Coronary flow reserve is reduced in young men with IDDM

Chemokine Fractalkine and Non-Obstructive Coronary Artery Disease-Is There a Link?

Non-obstructive coronary artery disease (NO-CAD) constitutes a heterogeneous group of conditions collectively characterized by less than 50% narrowing in at least one major coronary artery with a fractional flow reserve (FFR) of ≤0.80 observed in coronary angiography. The pathogenesis and progression of NO-CAD are still not fully understood, however, inflammatory processes, particularly atherosclerosis and microvascular dysfunction are known to play a major role in it. Chemokine fractalkine (FKN/CX3CL1) is inherently linked to these processes. FKN/CX3CL1 functions predominantly as a chemoattractant for immune cells, facilitating their transmigration through the vessel wall and inhibiting their apoptosis. Its concentrations correlate positively with major cardiovascular risk factors. Moreover, promising preliminary results have shown that FKN/CX3CL1 receptor inhibitor (KAND567) administered in the population of patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), inhibits the adverse reaction of the immune system that causes hyperinflammation. Whereas the link between FKN/CX3CL1 and NO-CAD appears evident, further studies are necessary to unveil this complex relationship. In this review, we critically overview the current data on FKN/CX3CL1 in the context of NO-CAD and present the novel clinical implications of the unique structure and function of FKN/CX3CL1 as a compound which distinctively contributes to the pathomechanism of this condition.

Coronary microvascular dysfunction and cardiovascular disease: Pathogenesis, associations and treatment strategies

Coronary microvascular dysfunction (CMD) is a high-risk factor for a variety of cardiovascular events. Due to its complex aetiology and concealability, knowledge of the pathophysiological mechanism of CMD is still limited at present, which greatly restricts its clinical diagnosis and treatment. Studies have shown that CMD is closely related to a variety of cardiovascular diseases, can aggravate the occurrence and development of cardiovascular diseases, and is closely related to a poor prognosis in patients with cardiovascular diseases. Improving coronary microvascular remodelling and increasing myocardial perfusion might be promising strategies for the treatment of cardiovascular diseases. In this paper, the pathogenesis and functional assessment of CMD are reviewed first, along with the relationship of CMD with cardiovascular diseases. Then, the latest strategies for the treatment of CMD and cardiovascular diseases are summarized. Finally, urgent scientific problems in CMD and cardiovascular diseases are highlighted and future research directions are proposed to provide prospective insights for the prevention and treatment of CMD and cardiovascular diseases in the future.

Cardiovascular outcomes in type 1 and type 2 diabetes

Diabetes is one of the most prevalent cardiometabolic disorders on the planet. Type 1 diabetes accounts for only a minority of all cases (recently estimated to be ~2% globally); however, since this is a disorder with an early onset, many people live with type 1 diabetes for a long time. CVD and premature death are the main long-term outcomes for both types of diabetes; however, the type of diabetes that carries the highest risk of these outcomes is a controversial topic and has not been widely studied. Because of the association between diabetes and CVD, the rise in type 2 diabetes prevalence over the past decades has huge effects on global health. The excess risk in people with diabetes compared with those without depends, to a large extent, on the presence of other factors, such as general cardiovascular risk factors (e.g. elevated LDL-cholesterol, hypertension and smoking) and also factors that are more specific to diabetes (e.g. HbA1c, and micro- and macroalbuminuria). Some contributory factors are modifiable, while others are not, such as age, sex and type of diabetes. Older people with type 2 diabetes who have risk factors that are under control can achieve levels of CVD risk that are similar to that of the general population, while younger individuals with type 1 diabetes are mostly unable to achieve similar levels of risk, probably because of long and cumulative exposure to raised blood glucose levels. Despite reports of declining rates of CVD among people with type 1 and type 2 diabetes, rising rates of both types of diabetes lead to a continuing rise in the number of people with cardiometabolic disorders worldwide, offsetting the progress made in many countries. Comparison between individuals with type 1 and type 2 diabetes with respect to risk of CVD is fraught with difficulties and highly dependent on other, concomitant factors, some of which are modifiable and others not. Nonetheless, as a whole, what matters most in determining the management of diabetes is absolute risk and lifetime risk. Life-long efforts to achieve glycaemic control, control of lipids and hypertension, and not smoking are key to prevention, with a healthy lifestyle and pharmacological therapy to be implemented as needed.

H2O2 Mediates VEGF- and Flow-Induced Dilations of Coronary Arterioles in Early Type 1 Diabetes: Role of Vascular Arginase and PI3K-Linked eNOS Uncoupling

In diabetes, the enzyme arginase is upregulated, which may compete with endothelial nitric oxide (NO) synthase (eNOS) for their common substrate L-arginine and compromise NO-mediated vasodilation. However, this eNOS uncoupling can lead to superoxide production and possibly vasodilator hydrogen peroxide (H₂O₂) formation to compensate for NO deficiency. This hypothesis was tested in coronary arterioles isolated from pigs with 2-week diabetes after streptozocin injection. The NO-mediated vasodilation induced by flow and VEGF was abolished by NOS inhibitor L-NAME and phosphoinositide 3-kinase (PI3K) inhibitor wortmannin but was not affected by arginase inhibitor N^ω-hydroxy-nor-L-arginine (nor-NOHA) or H₂O₂ scavenger catalase in control pigs. With diabetes, this vasodilation was partially blunted, and the remaining vasodilation was abolished by catalase and wortmannin. Administration of L-arginine or nor-NOHA restored flow-induced vasodilation in an L-NAME sensitive manner. Diabetes did not alter vascular superoxide dismutase 1, catalase, and glutathione peroxidase mRNA levels. This study demonstrates that endothelium-dependent NO-mediated coronary arteriolar dilation is partially compromised in early type 1 diabetes by reducing eNOS substrate L-arginine via arginase activation. It appears that upregulated arginase contributes to endothelial NO deficiency in early diabetes, but production of H₂O₂ during PI3K-linked eNOS uncoupling likely compensates for and masks this disturbance.

Traditional chinese medicine in coronary microvascular disease

Coronary microvascular disease (CMVD) is common in patients with cardiovascular risk factors and is associated with an increased risk of adverse cardiovascular events. Although the study of CMVD in modern medicine is ongoing, there is still no effective treatment for it. Traditional Chinese medicine (TCM) has some clinical advantages based on syndrome differentiation and individualized treatment. In this review, we review the clinical significance, pathogenesis, and current treatments of CMVD and systematically summarize the clinical efficacy and potential action mechanisms of TCM for CMVD. In addition, the scientific problems that need to be solved urgently and the research strategy of TCM for CMVD are described. CMVD has great clinical significance, but there are still many gaps in the related research. This review aims to attract the attention of clinicians to CMVD and promote research on CMVD in TCM.

HuR/Cx40 downregulation causes coronary microvascular dysfunction in type 2 diabetes

Patients with diabetes with coronary microvascular disease (CMD) exhibit higher cardiac mortality than patients without CMD. However, the molecular mechanism by which diabetes promotes CMD is poorly understood. RNA-binding protein human antigen R (HuR) is a key regulator of mRNA stability and translation; therefore, we investigated the role of HuR in the development of CMD in mice with type 2 diabetes. Diabetic mice exhibited decreases in coronary flow velocity reserve (CFVR; a determinant of coronary microvascular function) and capillary density in the left ventricle. HuR levels in cardiac endothelial cells (CECs) were significantly lower in diabetic mice and patients with diabetes than the controls. Endothelial-specific HuR-KO mice also displayed significant reductions in CFVR and capillary density. By examining mRNA levels of 92 genes associated with endothelial function, we found that HuR, Cx40, and Nox4 levels were decreased in CECs from diabetic and HuR-KO mice compared with control mice. Cx40 expression and HuR binding to Cx40 mRNA were downregulated in CECs from diabetic mice. Cx40-KO mice exhibited decreased CFVR and capillary density, whereas endothelium-specific Cx40 overexpression increased capillary density and improved CFVR in diabetic mice. These data suggest that decreased HuR contributes to the development of CMD in diabetes through downregulation of gap junction protein Cx40 in CECs.

Microvascular Dysfunction in Patients With Type II Diabetes Mellitus: Invasive Assessment of Absolute Coronary Blood Flow and Microvascular Resistance Reserve

Background: Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups. Methods: In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction. Results: The median FFR value was 0.83 [0.79-0.87] without any significant difference between the two groups. Absolute resting and hyperemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group (CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, [p < 0.05 for both]). Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all p < 0.05). Conclusions: Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

Efficacy of coronary sinus Reducer in patients with refractory angina and diabetes mellitus

Coronary sinus Reducer (CSR) implantation is currently recommended to relieve angina in patients with refractory symptoms despite optimal medical therapy and maximally achievable revascularization. The impact of diabetes mellitus on outcome after CSR implantation is at present unknown. We aimed to explore the impact of CSR in refractory angina patients with diabetes mellitus. Data from consecutive patients undergoing CSR implantation at four different centres between 2014 and 2018 were included. Patients were divided according to the presence or absence of diabetes mellitus. Primary objective of this analysis was to evaluate the clinical response to CSR implantation defined as an improvement of ≥ 1 classes of the Canadian Cardiovascular Society (CCS) Classification. A total of 219 patients were included, 116 (53%) of whom had diabetes mellitus. The median age of the population was 69 years and 167 patients (76%) were male. There were no significant differences between groups of patients with and without diabetes mellitus with respect to CCS class at baseline (p value = 0.32) and at follow-up (p = 0.75). Over a median follow-up of 393 [224-1004] days, 84 (72%) of the patients with diabetes mellitus met the primary outcome, similarly to those without diabetes mellitus (p = 0.28). Fifty-three patients (24%) did not have an improvement in CCS class and no one experienced worsening of angina. CSR implantation was equally effective in improving angina symptoms among patients with refractory angina and diabetes mellitus compared to patients without diabetes mellitus.

Effect of hypoglycaemia on measures of myocardial blood flow and myocardial injury in adults with and without type 1 diabetes: A prospective, randomised, open-label, blinded endpoint, cross-over study

AIMS

This study examined the effect of experimentally-induced hypoglycaemia on measures of myocardial blood flow and myocardial injury in adults with, and without, type 1 diabetes.

METHODS

In a prospective, randomised, open-label, blinded, endpoint cross-over study, 17 young adults with type 1 diabetes with no cardiovascular risk factors, and 10 healthy non-diabetic volunteers, underwent hyperinsulinaemic-euglycaemic (blood glucose 4.5-5.5 mmol/L) and hypoglycaemic (2.2-2.5 mmol/L) clamps. Myocardial blood flow was assessed using transthoracic echocardiography Doppler coronary flow reserve (CFR) and myocardial injury using plasma high-sensitivity cardiac troponin I (hs-cTnI) concentration.

RESULTS

During hypoglycaemia, coronary flow reserve trended non-significantly lower in those with type 1 diabetes than in the non-diabetic participants (3.54 ± 0.47 vs. 3.89 ± 0.89). A generalised linear mixed-model analysis examined diabetes status and euglycaemia or hypoglycaemia as factors affecting CFR. No statistically significant difference in CFR was observed for diabetes status (p = .23) or between euglycaemia and hypoglycaemia (p = .31). No changes in hs-cTnI occurred during hypoglycaemia or in the recovery period (p = .86).

CONCLUSIONS

A small change in CFR was not statistically significant in this study, implying hypoglycaemia may require more than coronary vasomotor dysfunction to cause harm. Further larger studies are required to investigate this putative problem.

Concurrent diabetes and heart failure: interplay and novel therapeutic approaches

Diabetes mellitus increases the risk of developing heart failure, and the co-existence of both diseases worsens cardiovascular outcomes, hospitalization and the progression of heart failure. Despite current advancements on therapeutic strategies to manage hyperglycemia, the likelihood of developing diabetes-induced heart failure is still significant, especially with the accelerating global prevalence of diabetes and an ageing population. This raises the likelihood of other contributing mechanisms beyond hyperglycemia in predisposing diabetic patients to cardiovascular disease risk. There has been considerable interest in understanding the alterations in cardiac structure and function in the diabetic patients, collectively termed as "diabetic cardiomyopathy". However, the factors that contribute to the development of diabetic cardiomyopathies is not fully understood. This review summarizes the main characteristics of diabetic cardiomyopathies, and the basic mechanisms that contribute to its occurrence. This includes perturbations in insulin resistance, fuel preference, reactive oxygen species generation, inflammation, cell death pathways, neurohormonal mechanisms, advanced glycated end-products accumulation, lipotoxicity, glucotoxicity, and posttranslational modifications in the heart of the diabetic. This review also discusses the impact of antihyperglycemic therapies on the development of heart failure, as well as how current heart failure therapies influence glycemic control in diabetic patients. We also highlight the current knowledge gaps in understanding how diabetes induces heart failure.

Overexpression of p53 due to excess protein O-GlcNAcylation is associated with coronary microvascular disease in type 2 diabetes

AIMS

We previously reported that increased protein O-GlcNAcylation in diabetic mice led to vascular rarefaction in the heart. In this study, we aimed to investigate whether and how coronary endothelial cell (EC) apoptosis is enhanced by protein O-GlcNAcylation and thus induces coronary microvascular disease (CMD) and subsequent cardiac dysfunction in diabetes. We hypothesize that excessive protein O-GlcNAcylation increases p53 that leads to CMD and reduced cardiac contractility.

METHODS AND RESULTS

We conducted in vivo functional experiments in control mice, TALLYHO/Jng (TH) mice, a polygenic type 2 diabetic (T2D) model, and EC-specific O-GlcNAcase (OGA, an enzyme that catalyzes the removal of O-GlcNAc from proteins)-overexpressing TH mice, as well as in vitro experiments in isolated ECs from these mice. TH mice exhibited a significant increase in coronary EC apoptosis and reduction of coronary flow velocity reserve (CFVR), an assessment of coronary microvascular function, in comparison to wild-type mice. The decreased CFVR, due at least partially to EC apoptosis, was associated with decreased cardiac contractility in TH mice. Western blot experiments showed that p53 protein level was significantly higher in coronary ECs from TH mice and T2D patients than in control ECs. High glucose treatment also increased p53 protein level in control ECs. Furthermore, overexpression of OGA decreased protein O-GlcNAcylation and down-regulated p53 in coronary ECs, and conferred a protective effect on cardiac function in TH mice. Inhibition of p53 with pifithrin-α attenuated coronary EC apoptosis and restored CFVR and cardiac contractility in TH mice.

CONCLUSIONS

The data from this study indicate that inhibition of p53 or down-regulation of p53 by OGA overexpression attenuates coronary EC apoptosis and improves CFVR and cardiac function in diabetes. Lowering coronary endothelial p53 levels via OGA overexpression could be a potential therapeutic approach for CMD in diabetes.

Sex-specific differences in coronary blood flow and flow velocity reserve in symptomatic patients with non-obstructive disease

AIMS

Reduced coronary flow velocity reserve (CFVR) is associated with adverse cardiovascular outcomes. Whether CFVR and coronary blood flow (CBF) are similar in men and women with chest pain and non-obstructive CAD remains unknown. We hypothesised sex differences in CFVR and CBF.

METHODS AND RESULTS

A total of 1,683 patients with signs/symptoms of ischaemia and angiographically unobstructed coronary arteries (<40% angiographic stenosis) underwent coronary vasomotion evaluation. CFVR was measured as hyperaemic/resting average velocity in the LAD. Mid-LAD diameter was measured with quantitative angiography and CBF calculated at rest (rCBF) and hyperaemia (hCBF). Resting microvascular resistance (rMR) was calculated as mean arterial pressure/rCBF. Of the total number of patients, 1,096 (65%) were women, median age 51 [42, 59] years. Compared to men, women had lower median CFVR (2.7 [2.4, 3.2] vs 3.1 [2.7, 3.6], p<0.001), higher rCBF (49.7 [34.0, 71.1] vs 45.9 [31.8, 68.7] ml/min, p=0.04), lower hCBF (139.5 [93.0, 195.2] vs 147.1 [95.7, 218.6] ml/min, p=0.02), but similar rMR (p=0.82). Female sex was an independent predictor of lower CFVR, higher rCBF, and lower hCBF.

CONCLUSIONS

Compared to men, women with signs/symptoms of ischaemia and non-obstructive CAD have lower CFVR, higher rCBF, and lower hCBF. Female sex is a predictor of these sex-specific differences. The clinical diagnostic and prognostic implications of sex differences in coronary physiology need further evaluation.

Prognostic value of myocardial perfusion scintigraphy in diabetic patients and without coronary lesion

OBJECTIVE

To determine the prognostic value of myocardial perfusion scintigraphy-gated SPECT in patients with diabetes mellitus and without obstructive coronary artery disease.

MATERIALS AND METHODS

This retrospective study included consecutive patients undergoing adenosine stress-rest myocardial perfusion imaging (MPI) by ^99mTc-tetrofosmin between 2009 and 2011. The patients had diabetes mellitus and coronary angiography without significant coronary lesions. In total, 37 diabetic patients (female/male: 20/17; mean age: 65.2 (range: 40-78). 29 non-diabetic patients were included wich are matched with the group of diabetic patients with positive MPI. The group of non-diabetic patients had scintigraphy with myocardial ischemia and without angiographic lesions. A 36-month clinical follow-up was performed, and major cardiac events were recorded.

RESULTS

In 78.3% (29/37) of diabetic patients the scintigraphic study showed myocardial ischemia, while it was negative in the 21.7%. The cardiac event rate in both groups was 6%. In diabetics with a myocardial perfusion study with myocardial ischemia, there were 3 major cardiac events. In diabetic patients with negative study had no cardiac event. In the non-diabetic control group the cardiac events rate was 3.4% (1/29).

CONCLUSION

In diabetic patients without obstructive coronary disease, myocardial perfusion study can be predictor of cardiac events. A negative study can be an indicator of a better cardiovascular prognosis.

Myocardial flow reserve assessed by cardiac 82Rb positron emission tomography/computed tomography is associated with albumin excretion in patients with Type 1 diabetes

AIMS

To evaluate myocardial flow reserve (MFR) and coronary artery calcium (CAC) in persons with Type 1 diabetes with or without albuminuria and in non-diabetic controls. MFR reflects the function of large epicardial arteries and myocardial microcirculation. CAC represents structural aspects of atherosclerosis. In addition, we evaluated the association of MFR and CAC with retinopathy, another microvascular complication.

METHODS AND RESULTS

Cross-sectional study in Type 1 diabetes, stratified by normoalbuminuria (NORMO; n = 30) and macroalbuminuria (MACRO; n = 30), and in non-diabetic controls (n = 30). MFR (pharmacological stress flow/rest flow) was evaluated by cardiac 82Rb positron emission tomography/computed tomography. MFR was similar in patients with NORMO and controls (3.1 ± 0.79 vs. 3.0 ± 0.79; P = 0.74). Patients with MACRO had lower (impaired) MFR when compared with NORMO (2.1 ± 0.92 vs. 3.1 ± 0.79; P < 0.0001). The CAC score [median (interquartile range)] was higher in NORMO when compared with controls [72 (22-247) vs. 0 (0-81), P = 0.03], and comparable between MACRO and NORMO. MFR was comparable in patients with diabetes and simplex or no retinopathy (n = 24 and n = 12, 2.8 ± 0.84 vs. 3.3 ± 0.77, P = 0.11), but lower in proliferative (n = 24) compared with simplex retinopathy (2.1 ± 0.97 vs. 2.8 ± 0.84, P = 0.02). The CAC score was comparable between groups of retinopathy.

CONCLUSION

Myocardial microvascular function was comparable in non-diabetic controls and patients with Type 1 diabetes and NORMO; but impaired in the presence of microvascular complications (MACRO and proliferative retinopathy). Coronary calcification was elevated in diabetes, however, not explained by albuminuria.

Arterial Stiffness Predicts Mortality in Individuals With Type 1 Diabetes

OBJECTIVE

Type 1 diabetes is accompanied by a significant burden of cardiovascular disease (CVD), which is poorly explained by traditional risk factors. We therefore aimed to explore whether arterial stiffness estimated by the augmentation index (AIx) predicts mortality in individuals with type 1 diabetes.

RESEARCH DESIGN AND METHODS

After baseline examination comprising pulse wave analysis by applanation tonometry alongside assessment of traditional cardiovascular risk factors, 906 individuals with type 1 diabetes from the Finnish Diabetic Nephropathy (FinnDiane) Study were followed up for a median of 8.2 years (interquartile range 5.7-9.7). Associations between baseline hemodynamics, including AIx, and all-cause mortality as well as a composite of cardiovascular and/or diabetes-related mortality were investigated using multivariable Cox regression models.

RESULTS

The 67 individuals who died during follow-up had higher baseline AIx (median 28% [interquartile range 21-33] vs. 19% [9-27]; P < 0.001) compared with those alive. This association was independent of conventional risk factors (age, sex, BMI, HbA_1c, estimated glomerular filtration rate [eGFR], and previous CVD event) in Cox regression analysis (standardized hazard ratio 1.71 [95% CI 1.10-2.65]; P = 0.017) and sustained in a subanalysis of individuals with chronic kidney disease. Similarly, higher AIx was associated with the composite secondary end point of cardiovascular and diabetes-related death (N = 53) after adjustments for sex, BMI, eGFR, previous CVD event, and height (standardized hazard ratio 2.30 [1.38-3.83]; P = 0.001).

CONCLUSIONS

AIx predicts all-cause mortality as well as a composite cardiovascular and/or diabetes-related cause of death in individuals with type 1 diabetes, independent of established cardiovascular risk factors.

Comparison of Major Adverse Cardiac Events Between Instantaneous Wave-Free Ratio and Fractional Flow Reserve-Guided Strategy in Patients With or Without Type 2 Diabetes: A Secondary Analysis of a Randomized Clinical Trial

Importance

Invasive physiologic indices such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are used in clinical practice. Nevertheless, comparative prognostic outcomes of iFR-guided and FFR-guided treatment in patients with type 2 diabetes have not yet been fully investigated.

Objective

To compare 1-year clinical outcomes of iFR-guided or FFR-guided treatment in patients with and without diabetes in the Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularization (DEFINE-FLAIR) trial.

Design, Setting, and Participants

The DEFINE-FLAIR trial is a multicenter, international, randomized, double-blinded trial that randomly assigned 2492 patients in a 1:1 ratio to undergo either iFR-guided or FFR-guided coronary revascularization. Patients were eligible for trial inclusion if they had intermediate coronary artery disease (40%-70% diameter stenosis) in at least 1 native coronary artery. Data were analyzed between January 2014 and December 2015.

Interventions

According to the study protocol, iFR of 0.89 or less and FFR of 0.80 or less were used as criteria for revascularization. When iFR or FFR was higher than the prespecified threshold, revascularization was deferred.

Main Outcomes and Measures

The primary end point was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. The incidence of MACE was compared according to the presence of diabetes in iFR-guided and FFR-guided groups.

Results

Among the total trial population (2492 patients), 758 patients (30.4%) had diabetes. Mean age of the patients was 66 years, 76% were men (1868 of 2465), and 80% of patients presented with stable angina (1983 of 2465). In the nondiabetes population (68.5%; 1707 patients), iFR guidance was associated with a significantly higher rate of deferral of revascularization than the FFR-guided group (56.5% [n = 477 of 844] vs 46.6% [n = 402 of 863]; P < .001). However, it was not different between the 2 groups in the diabetes population (42.1% [n = 161 of 382] vs 47.1% [n = 177 of 376]; P = .15). At 1 year, the diabetes population showed a significantly higher rate of MACE than the nondiabetes population (8.6% vs 5.6%; adjusted hazard ratio [HR], 1.88; 95% CI, 1.28-2.64; P < .001). However, there was no significant difference in MACE rates between iFR-guided and FFR-guided groups in both the diabetes (10.0% vs 7.2%; adjusted HR, 1.33; 95% CI, 0.78-2.25; P = .30) and nondiabetes population (4.7% vs 6.4%; HR, 0.83; 95% CI, 0.51-1.35; P = .45) (interaction P = .25).

Conclusions and Relevance

The diabetes population showed significantly higher risk of MACE than the nondiabetes population, even with the iFR-guided or FFR-guided treatment. The iFR-guided and FFR-guided treatment showed comparable risk of MACE and provided equal safety in selecting revascularization target among patients with diabetes.

Trial Registration

ClinicalTrials.gov identifier: NCT02053038.

Crossing signals: bioactive lipids in the microvasculature

The primary function of the arterial microvasculature is to ensure that regional perfusion of blood flow is matched to the needs of the tissue bed. This critical physiological mechanism is tightly controlled and regulated by a variety of vasoactive compounds that are generated and released from the vascular endothelium. Although these substances are required for modulating vascular tone, they also influence the surrounding tissue and have an overall effect on vascular, as well as parenchymal, homeostasis. Bioactive lipids, fatty acid derivatives that exert their effects through signaling pathways, are included in the list of vasoactive compounds that modulate the microvasculature. Although lipids were identified as important vascular messengers over three decades ago, their specific role within the microvascular system is not well defined. Thorough understanding of these pathways and their regulation is not only essential to gain insight into their role in cardiovascular disease but is also important for preventing vascular dysfunction following cancer treatment, a rapidly growing problem in medical oncology. The purpose of this review is to discuss how biologically active lipids, specifically prostanoids, epoxyeicosatrienoic acids, sphingolipids, and lysophospholipids, contribute to vascular function and signaling within the endothelium. Methods for quantifying lipids will be briefly discussed, followed by an overview of the various lipid families. The cross talk in signaling between classes of lipids will be discussed in the context of vascular disease. Finally, the potential clinical implications of these lipid families will be highlighted.

Non-invasive Risk Stratification for Coronary Artery Disease: Is It Time for Subclassifications?

PURPOSE OF REVIEW

Coronary artery disease (CAD) is the leading contributor to cardiovascular disease; it is the most prevalent non-communicable disease globally and has high morbidity, mortality and health care cost. Risk stratification is defined as prevention or containment of disease prior to it occurring or progressing, and non-invasive surrogates include history, examination, biomarkers and non-invasive imaging. This review aims to highlight advancement in current diagnostic strategies and explores gaps for CAD secondary to atherosclerosis and non-obstructive vascular diseases.

RECENT FINDINGS

Cardiac risk scores have largely proven inadequate in risk stratifying heterogeneous patient populations. Greater emphasis should also be provided to posttest risk stratification. Non-invasive imaging with MRI is the most accurate but least cost efficacious presently due to availability and expertise. Echocardiography and nuclear imaging have good accuracy, but radiation limits the latter. Novel echocardiographic technologies may increase its appeal. Cardiac CT angiography is increasingly promising. Non-invasive and minimally invasive imaging has significantly influenced the cost-efficacy trajectory of coronary artery disease diagnosis and management. Recent studies suggest that future guidelines will incorporate more subclassifications from the findings of these novel technologies and for more diverse patient demographics.

Differential association of diabetes mellitus and female sex with impaired myocardial flow reserve across the spectrum of epicardial coronary disease

Aims 

Diabetes mellitus (DM) affects the macro- and microvasculature, leading to impairment in coronary vascular reactivity. Microvascular dysfunction is more prevalent in females compared to males, leading to increased cardiovascular risk in women. The purpose of this study was to quantify the association between diabetes and female sex on myocardial flow reserve (MFR) across the spectrum of epicardial coronary artery disease (CAD).

Methods and results 

In 222 patients with known or suspected CAD (63.7 ± 10.7 years, 66 females, 85 with diabetes) who had rubidium-82 positron emission tomography (PET) and invasive coronary angiography within 6 months, a multiple linear regression model was developed to predict MFR based on clinical risk factors and imaging results across a spectrum of regional epicardial disease. A significant interaction effect suggested that impairment of MFR is accelerated in diabetics with increasing severity of epicardial disease. Furthermore, female sex (−13%), decade of age (−6%), ischaemia on electrocardiogram (−10%), resting rate-pressure product (−3%), and rest end-diastolic volume (−0.2%) were associated with reductions in MFR independent of the combined extent and severity of epicardial disease.

Conclusion

In the presence of significant obstructive epicardial disease, MFR decreases more rapidly in patients with DM compared to those without. Additional patient demographics and risk factors such as female sex and older age, and stress PET functional parameters should also be considered in the clinical interpretation of MFR. This has implications for the diagnosis and management of CAD patients with these and other risk factors for microvascular disease.

Requisite roles of LOX-1, JNK, and arginase in diabetes-induced endothelial vasodilator dysfunction of porcine coronary arterioles

Diabetes is associated with cardiac inflammation and impaired endothelium-dependent coronary vasodilation, but molecular mechanisms involved in this dysfunction remain unclear. We examined contributions of inflammatory molecules lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), stress-activated kinases (c-Jun N-terminal kinase [JNK] and p38), arginase, and reactive oxygen species to coronary arteriolar dysfunction in a porcine model of type 1 diabetes. Coronary arterioles were isolated from streptozocin-induced diabetic pigs and control pigs for vasoreactivity and molecular/biochemical studies. Endothelium-dependent nitric oxide (NO)-mediated vasodilation to serotonin was diminished after 2 weeks of diabetes, without altering endothelium-independent vasodilation to sodium nitroprusside. Superoxide scavenger TEMPOL, NO precursor L-arginine, arginase inhibitor nor-NOHA, anti-LOX-1 antibody or JNK inhibitors SP600125 and BI-78D3 improved dilation of diabetic vessels to serotonin. However, hydrogen peroxide scavenger catalase, anti-IgG antibody or p38 kinase inhibitor SB203580 had no effect. Combined inhibition of arginase and superoxide levels did not further improve vasodilation. Arginase-I mRNA expression, LOX-1 and JNK protein expression, and superoxide levels were elevated in diabetic arterioles. In conclusion, sequential activation of LOX-1, JNK, and L-arginine consuming enzyme arginase-I in diabetes elicits superoxide-dependent oxidative stress and impairs endothelial NO-mediated dilation in coronary arterioles. Therapeutic targeting of these adverse vascular molecules may improve coronary arteriolar function during diabetes.

Association of Hemorheology With High-Sensitivity Cardiac Troponin T Levels in Patients With Type 2 Diabetes Mellitus Assessed by Microchannel Array Flow Analyzer

Background

Recent studies on high-sensitivity cardiac troponin T (hs-cTnT) and whole blood passage time (WBPT), estimated by hemorheology assessed with the microchannel array flow analyzer (MC-FAN), have revealed the significance of cardiovascular risk factors. However, there are no known reports on the relationship between these two clinical parameters. This cross-sectional study aimed to clarify the associations between WBPT and hs-cTnT levels in patients with type 2 diabetes mellitus from the perspective of subclinical myocardial injury or the primary prevention of cardiovascular events.

Methods

A total of 301 outpatients (men, 116; women, 185; mean age, 65 ± 11 years), with no history of cardiovascular diseases, undergoing treatment for diabetes mellitus were enrolled. Hs-cTnT levels and WBPT were measured using a commercial device, and the relationship between hs-cTnT levels and various clinical parameters, including WBPT, was examined.

Results

Hs-cTnT levels were detected in 261 (86.7%) patients. WBPT was significantly higher in patients with detectable hs-cTnT levels than in those with undetectable hs-cTnT levels (64 ± 18 s vs. 51 ± 13 s, P < 0.001). In patients with detectable hs-cTnT levels, there was a significantly positive correlation between WBPT and hs-cTnT levels (r = 0.40; P < 0.001). Furthermore, multiple regression analysis revealed that WBPT (β = 0.24; P < 0.001) was an independent variable when hs-cTnT was a subordinate factor. Conversely, patients with high (≥ 70 s; odds ratio, 5.3 (95% CI, 1.6 - 16.1); P < 0.01) and median (50.2 - 69.8 s; odds ratio, 3.8 (95% CI, 1.2 - 12.4); P < 0.05) WBPT had a significantly higher risk for high hs-cTnT levels (≥ 0.014 ng/mL) than those with low WBPT (≤ 50.0 s).

Conclusions

The results of this study indicated independent associations of hemorheology with hs-cTnT in patients with type 2 diabetes mellitus assessed by MC-FAN. We suggest that an increase in hs-cTnT levels can be prevented by maintaining WBPT at ≤ 50.0 s.

Diabetic Microvascular Disease: An Endocrine Society Scientific Statement

Both type 1 and type 2 diabetes adversely affect the microvasculature in multiple organs. Our understanding of the genesis of this injury and of potential interventions to prevent, limit, or reverse injury/dysfunction is continuously evolving. This statement reviews biochemical/cellular pathways involved in facilitating and abrogating microvascular injury. The statement summarizes the types of injury/dysfunction that occur in the three classical diabetes microvascular target tissues, the eye, the kidney, and the peripheral nervous system; the statement also reviews information on the effects of diabetes and insulin resistance on the microvasculature of skin, brain, adipose tissue, and cardiac and skeletal muscle. Despite extensive and intensive research, it is disappointing that microvascular complications of diabetes continue to compromise the quantity and quality of life for patients with diabetes. Hopefully, by understanding and building on current research findings, we will discover new approaches for prevention and treatment that will be effective for future generations.

Coronary microvascular dysfunction in diabetes mellitus

The significance, mechanisms and consequences of coronary microvascular dysfunction associated with diabetes mellitus are topics into which we have insufficient insight at this time. It is widely recognized that endothelial dysfunction that is caused by diabetes in various vascular beds contributes to a wide range of complications and exerts unfavorable effects on microcirculatory regulation. The coronary microcirculation is precisely regulated through a number of interconnected physiological processes with the purpose of matching local blood flow to myocardial metabolic demands. Dysregulation of this network might contribute to varying degrees of pathological consequences. This review discusses the most important findings regarding coronary microvascular dysfunction in diabetes from pre-clinical and clinical perspectives.

Integrative model of coronary flow in anatomically based vasculature under myogenic, shear, and metabolic regulation

Coronary blood flow is regulated to match the oxygen demand of myocytes in the heart wall. Flow regulation is essential to meet the wide range of cardiac workload. The blood flows through a complex coronary vasculature of elastic vessels having nonlinear wall properties, under transmural heterogeneous myocardial extravascular loading. To date, there is no fully integrative flow analysis that incorporates global and local passive and flow control determinants. Here, we provide an integrative model of coronary flow regulation that considers the realistic asymmetric morphology of the coronary network, the dynamic myocardial loading on the vessels embedded in it, and the combined effects of local myogenic effect, local shear regulation, and conducted metabolic control driven by venous O₂ saturation level. The model predicts autoregulation (approximately constant flow over a wide range of coronary perfusion pressures), reduced heterogeneity of regulated flow, and presence of flow reserve, in agreement with experimental observations. Furthermore, the model shows that the metabolic and myogenic regulations play a primary role, whereas shear has a secondary one. Regulation was found to have a significant effect on the flow except under extreme (high and low) inlet pressures and metabolic demand. Novel outcomes of the model are that cyclic myocardial loading on coronary vessels enhances the coronary flow reserve except under low inlet perfusion pressure, increases the pressure range of effective autoregulation, and reduces the network flow in the absence of metabolic regulation. Collectively, these findings demonstrate the utility of the present biophysical model, which can be used to unravel the underlying mechanisms of coronary physiopathology.

Diabetes does not impact the diagnostic performance of contrast-based fractional flow reserve: insights from the CONTRAST study

BACKGROUND

Adenosine-free coronary pressure wire metrics have been proposed to test the functional significance of coronary artery lesions, but it is unexplored whether their diagnostic performance might be altered in patients with diabetes.

METHODS

We performed a post-hoc analysis of the CONTRAST study, which prospectively enrolled an international cohort of patients undergoing routine fractional flow reserve (FFR) assessment for standard indications. Paired, repeated measurements of all physiology metrics (Pd/Pa, iFR, contrast-based FFR, and FFR) were made. A central core laboratory analyzed blinded pressure tracings in a standardized fashion.

RESULTS

Of 763 subjects enrolled at 12 international centers, 219 (29%) had diabetes. The two groups were well-balanced for age, clinical presentation (stable or unstable), coronary vessel studied, volume and type of intracoronary contrast, and volume of intracoronary adenosine. A binary threshold of cFFR ≤ 0.83 produced an accuracy superior to both Pd/Pa and iFR when compared with FFR ≤ 0.80 in the absence of significant interaction with diabetes status; indeed, accuracy in subgroups of patients with or without diabetes was similar for cFFR (86.7 vs 85.4% respectively; p = 0.76), iFR (84.2 vs 80.0%, p = 0.29) and Pd/Pa (81.3 vs 78.9%, p = 0.55). There was no significant heterogeneity between patients with or without diabetes in terms of sensitivity and specificity of all metrics. The area under the receiver operating characteristic (ROC) curve was largest for cFFR compared with Pd/Pa and iFR which were equivalent (cFFR 0.961 and 0.928; Pd/Pa 0.916 and 0.870; iFR 0.911 and 0.861 in diabetic and non-diabetic patients respectively).

CONCLUSIONS

cFFR provides superior diagnostic performance compared with Pd/Pa or iFR for predicting FFR irrespective of diabetes (clinicaltrials.gov identifier NCT02184117).

Coronary Microvascular Dysfunction - Epidemiology, Pathogenesis, Prognosis, Diagnosis, Risk Factors and Therapy

Angina has traditionally been thought to be caused by obstructive coronary artery disease (CAD). However, a substantial number of patients with angina are found to not have obstructive CAD when undergoing coronary angiography. A significant proportion of these patients have coronary microvascular dysfunction (CMD), characterized by heightened sensitivity to vasoconstrictor stimuli and limited microvascular vasodilator capacity. With the advent of non-invasive and invasive techniques, the coronary microvasculature has been more extensively studied in the past 2 decades. CMD has been identified as a cause of cardiac ischemia, in addition to traditional atherosclerotic disease and vasospastic disease. CMD can occur alone or in the presence obstructive CAD. CMD shares many similar risk factors with macrovascular CAD. Diagnosis is achieved through detection of an attenuated response of coronary blood flow in response to vasodilatory agents. Imaging modalities such as cardiovascular magnetic resonance, positron emission tomography, and transthoracic Doppler echocardiography have become more widely used, but have not yet completely replaced the traditional intracoronary vasoreactivity testing. Treatment of CMD starts with lifestyle modification and risk factor control. The use of traditional antianginal, antiatherosclerotic medications and some novel agents may be beneficial; however, clinical trials are needed to assess the efficacy of the pharmacologic and non-pharmacologic therapeutic modalities. In addition, studies with longer-term follow-up are needed to determine the prognostic benefits of these agents. We review the epidemiology, prognosis, pathogenesis, diagnosis, risk factors and current therapies for CMD.

Bimodal Pattern of Coronary Microvascular Involvement in Diabetes Mellitus

Background

The contribution of functionally disturbed coronary autoregulation and structurally impaired microvascular vasodilatory function to reduced coronary flow velocity reserve, reflecting impaired coronary microcirculation in diabetes mellitus (DM), has not been clearly elucidated. The objective of this study was to identify the mechanism of coronary microvascular impairment in DM in relation to duration of disease.

Methods and Results

Coronary flow velocities in the anterior descending coronary artery were assessed by transthoracic echocardiography following angiography revealing normal epicardial coronary arteries in 55 diabetic and 47 nondiabetic patients. Average peak flow velocities, coronary flow velocity reserve, and microvascular resistance in baseline and hyperemic conditions (baseline and hyperemic microvascular resistance, respectively) were assessed. Reduced coronary flow velocity reserve in patients with short duration (<10 years) of DM compared with nondiabetic patients was primarily driven by increased baseline average peak flow velocity (26.50±5.6 versus 22.08±4.31, P=0.008) in the presence of decreased baseline microvascular resistance (3.69±0.86 versus 4.34±0.76, P=0.003). In contrast, decreased coronary flow velocity reserve in patients with long‐standing (≥10 years) DM compared with nondiabetic patients was predominantly driven by reduced hyperemic average peak flow velocity (41.57±10.01 versus 53.47±11.8, P<0.001) due to increased hyperemic microvascular resistance (2.13±0.42 versus 1.69±0.39, P<0.001).

Conclusions

Both altered coronary autoregulation and impaired microvascular vasodilatory function contribute to DM‐related coronary microvascular impairment in a time‐dependent manner. DM‐induced early functional microvascular autoregulatory impairment seems to evolve into structural microvascular impairment in the initially overperfused microvascular territory at the later stage of disease.

Coronary Microvascular Dysfunction, Microvascular Angina, and Management

Recent analyses have found that coronary microvascular dysfunction (CMD) portends a poor prognosis in patients with and without obstructive epicardial coronary artery disease (CAD). Chest pain in the absence of epicardial CAD is a common entity. Angina caused by CMD, microvascular angina (MVA), is often indistinguishable from that caused by obstructive epicardial CAD. The recent emergence of noninvasive techniques that can identify CMD, such as stress positron-emission tomography (PET) and cardiovascular magnetic resonance (CMR) myocardial perfusion imaging, allow improved identification of MVA. Using these tools, higher risk patients with MVA can be differentiated from those at lower risk in the heterogeneous population historically labeled as cardiac syndrome X. Likewise, MVA can be diagnosed in those with obstructive epicardial CAD who have persistent angina despite successful revascularization. There is little evidence to support current treatment strategies for MVA and current literature has not clearly defined CMD or whether therapy improves prognosis.

Coronary microvascular dysfunction after long-term diabetes and hypercholesterolemia

Coronary microvascular dysfunction (CMD) has been proposed as an important component of diabetes mellitus (DM)- and hypercholesterolemia-associated coronary artery disease (CAD). Previously we observed that 2.5 mo of DM and high-fat diet (HFD) in swine blunted bradykinin (BK)-induced vasodilation and attenuated endothelin (ET)-1-mediated vasoconstriction. Here we studied the progression of CMD after 15 mo in the same animal model of CAD. Ten male swine were fed a HFD in the absence (HFD, n = 5) or presence of streptozotocin-induced DM (DM + HFD, n = 5). Responses of small (∼300-μm-diameter) coronary arteries to BK, ET-1, and the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine were examined in vitro and compared with those of healthy (Normal) swine (n = 12). Blood glucose was elevated in DM + HFD (17.6 ± 4.5 mmol/l) compared with HFD (5.1 ± 0.4 mmol/l) and Normal (5.8 ± 0.6 mmol/l) swine, while cholesterol was markedly elevated in DM + HFD (16.8 ± 1.7 mmol/l) and HFD (18.1 ± 2.6 mmol/l) compared with Normal (2.1 ± 0.2 mmol/l) swine (all P < 0.05). Small coronary arteries showed early atherosclerotic plaques in HFD and DM + HFD swine. Surprisingly, DM + HFD and HFD swine maintained BK responsiveness compared with Normal swine due to an increase in NO availability relative to endothelium-derived hyperpolarizing factors. However, ET-1 responsiveness was greater in HFD and DM + HFD than Normal swine (both P < 0.05), resulting mainly from ET_B receptor-mediated vasoconstriction. Moreover, the calculated vascular stiffness coefficient was higher in DM + HFD and HFD than Normal swine (both P < 0.05). In conclusion, 15 mo of DM + HFD, as well as HFD alone, resulted in CMD. Although the overall vasodilation to BK was unperturbed, the relative contributions of NO and endothelium-derived hyperpolarizing factor pathways were altered. Moreover, the vasoconstrictor response to ET-1 was enhanced, involving the ET_B receptors. In conjunction with our previous study, these findings highlight the time dependence of the phenotype of CMD.

Assessment of arterio-ventricular coupling by tissue Doppler and wave intensity in type 2 diabetes

Aim

To evaluate ventricular-arterial coupling in preclinical cardiovascular disease, we used a new wave intensity approach and tissue Doppler in patients with and without type 2 diabetes mellitus (DM).

Methods

Sixty-five type 2 diabetes patients and 57 control individuals with normal systolic left ventricular function and without overt coronary or peripheral artery disease were assessed by tissue Doppler for myocardial velocities and by a combined Doppler and echo-tracking system (Aloka SSD-5500, Tokyo) for local arterial stiffness (epsilon, pulse wave velocity) and the characteristic peaks W1 and W2 of pulse wave intensity.

Results

Diabetes patients had significantly higher systolic blood pressure and pressure derivates (p<0.002). Diastolic myocardial velocity (Ve) was decreased (p<0.001). Epsilon and pulse wave velocity (p<0.001) were higher and so was W1 (11785±7491 vs. 9191±4299, p<0.04) but not W2. In the pooled data, independent predictors for Ve were age, septal wall thickness, Vs and HbA1C (R2 duration of diabetes (R2 0.479). 0.426) and for W1 systolic blood pressure, Vs, W2 and duration of diabetes (R2 0.479).

Conclusion

In type 2 diabetes pump function is preserved and maintained against increased arterial stiffness and impedance at the expense of increased myocardial oxygen requirements. Tissue Doppler and wave intensity measurements may be useful for therapeutic monitoring.

Review: Endothelial dysfunction and pre-symptomatic atherosclerosis in type 1 diabetes — pathogenesis and identification

The vascular endothelium offers an attractive model for detecting functional abnormalities prior to structural changes in the vasculature. Demonstration of progression from endothelial dysfunction through to atherosclerosis is required. Measurements of forearm bloodflow, biochemical markers and biophysical assessments of the endothelium have been employed as research tools for investigating pre-symptomatic atherosclerosis.

However, studies examining endothelial function in type 1 diabetes have been sparse and conflicting. Differences in methodology and the study populations were potential confounding factors. Augmented vasodilatory prostanoids compensate for reduced nitric oxide bioavailability in determining endothelial function in type 1 diabetes. Hyperglycaemia appears to be the initiating event in type 1 diabetes which promotes a variety of biochemical events which are pathogenic to the endothelium.

Improved understanding of the endothelium may facilitate the development of novel diagnostic tools and interventions targeting the accelerated atherosclerosis associated with type 1 diabetes.

Is activation in inflammatory bowel diseases associated with further impairment of coronary microcirculation?

BACKGROUND

Inflammatory bowel disease [IBD] includes a number of chronic relapsing diseases. In IBD intestinal microvascular endothelial cells are damaged by an abnormal immune response. Several studies have shown that IBD may cause increment in risk of developing atherosclerosis. IBD in activation was related to enhanced risks of worse cardiovascular [CV] outcome, on the other hand no risk increment was seen in remission comparing to control group in those studies. Coronary Flow Reserve [CFR] reflects coronary microvascular circulation. Coronary microvascular dysfunction may be defined as a predictor of CV outcome combined with previous described atherosclerotic risk factors. The present study was purposed to further evaluate whether or not CFR in the left anterior descending artery [LAD] is disturbed in IBD patients with activation in comparison to remission and healthy subjects.

METHODS

62 patients with IBD and 39 healthy volunteers were enrolled into the study. Patients' demographics were recorded. CFR evaluation of patients with IBD in both activation and remission period and control group were performed with transthoracic echocardiography.

RESULTS

CFR was significantly lowest in the active period of the IBD [2.26 [2.08-2.55] vs. 2.55 [2.18-3.00] and 3.10 [2.85-3.29] p<0.001]. CFR is negatively correlated with disease activity scores of IBD.

CONCLUSION

This study showed that CFR is more prominently disturbed in patients with IBD in activation. The activation of disease may have a major role in the progression of coronary microcirculatory dysfunction and future cardiovascular events.

Retinopathy is associated with impaired myocardial function assessed by advanced echocardiography in type 1 diabetes patients - The Thousand & 1 Study

AIMS

Retinopathy and heart disease in Type 1 Diabetes Mellitus (Type 1 DM) may be associated; however previous results have been conflicting. Tissue Doppler Imaging (TDI) and speckle-tracking echocardiography (STE) quantify myocardial function not assessable by conventional echocardiography. We investigated the association between severity of retinopathy and early myocardial dysfunction using conventional echocardiography, TDI and STE in Type 1 DM patients.

METHODS

Type 1 Diabetes Mellitus patients without known heart disease were included from the Steno Diabetes Center. The cross sectional association between retinopathy and myocardial function was analyzed in uni-and multivariable models. Retinopathy was categorized as nil-, simplex- or proliferative retinopathy.

RESULTS

A total of 1090 Type 1 Diabetes Mellitus patients were included, mean age was 49.6years and 53% were males. Left ventricular ejection fraction did not differ between groups of retinopathy. Global longitudinal strain (GLS) by STE decreased significantly with increasing degrees of retinopathy (nil; -18.6%, simplex; -18.2% (p=0.024), proliferative; -17.7% (p<0.001)), however differences attenuated in multivariable models (p⩾0.05). In univariable models, myocardial tissue velocities differed in relation to retinopathy: s' (nil; 6.9, simplex; 6.5, proliferative; 5.9 (p=0.001), e' (nil; 10.4, simplex; 9.2, proliferative; 7.9, p<0.001), a' (nil; 6.1, simplex; 6.7, proliferative; 7.0, p<0.001) and E/e' (nil; 6.7, simplex; 7.5, proliferative; 9.5, p<0.001). In multivariable models, differences persisted between nil and proliferative retinopathy for s', e' and E/e'.

CONCLUSION

Proliferative retinopathy is independently associated with decreased myocardial function assessed by Tissue Doppler Imaging in patients with Type 1 Diabetes Mellitus without history of heart disease.

Effect of postprandial hyperglycaemia on coronary flow reserve in patients with impaired glucose tolerance and type 2 diabetes mellitus

BACKGROUND

This study investigated whether postprandial hyperglycaemia has an adverse effect on coronary microvascular function and left ventricular diastolic function.

METHODS

In all, 28 patients with type 2 diabetes mellitus with no significant stenosis in left anterior descending artery were enrolled. In all subjects, plasma 1,5-anhydroglucitol was measured, and coronary flow reserve in the left anterior descending artery was evaluated using a Doppler wire. Membrane type-1 matrix metalloproteinase expression on circulating peripheral blood mononuclear cells was measured by flow cytometry. Correlation analyses were performed for coronary flow reserve and 1,5-anhydroglucitol, other coronary risk factors, membrane type-1 matrix metalloproteinase and E/e'.

RESULTS

Strong correlations were found only between 1,5-anhydroglucitol and coronary flow reserve and membrane type-1 matrix metalloproteinase. On multiple regression analysis, 1,5-anhydroglucitol remained an independent predictor of coronary flow reserve (β = 0.38, p = 0.048).

CONCLUSION

Postprandial hyperglycaemia appears to have an adverse effect on coronary microvascular function, suggesting that improvement of postprandial hyperglycaemia may contribute to the improvement of coronary microvascular dysfunction.

Emergence of Nonobstructive Coronary Artery Disease: A Woman's Problem and Need for Change in Definition on Angiography

Recognition of ischemic heart disease (IHD) is often delayed or deferred in women. Thus, many at risk for adverse outcomes are not provided specific diagnostic, preventive, and/or treatment strategies. This lack of recognition is related to sex-specific IHD pathophysiology that differs from traditional models using data from men with flow-limiting coronary artery disease (CAD) obstructions. Symptomatic women are less likely to have obstructive CAD than men with similar symptoms, and tend to have coronary microvascular dysfunction, plaque erosion, and thrombus formation. Emerging data document that more extensive, nonobstructive CAD involvement, hypertension, and diabetes are associated with major adverse events similar to those with obstructive CAD. A central emerging paradigm is the concept of nonobstructive CAD as a cause of IHD and related adverse outcomes among women. This position paper summarizes currently available knowledge and gaps in that knowledge, and recommends management options that could be useful until additional evidence emerges.

Prognostic value of calcium score and coronary flow velocity reserve in asymptomatic diabetic patients

BACKGROUND

The risk stratification of patients with diabetes mellitus (DM) is a major objective for the clinicians, and it can be achieved by coronary flow velocity reserve (CFVR) or with coronary artery calcium score (CS). CS evaluates underlying coronary atherosclerotic plaque burden and CFVR estimates both presence of coronary artery stenosis and microvascular function. Consequently, CFVR may provide unique risk information beyond the extent of coronary atherosclerosis.

AIM

Our aim is to assess joint prognostic value of CFVR and CS in asymptomatic DM patients.

MATERIALS AND METHODS

We prospectively included 200 asymptomatic patients (45,5 % male, mean age 57,35 ± 11,25), out of which, there were 101 asymptomatic patients with DM and 99 asymptomatic patients without DM, but with one or more conventionally risk factors for coronary artery disease. We analyzed clinical, biochemical, metabolic, inflammatory parameters, CS by Agatston method, transthoracic Doppler echocardiography CFVR of left anterior descending artery and echocardiographic parameters.

RESULTS

Total CS and CS LAD were significantly higher, while mean CFVR was lower in diabetics compared to the nondiabetics. During 1 year follow-up, 24 patients experienced cardio-vascular events (one cardiovascular death, two strokes, three myocardial infarctions, nine new onsets of unstable angina and nine myocardial revascularizations): 19 patients with DM and five non DM patients, (p = 0,003). Overall event free survival was significantly higher in non DM group, compared to the DM group (94,9 % vs. 81,2 %, p = 0,002 respectively), while the patients with CS ≥200 and CFVR <2 had the worst outcome during 1 year follow up in the whole study population as well as in the DM group. At multivariable analysis CFVR on LAD (HR 12.918, 95 % CI 3.865-43.177, p < 0.001) and total CS (HR 13.393, 95 % CI 1.675-107.119, p = 0.014) were independent prognostic predictors of adverse events in DM group of patients.

CONCLUSION

Both CS and CFVR provide independent and complementary prognostic information in asymptomatic DM patients. When two parameters are analyzed together, the risk stratification ability improves, even when DM patients are analyzed together with non DM patients. As a result, DM patients with CS ≥200 and CFVR <2 had the worst outcome. Consequently, the use of two tests identified subset of patients who can derive the most benefit from the intensive prevention measures.

Assessment of dipyridamole stress echocardiography for risk stratification of diabetic patients

BACKGROUND

Despite advances in medical therapy, cardiovascular disease, mainly coronary artery disease (CAD), remains the leading cause of mortality among patients with diabetes mellitus (DM). The objective of the present study was to assess the effectiveness of dipyridamole stress echocardiography in identify diabetic patients at high risk for cardiovascular events.

METHODS

Dipyridamole stress echocardiography was administered to 483 diabetic patients (294 women; mean age 63.41 ± 11.28 years) between July 2006 and December 2012.

RESULTS

Follow-up data were available for 264 patients (163 women; mean age 64.3 ± 10.5 years): 250 with a negative stress echocardiography and 14 with a positive stress echo. During a mean follow-up time of 18 ± 14 months, a cardiovascular event occurred in 18 (6.8%) patients, 12 (4.8%) in patients with a negative stress echo (n = 250) during a mean follow-up period of 20 ± 16 months and 6 (42%) in patients with positive stress echo (n = 14) during a mean follow-up of 13 ± 13 months. The positive and negative predictive values of stress echocardiography were 42% and 96% respectively. The accuracy value was 92%. A Cox regression model showed that CAD (hazard ratio [HR] 5.4, 95% confidence interval [CI] 1.9-15.4; p = 0.002) and positive stress echocardiography (HR 7.1, 95% CI 2.5-20.5; p < 0.001) were significant predictors of cardiovascular events.

CONCLUSIONS

For patients with diabetes, a negative dipyridamole stress echocardiogram predicts favorable outcome during the first year of follow-up. A new stress imaging test should be done after 12 months in diabetic patients.

Changes to both cardiac metabolism and performance accompany acute reductions in functional capillary supply

BACKGROUND

The relative importance of arteriole supply or ability to switch between substrates to preserve cardiac performance is currently unclear, but may be critically important in conditions such as diabetes.

METHODS

Metabolism of substrates was measured before and after infusion of polystyrene microspheres in the perfused working heart to mimic random capillary loss due to microvascular disease. The effect of acute loss of functional capillary supply on palmitate and glucose metabolism together with function was quantified, and theoretical tissue oxygen distribution calculated from histological samples and ventricular VO(2) estimated.

RESULTS

Microsphere infusion led to a dose-dependent decrease in rate-pressure product (RPP) and oxygen consumption (P<0.001). Microsphere infusion also increased work/unit oxygen consumption of hearts ('efficiency') by 25% (P<0.01). When corrected for cardiac work palmitate oxidation remained tightly coupled to very low workloads (RPP<2500 mmHg/min), illustrating a high degree of metabolic control. Arteriole occlusion by microspheres decreased the density of patent capillaries (P<0.001) and correspondingly increased the average capillary supply area by 40% (P<0.01). Calculated rates of oxygen consumption declined from 16.6±7.2 ml/100 ml/min to 12.4±9 ml/100 ml/min following arteriole occlusion, coupled with increases in size of regions of myocardial hypoxia (Control=22.0% vs. Microspheres=42.2%).

CONCLUSIONS

Cardiac mechanical performance is very sensitive to arteriolar blockade, but metabolite switching from fatty acid to glucose utilisation may also support cardiac function in regions of declining PO(2).

GENERAL SIGNIFICANCE

Preserving functional capillary supply may be critical for maintenance of cardiac function when metabolic flexibility is lost, as in diabetes.

Diabetes mellitus, prediabetes, and incidence of subclinical myocardial damage

BACKGROUND

Persons with prediabetes and diabetes mellitus are at high risk for cardiovascular events. However, the relationships of prediabetes and diabetes mellitus to the development of subclinical myocardial damage are unclear.

METHODS AND RESULTS

We measured cardiac troponin T with a highly sensitive assay (hs-cTnT) at 2 time points, 6 years apart, among 9051 participants of the community-based Atherosclerosis Risk in Communities Study with no diabetes mellitus, or prediabetes, and without cardiovascular disease including silent myocardial infarction by ECG. First, we examined the incidence of elevated hs-cTnT (≥14 ng/L) at 6 years of follow-up. Second, we examined clinical outcomes during the subsequent ≈14 years of follow-up among persons with and without incident elevations in hs-cTnT. Cumulative probabilities of elevated hs-cTnT at 6 years among persons with no diabetes mellitus, prediabetes, and diabetes mellitus were 3.7%, 6.4%, and 10.8%, respectively. Compared with normoglycemic persons, the adjusted relative risks for incident elevated hs-cTnT were 1.40 (95% CI, 1.08-1.80) for prediabetes and 2.47 (95% CI, 1.78-3.43) for diabetes mellitus. Persons with diabetes mellitus and incident elevations in hs-cTnT were at a substantially higher risk of heart failure (hazard ratio, 6.37 [95% CI, 4.27-9.51]), death (hazard ratio, 4.36 [95% CI, 3.14-6.07]), and coronary heart disease (hazard ratio, 3.84 [95% CI, 2.52-5.84]) compared with persons without diabetes mellitus and no incident elevation in hs-cTnT.

CONCLUSIONS

Prediabetes and diabetes mellitus were independently associated with the development of subclinical myocardial damage, as assessed by hs-cTnT, and those persons with evidence of subclinical damage were at highest risk for clinical events. These results support a possible deleterious effect of hyperglycemia on the myocardium, possibly reflecting a microvascular cause.

Intensive glucose control and hypoglycaemia: a new cardiovascular risk factor?

Intensive glucose control is widely practiced in patients with diabetes mellitus and patients acutely admitted to hospitals with concomitant stress-induced hyperglycaemia. Such a strategy increases the risk of hypoglycaemia by several-fold. Hypoglycaemia leads to a surge in catecholamine levels with a profound haemodynamic response. In patients with a decreased cardiac reserve, such significant changes can culminate in serious or even fatal cardiovascular outcomes. This review is aimed at discussing in depth the evidence to date that links hypoglycaemia with cardiovascular mortality, reviewing the likely mechanisms underlying this association, as well as summarising these from a cardiologist's perspective.

Inflammation and microvascular dysfunction in cardiac syndrome X patients without conventional risk factors for coronary artery disease

OBJECTIVES

The aim of this study was to ascertain whether coronary microvascular dysfunction (CMD) and inflammation are related in cardiac syndrome X (CSX).

BACKGROUND

CMD can lead to CSX, defined as typical angina and transient myocardial ischemia despite normal coronary arteriograms. Inflammation has been suggested to play a role in the pathogenesis of myocardial ischemia in CSX.

METHODS

We assessed 21 CSX patients (age 52 ± 10 years; 17 women) without traditional cardiovascular risk factors and 21 matched apparently healthy control subjects. Positron emission tomography was used to measure myocardial blood flow (MBF) and coronary flow reserve (CFR) in response to intravenous adenosine, whereas high-sensitivity C-reactive protein (CRP) was measured to assess inflammation. Patients were subdivided a priori into 2 groups according to CRP concentrations at study entry (i.e., ≤3 or >3 mg/l).

RESULTS

There were no differences in resting (1.20 ± 0.23 ml/min/g vs. 1.14 ± 0.20 ml/min/g; p = 0.32) or hyperemic MBF (3.28 ± 1.02 ml/min/g vs. 3.68 ± 0.89 ml/min/g; p = 0.18) between CSX patients and the control group, whereas CFR was mildly reduced in CSX patients compared with the control group (2.77 ± 0.80 vs. 3.38 ± 0.80; p = 0.02). Patients with CRP >3 mg/l had more severe impairment of CFR (2.14 ± 0.33 vs. 3.16 ± 0.76; p = 0.001) and more ischemic electrocardiographic changes during adenosine administration than patients with lower CRP, and a negative correlation between CRP levels and CFR (r = -0.49, p = 0.02) was found in CSX patients.

CONCLUSIONS

CSX patients with elevated CRP levels had a significantly reduced CFR compared with the control group, which is indicative of CMD. Our study thus suggests a role for inflammation in the modulation of coronary microvascular responses in patients with CSX.

Diabetic cardiomyopathy: pathophysiological mechanisms and cardiac dysfuntion

Several experimental, pathological, epidemiological, and clinical studies have clearly depicted that diabetes mellitus results in cardiac functional and structural changes. Diabetic cardiomyopathy results in both structural and functional alterations in the myocardium. Several mechanisms have been implicated in the pathophysiology of diabetic cardiomyopathy. Of these, metabolic disturbances, myocardial fibrosis, small vessel disease, and cardiac autonomic neuropathy are the major players in the pathophysiology of diabetic cardiomyopathy. This review is intended to discuss various such pathophysiological mechanisms of diabetic cardiomyopathy. We have also described the systolic and diastolic dysfunctioning and its corelation to structural changes in diabetes.

Quantitative cardiac positron emission tomography: the time is coming!

In the last 20 years, the use of positron emission tomography (PET) has grown dramatically because of its oncological applications, and PET facilities are now easily accessible. At the same time, various groups have explored the specific advantages of PET in heart disease and demonstrated the major diagnostic and prognostic role of quantitation in cardiac PET. Nowadays, different approaches for the measurement of myocardial blood flow (MBF) have been developed and implemented in user-friendly programs. There is large evidence that MBF at rest and under stress together with the calculation of coronary flow reserve are able to improve the detection and prognostication of coronary artery disease. Moreover, quantitative PET makes possible to assess the presence of microvascular dysfunction, which is involved in various cardiac diseases, including the early stages of coronary atherosclerosis, hypertrophic and dilated cardiomyopathy, and hypertensive heart disease. Therefore, it is probably time to consider the routine use of quantitative cardiac PET and to work for defining its place in the clinical scenario of modern cardiology.

Pravastatin-induced improvement in coronary reactivity and circulating ATP and ADP levels in young adults with type 1 diabetes

Aims: Extracellular ATP and ADP regulate diverse inflammatory, prothrombotic and vasoactive responses in the vasculature. Statins have been shown to modulate their signaling pathways in vitro. We hypothesized that altered intravascular nucleotide turnover modulates vasodilation in patients with type 1 diabetes (T1DM), and this can be partly restored with pravastatin therapy. Methods: In this randomized double blind study, plasma ATP and ADP levels and echocardiography-derived coronary flow velocity response to cold pressor test (CPT) were concurrently assessed in 42 normocholesterolemic patients with T1DM (age 30 ± 6 years, LDL cholesterol 2.5 ± 0.6 mmol/L) before and after four-month treatment with pravastatin 40 mg/day or placebo (n = 22 and n = 20, respectively), and in 41 healthy control subjects. Results: Compared to controls, T1DM patients had significantly higher concentrations of ATP (p < 0.01) and ADP (p < 0.01) and these levels were partly restored after treatment with pravastatin (p = 0.002 and p = 0.007, respectively), but not after placebo (p = 0.06 and p = 0.14, respectively). Coronary flow velocity acceleration was significantly lower in T1DM patients compared to control subjects, and it increased from pre- to post-intervention in the pravastatin (p = 0.02), but not in placebo group (p = 0.15). Conclusions: Pravastatin treatment significantly reduces circulating ATP and ADP levels of T1DM patients, and concurrently improves coronary flow response to CPT. This study provides a novel insight in purinergic mechanisms involved in pleiotropic effects of pravastatin.