Comparison between ventricular gradient and a new descriptor of the wavefront direction of ventricular activation and recovery

Association between T wave morphology parameters and abnormal cardiac SPECT imaging

BACKGROUND

T-wave morphology dispersion (TMD) described the electrocardiographic T-wave heterogeneity during a single cardiac cycle. Total cosine R-to-T (TCRT) is the average of the cosines of the angles between the QRS and T vectors on the ECG. We examine the predictive value of TMD and TCRT calculation to assess abnormal myocardial perfusion.

METHODS

Retrospective single center cohort study including all patients referred for evaluation of ischemia by myocardial SPECT scanning with no known history of ischemic heart disease, from 1 January 2019 to 31 December 2019. Study endpoint was the correlation between the calculated TMD and TCRT values and detection of myocardial injury or ischemia by myocardial SPECT.

RESULTS

Among 606 patients, calculated TCRT was 0.401 ± 0.53 for the normal group and 0.283 ± 0.62 for the abnormal group (p = 0.007). Measured TMD was 22.9 ± 16.6 degrees (p < 0.001) in the normal group, compared to 31.5 ± 22.8 degrees (p < 0.001) for the abnormal group.

CONCLUSIONS

The results demonstrate a correlation between the decreased TCRT values and increase TMD and myocardial ischemia seen in SPECT results. The TCRT and TMD can be used as simple and non-invasive markers to predict abnormal SPECT results and ischemic heart disease in patients with no known cardiac history.

T-wave morphology descriptors in patients with bulimia nervosa

PURPOSE

Bulimia nervosa (BN) is associated with increased risk of cardiovascular disease and arrhythmias. Some reports found abnormal electrocardiographic markers of arrhythmias in BN, while others did not. This study investigated novel parameters of T-wave morphology that were reported to be associated with adverse cardiovascular outcomes in other patient groups, among patients with BN under medical care.

METHOD

Thirty-five BN patients and 76 healthy controls were included. Total cosine R to T (TCRT) and T-wave Morphology Dispersion (TMD) parameters were computed according to accepted standards for an average beat and a random beat. Patients were followed for 11.1 ± 0.1 years for the emergence of arrhythmias or events of sudden death.

RESULTS

Twenty-five (71.4%) BN patients were hospitalized when enrolled, for a mean duration of 1.1 ± 0.2 months. The rest were ambulatory patients. The BN group had lower blood pressure, more smokers, and used antidepressants, neuroleptic drugs and benzodiazepines more than controls did. Other demographic parameters were comparable between groups. TCRT and TMD parameters were statistically similar and within the normal ranges reported by other research groups. None of the BN patients had prolonged QTc interval or electrolyte abnormalities on inclusion. During the follow-up period, no clinical symptoms suggestive of arrhythmias were reported, and no cardiovascular-related hospitalizations or deaths occurred in either group.

CONCLUSION

Medically treated BN patients have normal T-wave morphology parameters and hence, low risk for repolarization-associated malignant ventricular arrhythmias. The prognostic importance of these novel repolarization parameters remains to be explored among untreated patients, those who ingest emetic substances and patients with electrolyte imbalance.

LEVEL OF EVIDENCE

Level III.

T-wave morphology among medically treated patients with Anorexia Nervosa

Anorexia nervosa (AN) has the highest rate of mortality of any psychiatric disorder, and cardiovascular complications occur in up to 80% of patients with AN and account for up to 30% of mortality. A controversy exists as to whether patients with AN are prone to develop electrocardiographic abnormalities related to repolarization. We aim to study previously unexplored T wave morphology markers in medically-treated patients with AN. Fifty-eight patients with AN (32 with restricting type and 26 with binge-eating/purging type) and 82 healthy controls were included in the study. ECGs were conducted under strict conditions and total cosine R-to-T (TCRT) and T-wave morphology dispersion (TMD) were computed according to accepted standards for a random beat and for an averaged beat. Forty-six AN patients were hospitalized (79.3%) during the study for a mean duration of 1.5 ± 1.1 months. AN patients had comparable QTc, TCRT, mean TMD, TMDpre, TMDpost and TCRTc values to those of healthy adults. Flattened T wave occurred slightly more often among AN patients than in controls (1.57 ± 1.23 leads affected compared with 1.11 ± 0.80 leads, respectively, p = 0.017). QTc, TCRT and TMD parameters' values were unaffected by the clinical type of AN. In conclusion, weight-restored AN patients are characterized by T wave flattening, but normal other T wave morphology parameters, which seemingly reflects an overall low risk of repolarization-associated ventricular arrhythmias. Long-term follow-up studies should be conducted to evaluate the prognostic significance of these novel repolarization markers in untreated patients or early in the refeeding phase.

Normal ranges and potential modifiers of T-wave morphology parameters among healthy individuals: A meta-analysis

BACKGROUND

T-wave morphology parameters, such as total cosine R-to-T (TCRT), T-wave loop dispersion (TWLD), T-wave morphology dispersion (TMD), and T-wave residuum (TWR), were suggested to be robust markers for adverse cardiovascular outcomes. Yet, the normal range of these parameters is unknown. This study aimed to evaluate the weighted normal values of T-wave morphology parameters of healthy individuals and study the effect of potential modifiers.

METHODS

A systematic search of studies published in PubMed was conducted. Only those reporting on control groups of healthy individuals were included. Weighted means were calculated for TCRT, TWLD, TMD, and TWR. Linear regression analysis was conducted for age, percentage of males, heart rate, and QTc.

RESULTS

The weighted TCRT was 0.40 ± 0.05, significantly higher than the various cutoffs previously suggested to identify high risk. There was some overlap between the results of weighted normal TMD (19.42 ± 6.77°), TWLD (38.51 ± 0.31), and relative TWR (0.118 ± 0.056%) and reports on the same parameters from patients with cardiovascular disease. Women were also characterized by higher TWLD, TMD, and relative TWR. TCRT was negatively correlated with age and heart rate, and positively correlated with QTc duration, although all associations were weak (R²  < 0.9).

CONCLUSIONS

T-wave morphology parameters reported in the medical literature span a broad range of values in healthy individuals. Seemingly abnormal values of TWLD, TMD, and relative TWR were often reported in healthy adults. The variability between studies may stem from methodological issues. Therefore, standardizing the methodology for measuring T-wave morphology is imperative.

Global electrical heterogeneity: A review of the spatial ventricular gradient

The ventricular gradient, an electrocardiographic concept calculated by integrating the area under the QRS complex and T-wave, represents the degree and direction of myocardial electrical heterogeneity. Although the concept of the ventricular gradient was first introduced in the 1930s, it has not yet found a place in routine electrocardiography. In the modern era, it is relatively simple to calculate the ventricular gradient in three dimensions (the spatial ventricular gradient (SVG)), and there is now renewed interest in using the SVG as a tool for risk stratification of ventricular arrhythmias and sudden cardiac death. This manuscript will review the history of the ventricular gradient, describe its electrophysiological meaning and significance, and discuss its clinical utility.

Repolarisation descriptors and heart rate variability in hemodialysed patients

T wave morphology (TWM) descriptors derived from Holter electrocardiograms during hemodialysis (HD) are of potential value for cardiac risk assessment in HD patients. Our knowledge on autonomic regulation of TWM descriptors is limited. The purpose of this study was to investigate the association between TWM parameters and heart rate variability (HRV) during intradialytic monitoring. In each of 81 patients on maintenance HD, continuous electrocardiograms were recorded 5 times during HD on alternate weeks. TWM descriptors were calculated every 5 s in overlapping 10-s ECG segments and Low Frequency (LF) (0.04 Hz to 0.15 Hz), High Frequency (HF) (0.15 Hz to 0.40 Hz) powers of the spectrum of HRV were calculated every five min. The calculated values of TWM and HRV were averaged during the first hour of the recordings and subsequently over all recordings in each subject. Analyzable data for HRV and TWM were available in 71 HD patients (aged 61+/-15, 36 % diabetics, 32 % females). LF in normalized units correlated positively with Total Cosine R to T (r=0.374, p=0.001) and negatively with T wave morphology dispersion (r=-0.253, p=0.033) after adjusting for heart rate. A heart rate independent association between repolarisation descriptors and HRV exists in HD patients. Autonomic modulation needs to be considered when using TWM characteristics for risk profiling of HD patients.

The ECG vertigo in diabetes and cardiac autonomic neuropathy

The importance of diabetes in the epidemiology of cardiovascular diseases cannot be overemphasized. About one third of acute myocardial infarction patients have diabetes, and its prevalence is steadily increasing. The decrease in cardiac mortality in people with diabetes is lagging behind that of the general population. Cardiovascular disease is a broad term which includes any condition causing pathological changes in blood vessels, cardiac muscle or valves, and cardiac rhythm. The ECG offers a quick, noninvasive clinical and research screen for the early detection of cardiovascular disease in diabetes. In this paper, the clinical and research value of the ECG is readdressed in diabetes and in the presence of cardiac autonomic neuropathy.

The association between the spatial QRS-T angle with cardiac autonomic neuropathy in subjects with Type 2 diabetes mellitus

AIMS

To examine differences in the spatial QRS-T angle in patients with Type 2 diabetes mellitus with and without cardiac autonomic neuropathy.

METHODS

Two hundred and thirty-two patients with diabetes mellitus (105 with cardiac autonomic neuropathy and 127 without cardiac autonomic neuropathy) and 232 control subjects, matched by gender and age, were studied. Diagnosis of cardiac autonomic neuropathy was based on the classic autonomic function tests. All subjects underwent a digital electrocardiographic recording. Electrocardiographic parameters were measured using the Modular Electrocardiographic Analysis (MEANS) program. Left ventricular mass index (LVMi) and global myocardial performance index (Tei index) of the left ventricle were assessed by ultrasonography.

RESULTS

The spatial QRS-T angle was higher in the patients with diabetes in comparison with the control subjects (24.5 ± 10.7 vs. 9.7 ± 4.5°, P < 0.001) and in the patients with diabetes and cardiac autonomic neuropathy than in those without cardiac autonomic neuropathy (30.1 ± 11.3 vs. 19.5 ± 7.1, P < 0.001). No differences were found in the QT interval between the studied groups. Multivariate linear regression analysis in subjects with diabetes after controlling for age, gender, BMI, blood pressure, diabetes duration, HbA(1c) , lipids, microalbuminuria and insulin resistance, demonstrated significant and independent associations between the spatial QRS-T angle with presence and severity of cardiac autonomic neuropathy, all parameters of heart rate variability, LVMi and Tei index.

CONCLUSIONS

The spatial QRS-T angle is increased in patients with Type 2 diabetes who have cardiac autonomic neuropathy, suggesting increased ventricular arrhythmogenicity, and is associated with the structural and functional properties of the myocardium. Further research is warranted to evaluate its role in cardiovascular risk stratification of patients with diabetes.

Increased left ventricular arrhythmogenicity in metabolic syndrome and relationship with myocardial performance, risk factors for atherosclerosis, and low-grade inflammation

Metabolic syndrome (MetS) is a clustering of cardiovascular risk factors recently associated with left ventricular dysfunction. Limited data exist on the association between MetS and ventricular arrhythmogenicity. This study examined differences in ventricular arrhythmogenicity assessed by classic (QT interval) and newer (spatial QRS-T angle [spQRS-Ta]) electrocardiographic markers in subjects with and without MetS. A total of 306 subjects, 153 with and 153 without MetS, matched for sex and age were examined. The spQRS-Ta, which vectorcardiographically quantifies the deviation between the directions of ventricular depolarization and repolarization, was measured using a computer-based electrocardiograph. Left ventricular mass index and myocardial performance were evaluated echocardiographically. The spQRS-Ta was significantly higher in subjects with in comparison with those without MetS. Left ventricular mass index, QT interval, and its dispersion were not different between the 2 groups. Left ventricular myocardial performance was worse in subjects with MetS and was associated with higher values of the spQRS-Ta. Multivariate linear regression analysis demonstrated MetS status as the strongest predictor of ventricular arrhythmogenicity. Addition of the high-sensitivity C-reactive protein in the model increased the explained variance of the spQRS-Ta by 11%. In conclusion, ventricular arrhythmogenicity is present in MetS and is associated with myocardial dysfunction, risk factors for atherosclerosis, and low-grade inflammation. The independent association between the spQRS-Ta and MetS implies that the clustering of the metabolic disturbances has additional prognostic information than its individual components in terms of ventricular arrhythmogenicity and may explain in part the excess cardiovascular risk in subjects with MetS.

Determinants of the total cosine of the spatial angle between the QRS complex and the T wave (TCRT): implications for distinguishing primary from secondary T-wave abnormalities

BACKGROUND

Contrary to intuitive expectations and dissimilar from that which occurs in the atria, left ventricular (LV) depolarization and repolarization proceed in opposite directions, creating a concordance of the spatial QRS complex and T-wave angles (QRS-T). By defining the determinants of QRS-T, it might be possible to distinguish a primary (caused by an abnormality of repolarization) from a secondary (caused by a delay in ventricular depolarization) T-wave abnormality.

METHODS AND RESULTS

From a near-consecutive series of 154 patients (age, 60 +/- 16 years; 81 females) in sinus rhythm, Doppler echocardiographic and 12-lead electrocardiogram (ECG) findings were related to the total cosine of the angle subtended by the spatial QRS complex and T wave (TCRT). Using the QRS complex and T-wave angles in the frontal and horizontal planes, TCRT was obtained from the table cited in the article of Helm and Fowler (Am Heart J 1953;45:835). TCRT correlated negatively with age, QRS duration (QRS), interventricular septal thickness (IVS) and posterior wall thickness, LV mass, LV cross-sectional area (CSA), LV relative wall thickness (RWT), left atrial dimension, and atrial velocity time integral (all, P < .001), but it was not related to LV diastolic dimension or systolic function. In multivariate analyses of the entire cohort or of patients without a left bundle branch block, QRS, CSA, RWT, and atrial velocity time integral emerged as independent variables (all, P < .001). When patients with right bundle branch block were also excluded, IVS, instead of CSA and RWT, was significant (P < .001). Overall, TCRT distinguished normal patients from those with heart disease, and patients with diabetes mellitus and hypertension from those not having these conditions. However, residuals of regression, TCRT = (-1.6IVS [cm]) + (-0.01QRS [milliseconds]) + 3, distinguished patients with coronary disease, but not other disorders, from normals, and diabetics, but not patients with hypertension or hyperlipidemia, from those not having these conditions (the regression having adjusted for secondary QRS-T discordance).

CONCLUSIONS

The determinants of TCRT can be quantified and expressed as a regression that may be used to distinguish primary from secondary T-wave abnormalities.

Cardiac syndrome X. Diagnosis, pathogenesis and management

Patients with cardiac syndrome X (typical chest pain and normal coronary arteriograms) represent a heterogeneous syndrome, which encompasses different pathogenic mechanisms. Although symptoms in most patients with cardiac syndrome X are non-cardiac, a sizable proportion of them have angina pectoris due to transient myocardial ischemia. Thus radionuclide myocardial perfusion defects, coronary sinus oxygen saturation abnormalities and pH changes, myocardial lactate production and stress-induced alterations of cardiac high energy phosphate suggest an ischemic origin of symptoms in at least a proportion of patients with cardiac syndrome X. Microvascular abnormalities, caused by endothelial dysfunction, appear to be responsible for myocardial ischemia in patients with cardiac syndrome X. Endothelial dysfunction is likely to be multifactorial in these patients and it is conceivable that risk factors such as hypertension, hypercholesterolemia, diabetes mellitus and smoking can contribute to its development. Most patients with cardiac syndrome X are postmenopausal women and estrogen deficiency has been therefore proposed as a pathogenic factor in female patients. Additional factors such as abnormal pain perception may contribute to the pathogenesis of chest pain in patients with angina pectoris and normal coronary angiograms. Although prognosis is good regarding survival, patients with cardiac syndrome X have an impaired quality of life. Management of this syndrome represents a major challenge to the treating physician. Understanding the mechanism underlying the condition is of vital importance for patient management. Thus diagnostic tests should aim at identifying the cause of the symptoms in the individual patient, i.e. myocardial ischemia, increased pain perception, abnormalities of adrenergic tone, non-cardiac mechanisms, etc. Moreover, it is important to bear in mind that treatment of cardiac syndrome X should be mainly directed towards improving quality of life, as prognosis is usually good in these patients. Conventional antianginal agents such nitrates, calcium channel antagonists, beta-adrenoceptor antagonists and nicorandil are effective particularly in patients in whom chest pain and ECG changes are clearly suggestive of myocardial ischemia and in those with objective documentation of ischemia. Angiotensin-converting enzyme inhibitors have been shown to be useful in syndrome X patients with increased adrenergic tone, borderline systemic hypertension, and those with documented endothelial dysfunction. Analgesic interventions of different sorts have been proposed based on the hypothesis that somatic and visceral perception of pain is altered in cardiac syndrome X patients. Pharmacological agents such as imipramine and aminophylline, and neural electrical stimulation techniques have been assessed in recent years with encouraging results. Psychological treatment, particularly cognitive therapy, appears to be useful in defined patient subsets. Relaxation techniques such as transcendental meditation have been successfully used in small studies and shown to improve not only chest pain but also exercise-induced ST segment changes. Reports indicate that these techniques improve quality of life.