@article {720, title = {Linearly scaled, rate-invariant normal limits for QT interval: eight decades of incorrect application of power functions.}, journal = {J Cardiovasc Electrophysiol}, volume = {13}, year = {2002}, month = {2002 Dec}, pages = {1211-8}, abstract = {

INTRODUCTION: Normal limits for QT traditionally are derived as mean +/- 2*SD, with rate adjustment done by dividing QT values by power functions such as RR 1/2 (proportional scaling).

METHODS AND RESULTS: We evaluated procedures for deriving normal limits by comparing adjusted QT distributions versus heart rate using ECG data of 11,739 normal men and women aged > or = 40 years. QT decreased as predicted by many power functions with heart rate but its SD remained relatively unchanged. Consequently, proportional scaling induced rate-dependent distortion of normal limits. Furthermore, QT distributions by heart rate were variably skewed and non-normal. Therefore, normal limits expressed as mean +/- 2*SD were misleading. Omission of regression intercept was an additional reason for failure of Bazett{\textquoteright}s and Fridericia{\textquoteright}s formulas. Regularized normal limits for adjusted QT (Qta) were obtained with linear instead of proportional scaling of type QTa = QT + k1*(1 - RR(k2)), for instance, with k2 = 0.5, k1 = 0.360 for males and 0.353 for females, or with k2 = 0.42, k1 = 0.414 for males and 0.420 for females. With linear scaling, QTa = 460 msec was established as the upper 2\% normal limit, with 32 msec as the limit for a significant QTa increase from reference ECG in serial comparison.

CONCLUSION: 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.

}, keywords = {Adult, Aged, Aged, 80 and over, Electrocardiography, Female, Heart Rate, Humans, Male, Middle Aged, Prognosis, Reference Values, Sex Characteristics}, issn = {1045-3873}, doi = {10.1046/j.1540-8167.2002.01211.x}, author = {Rautaharju, Pentti M and Zhang, Zhu-Ming} } @article {761, title = {The association between the length of the QT interval and mortality in the Cardiovascular Health Study.}, journal = {Am J Med}, volume = {115}, year = {2003}, month = {2003 Dec 15}, pages = {689-94}, abstract = {

PURPOSE: A long QT interval is a risk factor for arrhythmic events and sudden death. Whether moderate QT prolongation is associated with clinical events in community-dwelling elderly patients is uncertain.

METHODS: We measured the QT interval in a population-based sample of 5888 men and women at least 65 years of age who were participants in the Cardiovascular Health Study. The association between Bazett{\textquoteright}s rate-corrected QT (QTc, in ms) and mortality during the subsequent 10 years was evaluated. We stratified participants by the presence or absence of coronary heart disease status at baseline, and adjusted for coronary heart disease risk factors.

RESULTS: The rates of all-cause and coronary heart disease mortality were greater in participants with longer QTc intervals. Among participants without known coronary heart disease, those whose QTc interval was >450 ms were at increased risk of all-cause mortality (relative risk [RR] = 1.34; 95\% confidence interval [CI]: 1.07 to 1.67) and coronary heart disease mortality (RR = 1.6; 95\% CI: 1.0 to 2.5) when compared with participants whose QTc interval was <410 ms. The associations were stronger among those with known coronary heart disease (RR for all-cause mortality = 2.3; 95\% CI: 1.6 to 3.3; and RR for coronary heart disease mortality = 2.0; 95\% CI: 1.1 to 3.7).

CONCLUSIONS: The QT interval from the standard electrocardiograms is of value for identification of elderly persons at increased risk of coronary heart disease and total mortality. A QTc interval >450 ms should prompt clinical evaluation and possible interventions to reduce the risk of coronary events.

}, keywords = {Aged, Arrhythmias, Cardiac, Cause of Death, Coronary Disease, Electrocardiography, Female, Follow-Up Studies, Heart Rate, Humans, Male, Randomized Controlled Trials as Topic, Risk Factors, Statistics as Topic, Survival Analysis, United States}, issn = {0002-9343}, doi = {10.1016/j.amjmed.2003.07.014}, author = {Robbins, John and Nelson, Jennifer Clark and Rautaharju, Pentti M and Gottdiener, John S} } @article {774, title = {Assessment of prolonged QT and JT intervals in ventricular conduction defects.}, journal = {Am J Cardiol}, volume = {93}, year = {2004}, month = {2004 Apr 15}, pages = {1017-21}, abstract = {

The JT interval or Bazett{\textquoteright}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.

}, keywords = {Adult, Aged, Aged, 80 and over, Arrhythmias, Cardiac, Bundle-Branch Block, Electrocardiography, Female, Heart Ventricles, Humans, Male, Middle Aged}, issn = {0002-9149}, doi = {10.1016/j.amjcard.2003.12.055}, author = {Rautaharju, Pentti M and Zhang, Zhu-Ming and Prineas, Ron and Heiss, Gerardo} } @article {887, title = {Comparison of mortality risk for electrocardiographic abnormalities in men and women with and without coronary heart disease (from the Cardiovascular Health Study).}, journal = {Am J Cardiol}, volume = {97}, year = {2006}, month = {2006 Feb 01}, pages = {309-15}, abstract = {

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.

}, keywords = {Aged, Coronary Disease, Electrocardiography, Female, Humans, Male, Risk}, issn = {0002-9149}, doi = {10.1016/j.amjcard.2005.08.046}, author = {Rautaharju, Pentti M and Ge, Sijian and Nelson, Jennifer C and Marino Larsen, Emily K and Psaty, Bruce M and Furberg, Curt D and Zhang, Zhu-Ming and Robbins, John and Gottdiener, John S and Chaves, Paulo H M} } @article {939, title = {Alcohol consumption and risk and prognosis of atrial fibrillation among older adults: the Cardiovascular Health Study.}, journal = {Am Heart J}, volume = {153}, year = {2007}, month = {2007 Feb}, pages = {260-6}, abstract = {

BACKGROUND: The relationship of alcohol consumption with risk of atrial fibrillation (AF) is inconsistent in previous studies, and its relationship with prognosis of AF is undetermined.

METHODS: As part of the Cardiovascular Health Study, a population-based cohort of adults 65 years and older from 4 US communities, 5609 participants reported their use of beer, wine, and spirits yearly. We identified cases of AF with routine study electrocardiograms and validated discharge diagnoses from hospitalizations.

RESULTS: A total of 1232 cases of AF were documented during a mean of 9.1 years of follow-up. Compared with long-term abstainers, the multivariable-adjusted hazard ratios were 1.25 (95\% CI, 1.02-1.54) among former drinkers, 1.09 (95\% CI, 0.94-1.28) among consumers of less than 1 drink per week, 1.00 (95\% CI, 0.84-1.19) among consumers of 1 to 6 drinks per week, 1.06 (95\% CI, 0.82-1.37) among consumers of 7 to 13 drinks per week, and 1.09 (95\% CI, 0.88-1.37) among consumers of 14 or more drinks per week (P trend = 0.64). In analyses of mortality among participants with AF, the hazard ratios were 1.27 (95\% CI, 1.06-1.52) among former drinkers, 0.94 (95\% CI, 0.76-1.18) among consumers of less than 1 drink per week, 0.98 (95\% CI, 0.78-1.23) among consumers of 1 to 6 drinks per week, 0.73 (95\% CI, 0.51-1.03) among consumers of 7 to 13 drinks per week, and 0.81 (95\% CI, 0.59-1.11) among consumers of 14 or more drinks per week (P trend = 0.12).

CONCLUSIONS: Current moderate alcohol consumption is not associated with risk of AF or with risk of death after diagnosis of AF, but former drinking identifies individuals at higher risk.

}, keywords = {Aged, Alcohol Drinking, Atrial Fibrillation, Female, Follow-Up Studies, Humans, Incidence, Longitudinal Studies, Male, Prognosis, Risk Factors}, issn = {1097-6744}, doi = {10.1016/j.ahj.2006.10.039}, author = {Mukamal, Kenneth J and Psaty, Bruce M and Rautaharju, Pentti M and Furberg, Curt D and Kuller, Lewis H and Mittleman, Murray A and Gottdiener, John S and Siscovick, David S} }