Diabetic heart disease: the clinical and pathological spectrum--Part I

Clinical and echocardiographic characteristics in patients with heart failure and type 2 diabetes

Objective: The coexistence of type 2 diabetes (T2D) and heart failure (HF) has obvious consequences during cardiovascular diagnosis. This study evaluated the relationship between T2D and clinical and echocardiographic features of patients with HF. Methods & results: 121 patients with HF were clinically evaluated by echocardiography in this case-control study. They were divided into two groups based on the presence of T2D. Patients with diabetes were subdivided and compared via an HbA1c control. Significant differences between T2D and non-T2D groups were detected by comparing the left atrial diameter, E/E' and left ventricular end-diastolic diameter. When comparing patients with diabetes, differences in acute heart failure episodes, left ventricular ejection fraction, left atrial diameter and E/E' were evaluated. Conclusion: T2D was associated with important cardiac alterations and more severe HF. Poor control of diabetes resulted in worse cardiovascular outcomes.

Strategy to identify subjects with diabetes mellitus more suitable for selective echocardiographic screening: The DAVID-Berg study

BACKGROUND

Despite the burden of pre-clinical heart failure (HF) among diabetes mellitus (DM) patients, routine screening echocardiography is not currently recommended. We prospectively assessed risk prediction for HF/death of a screening strategy combining clinical data, electrocardiogram, NTproBNP, and echocardiogram, aiming to identify DM patients more suitable for selective echocardiography.

METHODS

Among 4047 screened subjects aged≥55/≤80years, the DAVID-Berg Study prospectively enrolled 623 outpatients with DM, or hypertension, or known cardiovascular disease but with no HF history/symptoms. The present analysis focuses on data obtained during a longitudinal follow-up of the 219 patients with DM.

RESULTS

Mean age was 68years, 61% were men, and median DM duration was 4.9years. During a median follow-up of 5.2years, 50 subjects developed HF or died. A predictive model using clinical data demonstrated moderate predictive power, which significantly improved by adding electrocardiogram (C-statistic 0.75 versus 0.70; p<0.05), but not NTproBNP (C-statistic 0.72, p=0.20). Subjects with normal clinical variables or abnormal clinical variables but normal electrocardiogram had low events rate (1.3 versus 2.4events/100-person-years, p=NS). Conversely, subjects with both clinical and electrocardiogram abnormalities (47%) carried higher risk (9.0events/100-person-years, p<0.001). The predictive power for mortality/HF development increased when echocardiography was added (13.6events/100-person-years, C-statistic 0.80, p<0.05).

CONCLUSIONS

Our prospective study found that a selective echocardiographic screening strategy guided by abnormal clinical/electrocardiogram data can reliably identify DM subjects at higher risk for incident HF and death. This screening approach may hold promise in guiding HF prevention efforts among DM patients.

Effects of restoring normoglycemia in type 1 diabetes on inflammatory profile and renal extracellular matrix structure after simultaneous pancreas and kidney transplantation

AIMS

Patients with type 1 diabetes and end-stage renal disease with simultaneous pancreas and kidney (SPK) or kidney transplants alone (KA) were recruited 9-12 years post transplantation. We investigated differences between these groups with regard to inflammatory parameters and long-term structural changes in kidneys.

METHODS

Blood samples were analyzed by ELISA and multiplex for chemokines, cytokines, growth factors, cell adhesion molecules and matrix metalloproteinases. Kidney graft biopsies were analyzed by electron microscopy for glomerular basement membrane thickness. Heparan- and chondroitin sulfate disaccharide structures were determined by size exclusion chromatography mass-spectrometry.

RESULTS

The SPK and the KA group had average glycated hemoglobin A1c (HbA1c) of 5.8% (40 mmol/mol) and 8.6% (70 mmol/mol) respectively. SPK recipients also had 16.2% lower body mass index (BMI) and 46.4% lower triglyceride levels compared with KA recipients, compatible with an improved metabolic profile in the SPK group. Plasminogen activator inhibitor (PAI-1), C-reactive protein (CRP) and vascular endothelial growth factor (VEGF) were lower in the SPK group. In kidney graft biopsies of the KA-patients an 81.2% increase in average glomerular basement membrane thickness was observed, accompanied by alterations in heparan sulfate proteoglycan structure. In addition to a decrease in 6-O-sulfated disaccharides, an increase in non-N-sulfated disaccharides with a corresponding slight decrease in N-sulfation was found in kidney biopsies from hyperglycemic patients.

CONCLUSIONS

Patients with end stage renal disease subjected to KA transplantation showed impaired inflammatory profile, increased thickness of basement membranes and distinct changes in heparan sulfate structures compared with SPK recipients.

Cross-sectional assessment of the effect of kidney and kidney-pancreas transplantation on resting left ventricular energy metabolism in type 1 diabetic-uremic patients: a phosphorous-31 magnetic resonance spectroscopy study

OBJECTIVES

To test whether left ventricular (LV) dysfunction affecting type 1 diabetic-uremic patients was associated with abnormal heart high-energy phosphates (HEPs) and to ascertain whether these alterations were also present in recipients of kidney or kidney-pancreas transplantation.

BACKGROUND

Heart failure is the major determinant of mortality in patients with diabetic uremia. Both uremia and diabetes induce alterations of cardiac HEPs metabolism.

METHODS

Magnetic resonance imaging and phosphorous magnetic resonance spectroscopy of the LV were performed in the resting state by means of a 1.5-T clinical scanner. Eleven diabetic-uremic patients, 5 nondiabetic patients with uremia, 11 diabetic recipients of kidney transplantation, and 16 diabetic recipients of combined kidney-pancreas transplantation were studied in a cross-sectional fashion. Eleven nondiabetic recipients of kidney-only transplant and 13 healthy subjects served as control groups.

RESULTS

Uremic patients had higher LV mass, diastolic dysfunction, and lower phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio in comparison with recipients of kidney-pancreas or nondiabetic recipients of kidney transplant. In diabetic recipients of kidney transplant the PCr/ATP ratio was higher than in uremic patients but was lower than in the controls. Recipients of combined kidney-pancreas transplant had a higher ratio than uremic patients but no difference was found in comparison with controls.

CONCLUSIONS

Altered resting myocardial HEPs metabolism may contribute to LV dysfunction in diabetic-uremic patients. In diabetic recipients of kidney transplantation, a certain degree of LV metabolic and functional impairment was found. In combined kidney-pancreas recipients the resting LV metabolism and function were not different than in controls.

[Prevention and treatment of congestive heart failure in diabetic patients]

Diabetes mellitus is a strong risk factor for the development of cardiovascular disease, and is associated with a worse prognosis. The incidence of congestive heart failure is higher in diabetic patients, although the reasons for this increased rate are debated (higher incidence and severity of coronary heart disease and arterial hypertension, or a true diabetic cardiomyopathy). The treatment of heart failure in diabetic patients does not differ from that of non-diabetic patients, although recent studies of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers offer interesting new perspectives.

Transmural heterogeneity of myocardial integrated backscatter in diabetic patients without overt cardiac disease

It is important to detect early changes in diabetic myocardium, because some diabetic patients suffer from diabetic cardiomyopathy, especially those with poorer glycemic control or hypertension (HT). To clarify whether ultrasonic tissue characterization can noninvasively detect ultrastructural changes in diabetic myocardium, we analyzed the transmural heterogeneity in myocardial integrated backscatter (THIB) in 20 diabetic patients and 16 normal subjects. THIB was defined as the absolute value of difference of integrated backscatter between the endocardial and epicardial half of the myocardium. THIB in diabetic patients was significantly greater than that in normal subjects. In diabetic patients, there was a significant correlation between glycosylated hemoglobin and THIB, and the greater THIB was shown in patients with HT compared with those without HT. Early changes in the myocardium, related to increased interstitial collagen deposition or other occult cardiomyopathic changes, may be detected on the basis of quantitative analysis of THIB in diabetic patients.

Myocardial dysfunction and adrenergic cardiac innervation in patients with insulin-dependent diabetes mellitus

BACKGROUND

Insulin-dependent diabetes mellitus (IDDM) is associated with an increased incidence of heart failure due to several factors, and in some cases a specific cardiomyopathy has been suggested.

OBJECTIVES

This study sought to assess the mechanisms of exercise-induced left ventricular (LV) dysfunction in asymptomatic patients with IDDM in the absence of hypertensive or coronary artery disease.

METHODS

Fourteen consecutive patients with IDDM were enrolled (10 men, 4 women; mean [+/- SD] age 28.5 +/- 6 years); 10 healthy subjects matched for gender (7 men, 3 women) and age (28.5 +/- 3 years) constituted the control group. LV volume, LV ejection fraction (LVEF) and end-systolic wall stress were calculated by two-dimensional echocardiography at rest and during isometric exercise. LV contractile reserve was assessed by post-extrasystolic potentiation (PESP) obtained by transesophageal cardiac electrical stimulation and dobutamine infusion. Myocardial iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy was performed to assess adrenergic cardiac innervation.

RESULTS

Diabetic patients were classified into group A (n = 7), with an abnormal LVEF response to handgrip (42 +/- 7%), and group B (n = 7), with a normal response (72 +/- 8%). Baseline LVEF was normal in both group A and B patients (60 +/- 6% vs. 61 +/- 7%, p = NS). In group A patients, the LV circumferential wall stress-LVEF relation showed an impairment in LVEF disproportionate to the level of LV afterload. No significant changes in LVEF occurred during dobutamine (60 +/- 6% vs. 64 +/- 10%, p = NS), whereas PESP significantly increased LVEF (60 +/- 6% vs. 74 +/- 6%, p < 0.001); PESP at peak handgrip normalized the abnormal LVEF (42 +/- 7% vs. 72 +/- 5%, p < 0.001); and MIBG uptake normalized for body weight or for LV mass was lower than that in normal subjects (1.69 +/- 0.30 vs. 2.98 +/- 0.82 cpm/MBq per g, p = 0.01) and group B diabetic patients (vs. 2.79 +/- 0.94 cpm/MBq per g, p = 0.01). Finally, a strong linear correlation between LVEF at peak handgrip and myocardial MIBG uptake normalized for LV mass was demonstrated in the study patients.

CONCLUSIONS

Despite normal contractile reserve, a defective blunted recruitment of myocardial contractility plays an important role in determining exercise LV dysfunction in the early phase of diabetic cardiomyopathy. This abnormal response to exercise is strongly related to an impairment of cardiac sympathetic innervation.

Abnormal myocardial acoustic properties in diabetic patients and their correlation with the severity of disease

Although patients with diabetes mellitus may be afflicted by cardiomyopathy, its prevalence and nature are controversial. Studies have shown that fibrosis alters the acoustic properties of the heart in animals and humans and that the changes are detectable by cardiac tissue characterization with ultrasound. The present study was performed to characterize myocardial acoustic properties in patients with insulin-dependent diabetes to determine whether ultrasound tissue characterization could detect changes potentially indicative of occult cardiomyopathy. The magnitude of cyclic variation of myocardial ultrasound integrated backscatter and its phase delay with respect to the onset of the cardiac cycle in the septum and posterior wall of the left ventricle were measured in 54 patients with diabetes who had no overt cardiac disease. Conventional echocardiography documented normal ventricular systolic function in 96%. As compared with results in age-matched patients without diabetes studied previously, cyclic variation of integrated backscatter was reduced (4.6 +/- 0.8 vs. 3.6 +/- 1.4 dB; p less than 0.001). In addition, delay was significantly increased (0.86 +/- 0.09 vs. 0.99 +/- 0.15). The primary analysis of the data focused on differences among the diabetic patients. Reduction of cyclic variation of backscatter was greatest in patients with diabetes who had neuropathy (3.2 +/- 1.0 dB; p less than 0.001) as was the increase in delay (1.04 +/- 0.16, p less than 0.001 vs. values in patients without neuropathy). Retinopathy and nephropathy were associated with abnormal myocardial acoustic properties as well. Thus, abnormalities that may reflect fibrosis or other occult cardiomyopathic changes in diabetic patients without overt heart disease are readily detectable by myocardial tissue characterization with ultrasound and parallel the severity of noncardiac diabetic complications.