Effect of transcatheter aortic valve implantation on QT dispersion in patients with aortic stenosis

Background QT dispersion （QTd） is a predictor of ventricular arrhythmia. Ventricular arrhythmia is an important factor influencing morbidity and mortality in patients with aortic stenosis. Surgical aortic valve replacement reduced the QTd in this patients group. However, the effect of transcatheter aortic valve implantation （TAVI） on QTd in patients with aortic stenosis is unknown. The aim of this study was to investigate the effect of TAVI on QTd in patients with aortic stenosis. Methods Patients with severe aortic stenosis, who were not candi-dates for surgical aortic valve replacement due to contraindications or high surgical risk, were included in the study. All patients underwent electrocardiographic and echocardiographic evaluation before, and at the 6th month after TAVI, computed QTd and left ventricular mass index （LVMI）. Results A total 30 patients were admitted to the study （mean age 83.2 ± 1.0 years, female 21 and male 9, mean valve area 0.7 ± 3 mm2）. Edwards SAPIEN heart valves, 23 mm （21 patients） and 26 mm （9 patients）, by the transfemoral approach were used in the TAVI procedures. All TAVI procedures were successful. Both QTd and LVMI at the 6th month after TAVI were significantly reduced com-pared with baseline values of QTd and LVMI before TAVI （73.8 ± 4 ms vs. 68 ± 2 ms, P=0.001 and 198 ± 51 g/m2 vs. 184 ± 40 g/m2, P=0.04, respectively）. There was a significant correlation between QTd and LVMI （r=0.646, P〈0.001）. Conclusions QTd, which malign ventricular arrhythmia marker, and LVMI were significantly reduced after TAVI procedure. TAVI may decrease the possibility of ventricu-lar arrhythmia in patients with aortic stenosis.

Defective recovery of QT dispersion following transcatheter aortic valve implantation： frequency, predictors and prognosis

Background Corrected QT dispersion （cQTD） has been correlated with non-uniform ventricular repolarisation and increased mortality. In patients with aortic stenosis, cQTD has been shown improved after surgical valve replacement, but the effects of transcatheter aortic valve implantation （TAVI） are unknown. Therefore, we sought to explore the frequency, predictors and prognostic effects of defective cQTD recovery at 6 months after TAVI. Methods A total of 222 patients underwent TAVI with the Medtronic-CoreValve System between November 2005 and January 2012. Patients who were on class Ⅰ or Ⅲ antiarrhythmics or on chronic haemodialysis or who developed atrial fibrillation, a new bundle branch block or became pacemaker dependent after TAVI were excluded. As a result, pre-, post- and follow-up ECG （median： 6 months） analysis was available in 45 eligible patients. Defective cQTD recovery was defined as any progression beyond the baseline cQTD at 6 months. Results In the 45 patients, the mean cQTD was 47 ± 23 ms at baseline, 45 ±17 ms immediately after TAVI and 40 ± 16 ms at 6 months （15% reduction, P = 0.049）. Compared to baseline, cQTD at 6 months was improved in 60% of the patients whereas defective cQTD recovery was present in 40%. cQTD increase immediately after TAVI was an independent predictor of defective cQTD recovery at 6 months （per 10 ms increase; OR： 1.89, 95% CI： 1.15-3.12）. By univariable analysis, defective cQTD recovery was associated with late mortality （HR： 1.52, 95% CI： 1.05-2.17）. Conclusions Despite a gradual reduction ofcQTD after TAVI, 40% of the patients had defective recovery at 6 months which was associated with late mortality. More detailed ECG analysis after TAVI may help to avoid late death.

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.

Effects of 6-minute walk test on the QT dispersion in patients with congestive heart failure

Objective: To investigate the clinical value of QT dispersion (QTd) and the effects of 6-minute walk test (6-MWT) mimicking the patients' daily activities on QTd in patients with congestive heart failure (CHF).Methods: Twenty-eight CHF patients and 22 normal subjects participated these study, who all completed 6-MWT without developing severe arrhythmias.Before and after 6-MWT, standardized 12-lead surface ECGs were obtained to measure QTd and corrected QTd (QTcd).Results: Both before and after 6-MWT, the QTd and QTcd in CHF patients were longer than those in the controls (P<0.001), and QTd and QTcd after 6-MWT were significantly shorter than those before 6-MWT in CHF patients (P=0.007, and 0.018).There was no significant difference in the measurement in the control group.Conclusion: QTd and QTcd are longer in CHF patients than in normal subjects.Moderate exercise may improve the inhomogeneity of ventricular repolarization dispersion in CHF patients.

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.

Both transmural dispersion of repolarization and of refractoriness are poor predictors of arrhythmogenicity： a role for iCEB （QT/QRS）？

We read the original article by Nuis, et al. and the reply by Dogan, et al. with great interest. Nuis, et al. examined whether transcatheter aortic valve implantation （TAVI） in patients suffering from severe aortic stenosis led to changes in corrected QT dispersion （cQTD）, previously used to predict arrhythmic risk. Dogan, et al. proposed that a different marker, transmural dispersion of repolariza- tion （TDR）, has better accuracy in risk prediction.

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 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.

Improvement of increased cQTd is associated with heart function in patients with ischemic heart failure

Background Chronic heart failure （CHF） is life-threatening without timely or effective intervention. In this study, we investigated the association between QT dispersion corrected for heart rate （cQTd） and heart function in patients with CHF. Methods From January 2013 to December 2015, we continuously enrolled 240 patients categorized as New York Heart Association functional class （NYHA） III-IV with a left ventricular ejection fraction （LVEF） 〈 40%. Based on the etiology, the patients were divided into a dilated cardiomyopathy （DCM） group （n = 120） and an ischemic cardiomyopathy （ICM） group （n = 120）. Then, based on the cQTd width, the ICM group was divided into two subgroups： a QS group （cQTd ≤60 ms, n = 70） and a QL group （cQTd 〉 60 ms, n = 50）. All patients were examined by echocardiography and 12-lead electrocardiography （ECG） at 1, 3, 6, and 12 months after enrollment. Results After one year of optimized medical treatment, patients in both groups showed significant improvement in LVEF and NYHA classification from baseline. However, the cQTd in the ICM group, especially the QL, was significantly shorter than that in the DCM group at each time point. In addition, the cQTd was negatively correlated with LVEF and 6-min walking test and positively correlated with NYHA class in the ICM group. Conclusions The present findings clearly demonstrate that cQTd is a meaningful parameter for assessing heart function in the follow-up of ICM patients.

Transmural dispersion of repolarization：a complementary index for cardiac inhomogeneity

We read the article written by Nuis, et al. The authors investigated the effects of transcatheter aortic valve implantation （TAVI） on corrected QT dispersion （cQTD） in severe aortic stenosis patients. They concluded that, 40% of patients had defective cQTD recovery at six months after the procedure and this was associated with increased late mortality risk. We would like to contribute to the study from a different methodological perspective.

A step forward parameter for the effects of transcatheter aortic valve implantation： transmural dispersion of repolarization

We read the article ＂Effect of transcatheter aortic valve implantation on QT dispersion in patients with aortic stenosis＂ by Erkan, et al. with great interest. In this study, they investigated the effect of transcatheter aortie valve implantation （TAVI） on QT dispersion （QTd） in patients with symptomatic severe aortic stenosis.

Novel conduction-repolarization indices for the stratification of arrhythmic risk

Sudden cardiac death （SCD） affects approximately 800,000 individuals per annum globally. It is most frequently due to cardiac tachy-arrhythmias, which include mono-morphic or polymorphic ventricular tachycardia （VT）, torsade de pointes and ventricular fibrillation （VF）. Risk stratification for SCD remains a challenging problem in clinical practice.

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.