Association between the corrected QT intervals and combined intimal-medial thickness of the carotid artery in patients with type 2 diabetes

Risk stratification of cardiac arrhythmias and sudden cardiac death in type 2 diabetes mellitus patients receiving insulin therapy: A population-based cohort study

INTRODUCTION

Metabolic abnormalities may exacerbate the risk of adverse outcomes in patients with type 2 diabetes mellitus. The present study aims to assess the predictive value of HbA1c and lipid variability on the risks of sudden cardiac death (SCD) and incident atrial fibrillation (AF).

METHODS

The retrospective observational study consists of type 2 diabetic patients prescribed with insulin, who went to publicly funded clinics and hospitals in Hong Kong between January 1, 2009 and December 31, 2009. Variability in total cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), triglyceride, and HbA1c were assessed through their SD and coefficient of variation. The primary outcomes were incident (1) ventricular tachycardia/ventricular fibrillation, actual or aborted SCD and (2) AF.

RESULTS

A total of 23 329 patients (mean ± SD age: 64 ± 14 years old; 51% male; mean HbA1c 8.6 ± 1.3%) were included. On multivariable analysis, HbA1c, total cholesterol, LDL-C and triglyceride variability were found to be predictors of SCD (p < .05).

CONCLUSION

HbA1c and lipid variability were predictive of SCD. Therefore, poor glucose control and variability in lipid parameters in diabetic patients are associated with aborted or actual SCD. These observations suggest the need to re-evaluate the extent of glycemic control required for outcome optimization.

Association between heart rate-corrected QT interval and severe peripheral arterial disease in patients with type 2 diabetes and foot ulcers

BACKGROUND

A prolonged heart rate-corrected QT interval (QTc) has been associated with peripheral artery disease (PAD) in the general population. However, no study to date has identified a link between prolonged QTc and the severity of PAD in patients with diabetes mellitus and foot ulcers (DFUs). This study aimed to investigate this relationship.

METHODS

This multicenter study enrolled 281 patients with DFUs. The severity of PAD was classified into no severe PAD group (without stenosis or occlusion) and severe PAD group (with stenosis or occlusion) based on duplex ultrasonography. The association of prolonged QTc with severe PAD was evaluated in a multivariable mixed-effect logistic regression model, with the hospital as a random effect. Directed acyclic graphs were used to drive the selection of variables to fit the regression model.

RESULTS

Patients with severe PAD had longer QTc than those without. Based on the multivariable mixed-effect logistic regression model, a prolonged QTc was positively associated with severe PAD (odds ratio (OR) = 2.61; 95% CI: 1.07-6.35) and severe DFUs (Wagner grade score ≥ 3) (OR = 2.87; 95% CI: 1.42-5.81).

CONCLUSIONS

A prolonged QTc was associated with severe PAD in patients with DFUs. Further research is required to ascertain whether the association is causal.

Severity and multiplicity of microvascular complications are associated with QT interval prolongation in patients with type 2 diabetes

Aims/Introduction

A prolonged QT interval plays a causal role in life‐threatening arrhythmia, and becomes a risk factor for sudden cardiac death. Here, we assessed the association between microvascular complications and the QT interval in patients with type 2 diabetes.

Materials and Methods

Patients with type 2 diabetes (n = 219) admitted to Nippon Medical School Hospital (Tokyo, Japan) for glycemic control were enrolled. QT interval was measured manually in lead II on the electrocardiogram, and corrected for heart rate using Bazett's formula (QTc). Diabetic neuropathy, retinopathy and nephropathy were assessed by neuropathic symptoms or Achilles tendon reflex, ophthalmoscopy and urinary albumin excretion, respectively.

Results

In univariate analyses, female sex (P = 0.025), duration of type 2 diabetes (P = 0.041), body mass index (P = 0.0008), systolic blood pressure (P = 0.0011) and receiving insulin therapy (P < 0.0001) were positively associated with QTc. Patients with each of the three microvascular complications had longer QTc than those without: neuropathy (P = 0.0005), retinopathy (P = 0.0019) and nephropathy (P = 0.0001). As retinopathy or nephropathy progressed, QTc became longer (P < 0.001 and P < 0.001 for trend in retinopathy and nephropathy, respectively). Furthermore, QTc was prolonged with the multiplicity of the microvascular complications (P < 0.001 for trend). Multiple regression analyses showed that neuropathy, nephropathy and the multiplicity of the microvascular complications were independently associated with QTc.

Conclusions

Patients with type 2 diabetes with severe microvascular complications might be at high risk for life‐threatening arrhythmia associated with QT interval prolongation.

QT-interval parameters are increased in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) patients have increased cardiovascular morbidity and mortality. QT-interval parameters are presumed markers of cardiovascular risk and have not been previously evaluated in SLE. Standard 12-lead ECGs were obtained from 140 female SLE outpatients and 37 age and body mass index-matched controls. QT interval was measured in each lead and heart rate-corrected maximum QT-interval duration (QTcmax) and QT-interval dispersion (QTd) were calculated. Risk factors for cardiovascular disease and lupus clinical features, disease treatment, disease activity and damage index were recorded. SLE patients have increased QT-interval parameters when compared to controls (QTcmax: 427.91 31.53 ms1/2 versus 410.05 15.45 ms1/2, P 0.001; QTd: 52.38 22.21 ms versus 37.12 12.88 ms, P 0.001). These differences persisted after excluding those patients with arterial hypertension, diabetes and with ECG abnormalities (QTcmax: 419.90 28.78 ms1/2 versus 409.15 15.85 ms1/2, P 0.041; QTd: 54.74 26.00 ms versus 37.96 13.05 ms, P 0.001). Multivariate linear regression for factors associated with QTcmaxselected the presence of electrocardiographic left ventricular hypertrophy (ECG-LVH) ( P 0.003), nonspecific ST-T-wave abnormalities ( P 0.022) and left atrial enlargement ( P 0.044). Multivariate associates with QTd were age ( P 0.018), ECG-LVH ( P 0.022) and ST-T abnormalities ( P 0.031). In conclusion, SLE patients have increased QT interval parameters when compared to controls. This prolongation may lead to an increased cardiovascular risk. This finding might be due to subclinical atherosclerotic cardiovascular disease.

Prediabetes and blood pressure effects on heart rate variability, QT-interval duration, and left ventricular hypertrophy in overweight-obese adolescents

This ancillary, descriptive correlational study examined the effect of glucose regulation, blood pressure (BP), and their combined effects on cardiac autonomic function in 128 overweight-obese 11-18-year-olds. Measures included body mass index, resting BP, fasting glucose, glucose tolerance, and cardiac autonomic function (heart rate variability, QT, and Cornell voltage). After adjusting for age and gender, multivariate analysis of covariance revealed no differences in cardiac autonomic measures based on glucose regulation (p = .319), BP (p = .286), or the interaction between glucose regulation and BP (p = .132). The additive effect of prediabetes and elevated BP did not impact cardiac autonomic function in overweight-obese youth.

Carotid intima-media thickness and markers of inflammation, endothelial damage and hemostasis

BACKGROUND

Different soluble molecules involved in inflammation, endothelial damage, or hemostasis are recognized as potential cardiovascular risk markers. Studies to assess the role of these markers in the atherosclerotic process by evaluating their relationship to carotid intima-media thickness (C-IMT) tend to provide contrasting results.

PURPOSE

To perform a review of studies addressing the association between C-IMT and soluble markers and to investigate whether the observed inconsistencies could be explained by the characteristics of the patients included in different studies, for example prevalence of atherosclerotic disease (atherosclerotic burden), gender, age, or occurrence of specific vascular risk factors (VRFs).

DATA SOURCES

PubMed and Embase (January 1990 to March 2006).

STUDY SELECTION

Articles in English reporting original cross-sectional studies.

DATA EXTRACTION

Two authors independently extracted data on study design, population, sample size, ultrasonic methodology, and statistical approach.

DATA SYNTHESIS

Despite the marked heterogeneity of results presented in the literature, meta-analysis established that studies showing positive associations between C-IMT and plasma levels of C-reactive protein (CRP) or fibrinogen are in the majority. Funnel plot analyses suggested the absence of an important publication bias. Data on the relationships between C-IMT and other soluble markers are by contrast scanty, contradictory, or unconfirmed by multivariate (as opposed to univariate) analyses, and the freedom from publication bias here cannot be vouched for. The degree of atherosclerotic burden in the population studied does not account for the heterogeneity of findings reported. Gender, noninsulin-dependent diabetes mellitus (NIDDM) and hypercholesterolemia influence the association between C-IMT and CRP. Blood pressure and hypercholesterolemia influence the association between C-IMT and fibrinogen. For all the other soluble markers considered, the number of groups was too small for this kind of statistical considerations.

LIMITATIONS

Heterogeneity in ultrasound methodologies and in statistical approach limited comparability between studies. For most soluble markers, publication bias of positive results cannot be excluded.

CONCLUSIONS

Only CRP and fibrinogen seem to be unequivocally related to C-IMT. For all the other soluble markers considered, no clear-cut conclusions can be drawn.

QTc and autonomic neuropathy in diabetes: effects of acute hyperglycaemia and n-3 PUFA

BACKGROUND AND AIMS

Autonomic function is also regulated by glycaemia and exerts a crucial role in the control of blood pressure and cardiac function. The disruption of this physiological mechanism impacts deeply on cardiovascular mortality in diabetes. We investigated the influence of autonomic dysfunction on QTc interval and on sympatho-vagal balance (LF/HF), in response to acute hyperglycaemia and to membrane electrical stabilization (n-3 PUFA).

METHODS AND RESULTS

Twenty-four type 2 diabetic patients, without (N-: n=13) or with (N+: n=11) autonomic neuropathy and 13 healthy subjects (C) underwent BP and ECG monitoring during a 24-h period and during a 2-h hyperglycaemic clamp. Delta QTc during the night was blunted in diabetics (0.5+/-2.5 vs. C: 2.9+/-2.5%, p=0.001), and Delta LF/HF was decreased in N+ (-2.8+/-38.2 vs. C=34.8+/-28.1%, p=0.02). During hyperglycaemia, QTc increased in C; LF/HF significantly increased in C and N-. A 6-month treatment with n-3 PUFA partially restored Delta LF/HF and Delta QTc (2.1+/-1.40, p=0.04 vs. basal) only in N-.

CONCLUSION

Hyperglycaemia increases QTc interval and sympathetic activity; electrical membrane stabilization improves autonomic function only in the absence of overt autonomic neuropathy. Strategies to prevent the disruption of autonomic function with newer approaches, other than just glucose control, should be implemented.

Heart rate–corrected QT interval duration is significantly associated with blood pressure in Chinese hypertensives

INTRODUCTION

Many studies demonstrated that a prolonged heart rate-corrected QT interval (QTc) increases the risk of malignant ventricular arrhythmias and sudden death.

METHODS

We measured the electrocardiogram and blood pressure of 1480 hypertensive patients and assessed the relationship between the length of QTc and blood pressure.

RESULTS

The mean QTc is longer in female than in male participants. There was a positive association between QTc and blood pressure in both men and women. The estimated increase in systolic and diastolic blood pressure for each 100-millisecond increase in QTc was 6.4 and 5.0 mm Hg in men and 3.7 and 2.5 mm Hg in women, respectively.

CONCLUSION

Our study demonstrated a significant positive relationship between the QTc interval and baseline blood pressure in a Chinese hypertensive population.

Relationships between Heart Rate Variability and Urinary Albumin Excretion in Patients with Type 2 Diabetes

BACKGROUND

Although in type 1 diabetes the close association between heart rate variability and urinary albumin excretion (UAE) is recognized even in patients with normoalbuminuria, this association has not yet been fully established in patients with type 2 diabetes. Therefore, we investigated the association in patients with type 2 diabetes.

PATIENTS AND METHODS

All the hospital's 185 inpatients with type 2 diabetes were prospectively enrolled. Heart rate variability was evaluated by coefficients of variance of RR intervals (CVRR).

RESULTS

The mean age, duration of diabetes, and hemoglobin A1C of the patients were 59.7+/-9.9 years, 10.4+/-7.8 years, and 9.7+/-2.3%, respectively. An analysis of the patients showed a significant negative correlation between CVRR and log10-transformed (log) UAE (R=-0.3340, P <0.0001). CVRR showed a significant negative correlation with age, duration of diabetes, hemoglobin AIC, systolic blood pressure, diastolic blood pressure, and triglyceride level. Log UAE showed a significant positive correlation with body mass index, hemoglobin A1C, systolic blood pressure, diastolic blood pressure, total cholesterol, and triglyceride level. In the macroalbuminuric group (UAE above 300 mg/g creatinine; n=57), although CVRR showed a significant negative correlation with log UAE (R=-0.3571, P= 0.0064), but in normoalbuminuric (UAE below 30 mg/g Cr; n=79) and in microalbuminuric groups (30 to 300 mg/g Cr; n = 49), CVRR and log UAE showed no correlation.

CONCLUSIONS

Our data suggest that in type 2 diabetes, the association between CVRR and UAE is significant only in patients with macroalbuminuria.

Correlation of High-sensitivity C-reactive Protein and Plasma Fibrinogen with Individual Complications in Patients with Type 2 Diabetes

OBJECTIVE

We investigated the correlation between acute-phase reactants, ie, high-sensitivity C-reactive protein (hsCRP) or fibrinogen and diabetic complications.

METHODS

In 73 patients with type 2 diabetes, we investigated associations between both markers and carotid artery intimal medial complex thickness (IMT), heart rate variability, or urinary albumin excretion (UAE).

RESULTS

Log hsCRP and fibrinogen correlated significantly with each other (r = 0.3701, P = 0.0013). Fibrinogen correlated negatively with the coefficient of variation of RR intervals (CV(RR)) and positively with log UAE (r = -0.2433, P = 0.0381; r = 0.4815, P < 0.0001), while log hsCRP did not. Furthermore both log hsCRP and fibrinogen did not correlate with IMT.

CONCLUSION

We concluded that despite their close correlation, fibrinogen compared with hsCRP might be closely associated with diabetic microangiopathy and that both markers might not correlate with IMT as a marker of macroangiopathy.