Assessment of QT dispersion for prediction of mortality or arrhythmic events after myocardial infarction: results of a prospective, long-term follow-up study

Tpeak-Tend ECG Marker in Obesity and Cardiovascular Diseases: A Comprehensive Review

Globally, cardiovascular diseases are still the leading cause of death. Numerous methods are used to diagnose cardiovascular pathologies; there is still a place for straightforward and noninvasive techniques, such as electrocardiogram (ECG). Depolarization and repolarization parameters, including QT interval and its derivatives, are well studied. However, the Tpeak-Tend interval is a novel and promising ECG marker with growing evidence for its potential role in predicting malignant arrhythmias. In this review, we discuss the association between the Tpeak-Tend interval and several cardiovascular diseases, including long QT syndrome, cardiomyopathies, heart failure, myocardial infarction, and obesity, which constitutes one of the risk factors for cardiovascular diseases.

Assessment of Ventricular Repolarization in Sickle Cell Anemia Patients: The Role of QTc Interval, Tp-e Interval and Tp-e/QTc Ratio and Its Gender Implication

Background

Many specific and non-specific electrocardiographic abnormalities including ventricular arrhythmias have been reported in subjects with sickle cell anemia (SCA). In SCA patients, cardiac electrical abnormalities may be the leading cause of increased risk of arrhythmias. The corrected QT (QTc) interval, peak to the end of the T wave (Tp-e) interval and associated Tp-e/QTc ratio are promising measures of altered ventricular repolarization and increased arrhythmogenesis risk.

Aim

This study assessed ventricular repolarization abnormalities in subjects with SCA using the QTc interval, Tp-e interval and Tp-e/QTc ratio, and also evaluated the gender differences in these parameters, as well as their determinants.

Methods

Sixty subjects with SCA and 60 healthy control subjects, matched for age and gender, were studied. All participants underwent physical examination, hematological and biochemical evaluation, and 12-lead electrocardiography (ECG) recording. QT and Tp-e intervals were measured from the ECG, and the QTc interval was calculated using Bazett’s formula. Tp-e/QT and Tp-e/QTc ratios were also derived.

Results

QT and QTc intervals were prolonged in subjects with SCA. Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were prolonged in male SCA subjects, with a paradoxical shortening in female SCA subjects. Plasminogen activator inhibitor-1 (PAI-1) was an independent determinant of QTc, while body mass index (BMI) was an independent determinant of both Tp-e interval and Tp-e/QTc ratio.

Conclusion

Our results suggest an elevated risk for ventricular arrhythmogenesis in male SCA subjects. Furthermore, increased BMI and PAI-1 level are possible markers of ventricular repolarization abnormalities in SCA subjects.

Assessment of cardiac variables using a new electrocardiography lead system in horses

Aim:

The objective of this study was to assess a new lead system method to improve electrocardiographic measurement in horses.

Materials and Methods:

Twenty-two horses with an average age of 8.8±0.8 years were enrolled in this study. Horses were divided into two groups, consisting of a control group (n=11) and athlete group (n=11). Electrocardiography (ECG) and echocardiography were performed to provide information on the structure and function of the heart. Two lead systems, base apex and modified precordial leads, were used for the electrocardiogram to assess the cardiac electrophysiological functions.

Results:

PR interval, QT interval, and QRS-T angle presented significant differences between the control and athlete groups when the modified precordial lead system was used. However, significant variations in the mean electrical axis were found when the base apex lead system was used. The modified precordial lead system resulted in more significant differences in cardiac electrophysiological parameters than the base apex lead system. In the athlete group, echocardiography showed cardiac adaptations such as increases in the left atrial and left ventricular dimensions and stroke volume and a decrease in heart rate in response to exercise and training. The observed differences in cardiac morphology and function between groups suggested differences in health performance in the athlete group.

Conclusion:

These data provided the first evidence that the modified precordial lead system improved statistical variation in ECG recording and provided the most reliable method for health screening in horses.

Association of QT dispersion with mortality and arrhythmic events-A meta-analysis of observational studies

BACKGROUND

The risk stratification of coronary heart disease (CHD) and/or heart failure (HF) patients with easily measured electrocardiographic markers is of clinical importance. The aim of this meta-analysis is to indicate whether increased QT dispersion (QTd) is associated with fatal and nonfatal outcomes in patients with CHD and/or HF.

METHODS

We systematically searched MEDLINE and Cochrane databases without restrictions until August 15, 2018 using the keyword "QT dispersion". Studies including data on the association between QTd and all-cause mortality, sudden cardiac death (SCD) or arrhythmic events in patients with HF and/or CHD were classified as eligible.

RESULTS

In the analysis including patients with CHD and/or HF, we found that QTd did not differ significantly in patients with SCD compared to no SCD patients while QTd was significantly greater in the group of all-cause mortality patients and in patients who experienced a sustained ventricular arrhythmia. Subgroup analysis showed that in myocardial infarction studies, QTd was significantly higher in patients with an arrhythmic event compared to arrhythmic event-free patients while a nonsignificant difference was found in QTd in patients who died from any cause compared to survivors. Similarly, in HF patients, the QTd was significantly greater in patients with an arrhythmic event while a nonsignificant difference was found regarding all-cause mortality and SCD outcomes.

CONCLUSIONS

QTd has a prognostic role for stratifying myocardial infarction or HF patients who are at higher risk of arrhythmic events. However, no prognostic role was found regarding all-cause mortality or SCD in this patient population.

Association of QRS Complex Fragmentation with QT Interval Prolongation in Patients with Ischemic Heart Disease

BACKGROUND

The fragmented QRS complex (FQRS) was found to be associated to malignant ventricular arrhythmias and sudden death in patients with hypertrophic cardiomyopathy and other entities. There is scant data available correlating the presence of FQRS with QT interval prolongation in patients with ischemic heart disease (IHD).

METHODS

A descriptive, retrospective, cross-sectional study was performed in 123 patients with IHD to analyze and correlate the presence of FQRS with QT interval prolongation in the conventional 12-leads electrocardiogram in patients with documented chronic IHD.

RESULTS

There were 62% male patients. The mean age was 63.8±12.6 years. Thirty six (44%) patients had fragmented QRS (64% men and 36% women). The duration of QT and QTc, the mean values were 413±59ms, and 463±67ms, respectively. Of the 36 patients with FQRS, 23 patients have prolongation of the QTc interval, and 13 patients did not present it. Of the 45 patients without FQRS, 21 of them have prolongation of the QTc interval, and 24 patients did not have it. These data resulted in a sensitivity of 52% with a moderate SnNout, a specificity of 65% with moderate SpPin, a positive predictive accuracy of 64%, a negative predictive accuracy of 53%. These data resulted in a prevalence of 54%.

CONCLUSION

the presence of FQRS in the ECG has a moderate sensitivity and specificity, as well as, moderate negative and positive predictive value of the existence of QT interval prolongation in patients with ischemic heart disease.

Comparison of QT interval variability of coronary patients without myocardial infarction with that of patients with old myocardial infarction

BACKGROUND

The significant association of myocardial ischemia with elevated QT interval variability (QTV) has been reported in myocardial infarction (MI) patients. However, the influence of the time course of MI on QTV has not been investigated systematically.

METHOD

Short-term QT and RR interval time series were constructed from the 5 min electrocardiograms of 49 coronary patients without MI and 26 patients with old MI (OMI). The QTV, heart rate variability (HRV), and QT-RR coupling of the two groups were analyzed using various time series analysis tools in the time- and frequency-domains, as well as nonlinear dynamics.

RESULTS

Nearly all of the tested QTV indices for coronary patients with OMI were higher than those for patients without MI. However, no significant differences were found between the two groups in any of the variables employed to assess the HRV and QT-RR coupling. All of the markers that showed statistical significances in univariate analyses still possessed the capabilities of distinguishing between the two groups even after adjusting for studied baseline characteristics, including the coronary atherosclerotic burden.

CONCLUSIONS

The results suggested that the QTV increased in coronary patients with OMI compared to those without MI, which might reflect the influence of post-MI remodeling on the beat-to-beat temporal variability of ventricular repolarization. The non-significant differences in the HRV and QT-RR couplings could indicate that there were no differences in the modulation of the autonomic nervous system and interaction of QT with the RR intervals between the two groups.

Increased QT and P-wave dispersion during attack-free period in pediatric patients with migraine attacks

INTRODUCTION

Migraine is a common neurovascular disease characterised with recurrent attacks by pain-free periods. It has been suggested that both sympathetic and parasympathetic dysfunctions play a role in its pathophysiology.

AIM

The aim of our study was to investigate the ECG changes during attack-free period in children with migraine, in terms of QTc interval, QTc, and P-wave dispersion to evaluate the autonomic nervous system disturbance.

METHODS

Sixty children who were diagnosed with migraine were included as patient group and 50 healthy, age- and body mass index-matched children who were examined for innocent murmur were included as control group. The patients' routine ECG records were screened from the outpatient clinic files. The durations of P-wave, QT, and QTc intervals and dispersion values and heart rates (beats/minute) were compared between the patient and control groups.

RESULTS

P maximum and P dispersion were significantly higher, and P minimum was significantly lower in the migraine group compared with the control group. QT-QTc maximum and QT-QTc dispersion were significantly higher and QT-QTc minimum was significantly lower in the migraine group compared with the control group.

CONCLUSION

According to our findings, although migraine patients were asymptomatic and no arrhythmia was detected in the surface ECG, sympathovagal balance in the sympathetic system, which may be disrupted in favour of the sympathetic system, should continue even in the attack-free period, and we should be careful in terms of serious arrhythmias that may develop in these patients.

Progressive increase of the Tpeak-Tend interval is associated with ischaemia-induced ventricular fibrillation in a porcine myocardial infarction model

Aims

Repolarization indices of ECG have been widely assessed as predictors of ventricular arrhythmias. However, little is known of the dynamic changes of these parameters during continuous monitoring in acute ischaemic episodes. The objective of the study was to evaluate repolarization-related predictors of ventricular fibrillation (VF) during progression of experimental myocardial infarction.

Methods and results

Myocardial infarction was induced in 27 pigs by 40-min balloon inflation in the left anterior descending coronary artery, and 12-lead ECG was continuously recorded. Rate-corrected durations of the total Tpeak-Tend intervals measured from the earliest T-wave peak to the latest T-wave end in any lead were determined at baseline and at minute 1, 2, 5, and then every 5th minute of occlusion. There were 7 early (1-3 min) and 10 delayed (15-30 min) VFs in 16 pigs. Baseline Tpeak-Tend did not differ between animals with and without VF. Tpeak-Tend interval rapidly increased immediately after balloon inflation and was greater in VF-susceptible animals at 2-15 min compared with the animals that never developed VF (P < 0.05). Tpeak-Tend was tested as a predictor of delayed VFs. Median Tpeak-Tend at 10th min of occlusion was higher in delayed VF group (n = 10) than in animals without VF (n = 11): 138 [IQR 121-148] ms vs. 111 [IQR 106-127] ms, P = 0.02. Tpeak-Tend  ≥123 ms (10th min) predicted delayed VF episodes with HR = 4.5 95% CI 1.1-17.8, P = 0.031.

Conclusion

Tpeak-Tend prolongation during ischaemia progression predicts VF in the experimental porcine myocardial infarction model and warrants further testing in clinical settings of acute coronary syndromes.

Risk Stratification of Sudden Cardiac Death After Acute Myocardial Infarction

Despite advances in the diagnosis and treatment of acute coronary syndromes and an overall improvement in outcomes, mortality after myocardial infarction (MI) remains high. Sudden death, which is most frequently due to ventricular tachycardia or ventricular fibrillation, is the cause of death in 25% to 50% of patients with prior MI, and therefore represents an important public health problem. Use of the implantable cardioverter-defibrillator (ICD), which is the primary method of reducing the chance of arrhythmic sudden death after MI, is costly to the medical system and is associated with procedural and long-term risks. Additionally, assessment of left ventricular ejection fraction (LVEF), which is the primary method of assessing a patient's post-MI sudden death risk and appropriateness for ICD implantation, lacks both sensitivity and specificity for sudden death, and may not be the optimal way to select the subgroup of post-MI patients who are most likely to benefit from ICD implantation. To optimally utilize ICDs, it is therefore critical to develop and prospectively validate sudden death risk stratification methods beyond measuring LVEF. A variety of tests that assess left ventricular systolic function/morphology, potential triggers for ventricular arrhythmias, ventricular conduction/repolarization, and autonomic tone have been proposed as sudden death risk stratification tools. Multivariable models have also been developed to assess the competing risks of arrhythmic and non-arrhythmic death so that ICDs can be utilized more effectively. This manuscript will review the epidemiology of sudden death after MI, and will discuss the current state of sudden death risk stratification in this population.

Mechanism of electrocardiographic T-wave flattening in diabetes mellitus: experimental and simulation study

In the present study we investigated the contribution of ventricular repolarization time (RT) dispersion (the maximal difference in RT) and RT gradients (the differences in RT in apicobasal, anteroposterior and interventricular directions) to T-wave flattening in a setting of experimental diabetes mellitus. In 9 healthy and 11 diabetic (alloxan model) open-chest rabbits, we measured RT in ventricular epicardial electrograms. To specify the contributions of apicobasal, interventricular and anteroposterior RT gradients and RT dispersion to the body surface potentials we determined T-wave voltage differences between modified upper- and lower-chest precordial leads (T-wave amplitude dispersions, TWAD). Expression of RT gradients and RT dispersion in the correspondent TWAD parameters was studied by computer simulations. Diabetic rabbits demonstrated flattened T-waves in precordial leads associated with increased anteroposterior and decreased apicobasal RT gradients (P<0.05) due to RT prolongation at the apex. For diabetics, simulations predicted the preserved T-vector length and altered sagittal and longitudinal TWAD proven by experimental measurements. T-wave flattening in the diabetic rabbits was not due to changes in RT dispersion, but reflected the redistributed ventricular repolarization pattern with prolonged apical repolarization resulting in increased anteroposterior and decreased apicobasal RT gradients.

Effect of action potential duration on Tpeak-Tend interval, T-wave area and T-wave amplitude as indices of dispersion of repolarization: Theoretical and simulation study in the rabbit heart

BACKGROUND

The aim of the study was to differentiate the effect of dispersion of repolarization (DOR) and action potential duration (APD) on T-wave parameters being considered as indices of DOR, namely, Tpeak-Tend interval, T-wave amplitude and T-wave area.

METHODS

T-wave was simulated in a wide physiological range of DOR and APD using a realistic rabbit model based on experimental data. A simplified mathematical formulation of T-wave formation was conducted.

RESULTS

Both the simulations and the mathematical formulation showed that Tpeak-Tend interval and T-wave area are linearly proportional to DOR irrespectively of APD range, while T-wave amplitude is non-linearly proportional to DOR and inversely proportional to the minimal repolarization time, or minimal APD value.

CONCLUSION

Tpeak-Tend interval and T-wave area are the most accurate DOR indices independent of APD. T-wave amplitude can be considered as an index of DOR when the level of APD is taken into account.

Effects on QTc Interval of 2 Different Doses of Spinal Anesthesia in Inguinal Hernia Operations

Background

Cardiac arrhythmia is a significant cause of morbidity and mortality. In this study, through examination of the effects on the QTc interval of different doses of hyperbaric bupivacaine, we investigated the relationship with arrhythmia.

Material/Methods

A total of 60 patients were separated into 2 groups: spinal block was applied with 10 mg bupivacaine to Group S1 and with 15 mg to Group S2. The mean arterial pressure (MAP) and heart rate (HR) values were recorded before the spinal block and at 5 and 30 min after the block and at 60 min postoperatively. By recording the time of the spinal sensory block to reach T10 dermatome (Anaesth T) and the duration of the surgical procedure (Surg T.), the QTc intervals were calculated.

Results

The demographic data were similar in both groups. A statistically significant difference was determined between the S1 and S2 groups between the baseline and the 30 mins after spinal block QTc intervals (p=0.001). No statistically significant difference in HR values was determined between the groups at baseline, 5 min after spinal block, and 1 h after surgery (all p>0.05), but at 30 min after spinal block value there was a statistically significant difference (p=0.010). No statistically significant difference was determined in MAP values between the groups at baseline and 1 h after surgery (p>0.05).

Conclusions

The QTc interval lengthened in a dose-dependent manner after spinal anesthesia was applied with different doses of bupivacaine, but the doses used did not cause any severe arrhythmia.

Diagnostic Value of Electrocardiogram in Predicting Exaggerated Blood Pressure Response to Exercise Stress Testing

INTRODUCTION

It is believed that an exaggerated blood pressure response (EBPR) to exercise stress test is associated with a higher risk of cardiovascular events. It is also assumed that QT dispersion (QT-d), which was originally proposed to measure the spatial dispersion of ventricular recovery times, may have a relationship to cardiovascular events. The objective of this study was to examine the difference of changes in QT-d, Maxi-QT, Mini-QT, and QT-c (corrected QT interval) of the electrocardiogram in two groups of patients with exaggerated blood pressure responses (EBPR group) and normal responses (control group) to exercise testing. Also, the diagnostic value of each of these criteria in the prediction of EBPR was studied.

METHODS

This cross-sectional study was conducted from May 2015 to February 2016 on patients suspected of coronary artery disease (CAD) undergoing exercise testing who had been referred to Ghaem and Imam Reza hospitals in Mashhad (Iran). All patients underwent a treadmill exercise test with the 12-lead ECG, which was optically scanned and digitized for analysis of QT-d, QT max, and QT min. Patients were divided into two groups of normal and EBPR to exercise testing. QT changes of ECG were compared between the two groups, and the diagnostic accuracy of QT variables for prediction of EBPR to exercise testing was studied. A multiple linear regression analysis (MLR), Pearson Chi-qquare, independent samples t-test, and receiver operating characteristic (ROC) curve were used as statistical methods in IBM SPSS version 19.

RESULTS

Sixty patients (55% male) with a mean age of 50.48 ± 10.89 years were studied in two groups of normal (n=30) and exaggerated blood pressure response (n=30) to exercise testing. Maximum QT and QT dispersion were statistically different in individuals' exaggerated blood pressure response to exercise stress test (p < 0.05). The logistic regression analysis revealed that none of our parameters predicted the EBPR. The ROC curve showed that 50 and 345 milliseconds for QT dispersion and Maxi-QT were the optimal cut-off points for the prediction of EBPR.

CONCLUSION

It seems that Maxi-QT and QT-d may be predictors of EBPR during exercise testing. Also, a significant difference in maxi-QT and QT-d was observed between two groups of patients with normal and EBPR during the exercise testing.

QTC Dispersion and P-Wave Dispersion during Migraine Attacks

The aim of this study was to investigate increase of QTc dispersion and P-wave dispersion during migraine attacks. Fifty-five patients (16–65 years of age, 49 women, six men) with migraine were included in our study. Heart rate, QTc interval, maximum and minimum QTc interval, QTc dispersion, maximum and minimum P-wave duration and P-wave dispersion were measured from 12-lead ECG recording during migraine attacks and pain-free periods. ECGs were transferred to a personal computer via a scanner and then used for magnification of x400 by Adobe Photoshop software. Maximum QTc interval (454 ± 24 ms vs. 429 ± 23 ms, P < 0.001), QTc interval (443 ± 26 ms vs. 408 ± 22 ms, P <0.001) and QTc dispersion (63 ± 18 ms vs. 43 ± 14 ms, P <0.001) were found significantly higher during migraine attacks compared with pain-free periods. Maximum P-wave duration (107 ± 11 ms vs. 100 ± 11 ms, P <0.001) and P-wave dispersion (45 ± 13 ms vs. 35 ± 13 ms, P <0.001) were found higher during migraine attacks than pain-free periods. We concluded that migraine attacks are associated with increased QTc and P-wave dispersion compared with pain-free periods.

Prolonged Tp-e Interval, Tp-e/QT Ratio and Tp-e/QTc Ratio in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with increased risk of malignant ventricular arrhythmias. Cardiac electrical inhomogeneity may be the leading cause of the increased arrhythmic risk in patients with T2DM. The peak and the end of the T wave (Tp-e) interval and associated Tp-e/QT ratio are promising measures of ventricular repolarization indicating transmural dispersion of repolarization. The aim of this study was to assess ventricular repolarization in patients with T2DM by using Tp-e interval, Tp-e/QT ratio and Tp-e/corrected QT interval (QTc) ratio.

METHODS

Forty-three patients with T2DM and 43 healthy control subjects, matched by gender and age, were studied. All participants underwent electrocardiography (ECG) recording. PR, RR and QT intervals represents the ECG intervals. These are not abbreviations. In all literature these ECG intervals are written like in this text. Tp-e intervals were measured from 12-lead ECG. Rate QTc was calculated by using the Bazett's formula. Tp-e/QT ratio and Tp-e/QTc ratio were also calculated.

RESULTS

Mean Tp-e interval was significantly prolonged in patients with T2DM compared to controls (79.4±10.3, 66.4±8.1 ms, respectively; P<0.001). We also found significantly higher values of Tp-e/QT ratio and Tp-e/QTc ratio in patients with diabetes than controls (0.21±0.03, 0.17±0.02 and 0.19±0.02, 0.16±0.02, respectively; P<0.001). There was no difference in terms of the other ECG parameters between the groups.

CONCLUSION

Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were prolonged in patients with T2DM. We concluded that T2DM leads to augmentation of transmural dispersion of repolarization suggesting increased risk for ventricular arrhythmogenesis.

Early Myocardial Repolarization Heterogeneity Is Detected by Magnetocardiography in Diabetic Patients with Cardiovascular Risk Factors

Multi-channel magnetocardiography (MCG) is a sensitive technique to map spatial ventricular repolarization with high resolution and reproducibility. Spatial ventricular repolarization heterogeneity measured by MCG has been shown to accurately detect and localize myocardial ischemia. Here, we explored whether these measurements correlated with cardiovascular risk factors in patients with type 2 diabetes. Two hundreds and seventy-seven type 2 diabetic patients without known coronary artery disease (CAD) and arrhythmia were recruited consecutively from the outpatient clinic of National Taiwan University Hospital. The spatially distributed QTc contour maps were constructed with 64-channel MCG using the superconducting quantum interference device (SQUID) system. Indices of myocardial repolarization heterogeneity including the smoothness index of QTc (SI-QTc) and QTc dispersion were derived and analyzed for association with conventional cardiovascular risk factors. SI-QTc correlated strongly with the QTc dispersion (r = 0.70, p <0.0001). SI-QTc was significantly higher in patients with presence of metabolic syndrome in comparison to those without metabolic syndrome (8.56 vs. 7.96 ms, p = 0.02). In univariate correlation analyses, QTc dispersion was associated with smoking status (average 79.90, 83.83, 86.51, and 86.00 ms for never smokers, ex-smokers, current smokers reporting less than 10 cigarettes daily, and current smoker reporting more than 10 cigarettes daily, respectively, p = 0.03), body weight (r = 0.15, p = 0.01), and hemoglobin A1c (r = 0.12, p = 0.04). In stepwise multivariate regression analyses, QTc dispersion was associated with smoking (p = 0.02), body weight (p = 0.04), total cholesterol levels (p = 0.05), and possibly estimated glomerular filtration rate (p = 0.07). In summary, spatial heterogeneity of myocardial repolarization measured by MCG is positively associated cardiovascular risk factors including adiposity, smoking, and total cholesterol levels.

Sudden cardiac death from the perspective of coronary artery disease

Sudden cardiac death accounts for approximately 50% of all deaths attributed to cardiovascular disease in the United States. It is most commonly associated with coronary artery disease and can be its initial manifestation or may occur in the period after an acute myocardial infarction. Decreasing the rate of sudden cardiac death requires the identification and treatment of at-risk patients through evidence-based pharmacotherapy and interventional strategies aimed at primary and secondary prevention. For this review, we searched PubMed for potentially relevant articles published from January 1, 1970, through March 1, 2014, using the following key search terms: sudden cardiac death, ischemic heart disease, coronary artery disease, myocardial infarction, and cardiac arrest. Searches were enhanced by scanning bibliographies of identified articles, and those deemed relevant were selected for full-text review. This review outlines various mechanisms for sudden cardiac death in the setting of coronary artery disease, describes risk factors for sudden cardiac death, explores the management of cardiac arrest, and outlines optimal practice for the monitoring and treatment of patients after an acute ST-segment elevation myocardial infarction to decrease the risk of sudden death.

Relationship between QT interval dispersion in acute stroke and stroke prognosis: a systematic review

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Electrocardiogram-based predictors of clinical outcomes: a meta-analysis of the prognostic value of ventricular repolarization

OBJECTIVES

To estimate age- and sex-specific prognostic values of eight electrocardiographic repolarization descriptors to predict various mortality endpoints.

BACKGROUND

Using electrocardiographic markers for risk stratification is well studied; however, the prognostic value of many markers is controversial, and their clinical utility remains debatable. No meta-analyses exist that address the prognostic value of ECG markers.

METHODS

Data were synthesized from 106 primary studies using a random-effect variance model. Age and sex subgroups were analyzed using sensitivity analysis.

RESULTS

Four classic (i.e., duration, amplitude, inversion, and ST-T changes) and four novel (i.e., axis, loop, wavefront direction, and waveform complexity) repolarization descriptors were studied. These novel descriptors were particularly useful in predicting sudden death. Abnormal repolarization duration, vectors, and loops have greater impact on negative cardiovascular outcomes in women compared to men; additionally, ischemic repolarization changes have greater impact on negative cardiovascular outcomes in younger versus older adults.

CONCLUSIONS

Assessing repolarization abnormalities is particularly helpful in women and younger adults. Researchers need to further explore the clinical utility of these abnormalities in management algorithms.

Impact of myocardial reperfusion status on QT dispersion after successful recanalization of the infarct-related artery in acute myocardial infarction

OBJECTIVE

To determine whether adequate myocardial perfusion status after transluminal recanalization is associated with prompt improvement of QT dispersion (QTd).

BACKGROUND

Transluminal recanalization of the infarct-related coronary artery in acute myocardial infarction aims to promptly restore myocardial perfusion, to maximize electrical and mechanical recovery. QTd represents the heterogeneity of ventricular repolarization, which may affect electrical stability.

METHODS

Forty patients who underwent primary percutaneous coronary intervention for their first anterior acute ST-elevation myocardial infarction were prospectively enrolled. Myocardial reperfusion status was assessed by myocardial blush grade (MBG) on the final angiogram after successful recanalization (Thrombolysis In Myocardial Infarction Grade 3 flow).

RESULTS

Preprocedural QTd was similar in patients with final MBG 0-1, 2, and 3 (76 ± 24, 67 ± 13, and 69 ± 13 milliseconds, respectively; P = 0.661). After recanalization, QTd decreased in patients with MBG 3 (39 ± 16 milliseconds, P < 0.001) but not in patients with MBG 0-1 (74 ± 20 milliseconds) or MBG 2 (82 ± 16 milliseconds). Multivariate analysis showed that postprocedural MBG was an independent predictor of QTd after recanalization (standardized regression coefficient = -0.628, P < 0.001).

CONCLUSIONS

Adequate tissue perfusion may be crucial for electrical stability of the myocardium after reperfusion.

What does the T(peak)-T(end) interval reflect? An experimental and model study

BACKGROUND

It is unclear whether the Tpeak-Tend interval is an index of the transmural or the total dispersion of repolarization.

METHODS

We examined the Tpeak-Tend interval using a computer model of the rabbit heart ventricles based on experimentally measured transmural, apicobasal, and interventricular gradients of action potential duration.

RESULTS

Experimentally measured activation-recovery intervals increased from apex to base, from the left ventricle to the right ventricle, and in the apical portion of the left ventricle from epicardium to endocardium and from the right side of septum to the left side. The simulated Tpeak corresponded to the earliest end of repolarization, whereas the Tend corresponded to the latest end of repolarization. The different components of the global repolarization dispersion were discerned by simulation.

CONCLUSIONS

The Tpeak-Tend interval corresponds to the global dispersion of repolarization with distinct contributions of the apicobasal and transmural action potential duration gradients and apicobasal difference in activation times.

The relationship between QT dispersion and exaggerated blood pressure response to exercise stress testing

This study was aimed to investigate sensitivity and specificity of QT dispersion (QTd) as a predictor of hypertensive response to peak exercise stress testing (EST). Fifty-nine patients were divided in to two groups (32 patients with exaggerated blood pressure response (EBPR) to EST group and 27 patients for normotensive group) and the EST was monitored. The QTd and corrected QT (QTc) intervals were still found to be significant predictors of EBPR (P < 0.05). In receiver operating characteristic (ROC) analysis, a level of QTd ≥ 40 predicted EBPR with 84% sensitivity and 74% specificity. According to the present data, QTd might be an important predictive marker for EBPR.

The Effect of Diabetes Mellitus on the Ventricular Epicardial Activation and Repolarization in Mice

Cardiac repolarization is prolonged in diabetes mellitus (DM), however the distribution of repolarization durations in diabetic hearts is unknown. We estimated the ventricular repolarization pattern and its relation to the ECG phenomena in diabetic mice. Potential mapping was performed on the anterior ventricular surface in healthy (n=18) and alloxan-induced diabetic (n=12) mice with the 64-electrode array. Activation times, end of repolarization times, and activation-recovery intervals (ARIs) were recorded along with limb lead ECGs. ARIs were shorter in the left as compared to right ventricular leads (P<0.05). The global dispersion of repolarization, interventricular and apicobasal repolarization gradients were greater in DM than in healthy animals (P<0.03). The increased dispersion of repolarization and apicobasal repolarization gradient in DM correlated with the prolonged QTc and Tpeak-Tend intervals, respectively. The increased ventricular repolarization heterogeneity corresponded to the electrocardiographic markers was demonstrated in DM.

The terminal part of the QT interval (T peak to T end): a predictor of mortality after acute myocardial infarction

BACKGROUND

The terminal part of the QT interval (T peak to T end; Tp-e)-an index for dispersion of cardiac repolarization-is often prolonged in patients experiencing malignant ventricular arrhythmias after acute myocardial infarction (AMI). We wanted to explore whether high Tp-e might predict mortality or fatal arrhythmia post-AMI.

METHODS

Tp-e was measured prospectively in 1359/1384 (98.2%) consecutive patients with ST elevation (n = 525) or non-ST elevation (n = 859) myocardial infarction (STEMI or NSTEMI) admitted for coronary angiography.

RESULTS

Tp-e was significantly correlated with age, heart rate (HR), heart failure, LVEF, creatinine, three-vessel disease, previous AMI and QRS and QT duration. During a mean follow-up of 1.3 years (range 0.4-2.3),109 patients (7.9%) died; 25, 45, and 39 from cardiac arrhythmia, nonarrhythmic cardiac causes and other causes, respectively. Long Tp-e was strongly associated with increased risk of death, and Tp-e remained a significant predictor of death in multivariable Cox analyses (RR 1.5, 95% CI[1.3-1.7]). HR-corrected Tp-e (cTp-e) was the strongest predictor of death (RR 1.6 [1.4-1.9]). Tp-e and cTp-e were particularly strong predictors of fatal cardiac arrhythmia (RR 1.6 [1.2-2.1] and RR 1.8 [1.4-2.4]). Findings were similar in STEMI and NSTEMI. When comparing two methods for measuring Tp-e, one including the tail of the T wave and one not, the former had markedly higher predictive power (P < 0.001).

CONCLUSION

Tp-e, and in particular cTp-e, were strong predictors of mortality during the first year post-AMI, and should be further evaluated as prognostic factors additional to established post-AMI risk factors.

Effects of atomoxetine on cardiovascular functions and on QT dispersion in children with attention deficit hyperactivity disorder

BACKGROUND

Atomoxetine is a central norepinephrine reuptake inhibitor used to treat attention deficit/hyperactivity disorder. The effects of atomoxetine on cardiovascular functions and QT dispersion in children with attention deficit/hyperactivity disorder have not been previously reported. The aim of this study was to analyse cardiovascular functions and QT dispersion on the surface electrocardiogram of children with attention deficit/hyperactivity disorder during atomoxetine therapy.

METHODS

A total of 40 children - with a mean age of 8.6 plus or minus 2.3 years and a median age of 11 years; ranged from 8 to 14 years - with attention deficit/hyperactivity disorder - with six girls and 34 boys - were included in the study. We recorded the mean systolic and diastolic blood pressure, heart rate, corrected QT interval, QT dispersion, and left ventricular systolic functions at baseline and 5 weeks after atomoxetine therapy.

RESULTS

Atomoxetine decreased baseline mean systolic and diastolic blood pressure; baseline mean heart rate decreased; and baseline mean corrected QT interval and QT dispersion mildly increased. Atomoxetine decreased baseline mean ejection fraction and baseline mean shortening fraction.

CONCLUSION

The results of our study suggest that atomoxetine does not cause clinically significant alterations in QT dispersion, systolic and diastolic blood pressure, heart rate, corrected QT interval, and left ventricular systolic functions during short-term treatment in children with attention deficit/hyperactivity disorder.

QT interval variability in familial Mediterranean fever: a study in colchicine-responsive and colchicine-resistant patients

The association between familial Mediterranean fever (FMF), early atherosclerosis, and electrocardiographic markers for arrhythmias remains controversial. There are conflicting results as to the occurrence of high QT dispersion in FMF. The aim of the present study was to further investigate repolarization dynamics and other repolarization-associated pro-arrhythmogenic markers in FMF patients. To explore repolarization in FMF, patients who responded well to colchicine and patients who had not responded to colchicine, yet were amyloidosis-free, were included. We aimed to evaluate whether increased inflammatory burden, a characteristic of non-responsive patients, was specifically associated with abnormal repolarization. Included in the study were 53 FMF patients (27 colchicine non-responders) and 53 age- and sex-matched control subjects. Electrocardiograms were performed under strict standards. QT variability parameters were computed with custom-made computer software. No significant difference in any of the QT dynamic parameters was found in either FMF group compared with the healthy controls. Mean values of QT variability index, regardless of colchicine response, were similar to previously published results for healthy persons. In conclusion, patients with FMF who are continuously treated with colchicine and have not developed amyloidosis, regardless of their clinical response, have normal QT variability parameters, indicating normal repolarization dynamics and suggesting no increased risk of repolarization-associated cardiac arrhythmias.

Low hemoglobin levels during normovolemia are associated with electrocardiographic changes in pigs

We studied whether low hemoglobin concentrations during normovolemia change the myocardial electrical current (electrocardiogram) in a pig model. Normovolemic anemia was achieved by stepwise replacing blood with colloids (hydroxyethyl starch 6%). We measured the length of the PQ-, QT-, QTc, and the ST interval as well as the amplitude of the Q wave and T wave at hemoglobin concentrations of 9.5, 8.0, 5.5, 3.8, and 3.3 g·dL. Normovolemic anemia is accompanied by a gradual prolongation of the QT and QTc interval and a reduction in the amplitude of the T wave. The QRS complex is partly diminished in amplitude. Results were verified performing a time-frequency analysis on single heartbeats. During severe anemia and normovolemia, electrocardiographic changes can be detected. Further investigations are warranted to elucidate whether these changes indicate myocardial hypoxia.

Electrocardiogram-based predictors of sudden cardiac death in patients with coronary artery disease

Current recommendations on which patients with coronary artery disease (CAD) should be offered an implantable cardioverter defibrillator for the primary prevention of sudden cardiac death (SCD) rely heavily on the presence of depressed left ventricular ejection fraction. Because the majority of SCD victims with CAD have preserved left ventricular function, additional cardiac investigations are likely to play an increasing role in the risk stratification of CAD patients. A number of studies have demonstrated that certain parameters on the traditional 12-lead electrocardiogram (ECG) and other ECG-based investigations (such as signal-averaged ECG, heart rate turbulence, T-wave alternans) can provide important information on the underlying cardiac substrate abnormality that may predispose to ventricular arrhythmias and SCD. This article reviews some of the evidence for these ECG-based tests as predictors of SCD in patients with CAD and addresses their advantages and limitations.

Sudden cardiac death in hemodialysis patients: an in-depth review

Sudden cardiac death (SCD) is the leading cause of death in hemodialysis patients, accounting for death in up to one-quarter of this population. Unlike in the general population, coronary artery disease and heart failure often are not the underlying pathologic processes for SCD; accordingly, current risk stratification tools are inadequate when assessing these patients. Factors assuming greater importance in hemodialysis patients may include left ventricular hypertrophy, electrolyte shift, and vascular calcification. Knowledge regarding SCD in hemodialysis patients is insufficient, in part reflecting the lack of an agreed-on definition of SCD in this population, although epidemiologic studies suggest the most common times for SCD to occur are toward the end of the long 72-hour weekend interval between dialysis sessions and in the 12 hours immediately after hemodialysis. Accordingly, it is hypothesized that the dialysis procedure itself may have important implications for SCD. Supporting this is recognition that hemodialysis is associated with both ventricular arrhythmias and dynamic electrocardiographic changes. Importantly, echocardiography and electrocardiography may show changes that are modifiable by alterations to dialysis prescription. The most effective preventative strategy in the general population, implanted cardioverter-defibrillator devices, are less effective in the presence of chronic kidney disease and have not been studied adequately in dialysis patients. Last, many dialysis patients experience SCD despite not fulfilling current criteria for implantation, making appropriate allocation of defibrillators uncertain.

QT dispersion in childhood obstructive sleep apnoea syndrome

The difference between maximal and minimal QT interval and corrected QT interval defined as QT dispersion and corrected QT dispersion may represent arrhythmogenic risks. This study sought to evaluate QT dispersion and corrected QT dispersion in childhood obstructive sleep apnoea syndrome. Forty-four children (34 male) with obstructive sleep apnoea syndrome, aged 6.2 plus or minus 3.5 years along with 38 healthy children (25 male), 6.6 plus or minus 2.1 years underwent electrocardiography to measure QT and RR intervals. Means QT dispersion and corrected QT dispersion were significantly higher in obstructive sleep apnoea syndrome than controls, 52 plus or minus 27 compared to 40 plus or minus 14 milliseconds (p equal to 0.014), and 71 plus or minus 29 compared to 57 plus or minus 19 milliseconds (p equal to 0.010), respectively. Interestingly, QT dispersion and corrected QT dispersion in obstructive sleep apnoea syndrome with obesity, 57 plus or minus 30 and 73 plus or minus 31 milliseconds, were significantly higher than in control, 40 plus or minus 14 and 57 plus or minus 19 milliseconds (p equal to 0.009 and 0.043, respectively). However, QT dispersion and corrected QT dispersion in obstructive sleep apnoea syndrome without obesity, 43 plus or minus 20 and 68 plus or minus 26 milliseconds, were not significantly different. In conclusion, QT dispersion and corrected QT dispersion were significantly increased only in childhood obstructive sleep apnoea syndrome with obesity. Obesity may be the factor affecting the increased QT dispersion and corrected QT dispersion.

QT dispersion in patients with pulmonary embolism

BACKGROUND

Various ECG patterns have been associated with acute pulmonary embolism. However, there is no data regarding the association between QT interval measurements and pulmonary embolism. We aimed to investigate the association between QT dispersion and the severity of pulmonary embolism (PE).

METHODS

One hundred twenty-nine pulmonary embolism patients (mean age 58 ± 16.5 years) with ECGs obtained within the first 24 hours of hospital admission were included in the study. Patients were classified into low, intermediate and high-risk groups. We retrospectively measured ECG scores; maximum and minimum corrected QT intervals (QTc(max) and QTc(min)) and corrected QT interval dispersion (QTcd) in each risk group of patients.

RESULTS

There was an increasing ECG score through from low to high-risk PE [3 (Interquartile Range, IQR: 2), 5 (IQR: 6) and 10 (IQR: 7) p < 0.0001]. QT interval analysis showed that QTcd was higher in high-risk group than in low and intermediate-risk groups (59.5 ± 23.4, 69.2 ± 21, 95.9 ± 33.2, p <0.001 and p = 0.01, respectively). Patients who died after diagnosis had significantly higher QTcd values at baseline compared with the QTcd values of surviving patients (89.1 ± 45.5 to 65 ± 22.9, p = 0.001). The sensitivity of QTcd > 71.5 ms for prediction of mortality was 71% with a specificity of 73% (p = 0.001). We observed a strong correlation between QTcd and ECG score values (r = 0.69, p< 0.001). There was also a correlation between QTcd values and pulmonary artery pressure (PAP) (r = 0.27, p = 0.05).

CONCLUSION

QTcd is significantly increased in high-risk PE patients compared to intermediate and low-risk patients. In addition, QTcd is significantly correlated with ECG score and PAP.

QT Dispersion predicting acute rheumatic carditis

OBJECTIVE

To investigate QT dispersion in the surface electrocardiogram of children with rheumatic carditis.

METHODS

QT dispersion was quantitatively evaluated in 33 children with acute rheumatic carditis. As a control group, we studied 33 healthy children free of any disease. The children were eligible for participation if the following criteria were met: diagnosis of acute rheumatic fever based on the revised Jone's criteria and suffering from their first attack of carditis. The echo Doppler cardiogram was performed in all children, within 48-72 hours of hospitalisation.

RESULTS

Patients with carditis had a greater QT dispersion than the control group. When we analyse the QT dispersion according to the severity of the carditis, we observed that the dispersion tended to be greater in those with more severe valvar lesion. The sensitivity and specificity of the measurements of the QT dispersion in predicting acute carditis were estimated by using receiver operating characteristic curves. A QT dispersion greater than 40 milliseconds had a sensitivity of 63.6% and a specificity of 93.9% in predicting acute rheumatic carditis.

CONCLUSION

The lengthening of QT dispersion may reflect on cardiac involvement in rheumatic fever and be a new important parameter in the diagnosis and therapeutic decision for rheumatic carditis.

The prevalence and diagnostic/prognostic utility of sinus arrhythmia in the evaluation of congenital long QT syndrome

BACKGROUND

Congenital long QT syndrome (LQTS) affects 1 in 2,500 people and can cause syncope and sudden death. Sinus arrhythmia (SA) is nonpathologic baseline respiratory variation of the RR interval.

OBJECTIVE

This study sought to determine the frequency of SA and its clinical significance among patients with LQTS.

METHODS

We performed an institutional review board-approved retrospective review of all patients (N = 571) evaluated in our LQTS clinic from 7/2000 to 3/2008 diagnosed with LQTS (N = 281) or dismissed as otherwise normal (N = 290). Blinded to diagnosis, the first available electrocardiogram for each patient was examined to quantitate RR interval variability.

RESULTS

Overall, 151 of 281 patients (54%) with LQTS (159 female patients, average age 21.8 ± 16.5 years, average QTc 466 ± 43 ms) had SA with an average RR variability of 13% ± 8% compared with 201 of 290 (69%) patients dismissed as normal (178 female patients, average age 21.7 ± 16 years, average QTc 424 ± 30 ms) who demonstrated SA with RR variability of 16% ± 10% (P < .0001). These differences remained significant when patients on concurrent beta-blocker therapy were excluded (P < .001). SA was least common in LQT3 (23%) compared with LQT1 (61%, P < .005) and LQT2 (51%, P = .055). Patients presenting with torsades de pointes or aborted cardiac arrest had lower RR variability (10% ± 7%, P < .03).

CONCLUSION

SA frequency and magnitude of RR variability was lower among patients with LQTS compared with those patients dismissed as otherwise normal. This attenuation in RR interval variability remained when patients on beta-blocker therapy were excluded. Although the presence/absence of sinus arrhythmia is of little diagnostic value due to cohort overlap, LQTS patients with negligible RR interval variation may be at higher risk.

The effects of volatile induction and maintenance of anesthesia and selective spinal anesthesia on QT interval, QT dispersion, and arrhythmia incidence

OBJECTIVE

The effects of sevoflurane general anesthesia and bupivacaine selective spinal anesthesia on QT dispersion (QTd) and corrected QT (QTc) interval were investigated.

METHODS AND MATERIALS

This prospective, randomized, double-blind study was conducted between July and September 2009 in the Urology and General Surgery operating rooms. Forty ASA I-II patients undergoing noncardiac surgery were randomized into two groups: Group R (n=20) and Group V (n=20). In Group R, 5 mg bupivacaine was administered into the spinal space. Anesthesia induction in Group V was established with sevoflurane + 0.1 mg/kg vecuronium using the maximum vital capacity technique. Anesthesia was maintained with 2-3% sevoflurane + 50% N2O/O2 inhalation. All patients were tested with a 24-hour Holter ECG device. QT, QTc, and QTd intervals were measured using 12-lead ECG records at 1 and 3 minutes during preinduction, postinduction, postincision and postextubation periods. Mean arterial pressure (MAP), heart rate and ECG records were measured simultaneously.

RESULTS

None of the patients displayed arrhythmia. There was no significant difference between the groups with regard to QTd values (p>0.05). However, QTc was longer in Group V than in Group R after the induction of anesthesia at 3 minutes, after the intubation at 1 and 3 minutes, and after the incision at 1 and 3 minutes. MAP and heart rate were generally higher in Group V (p<0.05).

CONCLUSION

Although Volatile Induction and Maintenance of Anesthesia (VIMA) with sevoflurane might prolong the QTc interval and did not result in arrhythmia, selective spinal anesthesia with bupivacaine was not associated with alterations in the QT interval or arrhythmia.

The relationship between angiotensin converting enzyme gene I/D polymorphism and QT dispersion in patients with hypertrophic cardiomyopathy

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is characterized by disorganized myocardial architecture, and may cause ventricular arrhythmias and sudden death. The angiotensin-converting enzyme (ACE) with two deletion alleles (DD genotype) has been proposed to be associated with increased myocardial collagen content. We evaluated QT dispersion (QTd), which reflects regional differences in ventricular repolarization, in HCM patient and controls among the three different ACE genotypes.

MATERIALS AND METHODS

Sixty-three patients with HCM and 20 healthy subjects were included in the study. QT parameters were measured from 12 lead electrocardiograms. ACE genotypes were determined from the DNA extracted from peripheral blood by a polymerase chain reaction (PCR) method. QT parameters were compared among the three ACE genotypes both in HCM patients and controls.

RESULTS

Median ages were similar in HCM and control groups. QTd and corrected QTd (QTcd) were significantly greater in the HCM group compared with the controls. The frequencies of each genotype were similar in both groups. Although QTd and QTcd did not differ among the three genotypes in the control subjects, they were significantly greater in patients with DD genotype compared with other genotypes in the HCM group.

CONCLUSION

QTd and QTcd are increased in patients with HCM, especially in those with the DD genotype.

Coronary heart disease and cardiac conduction abnormalities in persons with psychotic disorders in a general population

We investigated the prevalence of coronary heart disease (CHD) and myocardial infarction (MI) in persons with DSM-IV psychotic disorders. We also examined cardiac conduction abnormalities, and the role of antipsychotic medication in them. The study was based on a nationally representative survey of 8028 persons aged 30 years or over from Finland. Diagnoses of CHD and MI were based on electrocardiographic findings, health examination, and register information. QTc was calculated using the Bazett formula, and Minnesota classification was used for conduction abnormalities. We found that large Q-waves suggesting past MI were significantly more frequent in persons with schizophrenia, while the prevalence of CHD in persons with psychotic disorders did not differ significantly from the remaining study sample. Prevalence of prolonged QTc interval was significantly increased in persons with schizophrenia and in users of typical antipsychotics. However, low-potency antipsychotic use but not diagnosis of schizophrenia remained an independent predictor of prolonged QTc interval in a logistic regression. Low-potency antipsychotic use was associated with ventricular conduction defects, and high-potency antipsychotic use with premature beats. Symptoms and signs of CHD should be actively monitored patients with schizophrenia, and the electrocardiogram should be monitored for all types of changes in persons receiving antipsychotic medication.

The association between T-wave morphology and life-threatening ventricular tachyarrhythmias in patients with congestive heart failure

BACKGROUND

Whether T-wave morphology descriptors on the 12-lead electrocardiogram (ECG) can predict the occurrence of life-threatening ventricular arrhythmia in patients with advanced congestive heart failure is unclear.

METHODS

Standard 12-lead ECGs were photoscanned and digitized for analysis in 27 heart failure patients with ventricular tachycardia/ventricular fibrillation (VT/VF; study group), as well as in 54 age- and sex-matched heart failure patients without life-threatening ventricular arrhythmia as a control group. Novel T-wave morphology descriptors were compared.

RESULTS

The results showed that the temporal descriptor, the lead dispersion (LD; 426.5 +/- 279.8 vs 189.0 +/- 125.7, P < 0.001), was significantly higher in the study than in the control group. The other T-wave morphology parameters, such as the T-wave morphology dispersion (45.7 +/- 20.1 vs 44.9 +/- 18.6), the total cosine between QRS and T wave (TCRT; -0.4 +/- 0.4 vs -0.5 +/- 0.3), and the normalized T-loop area (NTLA; 0.5 +/- 0.1 vs 0.4 +/- 0.1), were not significantly different between the two groups (all P value > 0.05). After an adjustment for other clinical variables, increased LD (odds ratio: 9.9, 95% confidence interval [CI]: 2.9-33.4, P < 0.001) or decreased NTLA (odds ratio: 0.4, 95% CI: 0.1-1.0, P =0.05) was associated with VT/VF.

CONCLUSION

The novel T-wave morphology analysis may help in identifying heart failure patients at high risk for VT/VF.

Risk stratification by T-wave morphology for cardiovascular mortality in patients with systolic heart failure

AIMS

The objective was to investigate the prognostic value of T-wave morphology in systolic heart failure patients. T-wave morphology descriptors on standard 12-lead electrocardiograms (ECG) have been shown to have prognostic importance concerning the arrhythmic susceptibility of patients with previous myocardial infarction. However, these descriptors have not been considered with regard to further risk stratification in patients with systolic heart failure.

METHODS AND RESULTS

Patients with systolic heart failure [defined by a left ventricular ejection fraction (LVEF) <50%] were enrolled. Standard digitized 12-lead ECGs were used for analysis of T-wave morphology descriptors [lead dispersion, T-wave morphology dispersion, percentage of the loop area, percentage of the outer area, and the total cosine between QRS and T-wave (TCRT)]. A total of 650 patients with a mean age of 63 +/- 14 years were enrolled and followed-up for 2.7 +/- 1.8 years. The mean LVEF was 36 +/- 9%. During this study, the total mortality rate was 32.7% and cardiovascular mortality rate was 22.3%. A stepwise backward Cox regression analysis showed that cardiovascular mortality was significantly associated with age (P < 0.001), diabetes mellitus (P = 0.022), haemoglobin (P = 0.001), LVEF (P = 0.001), and TCRT (P = 0.003). On the basis of a median TCRT of -0.473 as a cut-off point, a significant difference in cardiovascular mortality was observed from a Kaplan-Meier survival curve (P = 0.01). Total cosine between QRS and T-wave further stratified the risk of LVEF (P = 0.007), age (P = 0.001), haemoglobin (P < 0.001), and diabetes mellitus (P < 0.001) in cardiovascular mortality for these patients.

CONCLUSION

Total cosine between QRS and T-wave may provide further risk stratification for and therefore impact on the prognosis of patients with systolic heart failure.

[How to evaluate sudden cardiac death risk after myocardial infarction?]

Sudden cardiac death is the mode of death of more than half of coronary heart disease patients. Preventing sudden cardiac death involves prevention of ventricular arrhythmias occurrence as well as the treatment by an implantable cardioverter defibrillator. The evaluation of sudden cardiac death risk should consider the underlying cardiopathy, the associated coronary risk factors and all pharmacological treatment efficient to reduce ventricular remodeling and myocardial ischemia. Only significant low ejection fraction and positive ventricular testing in some cases are now considered are now considered by the current French recommendations for cardioverter defibrillator implantation in primary prevention. However, other noninvasive markers such as heart rate variability and T wave alternans are of interest in sudden cardiac death risk stratification after myocardial infarction.