Prolonged QTc Dispersion Correlates with Coronary Artery Disease in Acute ST Elevated Myocardial Infarction (STEMI).

Background: It has been found that there is strong association of QT dispersion and QT dispersion ratio with extent and severity of coronary artery disease. Qualitative importance of QTc dispersion on the base line ECG in patients with MI is recognized clinically but quantification of this phenomenon is less commonly used in clinical practice, which might be a better independent risk predictor of this group of patients. Methods: A total of 100 patients were selected, Study populations sub-divided into two groups on the basis of QTc dispersion. In group I (comparison group): QTc dispersion is <60 milliseconds (msec) in group II (study group) : QTc dispersion e”60milliseconds(msec). 50 patients in each group. QT dispersion was calculated on standard resting 12 lead ECGs. QT interval was measured from the beginning of the inscription of the QRS complex to the point at which the T wave returned to the isoelectric line. Angiographic severity of coronary artery disease was assessed by- Vessel score, Friesinger score and Leaman score. Interpretation of coronary angiogram was reviewed by at least two cardiologists. . Results: The mean vessel score for group I patients was 1.16±0.68 and that of group II patients was 2.30±0.64 and the mean difference was statistically significant (p<0.05). Patients those had single vessel involvement had mean QTc dispersion 57.05, patients those had double vessel disease mean QTc dispersion was 102.00 and patients those had triple vessel involvement had mean QTc dispersion 177.60. There was a strong positive correlation with the QTc dispersion and increasing number of vessel involvement (Pearson’s correlation coefficient). The mean Friesinger score for group I patients was 4.84±2.56 and that of group II patients was 9.80±2.60. The mean difference was significantly (p<0.05) higher in group II patients. There was a strong positive correlation between the QTc dispersion and Leaman score (Pearson’s correlation coefficient). In group I patients 56% had insignificant coronary artery disease and 44% had significant coronary artery disease defined by Friesinger index (n=100). In group II patients 6% had Insignificant coronary artery disease & had 94% significant coronary artery disease. Conclusion: QTc dispersion>60 ms had independent predictive value for the severity of coronary artery disease. The greater the QTc dispersion the higher the number of coronary artery involvement. We observed that there is a positive correlation between prolonged QT dispersion and coronary artery disease severity in terms of Vessel score, Friesinger score, Leaman score.

A comparison of the effects of desflurane, sevoflurane and propofol on QT, QTc, and P dispersion on ECG.

The aim of this prospective, randomized, and double-blinded study was to compare the effects of desflurane, sevoflurane, propofol on both atrial and ventricular wall function by measurement of QT dispersion (QTd), corrected QT dispersion (QTcd), and P dispersion (Pd) on electrocardiogram (ECG). Forty-six patients from the American Society of Anesthesiologists class I−II undergoing noncardiac surgery, were enrolled in this study. Patients were randomly allocated to receive desflurane, sevoflurane or propofol anesthesia. ECG recordings were taken before and after 5 minutes of drug administration. Induction with desflurane significantly increased the QTd compared to baseline (38 ± 2 ms vs. 62 ± 6 ms, P < 0.05). Sevoflurane and propofol anesthesia was not associated with any changes in QTd. QTcd was increased with desflurane induction and decreased with sevoflurane and propofol induction, but this decrease was only significant in the propofol group (67 ± 5 ms vs. 45 ± 3 ms, P < 0.05). Pd was significantly increased after induction with desflurane (34 ± 3 vs. 63 ± 6 ms, P < 0.05). There was a significant increase in QTd and Pd in desflurane group, but this increment did not cause any dangerous arrhythmias. QTcd significantly decreased in propofol group. We believe that further investigations are required for using desflurane as safe as sevoflurane and propofol in noncardiac surgery patients who have high cardiac arrhythmia and ischemia risk.

Effects of Levofloxacin on QTcd Interval in Elderly Patients Hospitalized with Acute Exacerbations of COPD / 中华医院感染学杂志

OBJECTIVE To study the effects of levofloxacin on QT correction dispersion(QTcd) interval in elderly patients hospitalized with acute exacerbations of COPD(AECOPD).METHODS Totally 124 patients received IV levofloxacin(500 mg qd) for 10-14 days.Evaluations included of 12-lead ECGs at baseline and blood examination before treatment,day 5 and after treatment.RESULTS QT correction(QTc) interval was no significant changes,but the QTcd interval was with significant prolongation.CONCLUSIONS IV levofloxacin could not cause QTc interval prolongation,but could make QTcd interval prolongation,which is a potential risk of arrhythmia in elderly patients with AECOPD.

Effect of Coronary Angioplasty on QT Dispersion

BACKGROUND AND OBJECTIVES: The change in QT dispersion (QTd) immediately after balloon angioplasty reflects the immediate impact of ischemia. We intended to analyze the immediate impact of ischemia on myocardial repolarization. MATERIALS AND METHODS: Forty-six patients who underwent percutaneous coronary intervention were enrolled. The standard 12-lead electrocardiogram (ECG) was recorded just before, during, and 1 minute, 5 minutes and 10 minutes after ballooning. QTd was determined by the difference between the maximum and minimum QT interval (QTi). We then calculated the corrected QTi (QTc) using Bazett's formula. QTd and QTi were compared according to the site of the ballooned vessel, number of ballooned vessels and history of acute myocardial infarction. RESULTS: QTd just before, during, and 1 minute, 5 minutes and 10 minutes after ballooning were 35.21+/-10.36 msec, 54.56+/-16.89 msec, 50.91+/-14.20 msec, 45.52+/-9.6 msec and 38.56+/-10.89 msec, respectively. QTd increased markedly during ballooning, but after myocardial ischemia was relieved, decreased rapidly. Ten minutes after ballooning, QTd was reduced to a similar level as that of baseline. There were no significant differences between the AMI and non-myocardial infarction groups, single-vessel and multi-vessel groups, and the location of the stenosed artery. There was no significant difference in QTi according to different stenosed vessel. CONCLUSION: QT (QTc) dispersion increased rapidly with myocardial ischemia and reduced rapidly after the myocardial ischemia was resolved. Therefore, increased QTd can be used as an early clue of myocardial ischemia.

The Relationship of QT Variables with Ischemic Heart Disease in Diabetic Patients

BACKGROUND: Diabetic patients have an excess risk of dying from cardiovascular disease, QT interval variables on EKG were suggested as a non-invasive diagnostic tool in the assessment of diabetic cardiac autonomic neuropathy. It has been recently reported that QT interval variables could predict cardiac death in diabetic patients. We investigated whether QT interval variables also predicted ischemic heart disease in diabetic patients. METHODS: Among non-insulin dependent diabetic patients who were admitted to Hangang Sacred Heart Hospital since 1993, we selected study subjects who had no ischemic heart disease at the time of EKG and were follewed up for more than 4 years. Sex, age, duration of diabetes, blood pressure, smoking, HbAlc, diabetic, retinopathy, serum creatinine concentration at the time of EKG and QT interval variables(QT, QTc,QT dispersion, QTc dispersion) were analysed by regression analysis with ischemic heart disease as the sole end point. RESULTS: Out of total 118 patients, 21 patients developed ischemic heart disease during follow-up. Patients were followed up for a mean of 68 months. Sex,age, duration of diabetes, serum creatinine concentration and all QT variables were identified as the potentially important variables in univariate analysis. In Cox multivariate analysis with these variables, serum creatinine concentration and all QT variables were significant and independent predictors of ischemic heart disease in diabetic patients. Among QT variables, QTc dispersin outperformed all other predictors(risk ratio 8.132; confidence interval 3.908~16.921) CONCLUSION: These results suggest that QT interval variables, especially QTc dispersion, could be a useful predictor of ischemic heart disease in diabetic patients and could be used as screening test to select diabetic patients for more extensive cardiac investigation.