Increased QT dispersion in patients with insulin-dependent diabetes mellitus

AIM: To compare the QT dispersion in unselected patients with insulin-dependent diabetes mellitus to non-diabetic control subjects and to assess the association between the QT dispersion and cardiac autonomic neuropathy, ischaemic heart disease, blood pressure level and nephropathy. METHODS: 42 patients with insulin-dependent diabetes mellitus and 80 control subjects aged 40-57 years participated. The QT interval was measured in a resting 12-lead electrocardiogram (ECG) and the QT dispersion defined as the difference between the maximum and minimum QT interval. Bazett's formula was used to correct for heart rate (QTc). The degree of cardiac autonomic neuropathy was assessed by five function tests and ischaemic heart disease was defined by a previous myocardial infarction, ECG abnormalities or a positive exercise test. RESULTS: Compared to control subjects, diabetic patients had a longer QTc interval (433 vs. 416 ms; P=0.002) and a higher QT dispersion (36 vs. 30 ms; P=0.02). In the diabetic group, the QTc interval was prolonged in patients with autonomic neuropathy (449 vs. 420 ms; P=0.007) and the QT dispersion was increased in patients with ischaemic heart disease (51 vs. 33 ms; P=0.004). No association was found to urinary albumin excretion rate or blood pressure. CONCLUSION: The QT dispersion as well as the QTc interval is increased in patients with insulin-dependent diabetes mellitus. The association between QT dispersion and ischaemic heart disease indicates that abnormalities in cardiac repolarisation may be caused by complications to diabetes rather than diabetes in itself.     

2型糖尿病患者心血管自主神经功能与QT离散度

目的 :探讨非胰岛素依赖型糖尿病 (2型糖尿病 )患者心血管自主神经功能与 QT离散度 (Q Td)、JT离散度 (JTd)和室性心律失常发生的关系。方法 :2型糖尿病患者 31例 ,按照标准心血管自主神经功能试验的结果分成阳性者及阴性组 ,16例健康人为正常对照组。所有入选人员均测 QTd、JTd及 2 4h Holter心电监测 ,并进行心律失常分析和比较。结果 :2型糖尿病患者心血管自主神经功能异常的发生率为 5 4.8% ,其发生率与病程呈正相关 ,QTd与 JTd显著延长 ,室性心律失常的发生率较高。结论 :QTd和 JTd可作为一项 2型糖尿病自主神经功能异常者发生室性心律失常重要的预测指标     

Increased QT dispersion during hypoglycaemia in patients with type 2 diabetes mellitus

OBJECTIVES: To study effects of insulin-induced hypoglycaemia on the cardiac repolarization, using QT interval measurements, in patients with type 2 diabetes. DESIGN: Hypoglycaemia was induced by an i.v. insulin-infusion and blood glucose was clamped at 2.7 mmol L-1 for 60 min (T = 90-150 min) in two experiments, with (+GLIB) and without (-GLIB) glibenclamide. In a third experiment, with similar hyperinsulinaemia, glucose was clamped at a euglycaemic level (;5 mmol L-1). ECG was continuously recorded for arrhythmia-monitoring, and 12-lead ECGs were recorded at T = 0 and 150 min. QT intervals were measured, and we determined QT dispersion (difference between the maximum and the minimum QT interval) reflecting interlead variability of repolarization. SUBJECTS: Thirteen patients with type 2 diabetes, on combined insulin and glibenclamide treatment, were studied during hypoglycaemia, and eight of them participated in the euglycaemic experiment. RESULTS: No significant arrhythmias were seen during hypoglycaemia but the mean QT intervals and QT dispersion increased significantly (P < 0.001), with no differences between -GLIB and +GLIB. During the euglycaemic clamp all QT measurements remained unchanged. Serum potassium decreased significantly (P < 0.001) during all three clamps, but the decrease was more pronounced during hypoglycaemia. The change in potassium was not correlated to the degree of QT prolongation or QT dispersion. CONCLUSIONS: Significant changes in the repolarization of the heart can be seen during hypoglycaemia in patients with type 2 diabetes, indicating an increased risk of arrhythmia at low blood glucose levels.     

冠心病合并2型糖尿病QT间期离散度变化的临床意义

目的探讨冠状动脉粥样硬化性心脏病(冠心病,CHD)合并2型糖尿病(DM)患者心电图QT间期离散度(QTd)变化的临床意义。方法冠心病患者252例,其中冠心病合并2型糖尿病组(CHD+DM组)150例和未合并糖尿病的冠心病组(CHD组)102例,127例健康体检者作为对照组;分析心电图QT间期离散度(QTd)及校正的QT间期离散度(QTcd)变化。结果 CHD+DM组的QTd值及QTcd值较健康对照组及CHD组明显延长(P0.01);CHD+DM组中同时合并肾病、眼病等微血管并发症者QTcd及QTd值较健康对照组和CHD组明显延长(P0.01);QTcd与血糖(r=0.290,P0.01)及血脂(r=0.167,P0.05)明显正相关。结论冠心病合并糖尿病者加重心室肌复极化的改变。     

QT dispersion is increased in diabetic patients with foot ulcer

QT dispersion, a measure of inhomogenous ventricular repolarization, was measured in diabetic patients with foot ulcer. We recruited 75 patients with non insulin-dependent diabetes mellitus: patients with neuropathic ulcer (n=15, NU group), with ischemic ulcer (n=20, IU group), with previous myocardial infarction (n=20, MI group) and without any diabetic microangiopathies (n=20, DC group). We also studied normal control subjects (n=15, NC group). The interlead variability of rate corrected QT interval (QTc dispersion) was calculated. QTc interval in the MI group was significantly higher than that in the NC or DC but showed no difference in the NU and IU groups. QTc dispersion in the IU (54+/-15 msec) as well as MI (60+/-21 msec) group were significantly higher than the NC (36+/-18 msec) or DC group (39+/-14 msec). This may be due to complicated coronary artery disease in the IU group. Furthermore, QTc dispersion was also increased (49+/-14 msec) in the NU group in which cardiac autonomic nervous dysfunction was suggested. Patients with both types of diabetic ulcer demonstrated increased QT dispersion due to atherosclerosis or neurological disorder.     

Effects of aliskiren on QT duration and dispersion in hypertensive patients with type 2 diabetes mellitus

Aim: To evaluate the effect of aliskiren compared to amlodipine on QT duration and dispersion in hypertensive patients with type 2 diabetes. Methods: A total of 170 outpatients aged 50–75 years with mild to moderate hypertension (SBP >130 and <180 mmHg and DBP >80 and <100 mmHg) and type 2 diabetes were randomly treated with aliskiren 300 mg or amlodipine 10 mg, both given once daily for 24 weeks, according to a prospective, open label, blinded‐end point, parallel group design. At the end of the placebo run‐in, and after 12, and 24 weeks of treatment blood pressure (BP) measurements (by mercury sphygmomanometer, Korotkoff I and V), plasma biochemistry and a standard 12‐lead surface ECG were evaluated. Results: Both aliskiren and amlodipine significantly reduced systolic blood pressure (SBP)/diastolic blood pressure (DBP) values (?27.2/?14.3 mmHg, p < 0.001 vs. placebo and ?27.8/?14.2 mmHg, p < 0.001 vs. placebo, respectively), with no statistical difference between the two drugs. Aliskiren, but not amlodipine, significantly reduced maximum QT interval (QTmax) (?14 ms at 12 weeks and ?17 ms at 24 weeks, both p < 0.05 vs. placebo) and corrected QT max (QTc max) (?26 ms and ?31 ms, p < 0.01) as well as the dispersion of both QT (?11 ms and ?13 ms, p < 0.01) and QTc (?18 ms and ?19 ms, p < 0.01). Conclusions: Despite similar BP lowering effect, aliskiren, but not amlodipine, reduced QT duration and dispersion, which might be related to the ability of aliskiren to interfere with mechanisms underlying myocardial electrical instability in the heart of diabetic hypertensive patients.     

Clinical and genetic determinants of urinary glucose excretion in patients with diabetes mellitus

Aims/IntroductionGlucosuria is a representative symptom in diabetes patients with poor glycemic control and in those treated with sodium–glucose cotransporter 2 inhibitors. Renal threshold levels of glucose excretion are known to vary among individuals, but factors contributing to glucosuria are not well characterized. The present study aimed to clarify clinical and genetic determinants of glucosuria in individuals with diabetes mellitus.Materials and MethodsThe 24‐h urinary glucose excretion was measured in 135 hospitalized patients on admission, with continuous measurement for five consecutive days in 75 patients. Genetic and clinical factors contributing to glucosuria were studied. As a genetic factor, SLC5A2 polymorphism was genotyped. A total of 476 participants (266 participants with type 2 diabetes and 210 healthy controls) were additionally genotyped for the association study of SLC5A2 with type 2 diabetes. A meta‐analysis was carried out with the present study and previous association studies.ResultsMultiple regression analysis showed that the independent variables of average blood glucose (β = 0.41, P = 1.4 × 10⁻⁷), estimated glomerular filtration rate (β = 0.28, P = 6.0 × 10⁻⁵), sex (β = 0.28, P = 5.7 × 10⁻⁵) and SLC5A2 rs9934336 polymorphism (β = 0.17, P = 0.02) were significantly correlated with urinary glucose excretion. The frequency of the A allele of rs9934336 tended to be lower in participants with type 2 diabetes than in controls (odds ratio 0.78, 95% confidence interval 0.53–1.13, not significant), and meta‐analysis showed a significant association between the A allele and type 2 diabetes (summary odds ratio for minor allele [A] 0.86, 95% confidence interval 0.78–0.94, P < 0.002).ConclusionsBlood glucose, estimated glomerular filtration rate, sex and SLC5A2 polymorphism were independent determinants of glucosuria in diabetes mellitus.     

2型糖尿病患者心血管自主神经功能与QT离散离及室性心律失常关系的研究

为探讨2型糖尿病患者心血管自主神经功能与QT离散度（QTd)及室性心律失常的关系。随机选取2型糖尿病患者60例,按标准心血管自主神经功能试验（下简称神功试验）结果分为阳性（异常）组35例和阴性组25例,另取35例健康人作为对照组。分别测定QTd和经心率校正的QTd(QTcd),同时记录24小时室性心律失常的发生率,进行对比分析。结果 60例糖尿病患者心血管神功试验的阳性率为58.3%,阳性组的QTd、QTcd较阴性组明显延长,室性心律失常及复杂性室性心律失常的发生率明显增高（P均＜0.01)。认为糖尿病患者的心血管自主神经功能与QTd与QTcd明显增加,其可能是导致室性心律失常和心源性猝死的重要原因之一。     

2型糖尿病合并冠心病患者心率变导与QT离散度的关系

目的　探讨 2型糖尿病 (T2DM )合并冠心病 (CHD)的心率变异 (HRV)与QT离散度 (QTd)的关系。方法　选择 2 0 0 1- 0 2～ 2 0 0 4 - 0 2东莞市人民医院 2型糖尿病 33例 (B组 )、2型糖尿病合并冠心病 30例 (A组 )患者 ,同时选择正常人 2 1例做对照 (C组 ) ,分别做 2 4h动态心电图 ,经电脑系统分析得出HRV时域和频域分析参数 ,做常规 12导联同步心电图 ,测定QT间期及QTd。结果　 (1)A组的HRV各项参数均低于B组和C组 (P<0 0 1) ,QTd均大于B组和C组 (P <0 0 5 ,P <0 0 1) ;B组的HRV各项参数亦均低于C组 (P <0 0 5 ) ,QTd亦均大于C组 (P <0 0 5 )。 (2 )A组和B组的QTd与SDNN、SDANN、SDNN index均存在着负相关 (P <0 0 5 )。结论　T2DM合并冠心病者心脏自主神经损害较单纯T2DM者重 ,前者迷走神经受损较后者更重。对T2DM及T2DM合并CHD患者常规 2 4h动态心电图检查 ,测量QTd是有益的 ,以便早期发现高危患者。     

The connection between QT dispersion and autonomic neuropathy in patients with type 2 diabetes.

It is controversial whether an increase in the QT dispersion (QTd) on the electrocardiogram (ECG) reflects cardiac autonomic neuropathy in diabetic patients. In the current study, the QTd was compared in 60 type 2 diabetic patients and in 30 healthy subjects, and its association with autonomic neuropathy in diabetic patients was investigated. An increased QTd was found in diabetic patients, compared to healthy subjects. The QTd had significant negative associations with the log of the low and high frequency power (log LF and HF, respectively) of the power spectral analyses (PSA) of heart rate variations and the systolic blood response during standing (Delta BP). There was no significant difference in the QTd between patients with and without sympathetic skin response (SSR), reflecting peripheral sympathetic function. A significant positive correlation was also found between QTd and the systolic blood pressure (SBP). On the other hand, there was no correlation between QTd and serum total cholesterol (TC), triglycerides (TG), fasting plasma glucose (FPG), hemoglobin (Hb) A (1C) concentrations or body mass index (BMI). By multiple regression analysis, the log HF, which reflects cardiac parasympathetic function, and the SBP alone were significantly associated with QTd as the dependent variable. The Delta BP and log LF, which partially reflect sympathetic nerve function, had no significant associations with QTd. These findings suggest that QTd reflects cardiac autonomic neuropathy (relative parasympathetic neuropathy) and that the QTd is also influenced by SBP, independent of autonomic neuro-function.     

Assessment of QT dispersion in symptomatic patients with congenital long QT syndromes.

It has been suggested that QT dispersion recorded on the surface electrocardiogram may be a predictor of arrhythmic events in patients with congenital QT prolongation. To evaluate this, 9 patients (6 female, mean age 17.6 years) with congenital long QT syndromes, all of whom had syncope and documented torsades de pointes, were studied. Patients were studied off treatment and during therapy with beta-blocking agents. Three patients were also studied after left stellate ganglionectomy. An age-matched control group was also studied. Good quality 12-lead electrocardiograms were recorded from all patients. For each lead, QT and RR intervals were measured, and QTc value was calculated. QT and QTc dispersions were calculated for each patient. Patients had a significantly longer mean QT interval compared with that of the control group (450 +/- 100 vs 359 +/- 63 ms; p = 0.015) at similar mean RR intervals (736 +/- 231 vs 783 +/- 289 ms), with a longer mean QTc value (0.53 +/- 0.08 vs 0.41 +/- 0.02 s1/2; p = 0.004). Patients also had longer QT and QTc dispersions compared with those of the control group (110 +/- 45 vs 43 +/- 12 ms [p = 0.004], and 0.108 +/- 0.03 vs 0.05 +/- 0.02 s1/2 [p = 0.002], respectively). QT and QTc dispersions on and off beta-blocking agents were not significantly different. Comparing patients with frequent and those with infrequent symptoms, there was no difference in QT or QTc dispersion either off treatment or during therapy with beta-blocking agents.(ABSTRACT TRUNCATED AT 250 WORDS)     

高血压病患者QT离散度变化的临床意义

目的　探讨高血压病患者QT离散度 (QTd)的变化 ,进一步明确QTd与左室肥厚及室性心律失常的关系。方法　对入选的 90例高血压患者经心电图及心脏超声检查后分为左室肥厚组 38例 ,左室正常组 5 2例 ,另 38例健康人作对照组 ,测量各组QTd并相互比较 ;统计各组室性心律失常的发生率并作比较。结果　 (1)高血压病左室肥厚组 (QTd 6 9 2 1± 12 82 )与高血压病左室正常组 (QTd41 5 4± 13 6 3)及正常对照组 (QTd 36 84± 13 71)比较 ,差异均有非常显著性 (P <0 0 1) ;而高血压左室正常组与正常对照组比较差异无显著性 (P >0 0 5 )。 (2 )高血压病左室肥厚组室性心律失常的发生率(13 16 % )高于左室正常组 (1 92 % ) ,差别有显著性。结论　QTd可作为预测高血压病左室肥厚及室性心律失常事件发生可能性的指标之一     

急性心肌梗死患者QT离散度临床意义的探讨

目的：探讨急性心肌梗死患者QT间期离散度与恶性室性心律失常发生率的关系.方法：观察64例AMI患者发病24小时内的QT离散度,并观察其与两周内恶性心律失常发生率的关系.结果：急性心肌梗死组QT离散度较对照组增大;发生恶性心律失常的患者QT离散度与未发生者有显著统计学差异.结论：急性心肌梗死患者QT离散度增大对恶性心律失常的发生有预测性.     

QT dispersion in patients with Takayasu arteritis

This study was designed to test the hypothesis that myocardial involvement exists in patients with Takayasu arteritis and is associated with increased QT dispersion, which is a marker of repolarization inhomogeneity. Twenty-one consecutive patients with Takayasu arteritis and no significant coronary artery disease were included. Twelve-lead electrocardiogram and exercise-induced thallium-201 myocardial scintigraphy were performed in all patients. Ten of 21 patients (48%) had abnormal findings on scintigraphy. Patients were divided into two groups by the presence (group P, n = 10) or absence (group N, n = 11) of exercise-induced thallium-201 myocardial scintigraphic perfusion abnormalities, including permanent defects in three, reversible defects in four, and slow washout in three. The QT dispersion at rest was significantly greater in group P than that in group N (54 +/- 12 vs 40 +/- 8 msec, p < 0.005). The QTc dispersion at rest was also significantly greater in group P than in group N (59 +/- 15 vs 43 +/- 11 msec, p < 0.01). In patients with Takayasu arteritis, myocardial involvement suggested by exercise-induced thallium-201 myocardial scintigraphic perfusion abnormalities is not rare, even when no significant coronary stenosis is present on angiography. Increased baseline QT dispersion was associated with scintigraphic abnormalities and may be a useful marker of myocardial involvement in patients with Takayasu arteritis.     

Clinical heterogeneity in elderly patients with diabetes mellitus

There is considerable heterogeneity in elderly patients with diabetes mellitus. It is of clinical importance to assess such heterogeneous features in each elderly patient, because this would lead to a better setting of target glucose level in the management of diabetes. In the present study, diabetic subjects were clinically investigated from three different aspects; past, current and future. First, the "past" aspect represents how long and how high the hyperglycemia the patient has had. Our cross-sectional investigation showed a broad range of duration of diabetes as well as of degree of hyperglycemia, and as a consequence, diabetic complications were diverse. Second, the "current" aspect implies the degree of insulin deficiency and its resistance. According to our observation, elderly patients had diverse degrees of impaired insulin secretion, together with age-related resistance to insulin. Third, "future" aspect refers to the expected length of life, which largely depends on the current age. The complication status (not limited to diabetic complications), however, also affects clinical course and death rates, indicating diversity of life expectancies due to complications besides current age. Thus, the present analysis showed that elderly individuals with diabetes mellitus exhibit a remarkable heterogeneity. The present study also indicated the clinical merit of assessment with the three aspects; past, current and future, in assessing clinical diversity of elder patients with diabetes.     

Amiodarone reduces QT dispersion in patients with hypertrophic cardiomyopathy.

To compare QT interlead variability (dispersion) in patients who receive a class III antiarrhythmic with those not on antiarrhythmic therapy, we measured QT in all 12 leads of a standard ECG in 24 patients with hypertrophic cardiomyopathy, 12 (50%) of whom were on amiodarone monotherapy and 12 (50%) who were not on amiodarone or other cardioactive medication which could affect QT. Age, functional class, chamber dimension or the degree of left ventricular hypertrophy expressed by maximal wall thickness (21 +/- 5 vs 20 +/- 4 mm; p = NS) was not different between the amiodarone and the non-amiodarone group. Maximal corrected QT (QTc) was greater in patients receiving (488 +/- 25 ms) compared to those not receiving amiodarone (451 +/- 23 ms) (p less than 0.001). However, QTc dispersion defined as the difference of maximum minus minimum QTc was decreased in the amiodarone (48 +/- 10 ms) compared to the non-amiodarone group (78 +/- 17 ms) (p less than 0.001). We conclude that in patients with hypertrophic cardiomyopathy, amiodarone prolongs QTc but reduces QTc dispersion. These results agree with expected changes in ventricular recovery time in patients who receive Class III antiarrhythmic agents and provide further support to the theory that QTc dispersion reflects regional differences in ventricular recovery time.