Is albuminuria an indicator of myocardial dysfunction in diabetic patients without overt heart disease? A study with Doppler strain and strain rate imaging

Heart Failure with Preserved Ejection Fraction: the Major Unmet Need in Cardiology

Heart failure with preserved ejection fraction (HFpEF) has recently been recognized as the single greatest unmet need in cardiovascular medicine. As the population ages and the comorbidity increases, the prevalence of HFpEF increases considerably. Even though there have been large numbers of studies on pathophysiology, diagnosis, and treatment of HFpEF for latest years, there are no current pharmacologic interventions that can reduce mortality. HFpEF is currently understood as a heterogeneous syndrome originated from the interplay of cardiac and extracardiac abnormalities recognized by systemic inflammation, endothelial and coronary microvascular dysfunction, cardiomyocyte dysfunction and skeletal muscle dysfunction. The difficult “jigsaw puzzle” called HFpEF has been filled with some pieces, but it is still not enough to meet clinical needs. Here, we review recent evidences and unsolved problems about HFpEF to improve our understanding of HFpEF. Finally, we hope to accelerate to completion of the problematic “jigsaw puzzle”.

Left atrial stiffness index as a marker of early target organ damage in hypertension

This study aimed to evaluate left atrial (LA) mechanics using two-dimensional speckle-tracking echocardiography (2DSTE) and investigate their correlations with measures of target organ damage (TOD) in hypertension. We enrolled 42 healthy controls (Group I) and 286 hypertension patients: Group II (n = 79) had an LA volume index (LAVI) <28 ml/m²; Group III (n = 92) had an LAVI ≥28 ml/m²; and Group IV (n = 115) had hypertension with left ventricular hypertrophy (LVH). We measured the following parameters: LA reservoir strain and strain rate (LA_S-S, LA_SR-S), LA conduit strain and strain rate (LA_S-E and LA_SR-E), and LA booster strain and strain rate (LA_S-A and LA_SR-A). The LA stiffness index (LASI) was defined as the ratio of early diastolic transmitral flow velocity/lateral mitral annulus myocardial velocity (E/e') to LA_S-S. We performed correlation and regression analyses of individual TOD with LA phasic functions, the LASI, and cardiovascular risk factors. Our findings showed that there was a trend toward a gradual increase in the LASI from controls to normal LA and enlarged LA patients and finally to hypertrophic LV patients. The LASI was significantly higher in Group III [0.28 (0.20, 0.38)] than in Group I [0.20 (0.16, 0.23)] and Group II [0.22 (0.18, 0.27)] and was the highest in Group IV [0.33 (0.26, 0.43)]. The LA reservoir and conduit function gradually decreased from Group I to Group IV. Multivariate regression analysis revealed that the LASI was independently correlated with individual TOD. In conclusion, abnormal LA mechanics precede LA enlargement and LVH, and an increased LASI can be used as a marker of early TOD in hypertension.

Myocardial dysfunction and cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is strongly associated with increased risk of myocardial dysfunction and cardiovascular disease (CVD), two separate conditions which often co-exist and influence each other's course. The prevalence of myocardial dysfunction may be as high as 75% in T2DM populations but is often overlooked due to the initial asymptomatic nature of the disease, complicating co-morbidities such as coronary artery disease (CAD) and obesity, and the lack of consensus on diagnostic criteria. More sensitive echocardiographic applications are furthermore needed to improve detection of early subclinical changes in myocardial function which do not affect conventional echocardiographic parameters. The pathophysiology of the diabetic myocardial dysfunction is not fully elucidated, but involves hyperglycemia and high levels of free fatty acids. It evolves over several years and increases the risk of developing overt HF, and is suggested to at least in part account for the worse outcome seen in T2DM individuals after cardiac events. CAD and stroke are the most frequent CV manifestations among T2DM patients and relate to a large degree to the accelerated atherosclerosis driven by inflammation. Diagnosing CAD is challenging due to the lower sensitivity inherent in the diagnostic tests and there is thus a need for new biomarkers to improve prediction and detection of CAD. It seems that a multi-factorial approach (i.e. targeting several CV risk factors simultaneously) is superior to a strict glucose lowering strategy in reducing risk for macrovascular events, and recent research may even support an effect also on HF outcomes.

Clinical features of subclinical left ventricular systolic dysfunction in patients with diabetes mellitus

Background

Left ventricular (LV) longitudinal systolic dysfunction has been identified even in asymptomatic patients with diabetes mellitus (DM) and preserved LV ejection fraction (LVEF). However, its relevant clinical features have not been fully evaluated.

Methods

We studied 144 asymptomatic DM patients without coronary artery disease. Their mean age was 57 ± 15 years, 79 (55%) were female, and mean LVEF was 66 ± 4% (all ≥50%). Global longitudinal strain (GLS) was determined as the average peak strain of 18 segments from the three standard apical views, and was expressed as an absolute value. With the pre-defined cutoff for subclinical LV systolic dysfunction in DM patients with preserved LVEF set at GLS < 18%, this dysfunction was detected in 53 patients (37%).

Results

Multivariate logistic regression analysis revealed that type 2 DM, hypertriglyceridemia, overweight/obesity, nephropathy and neuropathy were independently associated with GLS < 18%, with nephropathy being the highest risk factor (OR: 5.26; 95% CI 2.111-13.12, p < 0.001). For sequential logistic regression models, a model based on clinical variables including gender, type 2 DM and DM duration (χ² = 24.1) was improved by addition of overweight/obesity and hypertriglyceridemia (χ² = 45.6, p < 0.001), and further improved by addition of nephropathy and neuropathy (χ² = 70.2, p < 0.001) as variables. Furthermore, albuminuria significantly correlated with GLS (r = −0.51, p < 0.001), and a multivariate regression model showed it to be the factor most closely associated with GLS (β = −0.33, p < 0.001).

Conclusions

Diabetic complications, hypertriglyceridemia and overweight/obesity were closely associated with early stage of LV systolic longitudinal myocardial dysfunction in asymptomatic DM patients with preserved LVEF. Our findings can be clinically noticeable for the management of DM patients.

Association of low-grade albuminuria with adverse cardiac mechanics: findings from the hypertension genetic epidemiology network (HyperGEN) study

BACKGROUND

Albuminuria is a marker of endothelial dysfunction and has been associated with adverse cardiovascular outcomes. The reasons for this association are unclear but may be attributable to the relationship between endothelial dysfunction and intrinsic myocardial dysfunction.

METHODS AND RESULTS

In the Hypertension Genetic Epidemiology Network (HyperGEN) Study, a population- and family-based study of hypertension, we examined the relationship between urine albumin-to-creatinine ratio (UACR) and cardiac mechanics (n=1894, all of whom had normal left ventricular ejection fraction and wall motion). We performed speckle-tracking echocardiographic analysis to quantify global longitudinal, circumferential, and radial strain, and early diastolic (e') tissue velocities. We used E/e' ratio as a marker of increased left ventricular filling pressures. We used multivariable-adjusted linear mixed effect models to determine independent associations between UACR and cardiac mechanics. The mean age was 50±14 years, 59% were female, and 46% were black. Comorbidities were increasingly prevalent among higher UACR quartiles. Albuminuria was associated with global longitudinal strain, global circumferential strain, global radial strain, e' velocity, and E/e' ratio on unadjusted analyses. After adjustment for covariates, UACR was independently associated with lower absolute global longitudinal strain (multivariable-adjusted mean global longitudinal strain [95% confidence interval] for UACR Quartile 1 = 15.3 [15.0-15.5]% versus UACR Q4 = 14.6 [14.3-14.9]%, P for trend <0.001) and increased E/e' ratio (Q1 = 25.3 [23.5-27.1] versus Q4 = 29.0 [27.0-31.0], P=0.003). The association between UACR and global longitudinal strain was present even in participants with UACR < 30 mg/g (P<0.001 after multivariable adjustment).

CONCLUSIONS

Albuminuria, even at low levels, is associated with adverse cardiac mechanics and higher E/e' ratio.

Combination of a peroxisome proliferator-activated receptor-gamma agonist and an angiotensin II receptor blocker attenuates myocardial fibrosis and dysfunction in type 2 diabetic rats

Aims/Introduction

We aimed to examine the effect of an angiotensin II receptor blocker (ARB), a peroxisome proliferator‐activated receptor (PPAR)‐gamma agonist, and their combination on myocardial fibrosis and function in type 2 diabetic rats.

Materials and Methods

Five male Long‐Evans Tokushima Otsuka (LETO) rats and 20 male Otsuka Long‐Evans Tokushima Fatty (OLETF) rats were used. OLETF rats were assigned to four groups (n = 5 per group) at 28 weeks‐of‐age: untreated, losartan‐treated, rosiglitazone‐treated and combination‐treated. The ARB, losartan, was administered at a dose of 5 mg/kg/day, and the PPAR‐gamma agonist, rosiglitazone, was administered at a dose of 3 mg/kg/day by oral gavage for 12 weeks. Urine and blood samples were collected, and two‐dimensional echocardiograms and strain rate imaging were obtained at 28 and 40 weeks. Cytokines were evaluated by reverse transcriptase polymerase chain reaction, and histological analysis was carried out at 40 weeks.

Results

At 40 weeks, the global radial strains of the losartan‐treated (55.7 ± 4.5%, P = 0.021) and combination‐treated groups (59.3 ± 6.7%, P = 0.001) were significantly higher compared with the untreated OLETFs (44.3 ± 10.5%). No difference was observed when compared with LETO rats. Although the rosiglitazone‐treated group showed a better metabolic profile than the untreated OLETF group, there was no difference in the global radial strain (49.8 ± 6.0 vs 44.3 ± 10.5, P = 0.402). The expression of pro‐inflammatory cytokines, and collagen type I and III were consistently attenuated in the losartan‐treated and combination‐treated OLETF groups, but not in the rosiglitazone‐treated group.

Conclusions

A combination of rosiglitazone and losartan attenuates myocardial fibrosis and dysfunction in type 2 diabetic rats.

Systolic myocardial dysfunction in patients with type 2 diabetes mellitus: identification at MR imaging with cine displacement encoding with stimulated echoes

PURPOSE

To determine if cine displacement encoding with stimulated echoes (DENSE) can help to identify and determine the patterns of subclinical myocardial systolic dysfunction in patients with type 2 diabetes mellitus (DM) when compared with cine DENSE in control patients.

MATERIALS AND METHODS

After obtaining approval from the institutional ethics committee and written informed consent from the patients, 37 patients with type 2 DM without overt heart disease and 23 age-matched control patients were prospectively included in the study. The patients underwent standard cine magnetic resonance (MR) imaging with two-dimensional cine DENSE acquisitions. Circumferential (Ecc) and radial (Err) systolic strains were measured on short-axis views at basal, mid, and apical left ventricular levels. Longitudinal strain (Ell) was measured on four- and two-chamber views. Statistical testing included the intraclass correlation coefficient and multiple linear regression analysis.

RESULTS

The intraobserver intraclass correlation coefficient values were 0.85, 0.95, and 0.90, and the interobserver intraclass correlation coefficient values were 0.79, 0.91 and 0.80 for Ecc, Err, and Ell, respectively. The left ventricular ejection fraction was in the reference range and similar between the groups, and the patients with DM showed a decrease in Ecc (-14.4%±1.6 vs -17.0%±1.6, P<.001), Err (36.2%±10.9 vs 44.4%±9.9, P=.006) and Ell (-12.9%±2.1 vs -15.5%±1.6, P<.001) compared with the control patients. Finally, DM was independently associated with Ecc (P<.001), Err (P=.05) and Ell (P=.01) after adjustment for age, sex, hypertension, body mass index, and left ventricular mass.

CONCLUSION

Cine DENSE, a motion-encoding MR imaging technique for myocardial strain assessment with high spatial resolution, appears to be useful in the identification of subclinical myocardial dysfunction in patients with DM.

Diabetic cardiomyopathy: myth or reality?

Diabetes mellitus has reached an epidemic level worldwide. Cardiovascular diseases are the primary cause of death in diabetic patients, not only because of coronary artery disease and associated hypertension but also because of a direct adverse effect of diabetes on the heart, independent of other potential aetiological factors. However, the existence of this 'diabetic cardiomyopathy' remains controversial. We aimed to review current evidence for the existence of diabetic cardiomyopathy, focusing particularly on the clinical setting.

Impaired myocardial radial function in asymptomatic patients with type 2 diabetes mellitus: a speckle-tracking imaging study

BACKGROUND

Diabetic cardiomyopathy has been characterized by an early impairment of left ventricular (LV) longitudinal function as opposed to preserved LV radial function.

METHODS

Conventional echocardiography and longitudinal (ε(L)) and radial (ε(R)) systolic strain assessed by speckle-tracking imaging were obtained in 114 type 2 diabetic patients and 88 age-matched controls.

RESULTS

LV ejection fraction was similar in diabetic patients and controls. The presence of subclinical LV systolic dysfunction in diabetic patients was demonstrated by lower values of midwall fractional shortening (18% ± 3% vs 20% ± 3%, P = .006), ε(L) (-19% ± 3% vs -22% ± 2%, P < .001), and ε(R) (50% ± 16% vs 56% ± 12%, P = .003) compared with controls. On multivariate analysis, factors predicting strain values were diabetes (P = .001) and gender (P = .001) for ε(L) and diabetes (P = .003) for ε(R).

CONCLUSION

Diabetic patients without overt heart disease display subclinical alteration of both radial and longitudinal LV systolic function even after adjustment for blood pressure, age, and body mass index.

Left ventricular function and energy homeostasis in patients with type 1 diabetes with and without microvascular complications

BACKGROUND

This study was performed to assess left ventricular (LV) energy metabolism and function in patients with type 1 diabetes with or without overt microvascular complications.

METHODS

We performed cardiac Magnetic Resonance Imaging (MRI) and (31)P spectroscopy (MRS) in 24 patients with overt microvascular complications and in 15 carefully selected patients without complications in spite of a long duration of the disease (>20 years) and matched for anthropometric features. 31 healthy subjects served as a control group.

RESULTS

Systolic function was preserved in all study subjects. Patients with overt complications showed a higher LV wall mass/end diastolic volume ratio and altered parameters of diastolic function when compared to patients without complications and to controls. They were also characterized by lower PCr/ATP ratio (a recognized marker of energy metabolism). No effect of HbA1c was detected within groups.

CONCLUSIONS

In patients with type 1 diabetes 1) overt microvascular complications were associated with altered LV geometry, diastolic function and energy metabolism 2) in patients without complications and duration of disease >20 years no association with these alterations were found despite poor glycemic control. The features of this highly selected subgroup of patients demonstrated that long lasting chronic hyperglycemia per se is not sufficient to induce abnormality of cardiac energy metabolism and that additional yet to be identified (metabolic or genetic) factors must be important contributing factors.

Serial assessment of left ventricular remodeling and function by echo-tissue Doppler imaging after myocardial infarction in streptozotocin-induced diabetic swine

BACKGROUND

The aim of this study was to determine the value of Doppler tissue imaging (DTI) in detecting serial changes in left ventricular (LV) geometry and function after myocardial infarction (MI) in diabetic swine.

METHODS

Thirteen minipigs with streptozotocin-induced diabetes for 1 month and 13 controls were subjected to occlusion of the left anterior descending coronary artery. Echocardiography and DTI were performed before, 30 minutes, 90 minutes, and 4 weeks after left anterior descending coronary artery occlusion.

RESULTS

At baseline, LV end-diastolic volume and mass were greater in pigs with diabetes. After MI, LV ejection fractions and systolic mitral annular velocities were decreased and LV chambers dilated in both groups, which were exacerbated in animals with diabetes. At 30 minutes, 90 minutes, and 4 weeks after MI, strain rates were significantly lower in both infarct and noninfarct areas in the diabetic group than in controls.

CONCLUSIONS

DTI proved to be a useful tool in the serial assessment of subclinical LV dysfunction after MI in pigs with diabetes.