Corrected QT Interval Dispersion Research Articles

Electrocardiographic Abnormalities in Hospitalized Patients with COVID-19 and the Associations with Clinical Outcome

The cardiovascular (CV) system can often be affected during SARS-CoV-2 infection and several acute manifestations, such as myocardial infarction, pericarditis, myocarditis and arrhythmias have been described. We provide a retrospective overview of electrocardiographic (ECG) features and their relationship with clinical outcomes in a cohort of patients admitted to our COVID-19 Unit between November 2020 and May 2021. Resting standard 12-lead ECGs were performed in all patients at admission and in those recovering from SARS-CoV-2 infection also at discharge. Clinical and serological records alongside ECG measurements were retrospectively evaluated and statistical analysis was performed to identify relationships between variables. A total of 123 patients (44% females) with a mean age of 73.9 years were enrolled. Ninety-five (77%) patients recovered from SARS-CoV-2 infection and were discharged while 28 (23%) died in hospital. Almost 90% of patients displayed at least one CV risk factor and 41 (33%) patients had at least one previous CV event. We observed that heart rate, corrected QT interval dispersion (QTcd) and inverted T waves are independently associated with in-hospital death and inverted T waves show the strongest association. This association remained significant even after correcting for the number of CV risk factors at baseline and for the type of CV risk factor at baseline. Our study demonstrated that some ECG abnormalities at admission are independently associated with in-hospital death regardless of pre-existing CV risk factors. These findings may be of particular relevance in clinical settings with limited access to advanced techniques, such as cardiac magnetic resonance and could help improve the outcomes of patients with cardiac involvement related to SARS-CoV-2 infection.

Effect of particulate matter 2.5 on QT dispersion in patients with chronic respiratory disease

PM2.5 air pollutants increased risk of ventricular arrhythmias. The prolonged corrected QT interval (QTc) and QT dispersion (QTd) is common in patients with chronic airway disease and is associated with heightened risk of ventricular tachyarrhythmia. We sought to examine the effect of PM2.5 exposure on QTc and QTd in patients with chronic airway disease. We enrolled 73 patients with chronic airway disease into the study. The 12-lead ECGs were recorded during high-exposure and low-exposure periods of PM2.5. QTc and QTd were compared between 2 periods. Mean age was 70 ± 10 years. Mean FEV1/FVC was 63 ± 14%. There was no difference in QTc between PM2.5 high-exposure and low-exposure periods. However, QTd was significantly increased during PM2.5 high-exposure compared to low-exposure periods in male patients (43.5 ± 15.0 vs. 38.2 ± 12.1 ms, P = 0.044) but no difference was found in females. We found that patients who worked mostly indoor had less QTd than those working outdoor during PM2.5 low-exposure period. In addition, those who wore face mask tended to have less QTd during low-exposure period than those who did not. High PM2.5 exposure increased QTd in male patients with chronic airway disease. Working indoors and wearing face mask were associated with less QTd.

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.

Baseline Corrected QT Interval Dispersion Is Useful to Predict Effectiveness of Metoprolol on Pediatric Postural Tachycardia Syndrome.

ObjectivesThe study was designed to explore the role of baseline-corrected QT interval dispersion (QTcd) in predicting the effectiveness of metoprolol on pediatric postural tachycardia syndrome (POTS).MethodsThere were two groups in the study, the discovery group and the validation group. The children with POTS in the discovery group were treated with oral metoprolol, with the completed necessary medical records, head-up tilt test (HUTT), blood chemistry, and 12-lead ECG before treatment at the pediatrics of Peking University First Hospital, China. According to whether the symptom score (SS) was reduced by more than 2 points after administration with oral metoprolol as compared with that before treatment, the children with POTS were separated into responders and non-responders. The demographic characteristics, hemodynamic indicators, and the QTcd of the two groups were compared, and the estimate of the baseline QTcd in predicting the treatment response to metoprolol was tested through a receiver operating characteristic (ROC) analysis. Other 24 children suffering from POTS who were, administrated with metoprolol at the pediatrics of Peking University First Hospital were included in the validation group. The sensitivity, specificity, and accuracy of the baseline QTcd in the prediction of the effectiveness of metoprolol on POTS were validated in children.ResultsThe pre-treatment baseline QTcd in responders treated with metoprolol was longer than that of the non-responders in the discovery group [(66.3 ± 20.3) ms vs. (45.7 ± 19.9) ms, p = 0.001]. The baseline QTcd was negatively correlated with SS after metoprolol treatment (r = −0.406, p = 0.003). The cut-off value of baseline QTcd for the prediction of the effectiveness of metoprolol on pediatric POTS was 47.9 ms, yielding a sensitivity of 78.9% and a specificity of 83.3%, respectively. The validation group showed that the sensitivity, specificity, and accuracy of the baseline QTcd ≥ 47.9 ms before treatment for estimating the effectiveness of metoprolol on POTS in children were 73.7, 80.0, and 75.0%, respectively.ConclusionBaseline QTcd is effective for predicting the effectiveness of metoprolol on pediatric POTS.

Corrected QT interval and QT dispersion in temporal lobe epilepsy

BackgroundCardiac arrhythmias are expected among patients with epilepsy due to the effect of anti-epileptic drugs. Temporal lobe epilepsy also causes autonomic seizures that may affect heart rhythm. Prolongation of the corrected QT interval and QT dispersion is a risk factor for cardiac arrhythmia.ObjectivesWe aimed to assess corrected QT interval and QT dispersion in patients with epilepsy and if there is a difference between patients with temporal epilepsy versus non-temporal epilepsy.MethodsThis study was conducted on 100 patients (50 patients with temporal epilepsy and 50 patients with non-temporal epilepsy) and 50 age- and sex-matched healthy controls. They underwent a prolonged (6 to 24 h) 22 channel computerized electroencephalogram monitor with a 10–20 system. QT dispersion, QT interval, and corrected QT interval (using Bazett’s formula) were calculated.ResultsThis study showed significantly higher QT dispersion and corrected QT interval in patients with epilepsy when compared to the age- and sex-matched control group (P < 0.001, P < 0.001). Also, the corrected QT interval and QT dispersion were significantly higher in temporal epilepsy patients when compared to the non-temporal group (P < 0.001, P < 0.001).ConclusionCorrected QT interval and QT dispersion are higher in epileptic patients and more among temporal epilepsy patients in comparison to non-temporal epilepsy patients.

RISK PREDICTION FOR ARRHYTHMIA IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

The aim: To evaluate P-wave dispersion (PwD), as an independent predictor of atrial fibrillation, corrected QT interval dispersion (cQTD), the noninvasive marker of ventricular arrhythmia and sudden cardiac death, investigate the atrial electromechanical delay in patients with COPD and assess their relation with the severity of the disease. Materials and methods: We prospectively enrolled consecutive patients with newly diagnosed COPD (n = 53, age 41.2 ± 6.8 years), compared with an age-matched healthy control group (n = 51, age 40.9 ± 6.5 years). A standard 12-lead electrocardiogram of each patient was analyzed for PwD and сQTD. Atrial electromechanical delay was analyzed by echocardiographic tissue Doppler imaging. The difference between PAs-PAl, PAs-PAt, and PAl-PAt were defined as left intra-atrial, right intra-atrial, and interatrial electromechanical delays (EMD), respectively. Results: PwD was higher in COPD patients than in control subjects (39.47 ± 3.12 ms vs. 30.29 ± 3.17 ms, p &lt; 0.05). In comparison between control group and COPD subgroups (mild, moderate and severe), there was a statistically significant difference among these free groups in terms of PwD. Subgroup analyses showed that this difference was mainly due to patients with severe COPD. Regarding cQTD, there was a statistically significant increase in COPD patients 57.92 ± 3.43 ms vs 41.03 ± 5.21 ms, p &lt; 0.05 respectively. PAs, PAl and PAt durations, right intra-atrial and interatrial EMD were also significantly longer in COPD patients (p &lt; 0.05). Furthermore, there were significant negative correlations between FEV1 and PwD (r = – 0.46, p &lt; 0.05), right intra-atrial (r = – 0.39 ms, p &lt; 0.05), interatrial EMD ( r = – 0.35 ms, p &lt; 0.05) and cQTD (r = – 0.32, p &lt; 0.05). Conclusions: Atrial conduction time, such as inter- and intra-atrial EMD intervals, PwD and cQTD were longer than in healthy controls and correlated with the severity of COPD. These parameters offer a non-invasive and cost-effective assessment method for detecting patients at high risk of arrhythmia. Nevertheless, further prospective investigations on this issue are required.

Prognostic Scale to Stratify Risk of Intrahospital Death in Patients with Acute Myocardial Infarction with ST-Segment Elevation.

INTRODUCTION The scales available to predict death and complica-tions after acute coronary syndrome include angiographic studies and serum biomarkers that are not within reach of services with limited resources. Such services need specifi c and sensitive instruments to evaluate risk using accessible resources and information. OBJECTIVE Develop a scale to estimate and stratify the risk of intra-hospital death in patients with acute ST-segment elevation myocardial infarction. METHODS An analytical observational study was conducted in a universe of 769 patients with acute ST-segment elevation myocardial infarction who were admitted consecutively to the Camilo Cienfuegos Provincial Hospital in Sancti Spíritus Province, Cuba, from January 2013 to March 2018. The fi nal study cohort included 667 patients, ex-cluding 102 due to branch blocks, atrial fi brillation, drugs that prolong the QT interval, low life expectancy or history of myocardial infarction. The demographic variables of age, sex, skin color, classic cardiovas-cular risk factors, blood pressure, heart rate, blood glucose level, in addition to duration and dispersion of the QT interval with and without correction, left ventricular ejection fraction, and glomerular fi ltration rate were included in the analysis. Patients were categorized according to the Killip-Kimball Classifi cation for degree of heart failure. A risk scale was constructed, the predictive ability of which was evaluated using the detectability index associated with an receiver-operator curve.RESULTS Seventy-seven patients died (11.5%). Mean blood glucose levels were higher among the deceased, while their systolic and dia-stolic blood pressure, left ventricular ejection fraction, and glomerular fi ltration rate were lower than those participants discharged alive. Rel-evant variables included in the scale were systolic blood pressure, Killip-Kimball class, cardiorespiratory arrest, glomerular fi ltration rate, corrected QT interval dispersion, left ventricular ejection fraction, and blood glucose levels. The variable with the best predictive ability was cardiorespiratory arrest, followed by a blood glucose level higher than 11.1 mmol/L. The scale demonstrated a great predictive ability with a detectability index of 0.92. CONCLUSIONS The numeric scale we designed estimates and strati-fi es risk of death during hospitalization for patients with ST-segment elevation myocardial infarction and has good metric properties for predictive ability and calibration. KEYWORDS ST-segment elevation myocardial infarction, mortality, risk assessment, Cuba.

Evaluation of P Wave Dispersion for Prediction of Atrial Fibrillation and Corrected QT Interval Dispersion, Tp-e Interval, Tp-e/Corrected QT Ratio for Prediction of Ventricular Arrhythmic Events in Patients with Cardiac Syndrome X

Evaluation of P Wave Dispersion for Prediction of Atrial Fibrillation and Corrected QT Interval Dispersion, Tp-e Interval, Tp-e/Corrected QT Ratio for Prediction of Ventricular Arrhythmic Events in Patients with Cardiac Syndrome X

Assessment of Atrial Fibrillation and Ventricular Arrhythmia Risk After Transplant in Patients With End-Stage Renal Disease by P-wave/QT Interval Dispersion, T-Wave Peak-End Interval, and T-Wave Peak-End/QT Interval Ratio.

The association between end-stage renal disease with atrial fibrillation and ventricular arrhythmias is well documented. The aim of this study was to investigate whether kidney transplant has any effect on P-wave dispersion, a predictor of atrial fibrillation and corrected QT interval dispersion, T-wave peak-end interval, and T-wave peak-end/corrected QT ratio, which are predictors of ventricular arrhythmias in patients with end-stage renal disease. In a retrospective study, 234 patients (125 kidney transplant and 109 healthy control patients) were examined. P-wave dispersion, corrected QT dispersion, T-wave peak-end interval, and T-wave peak-end/corrected QT ratio values before and 3, 6, and 12 months after transplant were calculated and compared in transplant recipients. Baseline values of the control group were compared with 12-month values of kidney transplant patients. We observed a statistically significant decline in P-wave dispersion, corrected QT dispersion, T-wave peak-end interval, and T-wave peak-end/corrected QT ratio values among the pretransplant and 3-, 6-, and 12-month posttransplant measurements (P < .001 for all comparisons). However, the values of these measurements in the transplant group at 12 months were significantly higher than baseline values of the control group (P < .001 for all comparisons). P-wave dispersion, corrected QT dispersion, T-wave peak-end interval, and T-wave peak-end/corrected QT ratio were shown to be attenuated after transplant, although they remained higher than baseline measurements in healthy individuals. These results indirectly offer that there may be a reduction in risk of atrial fibrillation and ventricular arrhythmias after transplant.

Interictal electrocardiographic alternations in patients with drug-resistant epilepsy

PurposePrevious studies suggested the possible role of autonomic dysfunction in sudden unexpected death in epilepsy (SUDEP). The aim of this study is to assess the interictal ECG alternations especially heart rate variability (HRV), as a marker of autonomic dysfunction, in patients with drug-resistant epilepsy and determine the effect of epilepsy type and duration, seizure frequency and anti-epileptic drugs (AEDs) on ECG findings. MethodsIn this comparative cross-sectional study, the interictal ECG parameters of 64 consecutive patients with drug-resistant epilepsy and the same number of age and sex-matched controls were analyzed. Epilepsy type and duration, seizure frequency, MRI findings and patients’ anti-convulsive medications were determined. ResultsOur study showed significant longer mean PR interval, shorter mean QRS duration, shorter mean QTc interval and longer corrected QT interval dispersion (QTcd) in patients with epilepsy compared to healthy subjects. The analysis of RR intervals revealed reduced RR standard deviation (SDNN), which is a marker of reduced HRV. A positive linear correlation was found between QRS duration and epilepsy duration. No significant correlation was found between taking a certain kind of AED, and ECG alternations, except for mild QTcd prolongation in patients taking valproate. ConclusionOur study showed clinically important alternations in interictal ECG parameters in patients with drug-resistant epilepsy which could result in sudden cardiac death.

Atrial and Ventricular Electrocardiographic Dromotropic Disturbances in Down Syndrome Patients with Structurally Normal Heart: A Cross-Sectional Study

Background: We designed a cross-sectional study to determine electrocardiographic disorders in Down syndrome patients with congenitally normal hearts in a bid to predict fatal cardiac arrhythmia in the future. Materials and Methods: We investigated 60 children with DS without congenital abnormal hearts. Sixty healthy juveniles were also included in the study as a control group. Physical examination, electrocardiography, and echocardiography were performed in all subjects. Corrected QT interval (QTc) was measured according to Bazett’s formula. Results: Patients with DS consisted of 32 males (53.33%), and 28 females (46.66%), aged 6–13 (9.21 ± 6.24) years old. Healthy subjects comprised 31 males (51.66%), and 29 females (48.33%) with a mean age of 9.15 ± 5.01. The two groups were significantly different in terms of heart rate (P=0.006), maximum P-wave duration (P=0.001), and P-wave dispersion (PWd, P=0.0001). There was no statistically significant difference regarding minimum P-wave duration (P=0.176). The patients with DS had a greater maximum QTc interval, QT dispersion, and corrected QT interval dispersion (QTc-d) than the healthy control subjects (P=0.001). However, there was no difference in maximum QT interval and minimum QTc interval between the two groups (P=0.67 and P=0.553, respectively). A positive correlation was found between age, heart rate, and all electrocardiographic variables. Conclusion: All DS patients, even in the absence of concomitant congenital heart disease should be followed up carefully by electrocardiography, looking for increased PWd and QTc-d to detect predisposed cases to arrhythmia.

Rhythm and orthopedics: The effect of music therapy in cast room procedures, a prospective clinical trial

IntroductionCast room procedures generally cause anxiety in patients. Anxiety complicates the procedure as well as increases the risk of a complication. Listening to music was found to be the safest and most common non-drug treatment method. The aim of this study is to evaluate the effect of listening to music on adult patients in cast room procedures. This study points out the relation between anxiety and anxiety relevant cardiac arrhythmia. Materials and methodsThe study was performed on 199 patients with stable general condition, aged above 18. The patients were divided into two groups. Randomization method used in the study was coin flip. The first group (Group 1) listened to music during cast room procedures whereby the second group (Group 2) did not listen to music. Length of the procedure, complication, blood pressure and heart rate evaluations before and after the procedure, Visual Analogue Scale (VAS scores for pain), State-Trait Anxiety Inventory (STAI) anxiety score, patient satisfaction, willingness of the patient to repeat the procedure, P wave dispersion (Pd) and corrected QT interval dispersion (QTcd) as electrocardiographic arrhythmia predictors were evaluated. The Clinical Research Ethics Committee approval was obtained for this study. ResultsSignificant difference was shown between the two groups for the following criteria: VAS scores (p = 0.005), anxiety scores (p = 0.032), processing time (p = 0.027), and QTcd values (p = 0.031). Patient satisfaction (p < 0.001) and willingness to repeat the procedure (p < 0.001) were higher for the group who listened to music. No significant difference in Pd values, blood pressure and heart rate was reported within the groups. ConclusionMusic therapy is a non-invasive, safe, nonpharmacologic, anxiolytic, and analgesic treatment. Music therapy should become standard protocol in cast room procedures. One of the most important achievements of this study was the fact that music decreases anxiety and anxiety-related cardiac arrhythmia. Therefore, conducting further prospective studies including high cardiac risk patients especially with arrhythmia is crucial.

Assessment of atrial fibrillation and ventricular arrhythmia risk in patients with asthma by P wave/corrected QT interval dispersion.

Although the relationship between obesity-asthma, obesity-atrial fibrillation (AF) and obesity-sudden cardiac death is clearly known, the risk of AF and ventricular arrhythmia has not been clearly determined in asthmatic patients. The aim of this study was to investigate whether AF, ventricular arrhythmia, and sudden cardiac death risk were increased in asthmatic patients using P wave dispersion (PWD) and corrected QT interval dispersion (CQTD). The study was designed as a cross-sectional study. A total of 164 participants (88 patients with asthma and 76 healthy volunteers) were enrolled into the study. PWD and CQTD were measured and recorded in both groups. The statistical difference between the two groups was examined. PWD was higher in the asthma patients than in control subjects (31.53 ± 3.18 vs. 30.33 ± 3.53, p = 0.023). However, there was no statistically difference between the groups in terms of CQTD measurement (43.9 ± 1.84 vs. 43.63 ± 2.06, p = 0.385). In comparison between control group and asthma subgroups (mild, moderate and severe), there was a statistically significant difference among these four groups in terms of PWD (p = 0.017). Subgroup analyses showed that this difference was mainly due to patients with severe asthma. PWD value was elevated in asthmatic compared to the control group. The CQTD was not statistically significant between the groups. These results indicate that the risk of developing AF in asthmatic patients might be higher than in the normal population. Ventricular arrhythmia and sudden cardiac death risk may not be high in asthmatic patients.

Assessment of Atrial Fibrillation and Ventricular Arrhythmia Risk after Bariatric Surgery by P Wave/QT Interval Dispersion

The association of obesity with atrial fibrillation (AF) and with ventricular arrhythmias is well documented. The aim of this study was to investigate whether weight reduction by a laparoscopic sleeve gastrectomy has any effect on P wave dispersion (PWD), a predictor of AF, and corrected QT interval dispersion (CQTD), a marker of ventricular arrhythmias, in obese individuals. In a prospective study, a total of 114 patients (79 females, 35 males) who underwent laparoscopic sleeve gastrectomy were examined. The patients were followed 1year. PWD and CQTD values before and 3rd, 6th, and 12th months after the surgery were calculated and compared. There was a statistically significant decline in body mass index (BMI), PWD, and CQTD values among baseline, 3rd, 6th, and 12th months (p<0.001 for all comparisons). Correlation analysis showed a statistically significant correlation between ΔPWD and ΔBMI (r = 0.719, p < 0.001), ΔPWD and Δleft ventricular end-diastolic diameter (LVEDD) (r = 0.291, p = 0.002), ΔPWD and Δleft atrial diameter (LAD) (r = 0.65, p < 0.001), ΔCQTD and ΔBMI (r = 0.266, p = 0.004), ΔCQTD and ΔLVEDD (r = 0.35, p < 0.001), ΔCQTD and ΔLAD (r = 0.289, p = 0.002). In multiple linear regression analysis, there was a statistically significant relationship between ΔPWD and ΔBMI (β = 0.713, p < 0.001), ΔPWD and ΔLVEDD (β = 0.174, p = 0.016), ΔPWD and ΔLAD (β = 0.619, p < 0.001), ΔCQTD and ΔBMI (β = 0.247, p = 0.011), ΔCQTD and ΔLVEDD (β = 0.304, p < 0.001), ΔCQTD and ΔLAD (β = 0.235, p = 0.009). PWD and CQTD values of patients were shown to be attenuated after bariatric surgery. These results indirectly offer that there may be a reduction in risk of AF, ventricular arrhythmia, and sudden cardiac death after obesity surgery.

QRS duration and dispersion for predicting ventricular arrhythmias in early stage of acute myocardial infraction

ObjectiveTo determine the relationship between QRS duration and dispersion and the occurrence of ventricular arrhythmias in early stages of acute myocardial infarction (AMI). DesignA retrospective, longitudinal descriptive study was carried out. SettingHospital General Universitario “Camilo Cienfuegos”, Sancti Spíritus, Cuba. Secondary health care. Patients or participantsA total of 209 patients diagnosed with ST-segment elevation AMI from January 2012 to June 2014. Main variables of interestThe duration and dispersion of the QT interval, corrected QT interval, and QRS complex were measured in the first electrocardiogram performed at the hospital. The presence of ventricular tachycardia/fibrillation was assessed during follow-up (length of hospital stay). ResultsArrhythmias were found in 46 patients (22%); in 25 of them (15.9%), arrhythmias originated in ventricles, and were more common in those subjects with extensive anterior wall AMI, which was responsible for 81.8% of the ventricular fibrillations and more than half (57.1%) of the ventricular tachycardias. The widest QRS complexes (77.3±13.3 vs. 71.5±6.4ms; p=0.029) and their greatest dispersion (24.1±16.2 vs. 16.5±4.8ms; p=0.019) were found on those leads that explore the regions affected by ischaemia. The highest values of all measurements were found in extensive anterior wall AMI, with significant differences: QRS 92.3±18.8ms, QRS dispersion 37.9±23.9ms, corrected QT 518.5±72.2ms, and corrected QT interval dispersion 94.9±26.8ms. Patients with higher QRS dispersion values were more likely to have ventricular arrhythmias, with cutoff points at 23.5ms and 24.5ms for tachycardia and ventricular fibrillation, respectively. ConclusionsIncreased QRS duration and dispersion implied a greater likelihood of ventricular arrhythmias in early stages of AMI than increased duration and dispersion of the corrected QT interval.

Duración y dispersión del QRS para predecir arritmias ventriculares en las fases iniciales del infarto agudo de miocardio

ObjectiveTo determine the relationship between QRS duration and dispersion and the occurrence of ventricular arrhythmias in early stages of acute myocardial infarction (AMI). DesignA retrospective, longitudinal descriptive study was carried out. SettingHospital General Universitario “Camilo Cienfuegos”, Sancti Spíritus, Cuba. Secondary health care. Patients or participantsA total of 209 patients diagnosed with ST-segment elevation AMI from January 2012 to June 2014. Main variables of interestThe duration and dispersion of the QT interval, corrected QT interval, and QRS complex were measured in the first electrocardiogram performed at the hospital. The presence of ventricular tachycardia/fibrillation was assessed during follow-up (length of hospital stay). ResultsArrhythmias were found in 46 patients (22%); in 25 of them (15.9%), arrhythmias originated in ventricles, and were more common in those subjects with extensive anterior wall AMI, which was responsible for 81.8% of the ventricular fibrillations and more than half (57.1%) of the ventricular tachycardias. The widest QRS complexes (77.3±13.3 vs. 71.5±6.4ms; P=.029) and their greatest dispersion (24.1±16.2 vs. 16.5±4.8ms; P=.019) were found on those leads that explore the regions affected by ischemia. The highest values of all measurements were found in extensive anterior wall AMI, with significant differences: QRS 92.3±18.8ms, QRS dispersion 37.9±23.9ms, corrected QT 518.5±72.2ms, and corrected QT interval dispersion 94.9±26.8ms. Patients with higher QRS dispersion values were more likely to have ventricular arrhythmias, with cutoff points at 23.5ms and 24.5ms for tachycardia and ventricular fibrillation, respectively. ConclusionsIncreased QRS duration and dispersion implied a greater likelihood of ventricular arrhythmias in early stages of AMI than increased duration and dispersion of the corrected QT interval.

Effects of a high salt intake and potassium supplementation on QT interval dispersion in normotensive healthy subjects.

To evaluate the effects of dietary sodium intake on QT interval dispersion (QTd) in normotensive healthy subjects and assess the protective effects of dietary potassium. Methods All subjects were sequentially maintained on a protocol with a three-day baseline investigation, seven-day low-salt period (3 g/day (d), NaCL), seven-day salt loading period (18 g/d, NaCL) and a seven-day salt loading with potassium supplementation period (4.5 g/d, KCL). On the last day of each period, 24-hour urine samples were collected, the blood pressure values were measured and an electrocardiogram was recorded. The QT interval, QTd and T peak-T end interval (Tp-Te) were subsequently measured and calculated. Patients Sixty-four normotensive subjects, men and women, ranging from 28 to 60 years of age, were enrolled. Results There were no great fluctuations in heart rate after salt loading, whereas the systolic blood pressure (SBP, mmHg) and diastolic blood pressure (DBP, mmHg) increased and the corrected QT interval (QTc), corrected QT interval dispersion (QTdc) and Tp-Te values were significantly prolonged compared to that observed in the low-salt period (SBP, 118.6 ± 13.5 vs. 111.7 ± 11.3, p<0.01; DBP, 76.9 ± 8.6 vs. 71.7 ± 7.7, p<0.01; QTdc, 60.3 ± 19.4 vs. 55.6 ± 19.4, p<0.05; Tp-Te, 83.0 ± 10.1 vs. 79.8 ± 8.5, p<0.01). Surprisingly, all of these changes were reversed by potassium supplementation (SBP, 114.5 ± 12.3 vs.118.6 ± 13.5, p<0.01; DBP, 72.2 ± 7.9 vs.76.9 ± 8.6, p<0.01;QTd, 42.6 ± 15.1 vs. 47.4 ± 19.0, p<0.05; QTdc, 52.2 ± 18.0 vs. 60.3 ± 19.4, p<0.05; Tp-Te, 79.1 ± 8.5 vs. 83.0 ± 10.1, p<0.01). Conclusion Salt loading prolongs the QT interval, QTd and Tp-Te, while dietary potassium supplementation reverses these alterations. These findings suggest that potassium supplementation may improve variation in the healing time and prevent arrhythmia.

Parameters of Cardiac Electrical Instability in Chronic Haemodialysis Patients

Background: A large proportion of cardiovascular mortality in dialysis patients is caused by sudden death that is related to the dialysis procedure. Parameters of heart rate variability, P wave duration and dispersion and rate corrected QT and QT dispersion are readily used to assess cardiac electrical stability. However, there are relatively few data discussing the factors associated with arrhythmia in dialysis patients. Methods: The study included 30 patients on regular haemodialysis. All patients had full history taking (age, sex, duration of haemodialysis in months and smoking history), clinical examination, laboratory investigations (serum Mg, K, Na and complete blood picture), echocardiography and 24-hours Holter recording. Results: The study included 30 patient on regular haemodialysis (mean duration 30.9±13.2 months), 53.3% males with mean age 43.9±10.1 years. All ECG and Holter derived parameters showed statistically significant changes during haemodialysis. There were increase in P wave duration and dispersion, rate corrected QT interval and QT dispersion and decrease in heart rate variability, that are arrhythmogenic. Moreover, the incidence of both supraventricular and ventricular ectopics increased during dialysis. Smoking and long term dialysis were associated with more arrhythmia risk. Conclusions: Patients on regular haemodialysis are susceptible to cardiac arrhythmias. The process of haemodialysis itself is arrhythmogenic. Smoking and long term haemodialysis are associated with higher incidence of cardiac electrical instability.

Predictors of early death in patients with acute pulmonary embolism

AimWe aimed to determine the predictors of early death in the course of acute pulmonary embolism (APE). Materials and methodsWe included 206 patients who had been admitted to our hospital between January 2011 and April 2013 with the diagnosis of APE. We derived a new model including corrected QT interval dispersion (QTcd) and P wave dispersion (Pd), echocardiographic findings, laboratory markers, and blood cell count indices to predict early death in patients with APE. ResultsThirty patients (14.5%) died; 176 patients (85.5%) lived after diagnosis of APE. Logistic regression (LR) analysis found that troponin I (odds ratio [OR], 1.084 [95% confidence interval {CI}, 1.009-1.165]), creatinine (OR, 4.153 [95% CI, 1.375-12.541]), mean platelet volume (OR, 1.991 [95% CI, 1.230-3.223]), neutrophil to lymphocyte ratio (NLR) (OR, 1.079 [95% CI, 1.005-1.160]), QTcd (OR, 1.084 [95% CI, 1.043-1.127]), Pd (OR, 1.049 [95% CI, 1.004-1.096]) were associated with early death in APE. New LR model (area under the curve [AUC], 0.970) performed better than the simplified pulmonary embolism severity index (sPESI) score (AUC, 0.859) in predicting early death in APE (P = .021).The predictivity of the sPESI score significantly improved after its single combination with creatinine, QTcd, or troponin I. When the combined model was constructed together with these 6 independent variables and sPESI score, stepwise LR model automatically excluded Pd and NLR, and the AUC from the rest of the combined model was 0.976, which is significantly different from the AUC of sPESI (0.859) (P = .0031). ConclusionsCreatinine, troponin I, and QTcd significantly improves sPESI score. A new model with troponin I, creatinine, mean platelet volume, NLR, QTcd, and Pd seems to have greater prognostic power than the sPESI scoring system.

Efecto del esmolol sobre el intervalo QT corregido y alteraciones de la dispersión del intervalo QT corregido observadas durante la inducción de la anestesia en pacientes hipertensos que recibieron un inhibidor de la enzima convertidora de la angiotensina

Background and objectivesThe importance of minimizing the exaggerated sympatho-adrenergic responses and QT interval and QT interval dispersion changes that may develop due to laryngoscopy and tracheal intubation during anesthesia induction in the hypertensive patients is clear. Esmolol decreases the hemodynamic response to laryngoscopy and intubation. However, the effect of esmolol in decreasing the prolonged QT interval and QT interval dispersion as induced by laryngoscopy and intubation is controversial. We investigated the effect of esmolol on the hemodynamic, and corrected-QT interval and corrected-QT interval dispersion changes seen during anesthesia induction in hypertensive patients using angiotensin converting enzyme inhibitors. MethodsSixty ASA I-II patients, with essential hypertension using angiotensin converting enzyme inhibitors were included in the study. The esmolol group received esmolol at a bolus dose of 500mcg/kg followed by a 100mcg/kg/min infusion which continued until the fourth minute after intubation. The control group received 0.9% saline similar to the esmolol group. The mean blood pressure, heart rate values and the electrocardiogram records were obtained as baseline values before the anesthesia, 5min after esmolol and saline administration, 3min after the induction, and 30s, 2min and 4min after intubation. ResultsThe corrected-QT interval was shorter in the esmolol group (P=.012), the corrected-QT interval dispersion interval was longer in the control group (P=.034) and the mean heart rate was higher in the control group (P=.022) 30s after intubation. The risk of arrhythmia frequency was higher in the control group in the 4-min period following intubation (P=.038). ConclusionEndotracheal intubation was found to prolong corrected-QT interval and corrected-QT interval dispersion, and increase the heart rate during anesthesia induction with propofol in hypertensive patients using angiotensin converting enzyme inhibitors. These effects were prevented with esmolol (500mcg/kg bolus, followed by 100mcg/kg/min infusion). During induction, the blood pressure tends to decrease with esmolol where care is needed.