Ө(R|STT) the spatial angle between the mean QRS and STT vectors (54% increased risk) and QRS nondipolar voltage (46% increased risk). In conclusion, wide Ө(Tp|Tref), wide Ө(R|STT), and increased QRS nondipolar voltage in women and wide Ө(Tp|Tref), increased epicardial repolarization time, prolonged TpTe interval and T wave complexity in men were independent predictors of incident HF, and the presence of these abnormal findings could warrant additional diagnostic evaluation for possible preventive action for HF., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Widening of the electrocardiographic (ECG) spatial QRS-T angle has been predictive of cardiovascular disease (CVD) events in the general population. However, its prognostic significance in human immunodeficiency virus (HIV)-infected patients remains unknown. The spatial QRS-T angle was derived from the baseline resting 12-lead electrocardiogram of 4,453 HIV-infected patients aged 43.5 ± 9.3 years from the Strategies for Management of Antiretroviral Therapy (SMART) trial. CVD events were identified during a median follow-up of 28.7 months. Quartiles of the spatial QRS-T angle was calculated for men and women separately, and values in the upper quartile were considered as a widened angle (values >74° for women and >93° for men). A multivariate Cox proportional hazards analysis was used to examine the association between a widened baseline spatial QRS-T angle and incident CVD events. During 11,965 person-years of follow-up, 152 CVD events occurred at a rate of 1.27 events/100 person-years. The rate of CVD events in those with a widened spatial QRS-T angle was almost double the rate in those with a normal spatial QRS-T angle (rate ratio 1.94, 95% confidence interval 1.40 to 2.69; p <0.001). In a model adjusted for study treatment arm, demographics, CVD risk factors, HIV characteristics, inflammatory markers, and other ECG abnormalities, a widened spatial QRS-T angle was associated with a >50% increased risk of CVD events compared to a normal spatial QRS-T angle (hazard ratio 1.53, 95% confidence interval 1.07 to 2.17; p = 0.02). No interaction was seen by SMART trial arm (p value for interaction = 0.37) or gender (p value for interaction = 0.84). In conclusion, a widened spatial QRS-T angle was independently predictive of CVD events in HIV-infected patients receiving antiretroviral therapy. This highlights the potential role of routine electrocardiography as a simple noninvasive CVD risk-screening tool in HIV-infected patients., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Electrocardiographic bundle branch block (BBB) has higher cardiac and all-cause death. However, reports on the association between BBBs and mortality in the general populations are conflicting. The aim of this study was to evaluate the risk for coronary heart disease (CHD) and all-cause death associated with left BBB (LBBB) and right BBB (RBBB) during 14 years of follow-up in 66,450 participants from the Women's Health Initiative (WHI) study. Cox proportional-hazards regression was performed for mortality risk in Women with LBBB (n = 714) and those with RBBB (n = 832). In risk models adjusted for demographic and clinical risk factors in women with cardiovascular disease (CVD), hazard ratios for CHD death were 2.92 (95% confidence interval 2.08 to 4.08, p <0.001) for LBBB and 1.62 (95% confidence interval 1.08 to 2.43, p <0.05) for RBBB, and only LBBB was a significant predictor of all-cause death (hazard ratio 1.43, 95% confidence interval 1.11 to 1.83, p <0.01). In CVD-free women, only LBBB was a significant predictor of CHD death (fully adjusted hazard ratio 2.17, 95% confidence interval 1.37 to 3.43, p <0.01), and neither blocks was predictive of all-cause death. From several repolarization variables that were significant mortality predictors in univariate risk models, after adjustment for other electrocardiographic covariates and risk factors, ST J-point depression in lead aVL ≤-30 μV in women with LBBB was an independent predictor of CHD death, with a more than fivefold increase in risk. None of the repolarization variables were independent predictors in women with RBBB. In conclusion, prevalent LBBB in CVD-free women and LBBB and RBBB in women with CVD were significant predictors of CHD death. In women with LBBB, ST J-point depression in lead aVL was a strong independent predictor of CHD death., (Copyright © 2012 Elsevier Inc. All rights reserved.)

A United States 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 electrocardiographic (ECG) abnormalities among black and white men and women. The participants were recruited from 2003 to 2007 by random selection from a commercially available nationwide list, with oversampling of blacks and those from the stroke belt, with a cooperation rate of 49%. The measurement of risk factors and 12-lead electrocardiograms (centrally coded using Minnesota code criteria) showed 28% had ≥1 major ECG abnormality. The prevalence of abnormalities was greater (≥35%) for those ≥65 years old, with no differences between blacks and whites. However, among men <65 years, blacks had more major abnormalities than whites, most notably for atrial fibrillation, major Q waves, and left ventricular hypertrophy. Men generally had more ECG abnormalities than women. The most common ECG abnormalities were T-wave abnormalities. The average heart rate-corrected QT interval was longer in women than in men, similar in whites and blacks, and increased with age. However, the average heart rate was greater in women than in men and in blacks than in whites and decreased with age. The prevalence of ECG abnormalities was related to the presence of hypertension, diabetes, blood pressure, and age. In conclusion, black men and women in the United States have a significantly greater prevalence of ECG abnormalities than white men and women at age 45 to 64 years; however, these proportions, although larger, tended to equalize or reverse after age 65., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The Minnesota Code (MC) and Novacode (Nova) are the most widely used electrocardiographic (ECG) classification systems. The comparative strengths of their classifications for Q- and ST-T-wave abnormalities in predicting coronary heart disease (CHD) events and total mortality have not been evaluated separately by gender. We studied standard 12-lead electrocardiograms at rest from 4,988 participants in the Cardiovascular Health Study. Average age at baseline was 73 years, 60% of participants were women 85% were white, and 22% had a history of cardiovascular disease or presence of ECG myocardial infarction by MC or Nova. Starting in 1989 with an average 17-year follow-up, 65% of participants died and 33% had incident CHD in a cohort free of cardiovascular disease at baseline. Of these, electrocardiograms with major Q-wave or major ST-T abnormalities by MC or Nova predicted increased risk for CHD events and total mortality with no significant differences in predictability between men and women. The study also found that women had fewer major Q-wave changes but more major ST-T abnormalities than men. However, there were no gender differences in predicting CHD events and total mortality. In conclusion, ECG classification systems for myocardial infarction/ischemia abnormalities by MC or Nova are valuable and useful for men and women in clinical trials and epidemiologic studies., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Electrocardiographic (ECG) Q- and ST-T-wave abnormalities predict coronary heart disease (CHD) and total mortality. No comparison has been made of the classification of these abnormalities by the 2 most widely used ECG coding systems for epidemiologic studies-the Minnesota Code (MC) and Novacode (NC). We evaluated 12-lead electrocardiograms from 64,597 participants (49 to 79 years old, 82% non-Hispanic white) in the Women's Health Initiative clinical trial in 1993 to 1998, with a maximum of 11 years of follow-up. We used MC and NC criteria to identify Q-wave, ST-segment, and T-wave abnormalities for comparison. In total, 3,322 participants (5.1%) died during an average 8-year follow-up, and 1,314 had incident CHD in the baseline cardiovascular disease-free group. Independently, ECG myocardial infarction criteria by the MC or NC were generally equivalent and were strong predictors for CHD death and total mortality (hazard ratio 1.62, 95% confidence interval 1.05 to 2.51 for CHD death; hazard ratio 1.36, 95% confidence interval 1.09 to 1.71 for total mortality) in a multivariable analytic model. Electrocardiograms with major ST-T abnormalities by the MC or NC coding system were stronger in predicting CHD deaths and total mortality than was the presence of Q waves alone. In conclusion, the ECG classification systems for myocardial infarction/ischemia abnormalities from the MC and NC are valuable and useful in clinical trials and epidemiologic studies. ST-T abnormalities are stronger predictors for CHD events and total mortality than isolated Q-wave abnormalities., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

We compared the prognostic value of 12 electrocardiographic (ECG) variables in predicting risk of new-onset heart failure (HF) in a subgroup of 13,555 participants of the Atherosclerosis Risk in Communities (ARIC) study who were considered free of coronary heart disease at the onset of the study. Cox proportional hazards models were used to evaluate risk of HF for the highest decile of the distribution of each ECG variable (lowest decile for ST and T amplitudes in lead V(5)), with the remaining deciles as reference groups. Risk models were adjusted for demographic and clinical variables. In univariate Cox regression models, in men 11 and in women 8 of the 12 ECG variables were significant, strong predictors of risk of new-onset HF. Subsequently, 8 ECG variables with low mutual correlations were entered simultaneously into a multivariate Cox regression model. In men, large left ventricular mass by electrocardiogram, QT prolongation, and increased heart rate were the strongest independent predictors of new-onset HF, each with a twofold increased risk. Other independent predictors in men were ST depression in lead V(5), wide QRS/T angle, and old (silent) myocardial infarction, each with a >50% increased risk of incident HF. In women, QRS nondipolar voltage was associated with an 87% increased risk of incident HF, and other independent predictors, as in men, were wide QRS/T angle and increased heart rate. In conclusion, several ECG abnormalities are manifestations of evolving HF in men and women considered free of coronary heart disease.

Spatial QRS/T angle and spatial T-wave axis were shown to be strong independent predictors of incident coronary heart disease (CHD) and total mortality, but they are not routinely available. We evaluated whether frontal plane QRS/T angle, easily obtained as the difference between frontal plane axes of QRS and T, provides a suitable substitute for spatial QRS/T angle as a risk predictor. Our study consisted of 13,973 participants from the ARIC Study. Outcome variables were incident CHD and total mortality during a median follow-up of 14 years. Electrocardiographic variables were categorized as abnormal (>/=95th percentile), borderline (>/=75th and <95th percentile), and normal (<75th percentile) separately for men and women. Cox regression was used to assess the effect of electrocardiographic variables on risk of each outcome. The normal category was considered the reference cell. With adjustment for demographic and clinical characteristics, both QRS/T angles were approximately equally strong predictors of total mortality with >50% increased risk. Spatial QRS/T angle was a stronger predictor of incident CHD in women, with a 114% increased risk, but it was not significantly associated with risk of incident CHD in men. Similarly, frontal plane QRS/T angle was statistically significant for only women with a 74% increased risk of incident CHD. In conclusion, frontal plane QRS/T angle as an easily derived risk measure is a suitable clinical substitute for spatial QRS/T angle for risk prediction.

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.

The JT interval or Bazett's QTc - QRS has been advocated for detection of prolonged repolarization in ventricular conduction defects (VCDs). However, the use of neither JT nor QTc - QRS has been validated, and normal limits for rate-adjusted JT have not been established for VCDs or for normal ventricular conduction. Functional relations among RR, JT, and QT intervals were evaluated in 11,739 adult men and women with normal ventricular conduction and in 1,251 subjects with major VCD. The results showed that JT adjustment obtained as QTc - QRS retained a strong residual correlation with ventricular rate (r = 0.54), making its use ill-advised. In contrast, QT adjustment as a linear function of the RR interval for VCD as QT(RR,QRS) = QT - 155 x (60/heart rate - 1) - 0.93 x (QRS - 139) + k, with k = -22 ms for men and -34 ms for women, removed the rate dependence and produced upper 2% and 5% normal limits at 460 and 450 ms, respectively, which are identical to those in normal conduction. As an alternative, equally effective linear JT adjustment formulas were derived, including newly required normal standards. Thus, detection of prolonged repolarization in VCD requires the use of the JT interval or a bivariate model for QT with RR and QRS intervals as covariates.