Reduced myocardial flow reserve in non-insulin-dependent diabetes mellitus

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).

Obesity and diabetes: An update

The twin epidemic of obesity and diabetes is a major crisis globally. Several epidemiologic studies reveal the parallel escalation of obesity and diabetes. The term 'diabesity' expresses their close relationship to each other, wherein both these metabolic disorders are characterized by defects of insulin action. The pathophysiology connecting obesity and diabetes is chiefly attributed to two factors: insulin resistance and insulin deficiency. Recent years have seen an increasing body of work on the following metabolic defects common to both obesity and diabetes such as, impaired tissue perfusion, sleep disturbances, androgen dysfunction, altered Vitamin D levels and GI stress. The scope of this review is to present the most widely accepted theories that link the two diseases, provide an update on some proposed unifying metabolic defects and highlight current and future prevention and management strategies.

Diabetic Cardiomyopathy: Does the Type of Diabetes Matter?

In recent years, type 2 diabetes mellitus has evolved as a rapidly increasing epidemic that parallels the increased prevalence of obesity and which markedly increases the risk of cardiovascular disease across the globe. While ischemic heart disease represents the major cause of death in diabetic subjects, diabetic cardiomyopathy (DC) summarizes adverse effects of diabetes mellitus on the heart that are independent of coronary artery disease (CAD) and hypertension. DC increases the risk of heart failure (HF) and may lead to both heart failure with preserved ejection fraction (HFpEF) and reduced ejection fraction (HFrEF). Numerous molecular mechanisms have been proposed to underlie DC that partially overlap with mechanisms believed to contribute to heart failure. Nevertheless, the existence of DC remains a topic of controversy, although the clinical relevance of DC is increasingly recognized by scientists and clinicians. In addition, relatively little attention has been attributed to the fact that both underlying mechanisms and clinical features of DC may be partially distinct in type 1 versus type 2 diabetes. In the following review, we will discuss clinical and preclinical literature on the existence of human DC in the context of the two different types of diabetes mellitus.

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.

Association between coronary microvascular function and the vasa vasorum in patients with early coronary artery disease

BACKGROUND AND AIMS

The vasa vasorum (VV) plays a role in the initial phase of atherosclerosis, and abnormalities in microvascular function may be sensitive measures of the early development of atherosclerosis. The current study was designed to access the association between coronary microvascular function and VV density in patients undergoing cardiac catheterization.

METHODS

Twenty-four patients with early coronary artery disease underwent endothelium-dependent (coronary blood flow, CBF) and endothelium-independent (coronary flow velocity reserve, CFVR) coronary microvascular function testing, and optical coherence tomography (OCT) imaging of the left anterior descending coronary artery (LAD). Using an intracoronary Doppler guidewire, CBF was examined by evaluating changes in blood flow in response to acetylcholine and CFVR in response to adenosine. VV density (VV volume/vessel volume × 100, %VV) of the proximal 10 mm of the LAD was quantified by OCT.

RESULTS

The median values (Q1, Q3) of CFVR, % changes in CBF in response to acetylcholine, and the %VV were 2.70 (2.30, 2.90), -16.82 (-42.34, 54.52), and 2.62 (2.35, 3.35), respectively. %VV correlated inversely with CBF (r = -0.614, p = 0.001) and directly with CFVR (r = 0.423, p = 0.040). Multivariate analysis showed that only %VV was significantly correlated with CBF and the association was independent of other clinical variables, Framingham risk score, body mass index, and a family history of coronary heart disease.

CONCLUSIONS

This study demonstrates that VV density has negative correlation with endothelium-dependent microvascular function in patients with early coronary atherosclerosis. These observations link adventitial VV structure and function to microvascular dysfunction in early coronary atherosclerosis.

Coronary Endothelial Dysfunction in Women With Type 2 Diabetes Measured by Coronary Phase Contrast Flow Velocity Magnetic Resonance Imaging

OBJECTIVE

The aim of this study was to determine if differences in coronary endothelial function are observed between asymptomatic women with type 2 diabetes mellitus (DM) and control subjects using coronary phase contrast flow velocity magnetic resonance imaging in response to cold pressor stress, an established endothelium-dependent vasodilatory stress.

METHODS

Phase contrast flow velocity imaging of the right coronary artery was performed in 7 asymptomatic premenopausal women with DM and 8 healthy female participants in response to the cold pressor test at 3 T.

RESULTS

There was no significant difference in percent increase in coronary flow velocity from rest to peak flow velocity between DM and control subjects (32% ± 22% vs 46% ± 17%; P = 0.11). However, percent increase in coronary flow velocity was lower in DM than in control subjects (-3% ± 14% vs 31% ± 30%; P = 0.01) during the second minute of cold pressor stress, when endothelial-mediated vasodilation should occur.

CONCLUSIONS

Asymptomatic women with DM demonstrate reduced coronary flow velocity during the second minute of cold pressor stress, indicating coronary endothelial dysfunction.

Effects of dipeptidyl peptidase-4 (DPP-4) inhibition on angiogenesis and hypoxic injury in type 2 diabetes

AIMS

We examined whether, in diabetic Ob/Ob mice, the dipeptidyl peptidase-4 (DPP-4) inhibitor (PKF275-055), an antihyperglycemic drug, that inhibits the biological inactivation of SDF-1 (stromal cell-derived factor-1), may increase endothelial progenitor cells (EPCs) mobilization and incorporation, which, in turn, may regenerate capillaries and reduce myocardial ischemia induced by strenuous exercise.

MAIN METHODS

Half of sixteen control and Ob/Ob mice and eight Ob/Ob mice treated with PKF275-055 for four weeks underwent a forced swim protocol. Oral glucose tolerance, circulating EPCs, capillary ultrastructure and density, hypoxic areas and SDF-1 localization in myocardium were measured.

KEY FINDINGS

Ob/Ob mice were glucose intolerant, had a significant low number of circulating EPCs and myocardial capillaries compared to lean controls. The DPP-4 inhibitor significantly improved their glucose tolerance, doubled the number of circulating EPCs, stimulated the formation of functional vessels and SDF-1 localization in the endothelium of myocardial capillaries and arterioles. Cardiac hypoxia after forced swim in Ob/Ob mice was significantly reduced when they were treated with the DPP-4 inhibitor.

SIGNIFICANCE

DPP-4 inhibition may re-establish an adequate capillary network in the myocardium of diabetic Ob/Ob mice by the mobilization and SDF-1-mediated incorporation of EPCs and, consequently, reducing the susceptibility to myocardial ischemic injury provoked by strenuous exercise.

Coronary microvascular function, insulin sensitivity and body composition in predicting exercise capacity in overweight patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) has a negative impact on exercise capacity. The aim of this study was to determine how coronary microvascular function, glucose metabolism and body composition contribute to exercise capacity in overweight patients with CAD and without diabetes.

METHODS

Sixty-five non-diabetic, overweight patients with stable CAD, BMI 28-40 kg/m(2) and left ventricular ejection fraction (LVEF) above 35 % were recruited. A 3-hour oral glucose tolerance test was used to evaluate glucose metabolism. Peak aerobic exercise capacity (VO2peak) was assessed by a cardiopulmonary exercise test. Body composition was determined by whole body dual-energy X-ray absorptiometry scan and magnetic resonance imaging. Coronary flow reserve (CFR) assessed by transthoracic Doppler echocardiography was used as a measure of microvascular function.

RESULTS

Median BMI was 31.3 and 72 % had impaired glucose tolerance or impaired fasting glucose. VO2peak adjusted for fat free mass was correlated with CFR (r = 0.41, p = 0.0007), LVEF (r = 0.33, p = 0.008) and left ventricular end-diastolic volume (EDV) (r = 0.32, p = 0.01) while it was only weakly linked to measures of glucose metabolism and body composition. CFR, EDV and LVEF remained independent predictors of VO2peak in multivariable regression analysis.

CONCLUSION

The study established CFR, EDV and LVEF as independent predictors of VO2peak in overweight CAD patients with no or only mild functional symptoms and a LVEF > 35 %. Glucose metabolism and body composition had minor impact on VO2peak. The findings suggest that central hemodynamic factors are important in limiting exercise capacity in overweight non-diabetic CAD patients.

[No reflow: What are the predictors?]

INTRODUCTION

During the past 20 years, significant progress has been made in the recanalization of ACS with ST elevation. It is now accepted that the reopening of the large coronary vessels in the acute phase of infarction by thrombolysis or angioplasty is necessary but not sufficient, because in 20-50% of cases, the coronary recanalization is an illusion of reperfusion. This phenomenon is called "no reflow".

OBJECTIVE

The main objective of our study was to identify predictors of poor perfusion or "no reflow" in the acute phase of myocardial infarction.

METHODS

Observational prospective study, in the department of cardiology and internal medicine, university hospital of Blida, over a period of 28 months from 1st September 2010 to 31st January 2013. We identified all patients hospitalized for myocardial infarction in acute phase, who underwent primary angioplasty or thrombolysis with angiographic control during a good TIMI flow. The endpoint was regression of ST segment (regression<50% ST-segment defined no reflow).

RESULTS

Three hundred and seventy-nine patients were included. The mean age was 56.3±2.1, 87.8% of patients were male. In total, 35.9% hypertensive, 27.1% diabetic type 2, 50.1% and 10.8% dyslipidemia, smoking. One hundred and forty-seven (38.8%) developed a no reflow. Mortality was 3.9%, strongly correlated with no reflow (P=0.001). Predictors of no reflow after multivariate analysis were: age (OR 98, 0.961-0.996 95%, P=0.02), heart rate (1.01, 95% CI 0.998-1.02, P=0.035), the type 2 diabetes (odds ratio 1.87, CI 1.2-3.0, P=0.08), reaching the core (OR 7, 95% CI 1.2-18.4, P=0.027), direct stenting (OR 0.48, 95% CI 0.31-0.78, P=0.003). An interesting subgroup of patients was identified namely the subgroup strategy deferred primary angioplasty with stenting best reperfusion (OR 3.7, 95% CI 1.5-8.8, P=0.04), a lower rate of reocclusion of culprit artery and a lower rate of stenting with 23/51 (45.1%) versus 136/136 (100%) of immediate stenting group with a P<0.001.

CONCLUSION

No reflow is a common phenomenon, strongly correlated with mortality predictors are age, heart rate, diabetes, achieving the core and direct stenting. The distal embolization in primary angioplasty is an important phenomenon, a delayed stenting strategy appears to limit this phenomenon.

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.

Intracoronary administration of nicorandil during primary percutaneous coronary intervention: Impact on restoration of regional myocardial perfusion in reperfused myocardium during the subacute phase of myocardial infarction

Background

The impact of nicorandil as adjunctive therapy for percutaneous coronary intervention (PCI) in patients with ST-elevation myocardial infarction (STEMI) is controversial. We performed ¹⁵O-labeled water positron emission tomography (PET) to quantify regional myocardial perfusion in patients with STEMI who received nicorandil or no adjunctive therapy during PCI.

Methods

PCI was performed within 8 h after STEMI onset in 33 patients. 14 patients received intracoronary nicorandil 2 mg immediately after recanalization of the culprit lesion (Nico group). After 3–4 weeks, PET was performed in which myocardial blood flow (MBF) was measured at baseline and during adenosine triphosphate (ATP)-induced hyperemia. Myocardial vascular resistance (MVR) was calculated for all segments. Data were obtained from the reperfused (Rep) and normal segments (Cont) in each patient.

Results

In patients not given nicorandil (No-Nico group), the MBF was significantly lower in Rep than that in Cont at baseline and during hyperemia (Cont vs. Rep: 0.82 ± 0.14 vs. 0.68 ± 0.11, P = 0.001, ATP-Cont vs. ATP-Rep: 2.00 ± 0.72 vs. 1.52 ± 0.61, P = 0.017), which was restored in the Nico group (Cont vs. Rep: 0.79 ± 0.17 vs. 0.78 ± 0.20; ATP-Cont vs. ATP-Rep: 2.02 ± 0.84 vs. 1.84 ± 0.62). MVR was elevated in Rep at baseline and during hyperemia in the No-Nico group. MVR elevation in Rep was prevented in the Nico group.

Conclusions

¹⁵O-labeled water PET was feasible for segmental analysis of MBF during the subacute phase of STEMI. It revealed that intracoronary administration of nicorandil to STEMI patients who underwent PCI prevented MVR elevation and thus restored MBF in the reperfused segments to a level similar to that in the normal segments.

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¹⁵O-labeled water positron emission tomography (PET) is a tool to compare directly reperfused segments with normal segments simultaneously in each patient's hearts.

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¹⁵O-labeled water PET permits noninvasive quantitative measurement of myocardial blood flow during the subacute phase of myocardial infarction.

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¹⁵O-labeled water PET detects restoration of myocardial blood flow after intracoronary administration of nicorandil in STEMI patients.

The angiotensin receptor blocker losartan reduces coronary arteriole remodeling in type 2 diabetic mice

Cardiovascular complications are a leading cause of morbidity and mortality in type 2 diabetes mellitus (T2DM) and are associated with alterations of blood vessel structure and function. Although endothelial dysfunction and aortic stiffness have been documented, little is known about the effects of T2DM on coronary microvascular structural remodeling. The renin-angiotensin-aldosterone system plays an important role in large artery stiffness and mesenteric vessel remodeling in hypertension and T2DM. The goal of this study was to determine whether the blockade of AT1R signaling dictates vascular smooth muscle growth that partially underlies coronary arteriole remodeling in T2DM. Control and db/db mice were given AT1R blocker losartan via drinking water for 4 weeks. Using pressure myography, we found that coronary arterioles from 16-week db/db mice undergo inward hypertrophic remodeling due to increased wall thickness and wall-to-lumen ratio with a decreased lumen diameter. This remodeling was accompanied by decreased elastic modulus (decreased stiffness). Losartan treatment decreased wall thickness, wall-to-lumen ratio, and coronary arteriole cell number in db/db mice. Losartan treatment did not affect incremental elastic modulus. However, losartan improved coronary flow reserve. Our data suggest that Ang II-AT1R signaling mediates, at least in part, coronary arteriole inward hypertrophic remodeling in T2DM without affecting vascular mechanics, further suggesting that targeting the coronary microvasculature in T2DM may help reduce cardiac ischemic events.

Impaired coronary and retinal vasomotor function to hyperoxia in Individuals with Type 2 diabetes

PURPOSE

Adults with diabetes are at a high risk of developing coronary heart disease. The purpose of this study was to assess coronary artery vascular function non-invasively in individuals with and without Type 2 diabetes and to compare these coronary responses to another microvascular bed (i.e. retina). We hypothesized that individuals with diabetes would have impaired coronary reactivity and that these impairments would be associated with impairments in retinal reactivity.

METHODS

Coronary blood velocity (Transthoracic Doppler Echocardiography) and retinal diameters (Dynamic Vessel Analyzer) were measured continuously during five minutes of breathing 100% oxygen (i.e. hyperoxia) in 15 persons with Type 2 diabetes and 15 age-matched control subjects. Using fundus photographs, retinal vascular calibers were also measured (central retinal arteriole and venule equivalents).

RESULTS

Individuals with diabetes compared to controls had impaired coronary (-2.34±16.64% vs. -14.27±10.58%, P=0.03) and retinal (arteriole: -0.04±3.34% vs. -3.65±5.07%, P=0.03; venule: -1.65±3.68% vs. -5.23±5.47%, P=0.05) vasoconstrictor responses to hyperoxia, and smaller central arteriole-venule equivalent ratios (0.83±0.07 vs. 0.90±0.07, P=0.014). Coronary reactivity was associated with central retinal arteriole equivalents (r=-0.516, P=0.005) and retinal venular reactivity (r=0.387, P=0.034).

CONCLUSION

Diabetes impairs coronary and retinal microvascular function to hyperoxia. Impaired vasoconstrictor responses may be part of a systemic diabetic vasculopathy, which may contribute to adverse cardiovascular events in individuals with diabetes.

Patterns and determinants of temporal change in high-sensitivity cardiac troponin-T: The Atherosclerosis Risk in Communities Cohort Study

BACKGROUND

Patterns and determinants of temporal change in highly-sensitivity troponin-T (hs-cTNT), a novel measure of subclinical myocardial injury, among asymptomatic persons have not been well characterized.

METHODS

We studied 8571 ARIC Study participants, free of cardiovascular disease, who had hs-cTNT measured at two time-points, 6 years apart (1990-1992 and 1996-1998). We examined the association of baseline 10-year atherosclerotic cardiovascular (ASCVD) risk-group (<5%, 5-7.4%, ≥ 7.5%) and individual cardiac risk-factors with change across hs-cTNT categories using Poisson and Multinomial Logistic regression and with mean continuous hs-cTNT change using linear regression.

RESULTS

Mean age was 57 years and 43% were male. Mean (SD) 6-year hs-cTNT change was higher across increasing ASCVD risk-groups; +1.2 (6.1) ng/L [<5%], +2.1 (5.4) ng/L [5-7.4%], and +2.8 (8.8) ng/L [≥ 7.5%]. Major baseline determinants of temporal hs-cTNT increases were: age, male gender, hypertension, diabetes, and obesity. In addition, the relative risk (RR) of incident elevated hs-cTNT (≥ 14 ng/L) was 1.46 (95% CI 1.1-2.0) for persons with sustained hypertension compared to those who remained normotensive. Results for sustained obesity (RR 1.65 [1.19-2.29]) and hyperglycemia (RR 1.76 [1.16-2.67]) were similar. These associations were generally stronger after accounting for survival bias. However, smoking, LDL-cholesterol and triglycerides were not associated with hs-cTNT change. HDL-cholesterol was associated with declining hs-cTNT.

CONCLUSIONS

Persons in higher ASCVD risk-groups were more likely to have increases in hs-cTNT over 6 years of follow-up. The modifiable risk-factors primarily driving this association were diabetes, hypertension, and obesity; particularly when they were persistently elevated over follow-up. Future studies are needed to determine whether modifying these risk factors can prevent progression of subclinical myocardial injury.

Coronary flow reserve estimated by positron emission tomography to diagnose significant coronary artery disease and predict cardiac events

Coronary artery disease (CAD) is a major cause of death in Japan. Coronary angiography is useful to assess the atherosclerotic burden in CAD patients, but its ability to predict whether patients will respond favorably to optimal medical therapy and revascularization is limited. The measurement of the fractional flow reserve with angiography is a well-validated method for identifying ischemic vessels. However, neither an anatomical assessment nor a functional assessment can delineate microvasculature or estimate its function. The quantitative coronary flow reserve (CFR) estimated from sequential myocardial perfusion images obtained by positron emission tomography (PET) during stress provides an accurate index of hyperemic reactivity to vasodilatory agents in the myocardium. In fact, there is growing evidence that the CFR reflects disease activity in the entire coronary circulation, including epicardial coronary artery stenosis, diffuse atherosclerosis, and microvascular dilatory function. Importantly, reduced CFR is observed even in patients without flow-limiting coronary stenosis, and its evaluation can improve the risk stratification of patients at any stage of CAD. This review focuses on the application of CFR estimated by cardiac PET for the diagnosis and risk stratification of patients with CAD.

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.

Impact of nonculprit vessel myocardial perfusion on outcomes of patients undergoing percutaneous coronary intervention for acute coronary syndromes: analysis from the ACUITY trial (Acute Catheterization and Urgent Intervention Triage Strategy)

OBJECTIVES

This study evaluated the impact of nonculprit vessel myocardial perfusion on outcomes of non-ST-segment elevation acute coronary syndromes (NSTE-ACS) patients.

BACKGROUND

ST-segment elevation myocardial infarction patients have decreased perfusion in areas remote from the infarct-related vessel. The impact of myocardial hypoperfusion of regions supplied by nonculprit vessels in NSTE-ACS patients treated with percutaneous coronary intervention (PCI) is unknown.

METHODS

The angiographic substudy of the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) trial included 6,921 NSTE-ACS patients. Complete 3-vessel assessments of baseline coronary TIMI (Thrombolysis In Myocardial Infarction) flow grade and myocardial blush grade (MBG) were performed. We examined the outcomes of PCI-treated patients according to the worst nonculprit vessel MBG identified per patient.

RESULTS

Among the 3,826 patients treated with PCI, the worst nonculprit MBG was determined in 3,426 (89.5%) patients, including 375 (10.9%) MBG 0/1 patients, 475 (13.9%) MBG 2 patients, and 2,576 (75.2%) MBG 3 patients. Nonculprit MBG 0/1 was associated with worse baseline clinical characteristics. Patients with nonculprit MBG 0/1 versus MBG 3 had increased rates of 30-day (3.0% vs. 0.7%, p < 0.0001) and 1-year (4.4% vs. 1.0%, p < 0.0001) death. Similar results were found among patients with pre-procedural TIMI flow grade 3 in the culprit vessel, where nonculprit vessel MBG 0/1 (hazard ratio: 2.81 [95% confidence interval: 1.63 to 4.84], p = 0.0002) was the strongest predictor of 1-year mortality.

CONCLUSIONS

Reduced myocardial perfusion in an area supplied by a nonculprit vessel is associated with increased short- and long-term mortality rates in NSTE-ACS patients undergoing PCI. Furthermore, worst nonculprit MBG is able to risk-stratify patients with normal baseline flow of the culprit vessel.

Effect of type 2 diabetes mellitus on epicardial adipose tissue volume and coronary vasomotor function

Patients with coronary artery disease and/or type 2 diabetes mellitus (DM) generally exhibit more epicardial adipose tissue (EAT) than healthy controls. Recently, it has been proposed that EAT affects vascular function and structure by secreting proinflammatory and vasoactive substances, thereby potentially contributing to the development of cardiovascular disease. In the present study, the interrelation of EAT, coronary vasomotor function, and coronary artery calcium was investigated in patients with and without DM, who were evaluated for coronary artery disease. Myocardial blood flow (MBF) was assessed at rest and during adenosine-induced hyperemia using [(15)O]-water positron emission tomography combined with computed tomography to quantify coronary artery calcium and EAT in 199 patients (46 with DM). In this cohort (mean age 58 ± 10 years), the patients with DM had a greater body mass index, heart rate, and systolic blood pressure at rest (all p <0.05). Coronary artery calcium and the EAT volumes were comparable between those with and without DM. Both patient groups showed comparable MBF at rest and coronary vascular resistance. A lower hyperemic MBF and coronary flow reserve (CFR) and greater hyperemic coronary vascular resistance (all p <0.05) was observed in the patients with DM. A pooled analysis showed a positive association of EAT volume with hyperemic coronary vascular resistance but not with the MBF at rest, hyperemic MBF, or coronary vascular resistance at rest. In the group analysis, the EAT volume was inversely associated with hyperemic MBF (r = -0.16, p = 0.05) and CFR (r = -0.17, p = 0.04) and positively with hyperemic coronary vascular resistance (r = 0.26, p = 0.002) only in patients without DM. Multivariate regression analysis, adjusted for age, gender, and body mass index, showed an independent association between the EAT volume and hyperemic MBF (β = -0.16, p = 0.02), CFR (β = -0.16, p = 0.04), and hyperemic coronary vascular resistance (β = 0.25, p <0.001) in the non-DM group. In conclusion, these results suggest a role for EAT in myocardial microvascular dysfunction; however, once DM has developed, other factors might be more dominant in contributing to impaired myocardial microvascular dysfunction.

Fluvastatin-induced reduction of oxidative stress ameliorates diabetic cardiomyopathy in association with improving coronary microvasculature

Diabetic cardiomyopathy is associated with increased oxidative stress and vascular endothelial dysfunction, which lead to coronary microangiopathy. We tested whether statin-induced redox imbalance improvements could ameliorate diabetic cardiomyopathy and improve coronary microvasculature in streptozotocin-induced diabetes mellitus (DM). Fluvastatin (10 mg/kg/day) or vehicle was orally administered for 12 weeks to rats with or without DM. Myocardial oxidative stress was assessed by NADPH (nicotinamide adenine dinucleotide phosphate) oxidase subunit p22(phox) and gp91(phox) mRNA expression, and myocardial 8-iso-prostaglandin F(2α) (PGF(2α)) levels. Myocardial vascular densities were assessed using anti-CD31 and anti-α-smooth muscle actin (SMA) antibodies. Fluvastatin did not affect blood pressure or plasma cholesterol, but attenuated increased left ventricular (LV) minimum pressure and ameliorated LV systolic dysfunction in DM rats in comparison with vehicle (LV dP/dt, 8.9 ± 1.8 vs 5.4 ± 1.0 × 10(3) mmHg/s, P < 0.05). Myocardial oxidative stress increased in DM, but fluvastatin significantly reduced p22(phox) and gp91(phox) mRNA expression and myocardial PGF(2α) levels. Fluvastatin enhanced myocardial endothelial nitric oxide synthase (eNOS) protein levels and increased eNOS, vascular endothelial growth factor, and hypoxia-inducible factor-1α mRNA expression. CD31-positive cell densities were lower in DM rats than in non-DM rats (28.4 ± 13.2 vs 48.6 ± 4.3/field, P < 0.05) and fluvastatin restored the number (57.8 ± 18.3/field), although there were no significant differences in SMA-positive cell densities between groups. Fluvastatin did not affect cardiac function, oxidative stress, or vessel densities in non-DM rats. These results suggest that beneficial effects of fluvastatin on diabetic cardiomyopathy might result, at least in part, from improving coronary microvasculature through reduction in myocardial oxidative stress and upregulation of angiogenic factor.

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.

Neutrophil-to-lymphocyte ratio, insulin resistance, and endothelial dysfunction in patients with autosomal dominant polycystic kidney disease

Endothelial dysfunction (ED), insulin resistance (IR), and inflammation are risk factors for increased cardiovascular morbidity and mortality in autosomal dominant polycystic kidney disease (ADPKD). ADPKD patients may have increased carotid intima-media thickness (CIMT) and decreased coronary flow velocity reserve (CFVR). The neutrophil-to-lymphocyte ratio (NLR) was introduced as a marker to determine inflammation in various disorders. We aimed to investigate the relationship between NLR and IR, CFVR, CIMT, and the left ventricular mass index (LVMI) in normotensive ADPKD patients. Twentynine ADPKD patients (age 38.8 ± 10.2 years; 8 men and 21 women) and 19 healthy controls (age 33.8 ± 7.4 years; 8 men and 11 women) were included in this cross-sectional study. CFVR was calculated with echocardiography as the ratio of hyperemic to baseline diastolic peak coronary flow velocities. CIMT was measured in the distal common carotid artery by using a 10-MHz linear echocardiography probe. HOMA-IR was calculated NLR was calculated as the ratio of the neutrophil and lymphocyte counts. Age, sex, body mass index, and levels of glucose, creatinine, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, triglycerides, C-reactive protein (CRP), microalbuminuria, and creatinine clearance were similar between ADPKD patients and healthy subjects. NLR, CIMT, LVMI, and HOMA-IR were significantly higher and CFVR values were significantly lower in patients with ADPKD compared to that in healthy subjects. NLR showed positive correlation with CIMT, HOMA, insulin, glucose, and HDL cholesterol levels, while it was inversely correlated with CFVR and albumin level in all subjects. In patients with ADPKD, NLR showed positive correlation with HDL cholesterol level and inverse correlation with LVMI and albumin level. NLR that was found to be increased in patients with ADPKD may be a readily available marker of inflammation and ED.

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.

Cardiac mitochondrial dysfunction during hyperglycemia--the role of oxidative stress and p66Shc signaling

Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or by the effects of insulin resistance. Insulin deficiency leads to hyperglycemia which is the major initiator of diabetic cardiovascular complications escalating with time and driven by many complex biochemical and molecular processes. Four hypotheses, which propose mechanisms of diabetes-associated pathophysiology, are currently considered. Cardiovascular impairment may be caused by an increase in polyol pathway flux, by intracellular advanced glycation end-products formation or increased flux through the hexosamine pathway. The latter of these mechanisms involves activation of the protein kinase C. Cellular and mitochondrial metabolism alterations observed in the course of diabetes are partially associated with an excessive production of reactive oxygen species (ROS). Among many processes and factors involved in ROS production, the 66 kDa isoform of the growth factor adaptor shc (p66Shc protein) is of particular interest. This protein plays a key role in the control of mitochondria-dependent oxidative balance thus it involvement in diabetic complications and other oxidative stress based pathologies is recently intensively studied. In this review we summarize the current understanding of hyperglycemia induced cardiac mitochondrial dysfunction with an emphasis on the oxidative stress and p66Shc protein. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.

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.

Increased basal coronary blood flow as a cause of reduced coronary flow reserve in diabetic patients

A reduced coronary flow reserve (CFR) has been demonstrated in diabetes, but the underlying mechanisms are unknown. We assessed thermodilution-derived CFR after 5-min intravenous adenosine infusion through a pressure-temperature sensor-tipped wire in 30 coronary arteries without significant lumen reduction in 30 patients: 13 with and 17 without a history of diabetes. We determined CFR as the ratio of basal and hyperemic mean transit times (Tmn); fractional flow reserve (FFR) as the ratio of distal and proximal pressures at maximal hyperemia to exclude local macrovascular disease; and an index of microvascular resistance (IMR) as the distal coronary pressure at maximal hyperemia divided by the inverse of the hyperemic Tmn. We also assessed insulin resistance by the homeostasis model assessment (HOMA) index. FFR was normal in all investigated arteries. CFR was significantly lower in diabetic vs. nondiabetic patients [median (interquartile range): 2.2 (1.4–3.2) vs. 4.1 (2.7–4.4); P = 0.02]. Basal Tmn was lower in diabetic vs. nondiabetic subjects [median (interquartile range): 0.53 (0.25–0.71) vs. 0.64 (0.50–1.17); P = 0.04], while hyperemic Tmn and IMR were similar. We found significant correlations at linear regression analysis between logCFR and the HOMA index ( r2 = 0.35; P = 0.0005) and between basal Tmn and the HOMA index ( r2 = 0.44; P < 0.0001). In conclusion, compared with nondiabetic subjects, CFR is lower in patients with diabetes and epicardial coronary arteries free of severe stenosis, because of increased basal coronary flow, while hyperemic coronary flow is similar. Basal coronary flow relates to insulin resistance, suggesting a key role of cellular metabolism in the regulation of coronary blood flow.

Improved cardiac risk assessment with noninvasive measures of coronary flow reserve

BACKGROUND

Impaired vasodilator function is an early manifestation of coronary artery disease and may precede angiographic stenosis. It is unknown whether noninvasive assessment of coronary vasodilator function in patients with suspected or known coronary artery disease carries incremental prognostic significance.

METHODS AND RESULTS

A total of 2783 consecutive patients referred for rest/stress positron emission tomography were followed up for a median of 1.4 years (interquartile range, 0.7-3.2 years). The extent and severity of perfusion abnormalities were quantified by visual evaluation of myocardial perfusion images. Rest and stress myocardial blood flows were calculated with factor analysis and a 2-compartment kinetic model and were used to compute coronary flow reserve (coronary flow reserve equals stress divided by rest myocardial blood flow). The primary end point was cardiac death. Overall 3-year cardiac mortality was 8.0%. The lowest tertile of coronary flow reserve (<1.5) was associated with a 5.6-fold increase in the risk of cardiac death (95% confidence interval, 2.5-12.4; P<0.0001) compared with the highest tertile. Incorporation of coronary flow reserve into cardiac death risk assessment models resulted in an increase in the c index from 0.82 (95% confidence interval, 0.78-0.86) to 0.84 (95% confidence interval, 0.80-0.87; P=0.02) and in a net reclassification improvement of 0.098 (95% confidence interval, 0.025-0.180). Addition of coronary flow reserve resulted in correct reclassification of 34.8% of intermediate-risk patients (net reclassification improvement=0.487; 95% confidence interval, 0.262-0.731). Corresponding improvements in risk assessment for mortality from any cause were also demonstrated.

CONCLUSION

Noninvasive quantitative assessment of coronary vasodilator function with positron emission tomography is a powerful, independent predictor of cardiac mortality in patients with known or suspected coronary artery disease and provides meaningful incremental risk stratification over clinical and gated myocardial perfusion imaging variables.

Detection of myocardial microvascular disease using contrast echocardiography during adenosine stress in type 2 diabetes mellitus: prospective comparison with single-photon emission computed tomography

PURPOSE

To evaluate myocardial microvascular disease in patients with type 2 diabetes mellitus (DM) using myocardial contrast echocardiography (MCE) and to report on its diagnostic accuracy using single photon emission tomography (SPECT) as reference test.

METHODS

We prospectively enrolled 79 patients (25 DM; 66 ±11 years) who underwent simultaneous SPECT and MCE with contrast agent during adenosine stress. MCE and SPECT were visually analyzed using 17 segments. Quantitative MCE parameters were derived from replenishment curves. Microbubble velocity (β min(-1)), absolute myocardial blood flow (MBF ml/min/g), and reserve values were calculated. Diagnostic accuracy and area under curve (AUC) was reported.

RESULTS

Patients with DM had higher BMI vs non DM (33±7 vs 28±5kg/m(2) P=0 .007), with more prior myocardial infarction (40 vs 15% P=.01). Visual MCE was abnormal in 40 (51%) patients (60% in DM vs 46% in non DM P=0.04). SPECT was abnormal in 38 (48%) patients [60% in DM vs 42% non DM, P=0.01]. Reserve parameters were lower in DM vs. non DM patients: (β 1.77±1.12 vs 2.20±1.4, P<0.001 and MBF 2.86± 2.62 vs. 3.67±2.84, P<0.001). DM patients without CAD on SPECT had significantly lower β, and MBF reserve compared to non DM patients without CAD. Compared to SPECT, β reserve cutoff 1.6 had AUC 0.817, sensitivity 81%, and specificity 66% while MBF reserve cutoff 1.9 had AUC 0.760, sensitivity 79%, and specificity 63% in DM patients.

CONCLUSION

Diabetes is associated with myocardial microvascular abnormalities as evidenced by abnormal myocardial perfusion on visual and quantitative MCE.

PET and PET/CT in cardiovascular disease

The present review provides an overview of the role of cardiac positron emission tomography in the diagnosis and management of cardiovascular disease. It expands on the relative advantages and disadvantages over other imaging modalities as well as the available evidence supporting its value in the diagnosis and management of patients with coronary artery disease, the assessment of myocardial viability, and evaluation of the cardiac sympathetic nervous system. Furthermore, the recent developments, such as the implementation of high-end computed tomography devices to form hybrid systems, and the advances of molecular imaging probes in experimental applications are briefly discussed.

Coronary Flow Reserve of the Non-Ischemia Related Coronary Artery During Dobutamine Stress Echocardiography

Background

Incorporation of analysis of coronary velocities in stress studies adds diagnostic value to both clinical variables and dobutamine echocardiography. Micorcirculatory abnormalities may precede obstructive corornary disease. Therefore the aim of this study was to assess Doppler derived coronary velocity and flow of the left anterior descending coronary artery (LAD) during dobutamine stress echocardiography (DSE) in patients without LAD-related ischemia.

Methods

Sixty nine patients with chest pain underwent DSE studies to evaluate myocardial ischemia. All had trans-thoracic Doppler interrogation of the distal LAD before and just after termination of the DSE. Coronary velocity reserves (CFR) were calculated as the ratios of post-DSE/baseline diastolic velocities. Volumetric flow in the distal LAD was calculated from the diameter of LAD color jet and velocity integral. Volumetric flow reserve was calculated as the ratio of post-DSE baseline LAD flows.

Results

At rest all subjects had left ventricular wall motion score index (WMSI) = 1, while in 28, wall motion abnormality appeared in non-LAD territory with WMSI = 1.17 ± 0.08. Peak diastolic velocity after DSE increased form 28.5 ± 13.6 to 52.4 ± 23.7 cm/sec, P = 9.5 × 10^-11, and velocity-CFR was 2.08 ± 0.7. Diastolic LAD flow increased from 36.5 ± 23.8 to 75.75 ± 48.7 mL/min, P = 1.21 × 10^-7 and volumetric-CFR was 2.6 ± 2.8. Peak diastolic velocity-CFR in patients without LV wall motion abnormality was 2.4 ± 0.7 while in those with motion abnormality 1.77 ± 0.56, P = 0.00008. Flow-derived LAD-CFR was 3.3 ± 3.7 in those without compared to 1.88 ± 0.57 in patients with wall motion abnormality, P < 0.05.

Conclusion

LAD velocity and flow reserves are reduced in patients with remote myocardial ischemia, which may indicate early atherosclerotic involvement.

Inflammation is related to coronary flow reserve detected by positron emission tomography in asymptomatic male twins

OBJECTIVES

This study sought to examine the relationship between inflammation and coronary microvascular function in asymptomatic individuals using positron emission tomography (PET) and assessment of coronary flow reserve (CFR).

BACKGROUND

Coronary microvascular dysfunction is an early precursor of coronary artery disease (CAD) thought to result from endothelial cell activation and inflammation, but data are limited.

METHODS

We examined 268 asymptomatic male monozygotic and dizygotic twins. Plasma biomarkers of inflammation and endothelial cell activation included C-reactive protein (CRP), interleukin (IL)-6, white blood cell count (WBC), vascular cell adhesion molecule (VCAM)-1, and intercellular adhesion molecule (ICAM)-1. Blood flow quantitation was obtained with [¹³N] ammonia PET at rest and after adenosine stress. CFR was measured as the ratio of maximum flow to baseline flow at rest; abnormal CFR was defined as a ratio < 2.5. A summed stress score for visible perfusion defects was calculated.

RESULTS

In within-pair analyses, all biomarkers, except VCAM-1, were higher in twins with lower CFR than their brothers with higher CFR (p < 0.05). This was observed in the entire sample, as well as within pairs discordant for a CFR of <2.5. Associations persisted after adjusting for summed stress score and CAD risk factors. In contrast no biomarker, except IL-6, was related to the summed stress score of visible defects.

CONCLUSIONS

Even in asymptomatic subjects, a decrease in coronary microvascular function is accompanied by a systemic inflammatory response, independent of CAD risk factors. Our results, using a controlled twin design, highlight the importance of coronary microvascular function in the early phases of CAD.

Coronary microvascular reactivity to adenosine predicts adverse outcome in women evaluated for suspected ischemia results from the National Heart, Lung and Blood Institute WISE (Women's Ischemia Syndrome Evaluation) study

OBJECTIVES

We investigated whether coronary microvascular dysfunction predicts major adverse outcomes during follow-up among women with signs and symptoms of ischemia.

BACKGROUND

Altered coronary reactivity occurs frequently in women evaluated for suspected ischemia, and the endothelium-dependent component is linked with adverse outcomes. Possible links between endothelium-independent microvascular coronary reactivity and adverse outcomes remain uncertain.

METHODS

As part of the National Heart, Lung and Blood Institute-sponsored WISE (Women's Ischemia Syndrome Evaluation), we investigated relationships between major adverse outcomes and baseline coronary flow reserve (CFR) after intracoronary adenosine in 189 women referred to evaluate suspected ischemia.

RESULTS

At a mean of 5.4 years, we observed significant associations between CFR and major adverse outcomes (death, nonfatal myocardial infarction, nonfatal stroke, or hospital stay for heart failure). An exploratory receiver-operator characteristic analysis identified CFR <2.32 as the best discriminating threshold for adverse outcomes (event rate 26.7%; and >or=2.32 event rate 12.2%; p = 0.01). Lower CFR was associated with increased risk for major adverse outcomes (hazard ratio: 1.16, 95% confidence interval: 1.04 to 1.30; p = 0.009). This held true among the 152 women without obstructive coronary artery disease (CAD) (hazard ratio: 1.20, 95% confidence interval: 1.05 to 1.38; p = 0.008). The CFR significantly improved prediction of adverse outcomes over angiographic CAD severity and other risk conditions.

CONCLUSIONS

Among women with suspected ischemia and atherosclerosis risk factors, coronary microvascular reactivity to adenosine significantly improves prediction of major adverse outcomes over angiographic CAD severity and CAD risk factors. These findings suggest that coronary microvessels represent novel targets for diagnostic and therapeutic strategies to predict and limit adverse outcomes in women. (Women's Ischemia Syndrome Evaluation [WISE]; NCT00000554).

Coronary flow reserve is a comprehensive indicator of cardiovascular risk factors in subjects with chest pain and normal coronary angiogram

BACKGROUND

The aim of the present study was to analyze the parameters related to baseline coronary flow velocity (CFV) and coronary flow reserve (CFR) using Doppler transthoracic echocardiography (TTE), and to assess their associations with components of the Framingham risk score (FRS), which estimates 10-year risk of coronary heart disease, in subjects with chest pain and a normal coronary angiogram.

METHODS AND RESULTS

A total of 354 individuals (mean age: 55+/-11 years, M:F ratio =186:168) with angina or angina-like chest pain and a normal coronary arteriogram were enrolled. CFR, using TTE and adenosine or dipyridamole, was measured within 2 weeks after coronary angiogram. The clinical, electrocardiographic, echocardiographic and laboratory parameters related to baseline CVF and CFR were analyzed, and CFR was compared with FRS. There was an inverse correlation between baseline CFV and CFR (r=-0.374, P<0.001). On multivariate analysis the fulfilling of left ventricular hypertrophy criteria on electrocardiography was an independent predictor of baseline CFV for the upper 75% quartile (23.2> or =cm/s; odds ratio (OR) = 2.840, 95% confidence interval (CI) =1.155-6.983, P=0.023). On multivariate analysis hemoglobin A(1c) level was independently related to a CFR <2.0 (OR = 2.195, 95%CI = 0.920-1.005, P=0.013). CFR had an inverse correlation with FRS (r=-0.222, P<0.001). On multiple regression analysis among the components of the FRS system (FRSS), independent factors related to a CFR <2.0 included age (OR =1.033, 95%CI =1.000-1.067, P=0.041), high-density lipoprotein-cholesterol level (OR = 0.961, 95%CI = 0.933-0.991, P=0.012) and smoking status (OR = 2.461, 95%CI =1.078-5.618, P=0.033), respectively.

CONCLUSIONS

CFR can be a comprehensive indicator of cardiovascular risk factors, including parameters of the FRSS, in subjects with chest pain and a normal coronary angiogram.