Effect of slow coronary flow on electrocardiographic parameters reflecting ventricular heterogeneity

Ranolazine improved left ventricular diastolic functions and ventricular repolarization indexes in patients with coronary slow flow

Introduction

Coronary slow flow (CSF) is a condition commonly encountered during angiography. Recent studies have shown the adverse effects of CSF on left ventricular diastolic functions. CSF reportedly increases the novel ventricular repolarization parameters. Ranolazine is a preparation with a prominent anti-anginal activity that has positive effects on anti-arrhythmic and diastolic parameters. In this context, this study was carried out to investigate the effects of ranolazine on left ventricular diastolic functions and repolarization in patients with CSF.

Material and methods

Forty-six patients with CSF and 29 control subjects were included in the patient and control groups, respectively. Both groups received ranolazine for one month and were evaluated using 12-lead electrocardiography, conventional echocardiography, and tissue Doppler imaging at the baseline and after one month of ranolazine treatment.

Results

Corrected P, QT dispersion, and Tp-e interval values were significantly higher in the patient group than in the control group. There was a significant decrease in isovolumic relaxation time (IVRT) and deceleration time (DT) values after the ranolazine treatment compared to the baseline values in the patient group but not the control group. A significant increase was observed in the mean E and A velocities and the mean E/A ratio after the ranolazine treatment compared to the baseline values in the patient group. Additionally, there was a significant difference between the Tp-e interval and corrected P dispersion values measured after the ranolazine treatment compared to the baseline values in the patient group but not in the control group.

Conclusion

This study's findings demonstrated that ranolazine positively affected impaired diastolic functions and repolarization parameters, particularly in patients with CSF.

Evaluation of the relationship between the level of addiction and exhaled carbon monoxide levels with QT dispersion in smokers

INTRODUCTION

Smoking increases the risk of arrhythmia. QT dispersion (QTd) is an important indicator for the determination of ventricular arrhythmia. In this study, we aimed to determine the arrhythmia risk by evaluating QTd in smokers and to assess the relationship between the level of nicotine addiction and carbon monoxide (CO) level in the expiratory air.

METHODS

This study was designed as a single-center, cross-sectional study. Among the chronic smokers referred to the Smoking Cessation Clinic of a tertiary hospital between October 2019 and January 2020, all those who had no risk factors for cardiac arrhythmias, except smoking, were included in the study. Sociodemographic data and smoking characteristics of the participants were collected and exhaled CO levels were measured. QT intervals were measured in all leads by using a 12-lead standard electrocardiogram (ECG), and heart rate corrected QT (QTc) intervals, QT dispersion (QTd), and corrected QT dispersion (QTcd) were calculated.

RESULTS

The mean age of the 250 patients was 37.2±9.3 years and the majority of patients (65%) were male. The mean amount of smoking was 25.74±16.03 packs/year and the mean value of CO was 12.36±7.06 ppm. The mean QTd was 23.83±13.12 ms, and the mean QTcd was 26.63±15.02 ms. A statistically significant relationship was found between QTd and QTcd and level of addiction, consumption of sticks/day and packs/year, and exhaled CO values (all p<0.001).

CONCLUSIONS

It was found that as the level of addiction, cigarette use amount, exhaled CO levels, and BMI increased in smokers, QT dispersion and arrhythmia risk increased.

QT interval and P wave dispersion in slow coronary flow phenomenon

BACKGROUND

Slow coronary flow (SCF) phenomenon is an angiographic finding which is defined as slow contrast passage through coronary arteries which may predispose patients to serious cardiac complications such as fatal arrhythmias. P-wave and QT-interval dispersion are electrocardiographic findings which are related to atrial fibrillation and ventricular tachyarrhythmias. In the present study, the relation between SCF and presence of P-wave and QT-interval dispersion in electrocardiography has been evaluated.

METHODS

47 patients with normal coronary arteries and SCF and 40 patients with normal coronary artery flow without SCF were enrolled in this case control study. Standard electrocardiogram (ECG) was analyzed for P-wave and QT-interval dispersion. SCF was identified in normal coronary vessels by use of Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) method (TFC > 27). Corrected TIMI frame count (CTFC) of coronary vessels as well as mean CTFC along with QT-interval and P-wave dispersion were compared between 2 groups. The study data were analyzed by SPSS software and P value less than 0.050 was considered to be significant.

RESULTS

QT-interval [76.17 (35.23) ms versus 39.25 (19.26) ms] and P-wave [39.74 (17.48) ms versus 19.50 (8.54) ms] dispersion were significantly higher among patients with SCF phenomenon (P < 0.050). In addition, there was a positive significant linear correlation between TFC and P-wave and QT-dispersion (r = 0.857, r = 0.861, respectively, P < 0.050).

CONCLUSION

According to the results, increasing TFC among patients with SCF will result in P wave and QT interval dispersion and therefore this finding can be considered as an indicative marker for cardiac events.

Early repolarization pattern in the coronary slow flow phenomenon

BACKGROUND

The coronary slow flow phenomenon (CSFP) is well-documented, and the early repolarization pattern (ERP) has recently been shown to be a risk factor for the development of malignant ventricular arrhythmias.

METHODS

Those with true CSFP were included as cases and those with normal angiograms were included as controls. We assessed J-point elevation on surface electrocardiograms (ECGs) and defined ERP as notching or slurring of the terminal portion of the QRS takeoff.

RESULTS

We enrolled 115 cases (33 females, 82 males; mean age, 51.9 ± 11.5 years) and 45 controls (13 females, 32 males; mean age, 50.8 ± 11.7 years). ERP was more common among cases than among controls (65% vs. 28%, p = .001). Compared with the controls, cases were more likely to have J-point elevation in the inferior leads (25% vs. 13%, p = .002), in the D1 to aVL leads (22% vs. 15%, p = .001), and in the lateral leads (17.3% vs. 0%), p = .001). Notching was also significantly more common in cases than in controls (26.0% vs. 2.2%, p = .0001). Finally, concave/ascendant ST segment (33.9% vs. 5.2%, p = .006), horizontal/non-ascendant ST segment (14.7% vs. 1.7%, p = .054), and horizontal/non-ascendant ST segment and notching (15.6% vs. 2.2%, p = .012) patterns were more common in cases than in controls.

CONCLUSIONS

We report that CSFP is associated with J-wave and slurring ERPs. However, the clinical significance of these changes needs to be clarified.

Coronary microvascular dysfunction is associated with baseline QTc prolongation amongst patients with chest pain and non-obstructive coronary artery disease

BACKGROUND

Coronary microvascular dysfunction (CMD) causes ischemia and is linked to adverse cardiovascular events. Acute transmural ischemia is associated with QT prolongation, but whether CMD affects repolarization is unknown. The aim of this study was to determine if CMD is associated with prolongation of resting heart rate corrected QT interval (QTc).

METHODS

In patients presenting to the catheterization laboratory with chest pain and non-obstructive coronary artery disease (CAD) at angiography, coronary flow reserve (CFR) in response to intracoronary adenosine was measured and compared to baseline to give a CFR ratio. The Bazett's-derived QTc was manually derived from patients' 12-lead ECG obtained prior to the procedure. QTc was compared between patients with normal and abnormal (CFR ratio≤2.5) coronary microvascular function.

RESULTS

Of the 926 patients included in this study, 281 patients (30%) had CMD (mean age 53.2 years [SD 12.7], 25% male). QTc was significantly longer in those with an abnormal CFR response to adenosine (median [Q1, Q3] ms: 420 [409, 438] vs. 416 [405, 432]; p value<0.001) and patients in the lowest quartile of CFR had a significantly longer QTc compared to those in the highest quartile (median [Q1, Q3] ms: 420 [409, 439] vs. 413 [402, 426]; p<0.001). In a linear regression model adjusting for age and sex, CMD was associated with an increase in QTc of 3.09 ms (p=0.055).

CONCLUSION

Our data suggest that CMD may be associated with an increase in baseline QTc, however the precise clinical relevance of this finding needs to be better investigated in larger clinical studies.

New markers for ventricular repolarization in coronary slow flow: Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio

BACKGROUND

Coronary slow flow (CSF) is characterized by normal or near-normal coronary arteries with delayed opacification of the distal vasculature that it may cause angina pectoris, acute myocardial infarction, life-threatening arrhythmias, and sudden cardiac death. The Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio are also known as predictors of ventricular arrhythmogenesis. The aim of this study was to assess ventricular repolarization in patients with CSF by using Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio.

METHODS

This study included 50 patients with CSF and 51 control subjects. Coronary flow rates of all subjects were documented by thrombolysis in myocardial infarction (TIMI) frame count (TFC). Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio were measured from the 12-lead electrocardiogram. These parameters were compared between groups.

RESULTS

In electrocardiographic parameters analysis, QT, QTc, QTd, and QTcd were significantly increased in CSF patients compared with the control subjects (P < 0.001, P = 0.019, P < 0.001, P < 0.001, respectively). The Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio in the CSF patients were significantly higher than those in the control subjects (Tp-e: 117 ± 21 milliseconds [ms] vs 96 ± 16 ms, P < 0.001; Tp-e/QT: 0.30 ± 0.06 vs 0.27 ± 0.06, P = 0.005; Tp-e/QTc: 0.27 ± 0.06 vs 0.24 ± 0.05, P < 0.001). In the multivariate analysis, increased Tp-e and Tp-e/QT ratio were associated with CSF.

CONCLUSIONS

Our study revealed that when compared to the control subjects, Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc were significantly increased in the CSF patients.

Plasma factor XI and XII activity in patients with slow coronary flow

The exact pathophysiology of slow coronary flow (SCF) phenomenon, characterized by delayed opacification of coronary arteries during coronary angiography, is still unknown, although endothelial dysfunction, inflammation, vasomotor disorders and atherosclerosis are shown. The present study was conducted to investigate whether there is a coagulation pathway abnormality in patients with SCF measuring plasma factor XI and XII activity. The study included 55 patients with angiographically proven SCF (group I) and 40 individuals with normal coronary flow (NCF, group II). Baseline demographic properties were similar in both groups. Echocardiographic parameters were also similar in patients with SCF and NCF. Factor XI activity was significantly higher in group I when compared with group II. Factor XII activity was also significantly higher in group I when compared with group II (108.9 ± 19 vs. 98.8 ± 20, P = 0.018 and 131.2 ± 17 vs. 119.1 ± 16, P = 0.001, respectively). We conclude that SCF phenomenon appears to be associated with enhanced procoagulant state, which may support the role of inflammation and atherosclerosis in the pathogenesis of this phenomenon.

Acquired long QT syndrome: frequency, onset, and risk factors in intensive care patients

BACKGROUND

Acquired long QT syndrome is a reversible condition that can lead to torsades de pointes and sudden cardiac death.

OBJECTIVE

To determine the frequency, onset, frequency of medications, and risk factors for the syndrome in intensive care patients.

METHODS

In a retrospective chart review of 88 subjects, hourly corrected QT intervals calculated by using the Bazett formula were collected. Acquired long QT syndrome was defined as a corrected QT of 500 milliseconds or longer or an increase in corrected QT of 60 milliseconds or greater from baseline level. Risk factors and medications administered were collected from patients' medical records.

RESULTS

The syndrome occurred in 46 patients (52%); mean time of onset was 7.4 hours (SD, 9.4) from time of admission. Among the 88 patients, 52 (59%) received a known QTc-prolonging medication. Among the 46 with the syndrome, 23 (50%) received a known QT-prolonging medication. No other risk factor studied was significantly predictive of the syndrome.

CONCLUSIONS

Acquired long QT syndrome occurs in patients not treated with a known QT-prolonging medication, indicating the importance of frequent QT monitoring of all intensive care patients.

Impaired cerebral circulation in patients with slow coronary flow

Slow coronary flow (SCF) is characterized by delayed opacification of coronary arteries during coronary angiography and is associated with myocardial perfusion abnormalities, ischemia or myocardial infarction. We hypothesized that SCF could be a part of systemic circulatory abnormalities. Therefore, the present study was conducted to investigate whether cerebral blood flow velocity is altered in patients with SCF. The study included 16 patients suffering from chest pain with angiographically proven SCF and 16 subjects suffering from atypical chest pain with angiographically normal coronary flow. All study subjects were selected among those who undergone routine cardiac catheterization. SCF was defined based on thrombolysis in myocardial infarction frame count that reflects coronary artery flow. Thrombolysis in myocardial infarction frame count was significantly higher in patients with SCF than those with normal coronary flow. The average peak systolic, end diastolic and mean flow velocities of the middle cerebral artery were measured and recorded in both groups by transcranial Doppler ultrasonography. Baseline demographic properties were similar in both groups. Echocardiographic parameters were also similar in patients with SCF and those with normal coronary flow. In contrast, both right and left middle cerebral artery peak systolic, end diastolic and mean flow velocities were significantly lower in patients with SCF than those with normal coronary flow. We conclude that cerebral blood flow velocity is significantly lower in patients with SCF. SCF phenomenon may reflect a part of impaired systemic circulation.

The effects of perindopril on QT duration and dispersion in patients with coronary slow flow

Coronary slow flow (CSF) is characterized by delayed opacification of coronary arteries in the absence epicardial occlusive disease. QT duration and dispersion have been reported to be longer in patients with CSF. ACE inhibitors may improve CSF through positive effects on endothelial function. The study included 32 patients having CSF and 25 subjects having normal coronary arteries in coronary angiography. The patients were evaluated with 12-leads electrocardiography and echocardiography before and 3 months after treatment with perindopril. Compared to the control group, maximum corrected QT duration (QTcmax) (432.0 ± 28.9 vs. 407.0 ± 39.1 ms, p = 0.008) and QT dispersion (QTcD) (64.0 ± 16.5 vs. 37.3 ± 12.1 ms, p < 0.001), mitral inflow deceleration time (DT) (251.3 ± 49.4 vs. 218.8 ± 44.5 ms, p = 0.013), and isovolumetric relaxation time (IVRT) (115.8 ± 18.4 vs. 107.2 ± 22.9 ms, p < 0.001) were significantly longer and E/A ratio 0.85 ± 0.2 vs. 1.1 ± 0.3, p = 0.004) was lower in patients with CSF. QTcmax (to 407.0 ± 28.0 ms, p = 0.001), QTcD (to 44.5 ± 11.4 ms, p < 0.001), DT (to 221.6 ± 37.7 ms, p < 0.001) and IVRT (to 103.8 ± 16.1 ms, p < 0.001) were significantly decreased and E/A ratio (to 0.98 ± 0.3, p < 0.001) was significantly increased after treatment with perindopril. Coronary slow may be associated with prolonged QT interval and increased QT dispersion and impaired diastolic filling. Perindopril may be helpful in restoration of these findings.