The prognostic value of the frontal QRS-T angle is comparable to cardiovascular autonomic neuropathy regarding long-term mortality in people with diabetes. A population based study

Relationship Between Index of Cardiac Electrophysiological Balance, Frontal QRS-T Angle and Retinopathy in People with Type 2 Diabetes

BACKGROUND

Diabetic retinopathy (DR) is strongly associated with cardiovascular disease, which is a risk factor for sudden cardiac death (SCD). The index of cardiac electrophysiological balance (iCEB) and the frontal QRS-T angle are recommended to predict the risk of ventricular arrhythmias more than other ECG parameters. However, the relationships between these two markers and DR have not yet been explored. The aim of this study was to investigate the variation in the iCEB, corrected iCEB (iCEBc) and frontal QRS-T angle in different stages of DR and determine whether there are associations between these markers and DR.

METHODS

The sample comprised 665 patients with Type 2 diabetes mellitus (T2DM) who were classified into three groups: no DR (NDR), mild to moderate non-proliferative DR (NPDR), and vision-threatening DR (VTDR). Twelve-lead ECG was performed and the QT, QTc, QRS duration, iCEB, iCEBc and frontal QRS-T angle were recorded and compared across the groups.

RESULTS

The VTDR group had a significantly higher iCEBc and frontal QRS-T angle than the NDR and NPDR groups. After controlling for confounding variables, the correlations between the iCEBc (OR=2.217, 95% CI=1.464-3.358, P<0.001), frontal QRS-T angle (OR=1.017, 95% CI=1.008-1.025, P<0.001) and DR risk remained (P<0.05). Subjects in the fourth iCEBc quartile (adjusted OR=2.612, 95% CI=1.411-4.834, p=0.002) had a much higher chance of developing DR compared to those in the first quartile. In comparison to the first frontal QRS-T angle quartile, subjects in the third (adjusted OR=1.998, 95% CI=1.167-3.422, P=0.012) and fourth (adjusted OR=2.430, 95% CI=1.420-4.160, P=0.001) frontal QRS-T angle quartiles had significantly greater risks of DR.

CONCLUSION

With the progression of DR, the iCEBc and frontal QRS-T angle increase. An increased iCEBc and frontal QRS-T angle are associated with an increased risk of DR.

Intra-subject stability of different expressions of spatial QRS-T angle and their relationship to heart rate

Three-dimensional angle between the QRS complex and T wave vectors is a known powerful cardiovascular risk predictor. Nevertheless, several physiological properties of the angle are unknown or poorly understood. These include, among others, intra-subject profiles and stability of the angle relationship to heart rate, characteristics of angle/heart-rate hysteresis, and the changes of these characteristics with different modes of QRS-T angle calculation. These characteristics were investigated in long-term 12-lead Holter recordings of 523 healthy volunteers (259 females). Three different algorithmic methods for the angle computation were based on maximal vector magnitude of QRS and T wave loops, areas under the QRS complex and T wave curvatures in orthogonal leads, and weighted integration of all QRS and T wave vectors moving around the respective 3-dimensional loops. These methods were applied to orthogonal leads derived either by a uniform conversion matrix or by singular value decomposition (SVD) of the original 12-lead ECG, giving 6 possible ways of expressing the angle. Heart rate hysteresis was assessed using the exponential decay models. All these methods were used to measure the angle in 659,313 representative waveforms of individual 10-s ECG samples and in 7,350,733 individual beats contained in the same 10-s samples. With all measurement methods, the measured angles fitted second-degree polynomial regressions to the underlying heart rate. Independent of the measurement method, the angles were found significantly narrower in females (p &lt; 0.00001) with the differences to males between 10o and 20o, suggesting that in future risk-assessment studies, different angle dichotomies are needed for both sexes. The integrative method combined with SVD leads showed the highest intra-subject reproducibility (p &lt; 0.00001). No reproducible delay between heart rate changes and QRS-T angle changes was found. This was interpreted as a suggestion that the measurement of QRS-T angle might offer direct assessment of cardiac autonomic responsiveness at the ventricular level.

Diabetes without Overt Cardiac Disease Is Associated with Markers of Abnormal Repolarization: A Case-Control Study

Patients with diabetes mellitus (DM) are prone to advanced atherosclerosis, microvascular disease, and tissue fibrosis. Despite the increased risk for arrhythmias, little is known about cardiac repolarization abnormalities in DM. We aimed to determine whether abnormal T-wave morphology markers are common among patients with DM and no known cardiac disease. Patients were recruited and classified as having DM or impaired fasting glucose (IFG) according to accepted guidelines. Total cosine R to T (TCRT) and T-wave morphology dispersion (TMD) were computed with custom-designed software for randomly selected and averaged beats. Among 124 patients recruited; 47 were diagnosed with DM and 3 IFG. DM patients and the control group had similar clinical characteristics, other than statins and anti-diabetic drugs, which were more common among DM patients. Patients with DM/IFG had decreased TCRT values computed from a random beat (0.06 ± 0.10 vs. 0.43 ± 0.07, p < 0.01) and an average beat (0.08 ± 0.09 vs. 0.44 ± 0.06, p < 0.01), when compared with the control group. TMD parameters did not differ. In conclusion, TCRT is reduced in patients with DM and no known cardiac diseases. Further research is required to investigate whether repolarization-associated changes in DM are the consequence of subclinical atherosclerosis, diabetic cardiomyopathy, or a combination of the two.

Empagliflozin has favourable effect on frontal plane QRS-T angle in diabetic patients with cardiovascular disease

WHAT IS KNOWN AND OBJECTIVE

Empagliflozin treatment is significantly associated with lower risk of cardiovascular events in patients with diabetes mellitus (DM) independent of its antihyperglycemic effect. However, little is known regarding the impact of empagliflozin on electrocardiography (ECG) parameters. This study aimed to investigate whether empagliflozin has favourable effect on frontal plane QRS-T (fQRST) angle, which is an ECG sign of ventricular repolarization heterogeneity, in patients with type 2 DM.

METHODS

We prospectively enrolled 111 patients with known diagnosis of type 2 DM who newly prescribed empagliflozin on top of their standard anti-diabetic therapy. Patients were divided into two groups according to presence or absence of cardiovascular disease (CVD) at baseline and followed-up for 6 months. The impact of empagliflozin treatment on fQRST angle was investigated and patient groups were compared regarding the pre- and post-treatment fQRST angle.

RESULTS AND DISCUSSION

Among 111 patients, 32 (28.8%) had CVD and 79 (71.2%) had no CVD. Empagliflozin treatment lead a significant decrease in the mean fQRST angle throughout the study period and mean fQRST angle was significantly lower at 3- and 6-month follow-up visits compared to baseline values (62° ± 17.4° vs. 57.2° ± 14.8° vs. 50.5° ± 13.6°, p < 0.001 for all dual comparisons). However, despite similar antihyperglycemic effect with empagliflozin treatment in patients with and without CVD, the significant decrease in the mean fQRST angle was observed only in patients with CVD and no significant decrease was observed in the mean fQRST angle in patients without CVD.

WHAT IS NEW AND CONCLUSION

Empagliflozin leads a significant narrowing in the fQRST angle in type 2 DM patients with known CVD.

Frontal QRS-T angle as a predictive marker for myocardial damage in acute carbon monoxide poisoning

INTRODUCTION

The present study was undertaken to investigate the prognostic value of the frontal QRS-T angle associated with adverse cardiac outcomes in patients with carbon monoxide (CO) poisoning in early stages in the emergency department.

MATERIALS AND METHODS

The data of 212 patients with CO poisoning who were admitted to the ED between January 2010 and May 2020 were retrospectively analyzed. The frontal QRS-T angle was obtained from the automatic reports of the EKG device.

RESULTS

Compared to patients without myocardial damage, among patients with myocardial damage, statistically high creatinine, creatine kinase MB, cardiac troponin I, and frontal QRS-T angle values were found (p < 0.001 for all parameters), while the saturation of arterial blood pH and arterial oxygen values were found to be lower (p = 0.002 and p < 0.001, respectively). The frontal QRS-T angle values were correlated with creatine kinase, creatine kinase-MB, cardiac troponin I, and oxygen saturation (SpO₂) in arterial blood (r = 0. 232, p = 0.001; r = 0. 253, p = < 0.001; r = 0. 389, p = < 0.001; r = -0. 198, p = 0.004, respectively). The optimum cut-off value of the frontal QRS-T angle was found to be 44.5 (area under the curve: 0.901, 95% confidence interval: 0.814-0.988, sensitivity: 87%, specificity: 84%).

CONCLUSIONS

The frontal QRS-T angle, a simple and inexpensive parameter that can be easily obtained from 12-lead surface electrocardiography, can be used as an early indicator in the detection of myocardial damage in patients with CO poisoning.

[Diagnostic and prognostic significance of QRS-T angle]

The angle between theQRSandTvectors reflects the consistency or inconsistency of the processes of de- and repolarization of the ventricles of the heart and is considered one of the indicators of global electrical heterogeneity of myocardium. In recent years, the prognostic value of theQRS-Tangle has been demonstrated in relation to total and cardiovascular mortality, both in the population and in various groups of patients. The mechanisms of this phenomenon are not completely clear. The review analyses studies published over the past five years on the relationship between theQRS-Tangle and mortality, as well as coronary heart disease and heart failure. Possible mechanisms for increasing theQRS-Tangle are discussed. Data are given on the use of theQRS-Tangle in diagnostic and prognostic scales, including in combination with other indicators of global electrical heterogeneity of myocardium.

Effects of deep inspiration on QRS axis, T-wave axis and frontal QRS-T angle in the routine electrocardiogram

The frontal QRS-T angle on the electrocardiogram has been described as a variable of ventricular repolarization. We evaluated how deep inspiration affected QRS axis, T-wave axis and frontal QRS-T angle. We also assessed the effects on left ventricular volume on the association using myocardial perfusion SPECT. Fifty patients undergoing ECGs both in resting state and in deep inspiration and subsequent SPECT were enrolled. Frontal QRS-T angle was defined as the absolute value of the difference between the frontal QRS axis and T-wave axis. Change in frontal QRS-T angle was calculated using (QRS-T angle in deep inspiration-QRS-T angle in resting state). In resting state, QRS axis and T-wave axis were 20.9° ± 30.0° and 40.9° ± 36.1°, respectively. Frontal QRS-T angle was 35.9° ± 36.1°. Deep inspiration caused rightward shifts of QRS axis (42.3° ± 29.5°, p < 0.001) and T-wave axis (49.5° ± 39.7°, p < 0.001). However, deep inspiration did not affect frontal QRS-T angle (33.9° ± 35.8°, p = 0.44). Frontal QRS-T angle in deep inspiration had good correlation (r = 0.87, p < 0.001) and agreement with that in resting state. Left ventricular (LV) end-diastolic volume had a significant association with change in frontal QRS-T angle (r = 0.29, p = 0.04). Our data suggest that frontal QRS-T angle in deep inspiration has a good correlation with that in resting state, and the agreement is acceptable. In patients with dilated LV, QRS-T angle in deep inspiration may be susceptible to the overestimation.

Polyscore of Non-invasive Cardiac Risk Factors

Non-invasive risk stratification of cardiac patients has been the subject of numerous studies. Most of these investigations either researched unique risk predictors or compared the predictive power of different predictors. Fewer studies suggested a combination of a small number of non-invasive indices to increase the accuracy of high-risk group selection. To advance non-invasive risk assessment of cardiac patients, we propose a combination score (termed the Polyscore) of seven different cardiac risk stratifiers that predominantly quantify autonomic cardiovascular control and regulation, namely the slope of heart rate turbulence, deceleration capacity of heart rate, non-invasively assessed baroreflex sensitivity, resting respiration frequency, expiration triggered sinus arrhythmia, post-ectopic potentiation of systolic blood pressure, and frequency of supraventricular and ventricular ectopic beats. These risk stratification tests have previously been researched and their dichotomies defining abnormal results have been derived from previous reports. The Polyscore combination was defined as the number of positive tests among these seven risk predictors, giving a numerical scale which ranges from 0 (all tests normal) to 7 (all tests abnormal). The Polyscore was tested in a population of 941 contemporarily treated survivors of acute myocardial infarction (median age 61 years, 182 females) of whom 72 (7.65%) died during a 5-year follow-up. In these patients, all the risk predictors combined in the Polyscore were assessed during in-hospital 30-min simultaneous non-invasive recordings of high-frequency orthogonal electrocardiogram, continuous blood pressure and respiration. Compared to Polyscore 0 stratum, the hazard ratios of mortality during follow-up increased almost exponentially in strata 1 through 7 (vs. stratus 0, the hazard ratios were 1.37, 1.96, 7.03, 15.0, 35.7, 48.2, and 114, in strata 1 to 7, respectively; p < 0.0001). This allowed selecting low-risk (Polyscore ≤ 2), intermediate risk (Polyscore 3 or 4) and high-risk (Polyscore ≥ 5) sub-groups of the population that differed greatly in the Kaplan–Meier probabilities of mortality during follow-up. Since the Polyscore was derived from recordings of only 30-min duration, it can be reasonably applied in different clinical situations including population-wide screening. We can therefore conclude that the Polyscore is a reasonable method for cardiac risk stratification that is ready for prospective validation in future independent studies.