Relation of QT interval and QT dispersion to echocardiographic left ventricular hypertrophy and geometric pattern in hypertensive patients. The LIFE study. The Losartan Intervention For Endpoint Reduction

Left Ventricular Geometric Pattern Impacts QT Dispersion in Males Athletes and Sedentary Men

AIM

To (1) compare QT dispersion (QTd) and echocardiographic features between athletes with concentric left ventricular (LV) hypertrophy, athletes with eccentric LV hypertrophy, and sedentary controls with a normal LV geometric pattern and (2) quantify associations between QTd and echocardiographic features within these groups.

METHODS

Male athletes competing in different sports and sedentary men were stratified into groups according to their LV geometric pattern. These groups included eccentric LV hypertrophy (LV index > 115 g/m2, relative wall thickness [RWT] < 0.42) consisting of 38 athletes, concentric LV hypertrophy (LV index > 115 g/m2, RWT > 0.42) consisting of 40 athletes, and normal LV geometric pattern (LV index < 115 g/m2, RWT < 0.42) consisting of 40 sedentary controls. Following a cross-sectional design, participants underwent electrocardiographic (ECG) and echocardiographic screening. Data were compared between groups using one-way analyses of variance with Bonferroni post hoc tests. Associations between corrected QTd and echocardiographic variables were quantified using Pearson correlations.

RESULTS

Alongside structural disparities between groups, corrected QTd was significantly (p < 0.001) lower in athletes with eccentric LV hypertrophy compared to athletes with concentric LV hypertrophy and sedentary controls. Significant, moderate-to-very-large correlations were found between corrected QTd and interventricular septal wall thickness in athletes with concentric (r = 0.416, p = 0.008) or eccentric LV hypertrophy (r = 0.734, p < 0.001), and sedentary controls (r = 0.464, p = 0.003).

CONCLUSION

The provided comparative and relationship data may inform the development of more precise approaches for ECG and echocardiographic screening in athletes, particularly in those with concentric LV hypertrophy who may be at greater risk for developing prolonged QTd.

Electrocardiographic Abnormalities in Nigerian Hypertensives With Echocardiographic Left Ventricular Hypertrophy

Introduction To enhance the diagnosis of anatomic left ventricular hypertrophy (LVH) using electrocardiography (ECG), we aimed to identify common ECG amplitude and non-amplitude abnormalities in Nigerian patients with hypertensive echocardiographic LVH. Method The study included 1,765 patients with essential hypertension aged 18 years and older from the Federal Medical Centre Abuja Hypertension Registry (FMCAHR). Participants underwent echocardiography and ECG following the American College of Cardiology and the American Society of Echocardiography guidelines. Results The prevalence of overall ECG LVH amplitude criteria (43.8%) and individual criteria of Cornell voltage (27.1%), Sokolow-Lyon voltage (23.2%), and Gubner-Ungerleider (13.9%) were higher than non-amplitude ECG abnormalities among patients with echocardiographic LVH. The sensitivity and specificity of LVH criteria were 43.8% and 79.5% for overall ECG LVH, 23.2% and 87.2% for Sokolow-Lyon voltage, 27.1% and 93.3% for Cornell voltage, and 13.9% and 95.4% for Gubner-Ungerleider criteria, respectively. After multivariable adjustment, non-amplitude ECG changes, including prolonged corrected QT (QTc) (odds ratio (OR): 1.68, 95% confidence interval (CI): 1.06-2.66), left ventricular (LV) strain pattern (OR: 1.83, CI: 1.23-2.72), left axis deviation (OR: 1.56, CI: 1.09-2.24), poor R wave progression (OR: 2.36, CI: 1.40-3.97), premature ventricular contractions (OR: 1.80, CI: 1.10-2.91), premature atrial contractions (OR: 2.06, CI: 1.10-3.87), atrial fibrillation (OR: 2.40, CI: 1.20-4.82), and left atrial abnormality (OR: 8.43, CI: 2.95-24.05), were associated with echocardiographic LVH (p < 0.05). Conclusion In our cohort of hypertensive patients, ECG LVH amplitude criteria were the most frequently observed abnormalities associated with echocardiographic LVH. Our findings suggest that despite the low sensitivity, ECG LVH amplitude criteria may remain valuable in diagnosing echocardiographic LVH.

Relacorilant, a Selective Glucocorticoid Receptor Modulator in Development for the Treatment of Patients With Cushing Syndrome, Does Not Cause Prolongation of the Cardiac QT Interval

OBJECTIVE

To assess the effect of relacorilant, a selective glucocorticoid receptor modulator under investigation for the treatment of patients with endogenous hypercortisolism (Cushing syndrome [CS]), on the heart rate-corrected QT interval (QTc).

METHODS

Three clinical studies of relacorilant were included: (1) a first-in-human, randomized, placebo-controlled, ascending-dose (up to 500 mg of relacorilant) study in healthy volunteers; (2) a phase 1 placebo- and positive-controlled thorough QTc (TQT) study of 400 and 800 mg of relacorilant in healthy volunteers; and (3) a phase 2, open-label study of up to 400 mg of relacorilant administered daily for up to 16 weeks in patients with CS. Electrocardiogram recordings were taken, and QTc change from baseline (ΔQTc) was calculated. The association of plasma relacorilant concentration with the effect on QTc in healthy volunteers was assessed using linear mixed-effects modeling.

RESULTS

Across all studies, no notable changes in the electrocardiogram parameters were observed. At all time points and with all doses of relacorilant, including supratherapeutic doses, ΔQTc was small, generally negative, and, in the placebo-controlled studies, similar to placebo. In the TQT study, placebo-corrected ΔQTc with relacorilant was small and negative, whereas placebo-corrected ΔQTc with moxifloxacin positive control showed rapid QTc prolongation. These results constituted a negative TQT study. The model-estimated slopes of the concentration-QTc relationship were slightly negative, excluding an association of relacorilant with prolonged QTc.

CONCLUSION

At all doses studied, relacorilant consistently demonstrated a lack of QTc prolongation in healthy volunteers and patients with CS, including in the TQT study. Ongoing phase 3 studies will help further establish the overall benefit-risk profile of relacorilant.

Polypharmacy, Gender Disparities, and Ethnic and Racial Predispositions in Long QT Syndrome: An In-Depth Review

Long QT syndrome (LQTS) is a complex disorder of cardiac electrophysiology. It is characterized by delayed myocardial polarization leading to QT prolongation and alterations on the ST segment and T wave visible on electrocardiogram (ECG). Syncope is a common manifestation, and torsade de pointes (TdP) can lead to sudden cardiac death. Three major LQTS genes (KCI31, KCNH2, and SCN5) lead to most of the cases of LQTS. Lifestyle modifications, beta blockers, and implantable cardioverter defibrillator (ICD) placement are the main treatments for LQTS. Polypharmacy, including QT-prolonging drugs, has been shown to worsen LQTS. The impact on potassium channels and the human ether-a-go-go-related gene (hERG) is the mechanism behind the QT interval prolongation caused by these medications. There is an increased incidence of LQTS among African-American men and women as compared to Caucasians. Women with LQTS tend to have a higher mortality rate from the condition, especially during menstruation and shortly after giving birth. Genetic testing is reserved to those patientswho exhibit either a strong clinical index of suspicion or experience persistent QT prolongation despite their lack of symptoms. Knowing the genetics, racial, and gender discrepancies can help improve patient management and a better comprehension on each case. Proper understanding of how ion channels function and their interaction with medications will lead to a better comprehension and to develop effective forms to treat those patients.

Dofetilide use is not associated with increased mortality in patients with left ventricular hypertrophy and atrial fibrillation

BACKGROUND

Left ventricular hypertrophy (LVH) is common in patients with atrial fibrillation (AF), however, many antiarrhythmic drugs (AADs) are contraindicated. US guidelines recommend avoiding pure class III antiarrhythmics such as dofetilide in patients with significant LVH due to concern for an increased risk of death, however, clinical data is lacking. We sought to determine if dofetilide use was associated with increased mortality in patients with LVH.

METHODS

Patients ≥18 years of age with AF and LVH ≥ 1.4 cm were included. A group of patients treated with dofetilide and a control group of patients without a history of AAD use were propensity matched. The primary outcome was all-cause mortality at 3 years and secondary outcomes were total number of all-cause hospitalizations and hospitalizations related to AF.

RESULTS

There were 359 patients in each of the groups. Baseline variables were well-matched. The primary outcome of all-cause mortality occurred in 7% of patients in the dofetilide group and 12% of patients in the control group (hazard ratio: 0.90, 95% confidence interval: 0.53-1.53). Total all-cause hospitalizations were higher in the control group but hospitalizations for AF were no different.

CONCLUSIONS

In a propensity-matched cohort of 718 patients with AF and LVH, dofetilide was not associated with increased mortality at 3 years. Our study adds to prior data demonstrating the safety of dofetilide in this population despite guideline recommendations against its use. Given the limited options for AF management in LVH patients, dofetilide may be reasonable for symptomatic AF management.

Incident left bundle branch block predicts cardiovascular events and death in hypertensive patients with left ventricular hypertrophy. The LIFE Study

Aim: Whether incident left bundle branch block (LBBB) is associated with increased cardiovascular (CV) morbidity and mortality in treated hypertensive patients with left ventricular hypertrophy (LVH) is unknown. Thus, the present study aimed to examine CV outcomes of incident LBBB in treated hypertensive patients with LVH. Methods: In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, 9,193 hypertensive patients with LVH on screening electrocardiogram (ECG) were randomized to losartan or atenolol based treatment. Participants (n = 8,567) did not have LBBB (Minnesota code 7.1) on baseline ECG. Cox regression models controlling for significant covariates assessed independent associations of incident LBBB with CV events and all-cause mortality during 4.8 years mean follow-up. Results: Annual follow-up ECGs identified 295 patients (3.4%) with incident LBBB associated with male gender (P < 0.05), older age, higher Cornell voltage (both P < 0.005) and history of diabetes, isolated systolic hypertension and prevalent CV disease. When adjusted for the history of previous CV disease, diabetes, isolated systolic hypertension, the Framingham risk score, ECG-LVH and randomized study treatment, Cox regression models showed that incident LBBB predicted higher risk of the composite endpoint CV death, myocardial infarction and stroke [hazard ratio (HR) 1.9, 95% confidence intervals (CIs) 1.3–2.9, P < 0.001], CV death (HR 3.0, 95% CIs 1.84–5.0, P < 0.001), heart failure (HR 3.6, 95% CIs 1.9–6.6, P < 0.001) and all-cause mortality (HR 3.0, 95% CIs 2.0–4.3, P < 0.001). Conclusions: These data suggest that among hypertensive patients with ECG-LVH receiving aggressive antihypertensive therapy, incident LBBB independently predicts increased risk of subsequent CV events including congestive heart failure and CV and all-cause mortality (ClinicalTrials.gov identifier: NCT00338260).

QT Interval Dynamics and Cardiovascular Outcomes: A Cohort Study in an Integrated Health Care Delivery System

Background

Long QT has been associated with ventricular dysrhythmias, cardiovascular disease (CVD) mortality, and sudden cardiac death. However, no studies to date have investigated the dynamics of within‐person QT change over time in relation to risk of incident CVD and all‐cause mortality in a real‐world setting.

Methods and Results

A cohort study among members of an integrated health care delivery system in Northern California including 61 455 people (mean age, 62 years; 60% women, 42% non‐White) with 3 or more ECGs (baseline in 2005–2009; mean±SD follow‐up time, 7.6±2.6 years). In fully adjusted models, tertile 3 versus tertile 1 of average QT corrected (using the Fridericia correction) was associated with cardiac arrest (hazard ratio [HR], 1.66), heart failure (HR, 1.62), ventricular dysrhythmias (HR, 1.56), all CVD (HR, 1.31), ischemic heart disease (HR, 1.28), total stroke (HR, 1.18), and all‐cause mortality (HR, 1.24). Tertile 3 versus tertile 2 of the QT corrected linear slope was associated with cardiac arrest (HR, 1.22), ventricular dysrhythmias (HR, 1.12), and all‐cause mortality (HR, 1.09). Tertile 3 versus tertile 1 of the QT corrected root mean squared error was associated with ventricular dysrhythmias (HR, 1.34), heart failure (HR, 1.28), all‐cause mortality (HR, 1.20), all CVD (HR, 1.14), total stroke (HR, 1.08), and ischemic heart disease (HR, 1.07).

Conclusions

Our results demonstrate improved predictive ability for CVD outcomes using longitudinal information from serial ECGs. Long‐term average QT corrected was more strongly associated with CVD outcomes than the linear slope or the root mean squared error. This new evidence is clinically relevant because ECGs are frequently used, noninvasive, and inexpensive.

Female Patients With Sleep-Disordered Breathing Display More Frequently Heart Failure With Preserved Ejection Fraction

Objective: Sleep-disordered breathing (SDB) is a widespread disease that is often associated with heart failure (HF) with preserved ejection fraction (HFpEF). HFpEF is more frequent in women than in men, but detailed pathomechanisms remain unclear. We investigated HFpEF in women and men in a high-risk cohort with SDB monitoring.

Methods and Results: Three hundred twenty-seven patients (84.4% men) undergoing elective coronary artery bypass grafting were prospectively subjected to SDB monitoring, and an apnea–hypopnea index (AHI) ≥15/h defined SDB. HF was classified according to current guidelines. HFpEF was significantly more frequent in SDB patients compared to those without SDB (28 vs. 17%, P = 0.016). This distribution was driven by an increased frequency of HFpEF in female SDB patients (48% vs. only 25% in male, P = 0.022). In accordance, female patients with SDB exhibited significantly more impaired diastolic left ventricular filling compared to men (echocardiographic E/e′). In contrast to men, in women, minimum oxygen saturation (O_2min, measured by polygraphy, R² = 0.470, P < 0.001) and time of oxygen saturation <90% (R² = 0.165, P = 0.044) were significantly correlated with E/e′. Moreover, the correlation between O_2min and E/e′ was significantly different in women compared to men (P < 0.001). Intriguingly, this association remained independent of clinical covariates in women [age, body mass index, systolic contractile dysfunction, diabetes mellitus, and glomerular filtration rate (GFR), R² = 0.534, P = 0.042, multivariate regression analysis]. Since angiotensin II signaling has been mechanistically linked to HF, we measured protein expression of its cleavage enzyme ACE2 in human right atrial appendage biopsies (Western blot). Intriguingly, we found a significantly decreased ACE2 expression preferentially in women with SDB (2.66 ± 0.42 vs. 4.01 ± 2.47 in men with SDB, P = 0.005). In accordance, left ventricular mass index was significantly increased in women with SDB compared to women without SDB.

Conclusion: In patients with SDB, HFpEF and diastolic dysfunction were more frequent in women compared to men. In contrast to men, the severity of SDB was associated with the degree of diastolic dysfunction in women. These insights might help to find sex-specific therapies for patients with sleep-disordered breathing and heart failure.

Clinical Trial Registration: Unique identifier: NCT02877745, URL: http://www.clinicaltrials.gov.

The Diagnostic Yield of Routine Electrocardiography in Hypertension and Implications for Care in a Southwestern Nigerian Practice

BACKGROUND

Nigeria, like other developing nations, has an increasing burden of hypertension. Electrocardiography is an integral part of the diagnostic work-up for the newly diagnosed hypertensive subjects. The aim of this study was to determine the diagnostic yield of electrocardiography in hypertensive patients of a southwestern Nigerian hospital.

PATIENTS AND METHODS

This was a retrospective descriptive study of electrocardiographs of hypertensive patients over a six-year period. Electrographic variables of interest were cardiac rhythm and rate, left ventricular hypertrophy (LVH), left atrial enlargement (LAE), T wave abnormalities, cardiac axis, blocks, complexes, QT segment abnormalities, atrial fibrillation (AF)/flutter, supraventricular tachycardia and pre-excitation syndrome. The Pearson's chi square was used to test for differences across age groups (15-44yrs, 45-64yrs and >65yrs) and between male and female subjects with the significance level set at 5% (p< 0.05).

RESULTS

Hypertension was the indication for 40% of electrocardiographs completed and comprised of 3713 electrocardiograms (ECG) over a six-year period. The commonest abnormalities were left axis deviation (LAD) (32.2%), LVH (20.7%), rhythm abnormalities (16.7%) and LAE (14.5%). The diagnostic yield (presence of at least one electrographic abnormality) was 51% in 15-44 yrs age group, 64% in middle aged and 76.5% in the >65 yrs age group. While the male subjects in this study had a slightly increased likelihood of having an abnormal finding (odds ratio 1.18: 95% CI 1.02-1.35), the odds ratio for an abnormal ECG in subjects younger than 45 years was 0.48 (95% CI 0.41-0.57).

CONCLUSION

The diagnostic yield of electrocardiography in this study was considerable, although lowest in subjects younger than 45 years and increased with age. This may reflect an increased burden and earlier onset of hypertension and its complications. This should also engender prompt and aggressive management of hypertension, especially in the elderly in whom the cardiovascular complications from hypertension is most severe.

The protective effect of isosteviol sodium on cardiac function and myocardial remodelling in transverse aortic constriction rat

Pathological hypertrophy contributes to heart failure and there is not quite effective treatment to invert this process. Isosteviol has been shown to protect the heart against ischaemia-reperfusion injury and isoproterenol-induced cardiac hypertrophy, but its effect on pressure overload-induced cardiac hypertrophy is still unknown. Pressure overload induced by transverse aortic constriction (TAC) causes cardiac hypertrophy in rats to mimic the pathological condition in human. This study examined the effects of isosteviol sodium (STVNa) on cardiac hypertrophy by the TAC model and cellular assays in vitro. Cardiac function test, electrocardiogram analysis and histological analysis were conducted. The effects of STVNa on calcium transient of the adult rat ventricular cells and the proliferation of neonatal rat cardiac fibroblasts were also studied in vitro. Cardiac hypertrophy was observed after 3-week TAC while the extensive cardiac dysfunction and electronic remodelling were observed after 9-week TAC. Both STVNa and sildenafil (positive drug) treatment reversed the two process, but STVNa appeared to be more superior in some aspects and did not change calcium transient considerably. STVNa also reversed TAC-induced cardiac fibrosis in vivo and TGF-β1-induced fibroblast proliferation in vitro. Moreover, STVNa, but not sildenafil, reversed impairment of the autonomic nervous system induced by 9-week TAC.

Diagnostic yield of hypertrophic cardiomyopathy in first-degree relatives of decedents with idiopathic left ventricular hypertrophy

AIMS

Idiopathic left ventricular hypertrophy (LVH) is defined as LVH in the absence of myocyte disarray or secondary causes. It is unclear whether idiopathic LVH represents the phenotypic spectrum of hypertrophic cardiomyopathy (HCM) or whether it is a unique disease entity. We aimed to ascertain the prevalence of HCM in first-degree relatives of decedents from sudden death with idiopathic LVH at autopsy. Decedents also underwent molecular autopsy to identify the presence of pathogenic variants in genes implicated in HCM.

METHODS AND RESULTS

Families of 46 decedents with idiopathic LVH (125 first-degree relatives) were investigated with electrocardiogram, echocardiogram exercise tolerance test, cardiovascular magnetic resonance imaging, 24-h Holter, and ajmaline provocation test. Next-generation sequencing molecular autopsy was performed in 14 (30%) cases. Decedents with idiopathic LVH were aged 33 ± 14 years and 40 (87%) were male. Fourteen families (30%) comprising 16 individuals were diagnosed with cardiac disease, including Brugada syndrome (n = 8), long QT syndrome (n = 3), cardiomyopathy (n = 2), and Wolff-Parkinson-White syndrome (n = 1). None of the family members were diagnosed with HCM. Molecular autopsy did not identify any pathogenic or likely pathogenic variants in genes encoding sarcomeric proteins. Two decedents had pathogenic variants associated with long QT syndrome, which were confirmed in relatives with the clinical phenotype. One decedent had a pathogenic variant associated with Danon disease in the absence of any histopathological findings of the condition or clinical phenotype in the family.

CONCLUSION

Idiopathic LVH appears to be a distinct disease entity from HCM and is associated with fatal arrhythmias in individuals with primary arrhythmia syndromes. Family screening in relatives of decedents with idiopathic LVH should be comprehensive and encompass the broader spectrum of inherited cardiac conditions, including channelopathies.

Blood pressure-related electrocardiographic findings in healthy young individuals

Purpose: Elevated blood pressure induces electrocardiographic changes and is associated with an increase in cardiovascular disease later in life compared to normal blood pressure levels. The purpose of this study was to evaluate the association between normal to high normal blood pressure values (90-139/50-89 mmHg) and electrocardiographic parameters related to cardiac changes in hypertension in healthy young adults.Methods: Data from 1449 volunteers aged 18-30 years collected at our centre were analyzed. Only subjects considered healthy by a physician after review of collected data with systolic blood pressure values between 90 and 139 mmHg and diastolic blood pressure values between 50 and 89 mmHg were included. Subjects were divided into groups with 10 mmHg systolic blood pressure increment between groups for analysis of electrocardiographic differences. Backward multivariate regression analysis with systolic and diastolic blood pressure as a continuous variable was performed.Results: The mean age was 22.7 ± 3.0 years, 73.7% were male. P-wave area, ventricular activation time, QRS-duration, Sokolow-Lyon voltages, Cornell Product, J-point-T-peak duration corrected for heart rate and maximum T-wave duration were significantly different between systolic blood pressure groups. In the multivariate model with gender, body mass index and cholesterol, ventricular rate (standardized coefficient (SC): +0.182, p < .001), ventricular activation time in lead V6 (SC= +0.065, p = .048), Sokolow-Lyon voltage (SC= +0.135, p < .001), and Cornell product (SC= +0.137, p < .001) were independently associated with systolic blood pressure, while ventricular rate (SC= +0.179, p < .001), P-wave area in lead V1 (SC= +0.079, p = .020), and Cornell product (SC= +0.091, p = .006) were independently associated with diastolic blood pressure.Conclusion: Blood pressure-related electrocardiographic changes were observed incrementally in a healthy young population with blood pressure in the normal range. These changes were an increased ventricular rate, increased atrial surface area, ventricular activation time and increased ventricular hypertrophy indices on a standard 12 lead electrocardiogram.

Independent Influence of Blood Pressure on QTc Interval: Results from a General Chinese Population

Aims

We performed the current study primarily to characterize the independent association of blood pressure with heart rate-corrected QT (QTc) interval after adjusting for cardiovascular confounding factors and left ventricular mass (LVM) in a large general population in China.

Methods

All enrolled 10,553 permanent residents with age ≥ 35 years from Liaoning Province were investigated by a questionnaire and then subjected to physical examinations, laboratory analyses, and electrocardiogram (ECG) as well as echocardiogram at the same visit. Multivariate linear and logistic regression analyses were conducted to assess the independent association of blood pressure with QTc interval.

Results

Hypertensive subjects had significantly longer QTc interval and higher prevalence of prolonged QTc interval compared with normotensive ones in all subgroups stratified by gender and left ventricular hypertrophy (LVH) (all Ps ≤ 0.001). Multiple relevant clinical confounding factors and LVM were all adjusted in the multivariate linear and logistic regression analyses. As a result, both systolic blood pressure (SBP) and diastolic blood pressure (DBP) were independently associated with QTc interval (β = 0.12 and 0.16, respectively; Ps < 0.001). Furthermore, as categorical variables, hypertension was independently associated with prolonged QTc interval (OR = 1.71; P < 0.001). Sex-specific analyses revealed that the independent associations were detected in both males and females (all Ps < 0.001).

Conclusions

These key findings of the current study highlighted the fact that hypertension was significantly associated with prolonged QTc interval and the correlations were independent of confounding factors and LVM.

Association of left bundle branch block with new onset abnormal wall motion in treated hypertensive patients with left ventricle hypertrophy: the LIFE Echo Sub-study

AIMS

We aimed to investigate whether left bundle branch block (LBBB) is related to new-onset left ventricle (LV) wall motion abnormalities during treatment in hypertensive patients with electrocardiographic (ECG) defined left ventricular hypertrophy (LVH).

METHODS AND RESULTS

960 patients with essential hypertension and ECG-LVH participating in the LIFE Echo Sub-study were investigated at baseline and annually with echocardiography, during randomized antihypertensive therapy. After excluding patients with LV wall motion abnormalities at baseline and patients developing new-onset LBBB during study time, we investigated 784 patients. The participants with (n = 32) and without (n = 752) LBBB were similar regarding most baseline variables. Logistic regression models controlling for LV mass index, Framingham risk score, and randomized treatment assignment were used to assess the odds ratio of developing new-onset abnormal LV wall motion on annual follow-up echocardiograms. The likelihood of developing new global LV wall motion abnormalities in patients with LBBB was not higher compared to those without LBBB except at year 5 (p = .002). The likelihood of developing new segmental LV wall motion abnormalities in patients with LBBB was however higher compared to patients without LBBB after 1 year (OR = 3.1, 95% CI = 0.7-14.2, p = .173); 2 years (OR = 6.9, 2.1-22.4, p = .003); 3 years (OR = 5.3, 2.0-14.3, p < .001), 4 years (OR = 4.0, 1.6-10.3, p = .003 and 5 years (OR = 4.1, 1.0-16.2, p = .394) of treatment.

CONCLUSION

Among patients with ECG-LVH, undergoing antihypertensive treatment, the presence of LBBB independently identifies individuals with ∼3- to 7-fold greater odds of developing new segmental abnormal LV wall motion. These findings suggest that LBBB may be a marker for progressive myocardial disease.

The Effects of Trimetazidine on QT-interval Prolongation and Cardiac Hypertrophy in Diabetic Rats

Background

Trimetazidine (TMZ) is an anti-ischemic drug. In spite of its protective effects on cardiovascular system, there is no scientific study on the usefulness of TMZ treatment for prolonged QT interval and cardiac hypertrophy induced by diabetes.

Objectives

To evaluate the effects of TMZ on QT interval prolongation and cardiac hypertrophy in the diabetic rats.

Methods

Twenty-four male Sprague-Dawley rats (200-250 g) were randomly assigned into three groups (n = 8) by simple random sampling method. Control (C), diabetic (D), and diabetic administrated with TMZ at 10 mg/kg (T10). TMZ was administrated for 8 weeks. The echocardiogram was recorded before isolating the hearts and transfer to a Langendorff apparatus. Hemodynamic parameters, QT and corrected QT interval (QTc) intervals, heart rate and antioxidant enzymes were measured. The hypertrophy index was calculated. The results were evaluated by one-way ANOVA and paired t-test using SPSS (version 16) and p < 0.05 was regarded as significant.

Results

The diabetic rats significantly indicated increased hypertrophy, QT and QTc intervals and decreased Left ventricular systolic pressure (LVSP), Left ventricular developed pressure (LVDP), rate pressure product (RPP), Max dp/dt, and min dp/dt (±dp/dt max), heart rate, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase in the heart. Treatment with TMZ in the diabetic animals was significantly improved these parameters in comparison to the untreated diabetic group.

Conclusions

TMZ improves QTc interval prolongation and cardiac hypertrophy in diabetes.

The effect of transcatheter aortic valve implantation on Tp-e interval, Tp-e/QT and Tp-e/QTc ratios, and Tp-e dispersion in patients with severe aortic stenosis

Background

In this study, we aimed to investigate the effect of transcatheter aortic valve implantation using two types of bioprosthetic valves on novel ventricular repolarization markers including Tp-e, Tp-e/QT and Tpe/QTc ratios, and Tp-ed.

Methods

A total of 61 patients (17 males, 44 females; mean age 78.6±6.5 years; range 55 to 89 years) who underwent transcatheter aortic valve implantation with either a Medtronic CoreValve (n=40) or an Edwards SAPIEN XT valve (n=21) were retrospectively analyzed. The electrocardiographic parameters and left ventricular mass index were calculated prior to the procedure, on postoperative Day 1, and at three months after the procedure.

Results

The Tp-e interval, Tp-e/QT and Tp-e/QTc ratios, Tp-ed, and left ventricular mass index significantly reduced at three months of the procedure, compared to baseline values (p<0.01, for all). Similar findings were observed for QT, QTc, and QT dispersion (p<0.01, for all). These changes were independent from the types of bioprosthetic valves used. Before the procedure, the left ventricular mass index was positively correlated with the Tp-e (r=0.350, p=0.007), Tp-e/QT (r=0.314, p=0.015) and Tp-e/QTc ratios (r=0.285, p=0.029). In the multivariate analysis, Tp-e interval was found to be independently associated with the left ventricular mass index (b=0.350, p=0.007).

Conclusion

In the present study, the Tp-e interval, Tp-e/QT and Tp-e/QTc ratios, Tp-ed, and left ventricular mass index significantly reduced at three months after transcatheter aortic valve implantation indicating reverse left ventricular remodeling. The effects of two types of bioprosthetic valves on ventricular repolarization markers and left ventricular mass index were similar.

Left Ventricular Septal Hypertrophy in Elderly Patients With Aortic Stenosis

OBJECTIVES

Left ventricular (LV) septal hypertrophy in aortic stenosis raises diagnostic and therapeutic questions. However, the etiology and clinical consequences of this finding have not been well studied. The aim of this study was to perform a morphologic evaluation of the LV in aortic stenosis and to investigate the contributing factors and consequences of septal hypertrophy.

METHODS

Patients with moderate or severe aortic stenosis were prospectively enrolled. Patients with previous myocardial infarction, wall motion abnormalities, at least moderate valvular regurgitation, known cardiomyopathy, an LV ejection fraction of less than 50%, and age younger than 65 years were excluded.

RESULTS

Forty-one patients underwent a final analysis. Septal hypertrophy (LV septal wall thickness ≥15 mm) was confirmed in 21 of 41 patients. The septal hypertrophy group had higher peak aortic valve velocity, a higher diabetes mellitus rate, and a higher rate and longer duration of hypertension than those without septal hypertrophy. The peak aortic valve velocity (odds ratio, 7.1; 95% confidence interval, 1.4-37.1) and diabetes mellitus (odds ratio, 7.4; 95% confidence interval, 1.2-46.2) were the significant factors associated with septal hypertrophy by multivariate analysis. Intraventricular conduction disturbance on electrocardiography was more frequent in the septal hypertrophy group (P = .021).

CONCLUSIONS

Left ventricular septal hypertrophy was commonly observed in elderly patients with aortic stenosis, and a higher aortic valve velocity, hypertension, and diabetes mellitus were associated factors. Intraventricular conduction disturbance occurred more often in patients with septal hypertrophy than those without, which implies the pathophysiologic consequence. Further studies are needed to determine the impact of septal hypertrophy and intraventricular conduction disturbance on the prognosis of patients after aortic valve interventions.

Electrocardiogram QRS duration and associations with telomere length: A cross-sectional analysis in Australian rural diabetic and non-diabetic population

Prolonged electrocardiogram QRS durations are often present in aging populations. Shorter telomere length is considered a biomarker of cellular aging. Decreased telomere length has been associated with coronary artery risk, and ventricular remodeling. However, the association between telomeres and cardiac conduction abnormalities, such as increased QRS duration are not well understood. A retrospective cross-sectional population was obtained from the CSU Diabetes Screening Research Initiative database where 273 participants had both ECG-derived QRS duration and DNA to permit leukocyte telomere length (LTL) determination. Telomere length was determined using the monochrome multiplex quantitative PCR method to measure mean relative LTL. Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system. Relative LTL was moderately negatively associated with QRS duration in type 2 diabetes mellitus (T2DM) patients (R²=0.055), compared to controls (R²=0.010). In general linear models with no adjustments a significant interaction between QRS duration and LTL is observed for a combined population of T2DM and non-diabetics. When we compared T2DM to non-diabetics, we found that T2DM increased the effect size for relative LTL on QRS duration in comparison to controls. Hence, for each 0.1 unit of relative LTL attrition, QRS duration in T2DM patients increased by 3.24ms (95% CI, -63.00 to -1.84), compared to 1.65ms in controls (95% CI, -40.44 to 7.40). In summary we have observed an association between LTL in a rural aging mixed population of T2DM and non-diabetes. We have observed an unadjusted association between QRS duration and LTL in T2DM. We noted that the control group demonstrated no such association. This highlights the complexity of T2DM when exploring disease phenotype-telomere interactions.

Diffuse interstitial fibrosis assessed by cardiac magnetic resonance is associated with dispersion of ventricular repolarization in patients with hypertrophic cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is characterized by myocyte hypertrophy, disarray, fibrosis, and increased risk for ventricular arrhythmias. Increased QT dispersion has been reported in patients with HCM, but the underlying mechanisms have not been completely elucidated. In this study, we examined the relationship between diffuse interstitial fibrosis, replacement fibrosis, QTc dispersion and ventricular arrhythmias in patients with HCM. We hypothesized that fibrosis would slow impulse propagation and increase dispersion of ventricular repolarization, resulting in increased QTc dispersion on surface electrocardiogram (ECG) and ventricular arrhythmias.

Methods

ECG and cardiac magnetic resonance (CMR) image analyses were performed retrospectively in 112 patients with a clinical diagnosis of HCM. Replacement fibrosis was assessed by measuring late gadolinium (Gd) enhancement (LGE), using a semi-automated threshold technique. Diffuse interstitial fibrosis was assessed by measuring T1 relaxation times after Gd administration, using the Look–Locker sequence. QTc dispersion was measured digitally in the septal/anterior (V1–V4), inferior (II, III, and aVF), and lateral (I, aVL, V5, and V6) lead groups on surface ECG.

Results

All patients had evidence of asymmetric septal hypertrophy. LGE was evident in 70 (63%) patients; the median T1 relaxation time was 411±38 ms. An inverse correlation was observed between T1 relaxation time and QTc dispersion in leads V1–V4 (p<0.001). Patients with HCM who developed sustained ventricular tachycardia had slightly higher probability of increased QTc dispersion in leads V1–V4 (odds ratio, 1.011 [1.004–1.0178, p=0.003). We found no correlation between presence and percentage of LGE and QTc dispersion.

Conclusion

Diffuse interstitial fibrosis is associated with increased dispersion of ventricular repolarization in leads, reflecting electrical activity in the hypertrophied septum. Interstitial fibrosis combined with ion channel/gap junction remodeling in the septum could lead to inhomogeneity of ventricular refractoriness, resulting in increased QTc dispersion in leads V1–V4.

The Relationship between Angiotensin-II Type 1 Receptor Gene Polymorphism and Repolarization Parameters after a First Anterior Acute Myocardial Infarction

Background and Objectives

Genetic influence on T-wave peak to End (Tpe) time in patients with a first anterior acute myocardial infarction (AMI) is uncertain. A polymorphism in the angiotensin-II type 1 receptor (AT1R) gene was discovered recently. The polymorphism consists of an A or C variant, given three different possible genotypes: AA, AC, CC. The purpose of this study was to determine the effects of polymorphism of the AT1R gene polymorphism on Tpe after a first anterior AMI.

Subjects and Methods

The subjects were 142 patients (110 men, 32 women, 58±13 years) with a first anterior AMI; ten patients were excluded from this study. Based on the polymorphism of the AT1R gene, they were classified into two groups: Group 1 (AA genotype) of 91 patients and group 2 (AC and CC genotype) of 41 patients. A 12-lead resting ECG was recorded at admission to the coronary care unit in patients with anterior AMI and were manually measured with a ruler. QTc, QTd, QTcd, Tpe, Tpe/QT parameters were measured.

Results

There was no significant difference in the baseline characteristics of patients (p>0.05). We found significant reduction in QTc, QTd, QTcd, Tpe, Tpe/QT indices Group 1 (AA genotype) (mean 66±28 ms) than group 2 (AC and CC genotype) (mean 95±34 ms) (p<0.05).

Conclusion

In patients with a first anterior AMI, AT1R gene polymorphisms may influence on repolarization parameters. Although further studies are required.

Acute restraint stress provokes sudden cardiac death in normotensive rats and enhances susceptibility to arrhythmogenic effects of adrenaline in spontaneously hypertensive rats

BACKGROUND

A high incidence of cardiovascular events and sudden cardiac death (SCD) has been reported following unexpected acute psychosocial stress. The possible pathways by which acute restraint stress (ARS), a kind of acute psychosocial stress, leads to SCD were determined.

METHODS

Using 16-week-old male normotensive Wistar Kyoto rats (WKY, n=24) as controls and spontaneously hypertensive rats (SHR, n=24) as the hypertensive subjects with left ventricular hypertrophy (LVH), we assessed ARS-related incidence of SCD, cardiac and myocardial autonomic nervous system dysfunction, gap junction connexin-43 (Cx43) channel remodeling, and ventricular repolarization abnormality, based on electrocardiography, an adrenaline test, heart rate variability (HRV), and reverse transcriptase polymerase chain reaction analyses. Rats with ARS were introduced into restrainers that allowed head, limb, and tail movement.

RESULTS

In normotensive hearts without LVH, ARS induced a higher incidence of SCD attributed to lethal bradycardia, increased cardiac and myocardial sympathetic activation, and gap junction Cx43 channel remodeling, as evidenced by the increases in the ratio of low-frequency and high-frequency powers in HRV, the ratio of myocardial neuropeptide Y (NPY) and acetylcholinesterase (AChE) mRNA expressions, and the up-regulation of LV Cx43 mRNA expression; in hypertensive hearts with LVH, ARS enhanced susceptibility to the malignant arrhythmogenic effects of the adrenaline test (a kind of sympathetic stimuli) accompanied by abnormal ventricular repolarization, as evidenced by increased incidence of ventricular tachycardia and/or ventricular fibrillation during the adrenaline test and prolonged QTc immediately after ARS.

CONCLUSIONS

ARS may trigger cardiac and myocardial sympathetic predominance, and then induce gap junction Cx43 channel remodeling, finally leading to lethal bradycardia in normotensive WKY. ARS-induced abnormal ventricular repolarization may be responsible for ARS-enhanced susceptibility to sympathetic stimulation in SHR with LVH. Expressions of myocardial NPY, AChE, and Cx43 genes, HRV, QTc and LVH measures showed diagnostic and prognostic potential for predicting ARS-induced SCD.

Association Between ACE Gene Polymorphism and QT Dispersion in Patients with Acute Myocardial Infarction

Background:

Angiotensin converting enzyme (ACE) gene polymorphism is associated with high renin-angiotensin system causing myocardial fibrosis and ventricular repolarization abnormality. Based on these findings, this study was designed to determine the association between ACE gene insertion/deletion (I/D) polymorphism and QT dispersion after acute myocardial infarction (MI).

Objective and Methods:

The study included 108 patients with acute MI. Blood samples were obtained from all the patients for genomic DNA analysis. ECGs were recorded at baseline and at the end of a 6-month follow up. The OT dispersion was manually calculated.

Results:

The mean age of the patients was 57.5 ±9.9 years (ranging from 36 to 70). The patients with DD genotype showed longer QT dispersion than patients with II or DI genotype at the baseline, while at the end of the six-month follow up the patients with DI genotype showed longer QT dispersion than patients with DD or II genotypes. However, the magnitude of the QT dispersion prolongation was higher in patients carrying the ACE D allele than patients who were not carrying it, at baseline and at the end of six-month follow up (52.5 ±2.6 msn vs. 47.5±2.1 msn at baseline, 57±3.2 msn vs. 53±2.6 msn in months, P: 0.428 and P: 0.613, respectively).

Conclusion:

Carriers of the D allele of ACE gene I/D polymorphism may be associated with QT dispersion prolongation in patients with MI.An interaction of QT dispersion and ACE gene polymorphism may be associated with an elevation of serum type I-C terminal pro-collagen concentration, possibly leading to myocardial fibrosis, and increased action potential duration.

Interrelationship between electrocardiographic left ventricular hypertrophy, QT prolongation, and ischaemic stroke: the REasons for Geographic and Racial Differences in Stroke Study

AIMS

To determine if the association between electrocardiographic left ventricular hypertrophy (ECG-LVH) and ischaemic stroke is partially explained by the concomitant presence of QT prolongation.

METHODS AND RESULTS

A total of 24 948 (mean age = 65 ± 9.4 years; 40% black; 55% women) participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were included in this analysis. Electrocardiographic left ventricular hypertrophy was defined by the Sokolow-Lyon criteria. Heart rate-adjusted QT (QTa) was computed using a linear regression model. Adjudicated ischaemic stroke events were the outcome of interest. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between ECG-LVH and prolonged QTa, in isolation and combined, with ischaemic stroke. There were 2422 (9.7%) participants with ECG-LVH, 820 (3.3%) with prolonged QTa, and 161 (0.6%) with both. Over a median follow-up of 7.6 years, 714 (2.9%) ischaemic stroke events occurred. After adjustment for stroke risk factors and potential confounders, an increased risk of ischaemic stroke was observed among participants with ECG-LVH and prolonged QTa (HR = 1.85, 95% CI = 1.04-3.30), isolated ECG-LVH (HR = 1.40, 95% CI = 1.13-1.75), and isolated prolonged QTa (HR = 1.45, 95% CI = 1.04-2.03) compared with participants without either condition. When ECG-LVH and prolonged QTa were examined as separate variables, the risk of ischaemic stroke for each condition remained statistically significant.

CONCLUSION

The combination of ECG-LVH and prolonged QT is associated with a higher risk of ischaemic stroke compared with either condition in isolation, and the stroke risk for each condition does not depend on the presence of the other.

B-Type Natriuretic Peptide Deletion Leads to Progressive Hypertension, Associated Organ Damage, and Reduced Survival: Novel Model for Human Hypertension

Altered myocardial structure and function, secondary to chronically elevated blood pressure, are leading causes of heart failure and death. B-type natriuretic peptide (BNP), a guanylyl cyclase A agonist, is a cardiac hormone integral to cardiovascular regulation. Studies have demonstrated a causal relationship between reduced production or impaired BNP release and the development of human hypertension. However, the consequences of BNP insufficiency on blood pressure and hypertension-associated complications remain poorly understood. Therefore, the goal of this study was to create and characterize a novel model of BNP deficiency to investigate the effects of BNP absence on cardiac and renal structure, function, and survival. Genetic BNP deletion was generated in Dahl salt-sensitive rats. Compared with age-matched controls, BNP knockout rats demonstrated adult-onset hypertension. Increased left ventricular mass with hypertrophy and substantially augmented hypertrophy signaling pathway genes, developed in young adult knockout rats, which preceded hypertension. Prolonged hypertension led to increased cardiac stiffness, cardiac fibrosis, and thrombi formation. Significant elongation of the QT interval was detected at 9 months in knockout rats. Progressive nephropathy was also noted with proteinuria, fibrosis, and glomerular alterations in BNP knockout rats. End-organ damage contributed to a significant decline in overall survival. Systemic BNP overexpression reversed the phenotype of genetic BNP deletion. Our results demonstrate the critical role of BNP defect in the development of systemic hypertension and associated end-organ damage in adulthood.

Cardiac electrical activity in a genomically "humanized" chromogranin a monogenic mouse model with hyperadrenergic hypertension

The prohormone chromogranin A (CHGA) is ubiquitously found in vesicles of adrenal chromaffin cells and adrenergic neurons, and it is processed to the hypotensive hormone peptide catestatin (CST). Both CHGA and CST regulate blood pressure and cardiac function. This study addresses their role in cardiac electrical activity. We have generated two genomically "humanized" transgenic mouse strains (Tg31CHGA+/+; Chga-/- (HumCHGA31) and Tg19CHGA+/+; Chga-/- (HumCHGA19)) with varied CHGA expression and the ability to rescue the Chga-/- phenotype (hypertensive, hyperadrenergic with dilated cardiomyopathy). The normotensive HumCHGA31 mice express CHGA at levels comparable to wild-type. In contrast, the hypertensive HumCHGA19 mice have low levels of CHGA. EKG recordings revealed that the QT interval, R-amplitude, and QRS time-voltage integral are markedly longer in HumCHGA19 compared to wild-type and HumCHGA31 mice. These differences are accompanied by increased heart rate and QT variability, indicating that ventricular assault happens in a status of low levels of circulating CST.

Inter-relationship between electrocardiographic left ventricular hypertrophy and QT prolongation as predictors of increased risk of mortality in the general population

BACKGROUND

Prolonged-QT commonly coexists in the ECG with left ventricular hypertrophy (ECG-LVH). However, it is unclear whether to what extent QT prolongation coexisting with ECG-LVH can explain the prognostic significance of ECG-LVH, and whether prolonged-QT coexisting with ECG-LVH should be considered as an innocent consequence of ECG-LVH.

METHODS AND RESULTS

The study population consisted of 7506 participants (mean age, 59.4±13.3 years; 49% whites; and 47% men) from the US Third National Health and Nutrition Examination Survey. ECG-LVH was defined by Cornell voltage criteria. Prolonged heart-rate-adjusted QT (prolonged-QTa) was defined as QTa≥460 ms in women or 450 ms in men. Cox proportional hazards analysis was used to calculate the hazard ratios with 95% confidence intervals for the risk of all-cause mortality for various combinations of ECG-LVH and prolonged-QTa. ECG-LVH was present in 4.2% (N=312) of the participants, of whom 16.4% had prolonged-QTa. In a multivariable-adjusted model and compared with the group without ECG-LVH or prolonged-QTa, mortality risk was highest in the group with concomitant ECG-LVH and prolonged-QTa (hazard ratio, 1.63; 95% confidence interval, 1.12-2.36), followed by isolated ECG-LVH (1.48; 1.24-1.77), and then isolated prolonged-QTa (1.27; 1.12-1.46). In models with similar adjustment where ECG-LVH and prolonged-QTa were entered as 2 separate variables and subsequently additionally adjusted for each other, the mortality risk was essentially unchanged for both variables.

CONCLUSIONS

Although prolonged-QT commonly coexists with LVH, both are independent markers of poor prognosis. Concomitant presence of prolonged-QT and ECG-LVH carries a higher risk than either predictor alone.

QT interval prolongation in end-stage liver disease cannot be explained by nonhepatic factors

INTRODUCTION

QT interval prolongation in patients with end-stage liver disease (ESLD) is common. However, electrolyte abnormalities, renal insufficiency, treatment with QT-prolonging drugs, and other factors known to prolong QT interval independently of liver disease occur frequently in ESLD. Moreover, elevated heart rate may be present in ESLD and result in spurious QTc prolongation if the Bazett formula is used for rate correction. It thus remains unclear whether QT prolongation in ESLD is directly caused by liver failure, or indirectly by these confounding factors.

METHODS

Medical records of all patients (n = 437) who received orthotopic liver transplantation (OLTx) at our institution between 2008 and 2011 were reviewed. Data from 51 patients with available pre-OLTx dobutamine stress echo (DSE), post-OLTx ECG and without nonhepatic factors affecting QT interval duration were analyzed. For each patient, QT versus RR regression line was calculated from ECG tracings obtained during DSE. The QT interval on post-OLTx ECG was compared with the pre-OLTx QT predicted by the regression line for the same RR interval.

RESULTS

QT interval shortened significantly post-OLTx (from 394 ± 47 to 364 ± 45 ms at RR interval 750 ± 144 ms; P < 0.002) when compared using the regression method. Corrected QT intervals calculated by Bazett and Fridericia formulas also shortened. Patients with prolonged QT pre-OLTx had significantly higher INR and lower serum albumin.

CONCLUSION

ESLD impairs ventricular repolarization even in the absence of other known factors affecting repolarization. QT prolongation in ESLD is associated with impaired synthetic liver function.

Signs of cardiac autonomic imbalance and proarrhythmic remodeling in FTO deficient mice

In humans, variants of the fat mass and obesity associated (FTO) gene have recently been associated with obesity. However, the physiological function of FTO is not well defined. Previous investigations in mice have linked FTO deficiency to growth retardation, loss of white adipose tissue, increased energy metabolism and enhanced systemic sympathetic activation. In this study we investigated for the first time the effects of global knockout of the mouse FTO gene on cardiac function and its autonomic neural regulation. ECG recordings were acquired via radiotelemetry in homozygous knockout (n = 12) and wild-type (n = 8) mice during resting and stress conditions, and analyzed by means of time- and frequency-domain indexes of heart rate variability. In the same animals, cardiac electrophysiological properties (assessed by epicardial mapping) and structural characteristics were investigated. Our data indicate that FTO knockout mice were characterized by (i) higher heart rate values during resting and stress conditions, (ii) heart rate variability changes (increased LF to HF ratio), (iii) larger vulnerability to stress-induced tachyarrhythmias, (iv) altered ventricular repolarization, and (v) cardiac hypertrophy compared to wild-type counterparts. We conclude that FTO deficiency in mice leads to an imbalance of the autonomic neural modulation of cardiac function in the sympathetic direction and to a potentially proarrhythmic remodeling of electrical and structural properties of the heart.

Influence of the left ventricular types on QT intervals in hypertensive patients

Objective:

To investigate the possible electrophysiological background of the greater excitability of concentric and eccentric left ventricular hypertrophy types in relation to the asymmetric type.

Methods:

187 patients with essential hypertension, without ishaemic heart disease were divided into three groups with regard to left ventricule type: concentric (relative wall thickness >0.42, interventricular septum/left ventricular posterior wall ≤1.3), eccentric (left ventricular diameter in systoles >32, relative wall thickness <0.42), asymmetric left ventricular hypertrophy (interventricular septum/left ventricular posterior wall >1.3), and three subgroups: mild (interventricular septum or left ventricular posterior wall 11-12 mm), moderate (interventricular septum or left ventricular posterior wall 13-14 mm) and severe left ventricular hypertrophy (interventricular septum or left ventricular posterior wall ≥15 mm). In all patients QT intervals, QT dispersion, left ventricular mass index and ventricular arrhythmias were measured. An upper normal limit for QT corrected interval: 450/460 ms for men/women; for QT dispersion: 70 ms.

Results:

The QT corrected interval and QT dispersion were increased in severe concentric and eccentric left ventricular hypertrophy (443 and 480 ms for QT corrected; 53 and 45 ms for QT dispersion, respectively), not significantly. QT dispersion in men with severe left ventricular hypertrophy was significantly enlarged (67.5 vs. 30 ms, p=0.047). QT interval was significantly longer in patients with complex ventricular arrhythmias (p=0.037).

Conclusion:

No significant association of QT intervals or QT dispersion with the degree/type of left ventricular hypertrophy was found. QT corrected interval and QT dispersion tend to increase proportionally to the left ventricular mass only in the concentric and eccentric type.

Increased sarcolemmal Na(+)/H(+) exchange activity in hypertrophied myocytes from dogs with chronic atrioventricular block

Dogs with compensated biventricular hypertrophy due to chronic atrioventricular block (cAVB), are more susceptible to develop drug-induced Torsade-de-Pointes arrhythmias and sudden cardiac death. It has been suggested that the increased Na(+) influx in hypertrophied cAVB ventricular myocytes contribute to these lethal arrhythmias. The increased Na(+) influx was not mediated by Na(+) channels, in fact the Na(+) current proved reduced in cAVB myocytes. Here we tested the hypothesis that increased activity of the Na(+)/H(+) exchanger type 1 (NHE-1), commonly observed in hypertrophic hearts, causes the elevated Na(+) influx. Cardiac acid-base transport was studied with a pH-sensitive fluorescent dye in ventricular myocytes isolated from control and hypertrophied cAVB hearts; the H(+) equivalent flux through NHE-1, Na(+)-HCO(-) 3 cotransport (NBC), Cl(-)/OH(-) exchange (CHE), and Cl(-)/HCO(-) 3 exchange (AE) were determined and normalized per liter cell water and corrected for surface-to-volume ratio. In cAVB, sarcolemmal NHE-1 flux was increased by 65 ± 6.3% in the pH i interval 6.3-7.2 and NBC, AE, and CHE fluxes remained unchanged. Accordingly, at steady-state intracellular pH the total sarcolemmal Na(+) influx by NHE-1 + NBC increased from 8.5 ± 1.5 amol/μm(2)/min in normal myocytes to 15 ± 2.4 amol/μm(2)/min in hypertrophied cAVB myocytes. We conclude that compensated cardiac hypertrophy in cAVB dogs is accompanied with an increased sarcolemmal NHE-1 activity. This in conjunction with unchanged activity of the other acid-base transporters will raise the intracellular Na(+) in hypertrophied cAVB myocytes.

A novel electrocardiographic index for the diagnosis of diastolic dysfunction

Background

Although the assessment of diastolic dysfunction (DD) is an integral part of routine cardiologic examinations, little is known about associated electrocardiographic (ECG) changes. Our aim was to investigate a potential role of ECG indices for the recognition of patients with DD.

Methods and Results

ECG parameters correlating with echocardiographic findings of DD were retrospectively assessed in a derivation group of 172 individuals (83 controls with normal diastolic function, 89 patients with DD) and their diagnostic performance was tested in a validation group of 50 controls and 50 patients. The patient group with a DD Grade 1 and 2 showed longer QTc (422±24ms and 434±32ms vs. 409±25ms, p<0.0005) and shorter Tend–P and Tend–Q intervals, reflecting the electrical and mechanical diastole (240±78ms and 276±108ms vs. 373±110ms, p<0.0001; 409±85ms and 447±115ms vs. 526±119ms, p<0.0001). The PQ–interval was significantly longer in the patient group (169±28ms and 171±38ms vs. 153±22ms, p<0.005). After adjusting for possible confounders, a novel index (Tend–P/[PQxAge]) showed a high performance for the recognition of DD, stayed robust in the validation group (sensitivity 82%, specificity 93%, positive predictive value 93%, negative predictive value 82%, accuracy 88%) and proved a substantial added value when combined with the indexed left atrial volume (LAESVI, sensitivity 90%, specificity 92%, positive predictive value 95%, negative predictive value 86%, accuracy 91%).

Conclusions

A novel electrocardiographic index Tend–P/(PQxAge) demonstrates a high diagnostic accuracy for the diagnosis of DD and yields a substantial added value when combined with the LAESVI.

QT dispersion predicts mortality and correlates with both coronary artery calcification and atherosclerosis in hemodialysis patients

PURPOSE

QT dispersion (QTd) was shown to be an independent predictor of mortality in hemodialysis (HD) patients. It may be hypothesized that coronary artery calcification is related to QTd in HD patients because widespread calcification may also involve the cardiac conducting system in these patients. In this study, we aimed to investigate the relationships of corrected QTd (QTcd) with coronary artery calcification score (CACS), carotid plaque score (CPS) and possible influence of these parameters on survival of HD patients.

METHODS

Seventy-two HD patients (33 male, 39 female) were enrolled into the study. Mean age of the patients was 44 ± 12 years. Mean follow-up duration was 77 ± 24 months. CACS was determined by computed tomography. QTcd values were calculated as the difference of maximum and minimum QT intervals. Left ventricular mass index (LVMI) and CPS were measured by echocardiography.

RESULTS

QTcd was significantly correlated with CACS (r = 0.233, p = 0.049), CPS (r = 0.354, p = 0.003) and LVMI (p = 0.011, r = 0.299). CPS was found to be significantly higher in the group with high QTcd (>60 ms) [2 (1-4) versus 0 (0-1), p = 0.02]. CACS was significantly correlated with age (r = 0.44, p < 0.001), LVMI (r = 0.52, p < 0.001) and CPS (r = 0.32, p = 0.003). In Kaplan-Meier analysis, survival of patients with high QTcd was significantly lower than the patients with low QTcd. In Cox regression analysis for predicting mortality, age, serum albumin and QTcd were found to be the independent predictors of mortality.

CONCLUSIONS

QTcd independently predicted mortality, and it was significantly associated with coronary artery calcification, left ventricular hypertrophy and atherosclerosis in HD patients.

The blockade of angiotensin AT1 and aldosterone receptors protects rats from synthetic androgen-induced cardiac autonomic dysfunction

AIM

This study aimed to evaluate the combined effects of exercise and antagonists of the angiotensin II and aldosterone receptors on cardiac autonomic regulation and ventricular repolarization in rats chronically treated with nandrolone decanoate (ND), a synthetic androgen.

METHODS

Thirty male Wistar rats were divided into six groups: sedentary, trained, ND-treated, trained and ND-treated, trained and treated with both ND and spironolactone, and trained and treated with both ND and losartan. ND (10 mg kg(-1) weekly) and the antagonists (20 mg kg(-1) daily) of the angiotensin II AT1 (losartan) and aldosterone (spironolactone) receptors were administered for 8 weeks. Exercise training was performed using a treadmill five times each week for 8 weeks. Following this 8-week training and treatment period, electrocardiogram recordings were obtained to determine the time and frequency domains of heart rate variability (HRV) and corrected QT interval (QTc).

RESULTS

Nandrolone decanoate treatment increased the QTc interval and reduced the parasympathetic indexes of HRV (RMSSD, pNN5 and high-frequency power) in sedentary and trained rats. The ratio between low- and high-frequency power (LF/HF) was higher in ND-treated groups. Both losartan and spironolactone treatments prevented the effects of ND on the QTc interval and the HRV parameters (RMSSD, pNN5, high-frequency power, and the LF/HF ratio).

CONCLUSION

Our results show that chronic treatment with a high dose of ND induces cardiac parasympathetic dysfunction and disturbances in ventricular repolarization in both sedentary and exercised rats. Furthermore, inhibiting the renin-angiotensin-aldosterone system using losartan, or spironolactone, prevented these deleterious effects.

Electrocardiographic predictors of sudden cardiac death in patients with left ventricular hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) has been associated with increased risk of sudden cardiac death (SCD), and improvements in risk stratification methodology are warranted.

METHODS

We evaluated electrocardiographic intervals as potential markers of SCD risk in LVH. Corrected QT, QRS, and JT intervals were evaluated in consecutive cases with SCD and LVH from the ongoing Oregon Sudden Unexpected Death study who underwent a 12-lead electrocardiogram (EKG) and echocardiogram prior to and unrelated to the SCD event. Comparisons of age, gender, body mass index, LV ejection fraction, and EKG intervals together with clinical conditions (hypertension and diabetes) were conducted with geographically matched controls that had coronary artery disease but no history of ventricular arrhythmias or cardiac arrest. LVH was determined using the modified American Society of Echocardiography equation for LV mass. Independent samples t-test, Pearson's chi-square test, and multiple logistic regression were used for statistical comparisons.

RESULTS

Of the 109 cases and 49 controls who met study criteria, age, gender, and comorbidities were similar among cases and controls. The mean LV mass index was not significantly different in cases compared to controls. However mean QTc (470.6 ± 53.6 ms vs 440.7 ± 38.7 ms; P < 0.0001) and QRS duration (113.6 ± 30.0 ms vs 104.9 ± 18.7 ms; P = 0.03) were significantly higher in cases than controls. In logistic regression analysis, prolonged QTc was the only EKG interval significantly associated with SCD (OR 1.72 [1.23-2.40]).

CONCLUSION

Prolonged QTc was independently associated with SCD among subjects with LVH and merits further evaluation as a predictor of SCD in LVH.

Risk factors for sudden cardiac death among Japanese: the Circulatory Risk in Communities Study

OBJECTIVE

There is little evidence concerning risk factors for sudden cardiac death (SCD) among Asians.

PATIENTS AND METHODS

A prospective, nested, case-control study of Japanese patients aged between 30 and 84 years was undertaken using data collected from 26 870 participants in cardiovascular risk surveys conducted in four communities between 1975 and 2005. The incidence of SCD was ascertained by systematic surveillance, with 239 cases of SCD identified over this period. For each case of SCD, three control patients were selected, matched by age, sex, examination year, follow-up time, and community.

RESULTS

Hypertension, diabetes mellitus, smoking, major ST-T abnormalities, left high amplitude R waves, and increased heart rate (≥77 beat/min) were all independently associated with a 1.5-3.2-fold increase in SCD risk, whereas no associations were observed for body mass index and hypercholesterolemia. The population-attributable fraction [95% confidence interval (CI)] was 23.0% (2.9-39.0) for hypertension, 15.3% (3.8-25.5) for current smoking, 14.5% (8.0-20.5) for major ST-T abnormalities, and 8.1% (2.2-13.7) for diabetes mellitus. The number of SCD risk factors (hypertension, diabetes, smoking, and ECG abnormalities) was positively associated with increased SCD risk. The odds ratio for increased SCD risk with three or more risk factors versus zero risk factors was 5.76 (95% CI 3.20-10.39).

CONCLUSIONS

Among the Japanese population, hypertension, smoking, major ST-T abnormalities, left high amplitude R waves, and diabetes mellitus were associated with an increased incidence of SCD, whereas there were no associations of body mass index or hypercholesterolemia with SCD incidence.

Evaluation of cardiac performance by abdominal fetal ECG in twin-to-twin transfusion syndrome

OBJECTIVE

To investigate fetal cardiac performance by abdominal fetal electrocardiography (ECG) in monochorionic diamniotic pregnancies with twin-to-twin transfusion syndrome (TTTS-MCDA).

METHODS

Abdominal fetal ECG was attempted in 16 singleton, 21 non-TTTS-MCDA, and 14 TTTS-MCDA pregnancies at 16-27 weeks' gestation. Standard ECG parameters were compared across study groups and evaluated for their correlation with Doppler ultrasound indices.

RESULTS

Clear P-QRST complexes were recognized in all cases. In the TTTS-MCDA pregnancies, the QT interval and QTc were significantly longer than in both singletons and the non-TTTS-MCDA pregnancies (p = 0.002 and p = 0.0002, respectively), whereas in the recipient fetus, both the PR interval and PR/RR were significantly longer when compared with all other study groups (p = 0.019 and p = 0.012, respectively). Further comparison with Doppler ultrasound indices yielded significant reciprocal correlations between ductus venosus pulsatility index and the QT interval (r = 0.552, p = 0.041) and between umbilical artery pulsatility index and PR/RR (r = 0.654, p = 0.011) both demonstrated in recipient fetuses alone.

CONCLUSIONS

Abdominal fetal ECG is feasible in second-trimester twin pregnancies. In TTTS, there is evidence of a higher risk of cardiac dysfunction in the recipient twin.

Effects of aliskiren on QT duration and dispersion in hypertensive patients with type 2 diabetes mellitus

AIM

To evaluate the effect of aliskiren compared to amlodipine on QT duration and dispersion in hypertensive patients with type 2 diabetes.

METHODS

A total of 170 outpatients aged 50-75 years with mild to moderate hypertension (SBP >130 and <180 mmHg and DBP >80 and <100 mmHg) and type 2 diabetes were randomly treated with aliskiren 300 mg or amlodipine 10 mg, both given once daily for 24 weeks, according to a prospective, open label, blinded-end point, parallel group design. At the end of the placebo run-in, and after 12, and 24 weeks of treatment blood pressure (BP) measurements (by mercury sphygmomanometer, Korotkoff I and V), plasma biochemistry and a standard 12-lead surface ECG were evaluated.

RESULTS

Both aliskiren and amlodipine significantly reduced systolic blood pressure (SBP)/diastolic blood pressure (DBP) values (-27.2/-14.3 mmHg, p < 0.001 vs. placebo and -27.8/-14.2 mmHg, p < 0.001 vs. placebo, respectively), with no statistical difference between the two drugs. Aliskiren, but not amlodipine, significantly reduced maximum QT interval (QTmax) (-14 ms at 12 weeks and -17 ms at 24 weeks, both p < 0.05 vs. placebo) and corrected QT max (QTc max) (-26 ms and -31 ms, p < 0.01) as well as the dispersion of both QT (-11 ms and -13 ms, p < 0.01) and QTc (-18 ms and -19 ms, p < 0.01).

CONCLUSIONS

Despite similar BP lowering effect, aliskiren, but not amlodipine, reduced QT duration and dispersion, which might be related to the ability of aliskiren to interfere with mechanisms underlying myocardial electrical instability in the heart of diabetic hypertensive patients.

Would corrected QT dispersion predict left ventricular hypertrophy in hypertensive patients?

AIMS

We explored whether QT corrected dispersion (QTcD) can identify left ventricular hypertrophy (LVH) in hypertensives.

METHODS

We enrolled 100 hypertensive patients (study group) and 30 normotensive subjects (control group). Echocardiography was performed to measure left ventricular mass and left ventricular mass index. Electrocardiogram was performed to measure QTcD.

RESULTS

LVH was present in 42 patients (42%) of the study group, none among controls. Hypertensive patients had significantly greater indices of LVH and QTcD compared with controls (p <0.001 for all). Similarly, among hypertensive patients, those with LVH had a significantly greater QTcD compared with those without (p <0.001). Pearson's correlation coefficient test demonstrated strongly positive correlations between QTcD and the indices of LVH (p <0.001 for all). Analysis of the receiver operating characteristic curves identified 60 ms as the optimal cut-off value of QTcD that best predicts LVH in hypertensives. Using this value, QTcD was able to predict LVH with a sensitivity of 92.9% and specificity 98.2%.

CONCLUSIONS

QTcD is significantly increased in hypertensive patients with LVH compared with those without, being strongly correlated with the indices of LVH. A QTcD cut-off value of 60 ms predicted LVH in hypertensive patients with a high sensitivity and specificity.

A common variant near the KCNJ2 gene is associated with T-peak to T-end interval

BACKGROUND

T-peak to T-end (TPE) interval on the electrocardiogram is a measure of myocardial dispersion of repolarization and is associated with an increased risk of ventricular arrhythmias. The genetic factors affecting the TPE interval are largely unknown.

OBJECTIVE

To identify common genetic variants that affect the duration of the TPE interval in the general population.

METHODS

We performed a genome-wide association study on 1870 individuals of Finnish origin participating in the Health 2000 Study. The TPE interval was measured from T-peak to T-wave end in leads II, V(2), and V(5) on resting electrocardiograms, and the mean of these TPE intervals was adjusted for age, sex, and Cornell voltage-duration product. We sought replication for a genome-wide significant result in the 3745 subjects from the Framingham Heart Study.

RESULTS

We identified a locus on 17q24 that was associated with the TPE interval. The minor allele of the common variant rs7219669 was associated with a 1.8-ms shortening of the TPE interval (P = 1.1 × 10(-10)). The association was replicated in the Framingham Heart Study (-1.5 ms; P = 1.3 × 10(-4)). The overall effect estimate of rs7219669 in the 2 studies was -1.7 ms (P = 5.7 × 10(-14)). The common variant rs7219669 maps downstream of the KCNJ2 gene, in which rare mutations cause congenital long and short QT syndromes.

CONCLUSION

The common variant rs7219669 is associated with the TPE interval and is thus a candidate to modify repolarization-related arrhythmia susceptibility in individuals carrying the major allele of this polymorphism.

Usefulness of electrocardiographic QT interval to predict left ventricular diastolic dysfunction

Whether a normal electrocardiogram excludes left ventricular (LV) diastolic dysfunction (DD) and whether electrocardiographic parameters are associated with DD is unknown. We therefore sought to investigate the relation between electrocardiographic parameters and DD. We first evaluated 75 consecutive patients referred for echocardiography for clinical suspicion of heart failure (phase 1). Electrocardiography and comprehensive echocardiography were performed on all patients and were analyzed separately in a blinded fashion. Receiver operating characteristic curves and multivariate regression analyses were used to determine which electrocardiographic parameters were most closely associated with DD. Next, we prospectively validated our results in 100 consecutive, unselected patients undergoing echocardiography (phase 2). In phase 1 of our study, the mean age was 59 ± 14 years, 41% were women, 31% had coronary disease, 53% had hypertension, and 25% had diabetes. The mean ejection fraction was 54 ± 15%, and 64% had DD. Of all the electrocardiographic parameters, the QTc interval was most closely associated with DD. QTc was inversely associated with E' velocity (r = -0.54, p <0.0001), and the area under the receiver operating characteristic curve for QTc as a predictor of DD was 0.82. QTc prolongation was independently associated with reduced E' velocity (p = 0.021 after adjustment for age, gender, medications, QRS duration, and ejection fraction). In phase 2 of our study QTc was the electrocardiographic parameter most associated with reduced E' velocity (435 ± 31 vs 419 ± 24 ms; p = 0.004), confirming our phase 1 study findings. In conclusion, QTc prolongation was the electrocardiographic marker most predictive of DD and was independently associated with DD.

QT Dispersion Measured by Automatic Computerized 12-Lead Electrocardiography Contributes Significantly to Detection of Left Ventricular Hypertrophy in Japanese Patients

This study assessed the diagnostic value of QT dispersion for left ventricular hypertrophy (LVH) as determined by echocardiography. The QT and QRS interval parameters were determined automatically using computerized 12-lead electrocardiography in 153 Japanese outpatients. Corrected QT dispersion (QTcD) and maximal QRS duration (MaxQRS) were significantly correlated with left ventricular mass index. The sum of QTcD and MaxQRS showed the highest correlation with left ventricular mass index among QT and QRS interval parameters and their combinations. The cut-off points for LVH discrimination in this study were different to those reported in Western, mainly Caucasian, populations, suggesting the need for ethnicity-specific LVH detection criteria. A scoring system derived from multiple logistic regression analysis, employing a combination of QTcD, QRS time–voltage product and ST-T change, showed a specificity of 86.3%. It was concluded that QTcD, in addition to QRS time–voltage product and ST-T change, improved the detection of LVH.

Incidence of heart failure in relation to QRS duration during antihypertensive therapy: the LIFE study

BACKGROUND

Prolonged QRS duration (QRS) has been associated with left ventricular dyssynchrony and dysfunction and with the development of heart failure. However, whether persistence or development of increased QRS over time is associated with an increased incidence of heart failure in hypertensive patients, independent of blood pressure lowering and regression of electrocardiographic left ventricular hypertrophy (LVH) has not been examined.

METHODS AND RESULTS

The relation of QRS over time to incident heart failure was examined in 8945 hypertensive patients without history of heart failure who were randomly assigned to losartan-based or atenolol-based treatment. During 4.7 +/- 1.1 years follow-up, heart failure hospitalization occurred in 282 patients (3.2%): in 157 with in-treatment QRS less than 110 ms (4.6 per 1000 patient-years) and in 125 with persistence or development of QRS 110 ms or more (13.4 per 1000 patient-years). In univariate Cox analyses in which QRS during the study was entered as a time-varying covariate, in-treatment persistence or development of a QRS 110 ms or more was associated with a 153% increased risk of developing heart failure [hazard ratio 2.53, 95% confidence interval (CI) 2.00-3.20]. After adjusting for treatment, baseline risk factors for heart failure, incident myocardial infarction and for baseline and in-treatment electrocardiographic LVH and blood pressure, persistence or development of a QRS 110 ms or more remained associated with a 102% increased risk of new-onset heart failure (hazard ratio 2.02, 95% CI 1.49-2.74).

CONCLUSION

Persistence or development of a prolonged QRS during antihypertensive therapy is associated with an increased likelihood of new-onset heart failure, independent of blood pressure lowering, treatment modality and regression of electrocardiographic LVH in patients with essential hypertension. These findings suggest that serial assessment of QRS over time can be used to track the risk of heart failure in hypertensive patients.

Electrocardiographic changes with the onset of diabetes and the impact of aerobic exercise training in the Zucker Diabetic Fatty (ZDF) rat

Background

Early markers of diabetic autonomic neuropathy (DAN) in an electrocardiogram (ECG) include elevated R wave amplitudes, widening of QT_c intervals and decreased heart rate variability (HRV). The severity of DAN has a direct relationship with mortality risk. Aerobic exercise training is a common recommendation for the delay and possible reversal of cardiac dysfunction. Limited research exists on ECG measures for the evaluation of aerobic exercise training in Zucker Diabetic Fatty (ZDF) rat, a model of type 2 diabetes. The objective of this study was to assess whether aerobic exercise training may attenuate diabetes induced ECG changes.

Methods

Male ZDF (obese fa/fa) and control Zucker (lean fa/+) rats were assigned to 4 groups: sedentary control (SC), sedentary diabetic (SD), exercised control (EC) and exercised diabetic (ED). The exercised groups began 7 weeks of treadmill training after the development of diabetes in the ED group. Baseline (prior to the training) and termination measurements included body weight, heart weight, blood glucose and glycated hemoglobin levels and ECG parameters. One way repeated measures ANOVA (group) analyzed within and between subject differences and interactions. Pearson coefficients and descriptive statistics described variable relationships and animal characteristics.

Results

Diabetes caused crucial changes in R wave amplitudes (p < 0.001), heart rate variability (p < 0.01), QT intervals (p < 0.001) and QT_c intervals (p < 0.001). R wave amplitude augmentation in SD rats from baseline to termination was ameliorated by exercise, resulting in R wave amplitude changes in ED animals similar to control rats. Aerobic exercise training neither attenuated QT or QT_c interval prolongation nor restored decreases in HRV in diabetic rats.

Conclusion

This study revealed alterations in R wave amplitudes, HRV, QT and QT_c intervals in ZDF rats. Of these changes, aerobic exercise training was able to correct R wave amplitude changes. In addition, exercise has beneficial effect in this diabetic rat model in regards to ECG correlates of left ventricular mass.

Long QT syndrome in African-Americans

BACKGROUND

We evaluated the risk factors and clinical course of Long QT syndrome (LQTS) in African-American patients.

METHODS

The study involved 41 African-Americans and 3456 Caucasians with a QTc > or = 450 ms from the U.S. portion of the International LQTS Registry. Data included information about the medical history and clinical course of the LQTS patients with end points relating to the occurrence of syncope, aborted cardiac arrest, or LQTS-related sudden cardiac death from birth through age 40 years. The statistical analyses involved Kaplan-Meier time to event graphs and Cox regression models for multivariable risk factor evaluation.

RESULTS

The QTc was 29 ms longer in African-Americans than Caucasians. Multivarite Cox analyses with adjustment for decade of birth revealed that the cardiac event rate was similar in African-Americans and Caucasians with LQTS and that beta-blockers were equally effective in reducing cardiac events in the two racial groups.

CONCLUSIONS

The clinical course of LQTS in African-Americans is similar to that of Caucasians with comparable risk factors and benefit from beta-blocker therapy in the two racial groups.

Prognostic evaluation of QT-dispersion in elderly hypertensive and normotensive patients

BACKGROUND

QT-corrected interval dispersion (QTcD) is an indirect index of increased heterogeneity of ventricular repolarization. However, the prognostic value of (QTcD) in elderly hypertensive and normotensive patients has not been thoroughly investigated yet.

METHODS

The study population consisted of 60 consecutive patients (34 males/26 females; mean age: 63+/-11 years) with mild to moderate essential arterial hypertension and 48 consecutive age-matched healthy subjects (24 males/24 females; 65+/-16 years). QTcD was measured by a 12-lead electrocardiogram (ECG) as the difference between maximum and minimum QT-interval, corrected for heart rate. Ventricular arrhythmias were recorded by a 24-hour Holter ECG and classified by a modified Lown's score (range: 0-6). Left ventricular mass was measured echocardiographically and indexed by body surface area [left ventricular mass index (LVMI)]. Nine patients were lost during the follow-up period. Patients were followed up for 54+/-9 months, and the primary end-point was the major cardiovascular events (including cardiac mortality).

RESULTS

Major cardiovascular events occurred in 22 patients (22%). Patients with QTcD>or=45 ms (n=35) had a higher rate of major cardiovascular events (43% vs 11%; log rank: 14.8; P<0.001), a higher LVMI (146+/-29 vs 104+/-21 g/m2; P<0.001), greater values of systolic and diastolic blood pressure (154+/-16 vs 144+/-18 mmHg; P<0.01 and 92+/-10 vs 88+/-8 mmHg; P<0.05, respectively), a higher number of premature ventricular beats (354+/-870 vs 113+/-301; P<0.05), and a greater Lown's score (3.7+/-1.9 vs 1.4+/-1.8; P<0.05) than patients with QTcD<45 ms. QTcD (>or=or<45 ms) was an independent predictor of major cardiovascular events (odds ratio: 4.9; 95% confidence interval: 2.0-12.1; P=0.001) after adjustment for LVMI, Lown's score (>or=or<3), age (>or=or<65 years), and QTc max (>or=or<437 ms).

CONCLUSIONS

QTcD is an independent predictor of major cardiovascular events in elderly hypertensive and normotensive patients and might be used in their risk stratification.

QRS duration predicts sudden cardiac death in hypertensive patients undergoing intensive medical therapy: the LIFE study

AIMS

To determine whether QRS duration predicts sudden cardiac death (SCD) in patients with left ventricular hypertrophy and treated hypertension.

METHODS AND RESULTS

Over 4.8 +/- 0.9 years follow-up of 9193 hypertensive patients with electrocardiographic evidence of LVH who were treated with atenolol- or losartan-based regimens, 178 patients (1.9%) suffered SCD. In multivariable analysis including randomized treatment, changing blood pressure over time, and baseline differences between patients with and without SCD, QRS duration was independently predictive of SCD (HR per 10 ms increase = 1.22, P < 0.001). Baseline QRS duration remained a significant predictor of SCD even after controlling for the presence or absence of left bundle branch block (HR = 1.17, P = 0.001) and for changes in ECG LVH severity over the course of the study (HR = 1.16, P = 0.017).

CONCLUSION

In the setting of aggressive antihypertensive therapy, prolonged QRS duration identifies hypertensive patients at higher risk for SCD, even after controlling for left bundle branch block, other known risk factors for SCD, and changes in blood pressure and severity of left ventricular hypertrophy.