Relationship between QT dispersion and the incidence of early ventricular arrhythmias in patients with acute myocardial infarction

doi:10.1016/S0167-5273(97)00226-X

International Journal of Cardiology

Volume 62, Issue 3, 19 December 1997, Pages 211-216

https://doi.org/10.1016/S0167-5273(97)00226-X Get rights and content

Abstract

There is controversy about the influence of QT dispersion on the incidence of early ventricular arrhythmias in patients with acute myocardial infarction (AMI). The QT and QTc dispersion (QTd, QTcd) between two groups of patients with AMI were compared: 39 patients with early sustained ventricular tachycardia or ventricular fibrillation (VT/VF) and 40 patients without such arrhythmias. QTd and QTcd were calculated from the admission and predischarge ECG, expressed as the difference between the maximum and minimum QT and QTc interval in 12 leads. The coefficient of variability was also calculated (VQT, VQTc). Groups did not differ significantly in age, incidence of previous infarction, Killip class, electrolyte status, infarct location, expected and final ECG infarct size, enzymatic infarct size, thrombolytic treatment and reperfusion rate, i.e., in variables that could influence the VT/VF occurrence. On admission, patients with VT/VF had significantly greater QTd (77±23 vs 53±27 ms, P<0.001) and QTcd (90±29 vs 62±28 ms, P<0.001); VQT and VQTc were also significantly higher. Although similar differences existed on predischarge ECG, they were smaller. The results indicate that QT dispersion varies during the illness, and that measurements of QT dispersion could be helpful in predicting serious ventricular arrhythmias.

Introduction

Acute myocardial infarction (AMI) is the leading cause of death in developed countries [1]. Of all deaths due to AMI, more than 60% occur within the first few hours as a consequence of ventricular tachycardia and/or fibrillation (VT/VF) [2]. Therefore, it is of great clinical interest to procure simple and noninvasive measurements of myocardial electrical instability which could predict such fatal events.

It is well known that the prolonged QT interval in patients with AMI reflects abnormal ventricular repolarization and is associated with higher risk of life-threatening arrhythmias 3, 4. More recently, the dispersion of QT interval, defined as the interlead variability of QT interval in surface ECG, was found to be the measure of regional differences in ventricular repolarization important in the pathogenesis of ventricular arrhythmias 5, 6, 7, 8.

Although several studies reported that the measurement of QT dispersion is of value in the prediction of serious ventricular arrhythmias in patients with AMI 9, 10, 11, 12, some authors reached negative conclusions 13, 14. Because of this controversy [15], we tried to determine the relationship between the QT dispersion and the incidence of early ventricular arrhythmias in patients with AMI.

Section snippets

Methods

All patients with AMI admitted to our coronary care unit during 1996 were considered for inclusion in the study. Patients with atrial fibrillation or flutter, ventricular hypertrophy, preexcitation, intraventricular conduction abnormalities, permanent ventricular pacing, those treated with Class I or III antiarrhythmics and patients who died during hospitalization, were excluded. According to the VT/VF occurrence, two groups of patients were formed: 39 patients with early sustained VT or VF

Results

During 1996, 424 patients with AMI were admitted and treated in our coronary care unit. Among them, 48 patients suffered from early malignant ventricular arrhythmias (11.3%). There were 38 patients with sustained VT (9%), and ten patients with VF (2.3%). In four patients with VT, arrhythmia termination was achieved by intravenous lidocaine (10.5% success rate); others were successfully treated with DC cardioversion. Nine patients with early VT/VF were excluded from the study: two with extensive

Discussion

The QT interval does not exactly reflect the ventricular depolarization and repolarization time, because in all portions of the ventricles repolarization is not finished at the time when the end of the QT interval is recorded. These slight physiological differences in regional ventricular recovery time cannot be registered in the surface ECG and are not of clinical relevance. In patients with AMI, regional ischemia, combined with increased sympathetic activity, causes enlarged spacial and

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Cited by (27)

Does the Magnitude of the Electrocardiogram QT Interval Dispersion Predict Stroke Outcome?
2019, Journal of Stroke and Cerebrovascular Diseases
Citation Excerpt :
QT interval dispersion (QTd), defined as the difference between the maximal and minimal leads on a 12-lead electrocardiogram (ECG), is an expression of cardiac repolarization abnormalities. In a variety of clinical settings, including acute stroke, multiple studies have suggested that an increase in QTd places patients at increased risk to develop ventricular arrhythmias and adverse clinical outcomes.1-4 We sought to determine if admission QTd predicts short-term clinical outcome in patients with acute ischemic stroke (AIS) as well as to investigate if an AIS in the insular cortex region has a greater effect on QTd than strokes in other areas of the brain, as insular cortical involvement has been associated with increased sympathetic nervous system activity including arrhythmias.5
QT dispersion, maximal interlead difference in QT interval on 12-lead electrocardiogram (ECG), measures cardiac repolarization abnormalities. Data are conflicting whether QT dispersion predicts adverse outcome in acute ischemic stroke (AIS) patients. Our objective is to determine if QT dispersion predicts: (1) short-term clinical outcome in AIS, and (2) stroke location (insular versus noninsular cortex).
Admission ECGs from 412 consecutive patients with acute stroke symptoms from 2 university-based stroke centers were reviewed. QT dispersion was measured. A neuroradiologist reviewed brain imaging for insular cortex involvement. Favorable clinical outcomes at discharge were modified Rankin Scale (mRS) score of 0-1, discharge National Institutes of Health Stroke Scale (NIHSS) score less than 2, and discharge to home. Multiple logistic regressions were performed for each outcome measure and to determine the association between insular infarct and QT dispersion.
Of 145 subjects in the final analysis, median age was 65 years (interquartile range [IQR] 56-75), male patients were 38%, black patients were 68%, median QT dispersion was 78 milliseconds (IQR 59-98), and median admission NIHSS score was 4 (IQR 2-6). QT dispersion did not predict short-term clinical outcome for mRS score (odds ratio [OR] = 1.001, 95% confidence interval [CI] .99-1.01, P = .85), NIHSS at discharge (OR = .994, 95% CI .98-1.01, P = .30), or discharge disposition (OR = 1.001, 95% CI .99-1.01, P = .81). Insular cortex involvement did not correlate with QT dispersion magnitude (OR = 1.009, 95% CI .99-1.02, P = .45).
We could not demonstrate that QT dispersion is useful in predicting short-term clinical outcome at discharge in AIS. Further, the magnitude of QT dispersion did not predict insular cortical stroke location.
Relationship between QT interval dispersion in acute stroke and stroke prognosis: A systematic review
2014, Journal of Stroke and Cerebrovascular Diseases
QT dispersion (QTd) has been proposed as an indirect electrocardiography (ECG) measure of heterogeneity of ventricular repolarization. The predictive value of QTd in acute stroke remains controversial. We aimed to clarify the relationship between QTd and acute stroke and stroke prognosis.
A systematic review of the literature was performed using prespecified medical subjects heading terms, Boolean logic, and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Eligible studies included ischemic or hemorrhagic stroke and provided QTd measurements.
Two independent reviewers identified 553 publications. Sixteen articles were included in the final analysis. There were a total of 888 stroke patients: 59% ischemic and 41% hemorrhagic. There was considerable heterogeneity in study design, stroke subtypes, ECG assessment time, control groups, and comparison groups. Nine studies reported a significant association between acute stroke and baseline QTd. Two studies reported that QTd increases are specifically related to hemorrhagic strokes, involvement of the insular cortex, right-side lesions, larger strokes, and increases in 3,4-dihydroxyphenylethylene glycol in hemorrhagic stroke. Three studies reported QTd to be an independent predictor of stroke mortality. One study each reported increases in QTd in stroke patients who developed ventricular arrhythmias and cardiorespiratory compromise.
There are few well-designed studies and considerable variability in study design in addressing the significance of QTd in acute stroke. Available data suggest that stroke is likely to be associated with increased QTd. Although some evidence suggests a possible prognostic role of QTd in stroke, larger and well-designed studies need to confirm these findings.
Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients
2013, Annals of Physical and Rehabilitation Medicine
Citation Excerpt :
La dispersion du QT (QTd) se définit comme la différence entre l’intervalle le plus long et le plus court du segment QT sur un électrocardiogramme (ECG) à 12 dérivations. La mesure du QTd est une méthode non invasive pour évaluer l’instabilité électrique du myocarde [39] et est un facteur prédictif d’épisodes d’arythmie ventriculaire [8]. Une augmentation du QTd semble refléter une augmentation du tonus sympathique et une baisse du tonus parasympathique [35].
QT dispersion (QTd) is a marker of myocardial electrical instability, and is increased in metabolic syndrome (MetS). Moderate intensity continuous exercise (MICE) training was shown to improve QTd in MetS patients.
To describe long-term effects of MICE and high-intensity interval exercise training (HIIT) on QTd parameters in MetS.
Sixty-five MetS patients (53 ± 9 years) were assigned to either a MICE (60% of peak power output [PPO]), or a HIIT program (alternating phases of 15–30 s at 80% of PPO interspersed by passive recovery phases of equal duration), twice weekly during 9 months. Ventricular repolarization indices (QT dispersion = QTd, standard deviation of QT = sdQT, relative dispersion of QT = rdQT, QT corrected dispersion = QTcd), metabolic, anthropometric and exercise parameters were measured before and after the intervention.
No adverse events were noted during exercise. QTd decreased significantly in both groups (51 vs 56 ms in MICE, P < 0.05; 34 vs 38 ms in HIIT, P < 0.05). Changes in QTd were correlated with changes in maximal heart rate (r = −0.69, P < 0.0001) and in heart rate recovery (r = −0.49, P < 0.01) in the HIIT group only. When compared to MICE, HIIT training induced a greater decrease in weight, BMI and waist circumference. Exercise capacity significantly improved by 0.82 and 1.25 METs in MICE and HIIT groups respectively (P < 0.0001). Lipid parameters also improved to the same degree in both groups.
In MetS, long-term HIIT and MICE training led to comparable effects on ventricular repolarization indices, and HIIT might be associated with greater improvements in certain cardiometabolic risk factors.
La dispersion du QT (QTd) est un marqueur d’instabilité électrique du myocarde, qui est allongé dans le syndrome métabolique (MetS). L’entraînement continu à intensité modérée (MICE) a montré son efficacité dans l’amélioration du QTd chez les patients MetS.
Décrire les effets à long terme d’un entraînement MICE et d’un entraînement par intervalles à haute intensité (HIIT) sur les paramètres du QTd dans le MetS.
Soixante-cinq patients (53 ± 9 ans) présentant un MetS ayant réalisé soit dans un programme MICE (60 % de la puissance maximale aérobie [PMA]), soit un programme HIIT (alternant des périodes de 15–30 s à 80 % de la PMA intercalées avec des périodes de récupération passive de même durée), deux fois par semaine pendant neuf mois ont été étudiés. Les caractéristiques de la repolarisation ventriculaire (dispersion du QT = QTd, déviation standard du QT = sdQT, dispersion de la durée du QT = rdQT, dispersion corrigée de la durée du QT = QTcd), les paramètres métaboliques, anthropométriques et d’exercices étaient mesurés avant et après le programme d’entraînement.
Aucun effet indésirable n’a été rapporté pendant l’entraînement. Le QTd a diminué de façon significative dans les deux groupes (51 vs 56 ms dans le groupe MICE, p < 0,05 ; 34 vs 38 ms dans le groupe HIIT, p < 0,05). Les modifications du QTd étaient corrélées à celle de la fréquence cardiaque maximale (r = 0,69, p < 0,0001) et de la fréquence cardiaque de récupération (r = −0,49, p < 0,01) uniquement dans le groupe HIIT. Comparativement au MICE, l’entraînement HIIT a induit une diminution plus importante du poids, de l’IMC et du tour de taille. La capacité d’exercice a augmenté de façon significative de 0,82 et 1,25 METs respectivement pour les groupes MICE et HIIT (p < 0,0001). Les paramètres du bilan lipidique se sont également améliorés de manière similaire dans les deux groupes.
Dans le syndrome métabolique, les entraînements HIIT et MICE induisent des effets positifs similaires sur les caractéristiques de la repolarisation ventriculaire, mais l’HIIT paraît être associé à des améliorations plus importantes sur certains facteurs de risque cardiométaboliques.
Cardiovasular changes after placement of a classic endotracheal tube, double-lumen tube, and Laryngeal Mask Airway
2011, Journal of Clinical Anesthesia
Citation Excerpt :
Atrial fibrillation is characterized by disorganized atrial electrical activity, leading to loss of effective contraction [22]. QTd is a noninvasive method showing myocardial electrical instability [23] and higher sympathetic and lower parasympathetic input to the heart [24]. The QT interval is affected by catecholamines, HR, and autonomic tone [25].
To compare hemodynamic responses, P wave dispersion (Pd), and QT dispersion (QTd) after placement of a classic endotracheal tube (ETT), double-lumen tube (DLT), or Laryngeal Mask Airway (LMA).
Prospective study.
Outpatient surgery center.
75 adult, ASA physical status 1 and 2 patients undergoing cystoscopy and thoracoscopic surgery.
Patients were randomized to undergo placement of an ETT (Group T; n = 25), DLT (Group D; n = 25), or LMA (Group L; n = 25). Anesthesia was induced by etomidate 0.3 mg/kg and fentanyl 1.0 μg/kg, and maintained with nitrous oxide, oxygen, 2% to 3% sevoflurane, and rocuronium 0.5 mg/kg.
Mean arterial pressure (MAP) and heart rate (HR) were recorded immediately before intubation and after intubation at one, 3, 5, 10,15, 20, 25, and 30 minutes after intubation/airway insertion.
QT dispersion after tube placement was significantly higher than before tube placement in Group D (P = 0.0001) and Group L (P = 0.03). Mean arterial pressure and HR in Group T were significantly higher than in Group L at the first minute after tube placement (P = 0.02). Heart rate and MAP at baseline were significantly higher than the other measurement times in Groups T and D (P < 0.01).
The LMA caused no change in Pd, HR, or MAP values during or after airway placement, but caused QTd after airway insertion. The ETT caused a sudden increase at the first minute after tube placement, without any Pd or QTd. In addition, DLT caused QTd without any serious change in hemodynamics.
The Electrocardiogram as a Prognostic Tool for Predicting Major Cardiac Events
2007, Progress in Cardiovascular Diseases
Citation Excerpt :
QTd was shown to be increased in several cardiac diseases, including AMI, cardiomyopathy, and long QT syndrome, but there is a large overlap of values with normal reference subjects.34 There have been several studies suggesting a prognostic role for QTd in patients with CAD or CHF, and, in some studies, QTd was also found to be higher among patients who suffered from life-threatening ventricular arrhythmias (VAs), compared with those who did not.35-38 Other studies, however, failed to find any significant association between QTd and prognosis in patients with AMI, with or without signs of CHF,39-44 and similar discordant results have been reported in patients with inducibility of ventricular tachyarrhythmias.45-49
Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.
QT dispersion and left ventricular function after stent placement in acute myocardial infarction
2006, International Journal of Cardiology
QT dispersion is increased in acute myocardial infarction (AMI), but the relation of QT dispersion to left ventricular (LV) function has not yet been fully elucidated. The purpose of this study was to evaluate the relationship between QT dispersion and LV function in patients with successful coronary stenting in AMI.
Seventy five patients with AMI who underwent percutaneous transluminal coronary angioplasty (PTCA) were enrolled in this study. Corrected QT dispersion was measured before, immediately after, 24 h after, 48 h after, and 6 months after PTCA. Left ventricular ejection fraction (LVEF) was evaluated by left ventriculography at 6 months after PTCA.
Corrected QT dispersion at 24 h after and 48 h after PTCA were significantly related to LVEF by univariate analysis (r = − 0.282, p < 0.05 and r = − 0.326, p < 0.01, respectively). In multiple regression model, corrected QT dispersion at 24 h after and 48 h after PTCA revealed significant associations with LVEF (R² = 0.441, coefficient = − 0.283, p = 0.006 and R² = 0.411, coefficient = − 0.225, p = 0.039, respectively), but corrected QT dispersion before, immediately after, and 6 months after PTCA were not associated with LVEF.
Corrected QT dispersion at 24 h after and 48 h after PTCA in AMI correlate with LVEF at 6 months after PTCA.

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Relationship between QT dispersion and the incidence of early ventricular arrhythmias in patients with acute myocardial infarction

Abstract

Introduction

Section snippets

Methods

Results

Discussion

Am J Cardiol

Lancet

Am J Cardiol

Am J Cardiol

Am J Cardiol

J Am Coll Cardiol

Am J Cardiol

J Am Coll Cardiol

QT dispersion: an indication of arrhythmia risk in patients with long QT intervals

Br Heart J

QT interval dispersion: a non-invasive marker of susceptibility to arrhythmia in patients with sustained ventricular arrhythmias?

Br Heart J

QT dispersion

Br Heart J

QT dispersion in the 12-lead surface ECG reflects inhomogeneity in the terminal part of ventricular repolarization (abstract)

PACE