The association of QT dispersion and QT dispersion ratio with extent and severity of coronary artery disease

Effect and benefit of percutaneous coronary intervention in chronic total occlusion on ventricular repolarization: QT correction and dispersion

ST segment, T wave changes, QT interval changes, and QTc dispersion are among the parameters used to diagnose ischemic heart disease. The increase in the QT dispersion can be caused by myocardial ischemia, among other heart diseases, whereas cardiac diseases such as coronary artery disease (CAD) can be diagnosed by observing an abnormally high QTc dispersion. This study aimed to evaluate the variations in the QTc dispersion (depolarization and repolarization) of surface electrocardiography as a result of percutaneous coronary intervention (PCI) in patients with chronic total occlusion. This study took place in the Iraqi Center for Heart Disease from October 2020 to February 2021. 110 patients who suffered from chronic occlusion of the coronary artery and underwent PCI revascularization were examined. Twelve-lead electrocardiograms were recorded at the time of admission (12 hours before intervention) and more than one hour after the intervention. The measured ECG parameters included corrected QT interval durations and corrected QT dispersion in both pre and post-PCI electrocardiograms, and their values were compared. The average corrected QT interval and QTC dispersion changed significantly before and after the percutaneous coronary intervention. Performing percutaneous coronary intervention on patients who suffer from coronary artery total occlusion shows a major reduction in the corrected QT dispersion.

Tp-e/QTc ratio, SYNTAX, and GRACE score in patients who underwent coronary angiography owing to acute coronary syndrome

OBJECTIVE

Ventricular arrhythmias following acute coronary syndrome (ACS) range from benign to life-threatening fatal arrhythmias. Tpeak-end (Tp-e) interval has been shown to be an important parameter in the assessment of repolarization dispersion. We aimed to evaluate the relationship between SYNTAX and Global Registry of Acute Coronary Events (GRACE) risk score calculated on admission and Tp-e interval and Tp-e/QTc ratio.

METHODS

A total of 421 patients were included in the study. The patients were divided into 2 groups as low SYNTAX score (≤22) and moderate and high risk SYNTAX score (>22). According to the GRACE risk score, the patients were divided into 2 groups; high-risk patients ≥140 and <140 low-risk patients.

RESULTS

In the group with SYNTAX score >22, the Tp-e interval (p<0.001) and Tp-e/QTc ratio (p<0.001) was found to be significantly higher than in the group with a SYNTAX score ≤22. Tp-e interval (p<0.001) and Tp-e/QTc ratio (p=0.002) was higher in patients with GRACE risk score ≥140 compared with patients with a GRACE risk score <140. The correlation between Tp-e interval and Tp-e/QTc ratio and SYNTAX score (r=0.489; p<0.001) and GRACE risk score (r=0.274; p<0.001) were found to be significant. A significant and independent correlation was found between the SYNTAX score and Tp-e/QTc ratio (β=0.385; p<0.001).

CONCLUSION

Tp-e interval and Tp-e/QT ratio increased in patients with severe coronary artery disease assessed with SYNTAX score. Tp-e interval and Tp-e/QT ratio increased in patients with a high GRACE risk score.

Simple heart rate and QT parameters during stress exercise testing to assess presence and severity of stable coronary artery disease

Aim: The relationship between QT prolongation and myocardial ischemia is well known, however not many studies have correlated corrected QT interval and heart rate recovery with the severity of coronary artery disease (CAD). Methods: This was a single-center, prospective, observational study which included 127 patients with CAD and 124 patients without CAD. Results: Corrected QT variability from peak to recovery correlated well with CAD with a p value of 0.03. Receiver operative characteristic analysis did not show any significant diagnostic accuracy with any heart rate or QT parameters for predicting the presence or severity of CAD. Conclusion: Coronary artery disease is predicted by reduced ability of the heart rate to rise from rest to peak exercise and reduced recovery of heart rate and corrected QT from peak exercise to recovery at 1 min.

Late ventricular potentials in familial Mediterranean fever with and without AA amyloidosis

Objective

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by episodic and chronic inflammation that may lead to both accelerated coronary atherosclerosis and cardiac AA amyloidosis. We hypothesized that late ventricular potentials (LPs), an established electrocardiographic susceptibility marker of ventricular arrhythmias, will be more common in FMF than in the adjusted normal population due to these two types of inflammation-associated cardiac effects. Therefore, we aimed to evaluate the occurrence of LPs in FMF patients with and without amyloidosis.

Material and Methods

Signal-averaged electrocardiography was performed in consecutive patients with FMF using the Frank corrected orthogonal lead system. At least 200 consecutive beats were digitally recorded and averaged, and the presence of LPs was determined according to acceptable thresholds.

Results

There were 54 patients with colchicine-treated FMF, of whom 14 had biopsy-proven AA amyloidosis. None of the uncomplicated FMF patients and 2 of the 14 FMF amyloidosis patients had abnormal or borderline LPs.

Conclusion

Based on LPs as a susceptibility marker for arrhythmia, FMF patients, including the large majority of FMF patients with amyloidosis, are seemingly not at an increased risk to develop arrhythmias.

Correlation of corrected QT dispersion with the severity of coronary artery disease detected by SYNTAX score in non-diabetic patients with STEMI

Introduction

Determination of the QT interval dispersion by means of a standard ECG at rest has been widely used for cardiovascular risk assessment during the last 15 years as one of the recent explanations for the development of life threatening ventricular arrhythmias. However, little is known about the relation between QT dispersion and the severity of coronary artery atherosclerosis as defined by SYNTAX score.

Aim of work

The present study was done to assess the correlation between QTc dispersion and the severity of coronary artery disease in acute ST elevation myocardial infarction (STEMI) detected by SYNTAX score.

Patients and methods

It included 50 patients who were non-diabetic, non-hypertensive and diagnosed as acute STEMI within 6 months undergoing coronary angiography in the cath. lab. of Assiut University Hospital. QT dispersion was calculated as the difference between the longest (QT max) and the shortest QT (QTmin) interval recorded by standard 12 lead ECG. The QT interval was corrected by using Bazett's formula (QTc = QT/square root of R-R interval in seconds). Corrected QT dispersion (QTcd) was defined as the difference between the maximum and minimum QTc for a given heart rate. The SYNTAX score is calculated by syntax calculator, a new tool to grade the complexity of coronary artery disease.

Results

Out of 50 participating patients, there were 43 (86%) males with mean age 53.9 ± 12.1 years. The mean QTc dispersion was 83.1 ± 20.3 ms, while mean SYNTAX score was 11.6 ± 6.1. There is a strong positive correlation between QTc dispersion and SYNTAX score. This was not related to age, gender, risk factors or family history of ischemic heart disease. Of note, there was a relationship between QTc dispersion and serum creatinine.

Conclusions

Our study concluded that there is a significant positive correlation between corrected QT dispersion and severity of coronary artery disease as assessed by SYNTAX score.

QT Interval Derived Measurements in Patients with Cardiac Syndrome X Compared to Coronary Artery Disease

Previous studies assessing effect of ischemia on ventricular repolarization are mostly directed toward patients with coronary artery disease (CAD); however, similar reports on cardiac syndrome X (CSX) are scarce. Whether microvascular dysfunction of CSX and ischemia induced by CAD produce comparable effect on ventricular repolarization is unclear and deserve further studies. In the present study, ECG measures of ventricular repolarization were compared between CAD and CSX patients (40 subjects in each group). Following evaluation of sociodemographic characteristics, medical and past medical history, a resting ECG was used to assess measurements of ventricular repolarization in each patient, namely, QT interval (QT), corrected QT interval (QTc), QT dispersion (QTd), corrected QT dispersion (QTcd), adjacent QT dispersion (AdQTd), QT dispersion ratio (QTdR), JT dispersion (JTd), and Corrected JT dispersion (JTcd). Results showed comparable QT intervals and QTd in CAD and CSX patients even after adjustment for the possible variations in gender, age and body mass index of the studied groups. Although JTd was increased in CSX subjects (26.6 ± 7.2 ms) compared with CAD patients (22.7 ± 6.5 ms, p = 0.019), statistical significance disappeared after correcting JT for variations in heart rate. QT and QTc were significantly below 440 ms in CAD as well as CSX patients (p < 0.001). In contrast, maximum QTd, maximum QTcd and AdQTd of CAD and CSX patients were significantly above 440 ms (p < 0.001). The means of JTd and JTcd were significantly above 22 ms and 24 ms respectively (p < 0.001, p = 0.001) in CSX but not CAD patients (p = 0.529, p = 0.281). The present findings clearly demonstrate comparable measures of ventricular repolarization in CAD and CSX patients and consequently an equal risk of cardiac events in both groups.

Effects of the coronary collateral circulation on the Tp-e interval and Tp-e/QT ratio in patients with stable coronary artery disease

BACKGROUND

The clinical utility of the Tp-e interval and Tp-e/QT ratio in the risk stratification of ventricular arrhythmic events is controversial. Therefore, we investigated the impact of CCC on these electrocardiographic indexes in the course of stable CAD.

METHODS

Two hundred three consecutive patients with stable CAD who underwent coronary angiography and had documented total occlusion of one of the major coronary arteries were enrolled in this prospective cross-sectional study. The Tp-e interval and Tp-e/QT ratio were measured by 12-lead electrocardiogram.

RESULTS

The Tp-e interval, cTp-e interval, Tp-e/QT ratio, and cTp-e/QT ratio were lower in the grade 3 CCC group compared with the others in all leads. Multivariate linear regression analyses was performed to identify the clinical factors affecting the cTp-e interval and was indicated that age (β = 0.261, P < 0.001), male sex (β = 0.334, P < 0.001), poor Rentrop grade (β = -0.228, P < 0.001), and NLR (β = 0.137, P = 0.027) were independent predictors of a prolonged cTp-e interval.

CONCLUSION

It could be concluded that the decreased dispersion of ventricular repolarization might contribute to the lower incidence of ventricular arrhythmias and SCD in CAD patients with a good CCC.

The effect of acute psychological stress on QT dispersion in patients with coronary artery disease

BACKGROUND

An acute psychological stress can precipitate ventricular arrhythmias and sudden cardiac death in patients with coronary artery disease (CAD). However, the physiologic mechanisms by which these effects occur are not entirely clear. Mental stress-induced myocardial ischemia occurs in a significant percentage of the CAD population. It is unknown if the proarrhythmic effects of psychological stress are mediated through the development of myocardial ischemia.

OBJECTIVES

To examine the effects of psychological stress on QT dispersion (QTd) among CAD patients and whether these effects are mediated via the development of myocardial ischemia.

METHODS

Psychological stress was induced using a public speaking task. Twelve-lead electrocardiograms (ECG) were recorded at rest, during mental stress, and during recovery. QTd was calculated as the difference between the longest and the shortest QT interval in the 12-lead ECG. Rest-stress myocardial perfusion imaging was also performed to detect mental stress-induced myocardial ischemia.

RESULTS

Mental stress induced a significant increase in QTd compared to the resting condition (P < 0.001). This effect persisted beyond the first 10 minutes of recovery (P < 0.001). QTd was significantly associated with the development of mental stress ischemia with ischemic patients having significantly higher QTd during mental stress than nonischemic patients (P = 0.006). This finding remained significant after controlling for possible confounding factors (P = 0.01).

CONCLUSION

An acute psychological stress induces a significant increase in QTd, which persists for more than 10 minutes after the cessation of the stressor. This effect seems to be, at least partially, mediated by the development of mental stress-induced myocardial ischemia.

QT dispersion and transmural dispersion of repolarization in patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is a disease characterized by sporadic, paroxysmal attacks of fever and serosal inflammation. QT dispersion (QTd) and transmural dispersion of repolarization (TDR), simple noninvasive arrhythmogenic markers, that can be used to assess homogeneity of cardiac repolarization, have not been studied in FMF patients before. The aim of our study was to evaluate the QTd and TDR in FMF patients without overt cardiac involvement. A total of 50 patients with FMF (30 men, 20 women, 29.4 +/- 11.8 years) and 50 controls (30 men, 20 women; mean age 31.3 +/- 11.9 years) were included. QTd, corrected QTd (cQTd), maximum QT (QTmax), maximum corrected QT (cQTmax), minimum QT (QTmin), and minimum corrected QT intervals (cQTmin) and TDR were measured from standard 12-lead electrocardiography (ECG). We found that QTd, QTmax, and TDR were greater in FMF patients than in the control group (36.0 +/- 11.4 vs. 20 +/- 11.2, P < 0.001 and 354.8 +/- 30.9 vs. 342.8 +/- 18.0, P = 0.02; 62.0 +/- 16.0 vs. 49.0 +/- 9.5 P < 0.001, respectively), as were cQTd and cQTmax (40.4 +/- 13.5 vs. 21.9 +/- 12.4, P < 0.001 and 397.7 +/- 40.2 vs. 375.5 +/- 25.4 P = 0.001). A modest positive correlation was found between cQTd and C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (r = 0.30, P < 0.001; r = 0.40, P < 0.001; respectively). QTd, which is an index of inhomogeneity of ventricular repolarization and an important predictor of cardiovascular mortality, and TDR, which is a better marker of cardiac repolarization, increased in FMF patients similarly as in other rheumatologic diseases.