Effect of reperfusion strategy on QT dispersion in patients with acute myocardial infarction:Impact on in-hospital arrhythmia

BACKGROUND Myocardial ischemia and ST-elevation myocardial infarction(STEMI)increase QT dispersion(QTD)and corrected QT dispersion(QTcD),and are also associated with ventricular arrhythmia.AIM To evaluate the effects of reperfusion strategy[primary percutaneous coronary intervention(PPCI)or fibrinolytic therapy]on QTD and QTcD in STEMI patients and assess the impact of the chosen strategy on the occurrence of in-hospital arrhythmia.METHODS This prospective,observational,multicenter study included 240 patients admitted with STEMI who were treated with either PPCI(group I)or fibrinolytic therapy(group II).QTD and QTcD were measured on admission and 24 hr after reperfusion,and patients were observed to detect in-hospital arrhythmia.RESULTS There were significant reductions in QTD and QTcD from admission to 24 hr in both group I and group II patients.QTD and QTcD were found to be shorter in group I patients at 24 hr than those in group II(53±19 msec vs 60±18 msec,P=0.005 and 60±21 msec vs 69+22 msec,P=0.003,respectively).The occurrence of in-hospital arrhythmia was significantly more frequent in group II than in group I(25 patients,20.8%vs 8 patients,6.7%,P=0.001).Furthermore,QTD and QTcD were higher in patients with in-hospital arrhythmia than those without(P=0.001 and P=0.02,respectively).CONCLUSION In STEMI patients,PPCI and fibrinolytic therapy effectively reduced QTD and QTcD,with a higher observed reduction using PPCI.PPCI was associated with a lower incidence of in-hospital arrhythmia than fibrinolytic therapy.In addition,QTD and QTcD were shorter in patients not experiencing in-hospital arrhythmia than those with arrhythmia.

QT interval dispersion in the patients with central serous chorioretinopathy

AIM: To evaluate QT dispersion(QTD) in patients with central serous chorioretinopathy(CSC).METHODS: This clinical, comperative, case-control study included 30 patients with CSC at acute phase(Group 1) and 30 age- and sex-matched healthy subjects(Group 2, the control group). From all subjects, a 12-lead surface electrocardiography was obtained. The heart rate(HR), QT maximum(QT max), QT minimum(QT min), QT corrected(QT c), QTD and T mean were manually measured and analyzed. Student’s t-test and Pearson’s method of correlation were used for statistical analysis.· RESULTS: The patient and control groups were matched for age, smoking status(rate and duration) and gender. There were no significant differences with regard to these among the groups(P 】0.05). The participants included 19 men(63.3%) and 11 women(36.7%) in Group1, 20 men(66.7%) and 10 women(33.3%) in Group 2.QT max, QTD and QT c were significantly higher than those of healthy controls(P 【0.001 for QT max, P =0.01 for QTD and P =0.001 for QT c). QT min, T mean and HR did not differ significantly between the study groups(P =0.28 for QT min,P =0.56 for T mean and P 】0.05 for HR). No significant correlation was found between duration of the disorder and QTD values(r =0.13, P 】0.05).CONCLUSION: These findings suggest that CSC may be associated with an increase in QTD and that the patients might be at risk for ventricular arrhythmia.

QT Dispersion Level and Its Clinical Significance in Dilated Cardiomyopathy

Objective To evaluate the clinical significance of QT dispersion (QTd, QTcd) in dilated cardiomyopathy (DCM). Methods QTd and QTcd were measured on simultaneously recording 12 lead electrocardiograms (ECGs) in 60 DCM patients and compared with 60 healthy subjects. Results The values of QTd and QTcd in DCM were significantly higher than those in control group (P<0 01). With subgroup analysis, QTd and QTcd in patients with cardiac sudden death (CSD) were longer than those in survivors and those died of progressive heart failure (P<0 05), patients with ventricular tachycardia (VT) or with severe heart failure than those without (compared with patients with ventricular premature beats [VPB], P<0 05, compared with patients without ventricular arrhythmia [VA], P<0 01) or with mild heart failure (P<0 01). The values of QTd and QTcd in patients with VPB were greater than those in patients without VA(P<0 05). There were significant differences in the rates of VT, CSD and heart failure between the groups of QTd>110 ms and QTd≤110 ms(P<0 01 or P<0 05), in contrast to ejection fraction(EF) and fractional shortening (FS)(P>0 05). Conclusion The values of QTd and QTcd increased in DCM patients were susceptive index for monitoring maligant VA in DCM, also important prognostic markers of CSD. QTd was correlated with NYHA functional class but not with EF and FS.

Nifekalant hydrochloride terminating sustained ventricular tachycardia accompanied with QT dispersion prolongation

Background Ventricular tachycardia （VT） and ventricular fibrillation are the main reasons causing sudden cardiac death.This study aimed to investigate the effects of nifekalant hydrochloride （NIF） on QT dispersion （QTd） in treating VT.Methods A total of 16 consecutive patients suffered sustained VT was included and then randomly divided into two groups according to the administration duration of NIF.In long-time group （group L）, patients were injected with NIF continuously for at least 12 hours after a bolus dose.The patients in short-time group （group S） were injected with NIF just for 1 hour.Results There were 7 of all 10 episodes of VT which were terminated by NIF, including 4 episodes in group L were stopped over 1 hour after continuous infusion of NIF.One patient suffered from torsade de pointes.Electrocardiography analysis indicated that QTd was significantly decreased 12 hours after stopping of infusing NIF compared with that when VT stopped （（45.4±22.1） ms vs.（73.4±33.2） ms, P 〈0.01）, and the corrected QTd （QTcd） decreased too （（47.8±22.9） ms vs.（78.3±36.5） ms, P 〈0.01 ）.There was a positive correlation between the increase in QTd and dose of administrating NIF （P 〈0.01）, so was QTcd （P 〈0.01）.Conclusions More administration of NIF indicates higher terminating rate of VT and more QTd prolongation.However,the safety is acceptable if several important issues were noticed in using NIF, such as serum potassium concentration,stopping side-effect related agents, and carefully observing clinical responses.

QT DISPERSION: A RISK INDICATOR FOR SEVERE VENTRICULAR ARRHYTHMIA IN PATIENTS WITH ISCHEMIC AND IDIOPATHIC CARDIOMYOPATHY

Increased QT dispersion in the surface ECG (QTd = QTmax minus QTmin) is considered as an indicator of electrical inhomogeneitv and a useful predictor for severe ventricular arrhythmia and sudden cardiac death in patients with different heart diseases. Patients with ischemic and idiopathic cardiomyopathy have a very high incidence of severe ventricular arrhythmia and sudden cardiac death. We compared QT, QTc. JT and JTc dispersion in ischemic (ICMP) and idopathic (CCMP) cardiomyopathy patients with and without severe ventricular arrhythmia and normal controls.

Changes of QT Dispersion in Hemodialysis Patients after Administrating Zhigancao Decoction(炙甘草汤)

Objective： To observe the alteration of QT dispersion（QTd） and QTc dispersion（QTcd） in hemodialysis patients after oral administration of Zhigancao Decoction（炙甘草汤,Roasted Licorice Decoction,RLD）.Methods： To investigate the alteration of QTd and QTcd in 68 routine hemodialysis patients before and after hemodialysis with 12-lead electrocardiogram（ECG） after orally administrated RLD for 4 weeks.Blood was also taken for measurement of plasma electrolytes,liver function,renal function,hemoglobin（Hgb） and hematocrit（HCT）.Results： After hemodialysis,QTd and QTcd were prolonged evidently; the difference was significant between before and after hemodialysis（P〈0.05）.After RLD orally administrated for 4 weeks,QTd and QTcd only slightly increased after dialysis compared with pre-dialysis（P〉0.05）.The QTd and QTcd of the post-therapy-post-dialysis decreased significantly compared with the pre-therapy-post-dialysis（P〈0.05）.There were no other significant changes in other variables（post-therapy-pre-dialysis vs.pre-therapy-pre-dialysis,or post-therapy-post-dialysis vs.pre-therapy-post-dialysis; P〉0.05）.After therapy,the number of patients with supraventricular arrhythmia,occasional ventricular premature beat and multiple ventricular premature beat were decreased from 15 to 4,10 to 2 and 7 to 1,respectively.Conclusion： RLD therapy not only lowered the increased QTd and QTcd after hemodialysis,but also displayed a safety profile.

QT wave dispersion in patients with panic disorder

Objective QT dispersion （QTd）, defined as the maximal inter-lead difference in QT intervals on 12 leads of the surface electrocardiogram （ECG）, reflects the regional heterogeneity of ventricular repolarization and has been suggested as an important marker for risk of arrhythmia in addition to the QT interval. Some investigators proposed that it might be a predisposing factor for arrhythmic events and sudden death. Thus, we aimed to investigate whether QTd differs in patients with panic disorder from that in healthy controls. Methods In 40 panic disorder patients and 40 healthy controls, Qmax, Qmin, and QTd values were measured. In addition, the Hamilton depression rating scale and the panic agoraphobia scale were scored for both patients and healthy volunteers. Results Qmax and Qmin values in the panic disorder patients were significantly higher than those in healthy controls. The mean corrected QTd was significantly greater in the patients than in the controls. One-way analysis of covariance （ANCOVA; using left atrial size, age and heart rate as covariates） also corrected the significant difference. In addition, ANCOVA revealed a significant main effect for the diagnosis, indicating a significantly higher QTd for patients compared with controls. Conclusion QTd might be associated with panic disorder. Future studies in larger samples evaluating the effects of treatment are required.

Electrocardiographic alterations in patients with chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease(COPD)have an increased risk for cardiovascular events,and electrocardiography has an important role in detecting cardiac side effects of COPD-related hypoxia.