Coronary Microvascular Dysfunction Research Articles

Myocardial Ischemia: Differentiating between Epicardial Coronary Artery Atherosclerosis, Microvascular Dysfunction and Vasospasm in the Catheterization Laboratory.

Ischemic heart disease is currently the most common cause of mortality and morbidity worldwide. Although myocardial ischemia is classically determined by epicardial coronary atherosclerosis, up to 40% of patients referred for coronary angiography have no obstructive coronary artery disease (CAD). Ischemia with non-obstructive coronary artery disease (INOCA) has typically been underestimated in the past because, until recently, its prognostic significance was not completely clear. This review aims to highlight differences and patterns in myocardial ischemia caused by epicardial obstructive CAD, coronary microvascular dysfunction (CMD) or vasomotor abnormalities and to elucidate the state of the art in correctly diagnosing these different patterns.

Long-term prognostic impact of fasting plasma glucose and myocardial flow reserve beyond other risk factors and heart disease phenotypes.

Cardiometabolic risk factors, including high fasting plasma glucose (hFPG), are emerging prognostic determinants in patients with coronary artery disease (CAD) or heart failure (HF). Coronary microvascular dysfunction might be a comprehensive risk predictor in these patients. The purpose of this study was to assess whether hFPG and global myocardial blood flow (MBF) reserve measured by positron emission tomography (PET), expressing global coronary function, predict long-term prognosis beyond other risk factors and presence of obstructive CAD or left ventricular (LV) dysfunction associated with HF. We retrospectively collected long-term follow-up data in 103 patients (mean age 61 ± 10 years, 74 males) with stable chest pain or dyspnoea who underwent cardiac PET/computerized tomography and coronary angiography. Disease phenotypes included obstructive CAD (35%), LV dysfunction without obstructive CAD (43%), or none (22%). At multivariable logistic regression analysis, MBF reserve lower than the median value (OR 1.8, 95% CI 1.5-2.2) was significantly associated with male gender (OR 3.45, 95% CI 1.21-9.83) and hFPG (OR 3.87, 95% CI 1.17-12.84) among all risk factors. In a median follow-up of 10.9 years (interquartile range 7.8-13.9), 39 patients (37.8%) died (13.6% cardiac death). At multivariable Cox analyses including all risk factors and disease phenotypes, age (HR 1.07, 95% CI 1.02-1.12), hFPG (HR 2.18, 95% CI 1.02-4.63), and depressed MBF reserve (HR 4.47, 95% CI 1.96-10.18) were independent predictors of death (global χ 2 37.41, P = 0.0004). These results suggest a strong long-term prognostic role of hFPG and depressed MBF reserve in a high-risk population of patients with a high prevalence of obstructive CAD or HF.

Coronary Microvascular Dysfunction is Associated with Augmented Lysosomal Signaling in Hypercholesterolemic Mice.

Accumulating evidence indicates that coronary microvascular dysfunction (CMD) caused by hypercholesterolemia can lead to myocardial ischemia, with or without obstructive atherosclerotic coronary artery disease (CAD). However, the molecular pathways associated with compromised coronary microvascular function prior to the development of myocardial ischemic injury remain poorly defined. In this study, we investigated the effects of hypercholesterolemia on the function and integrity of the coronary microcirculation in mice and the underlying mechanisms. Mice were fed with a hypercholesterolemic Paigen's diet (PD) for 8 weeks. Echocardiography data showed that PD caused CMD, characterized by significant reductions in coronary blood flow and coronary flow reserve (CFR), but did not affect cardiac remodeling or dysfunction. Immunofluorescence studies revealed that PD-induced CMD was associated with activation of coronary arterioles inflammation and increased myocardial inflammatory cell infiltration. These pathological changes occurred in parallel with the upregulation of lysosomal signaling pathways in endothelial cells (ECs). Treating hypercholesterolemic mice with the cholesterol-lowering drug ezetimibe significantly ameliorated PD-induced adverse effects, including hypercholesterolemia, steatohepatitis, reduced CFR, coronary EC inflammation, and myocardial inflammatory cell infiltration. In cultured mouse cardiac endothelial cells (MCECs), 7-ketocholesterol (7K) increased mitochondrial reactive oxygen species (ROS) and inflammatory responses. Meanwhile, 7K induced the activation of TFEB and lysosomal signaling in MCECs, whereas the lysosome inhibitor bafilomycin A1 blocked 7K-induced TFEB activation and exacerbated 7K-induced inflammation and cell death. Interestingly, ezetimibe synergistically enhanced 7K-induced TFEB activation and attenuated 7K-induced mitochondrial ROS and inflammatory responses in MCECs. These results suggest that CMD can develop and precede detectable cardiac functional or structural changes in the setting of hypercholesterolemia, and that upregulation of TFEB-mediated lysosomal signaling in ECs plays a protective role against CMD.

Microvascular Dysfunction across the Spectrum of Heart Failure Pathology: Pathophysiology, Clinical Features and Therapeutic Implications.

Coronary microvascular dysfunction (CMD) plays a crucial role across the spectrum of heart failure (HF) pathology, contributing to disease development, progression, and outcomes. The pathophysiological mechanisms linking CMD to HF are complex and still not completely understood and include chronic inflammation, oxidative stress, and neurohormonal activation. Despite the diagnostic and prognostic relevance in patients with HF, there is no specific therapeutic strategy targeting CMD to date. Moreover, the diagnosis of this clinical condition is challenging. In this review article, we aim to discuss the different clinical pathogenetic mechanisms linking CMD to HF across the different spectra of these diseases, their prognostic relevance, and the possible therapeutic targets along with the remaining knowledge gaps in the field.

Factors Contributing to Coronary Microvascular Dysfunction in Patients with Angina and Non-Obstructive Coronary Artery Disease.

Coronary microvascular dysfunction (CMD), characterised by a reduced coronary flow reserve (CFR) or an increased index of microcirculatory resistance (IMR), has received considerable attention as a cause of chest pain in recent years. However, the risks and causes of CMD remain unclear; therefore, effective treatment strategies have not yet been established. Heart failure or coronary artery disease (CAD) is a risk factor for CMD, with a higher prevalence among women. However, the other contributing factors remain unclear. In this study, we assessed the risk in patients with angina and non-obstructive coronary artery disease (ANOCA), excluding those with heart failure or organic stenosis of the coronary arteries. Furthermore, we analysed whether the risk of CMD differed according to component factors and sex. This study included 84 patients with ANOCA (36 men and 48 women; mean age, 63 years) who underwent coronary angiography and functional testing (CFT). The CFT included a spasm provocation test (SPT), followed by a coronary microvascular function test (CMVF). In the SPT, patients were mainly provoked by acetylcholine (ACh), and coronary spasm was defined as >90% transient coronary artery constriction on coronary angiography, accompanied by chest pain or ischaemic changes on electrocardiography. In 15 patients (18%) with negative ACh provocation, ergonovine maleate (EM) was administered as an additional provocative drug. In the CMVF, a pressure wire was inserted into the left anterior descending coronary artery using intravenous adenosine triphosphate, and the CFR and IMR were measured using previously described methods. A CFR < 2.0 or IMR ≥ 25 was indicative of CMD. The correlations between various laboratory indices and CMD and its components were investigated, and logistic regression analysis was performed, focusing on factors where p < 0.05. Of the 84 patients, a CFR < 2.0 was found in 22 (26%) and an IMR ≥ 25 in 40 (48%) patients, with CMD identified in 46 (55%) patients. CMD was correlated with smoking (p = 0.020) and the use of EM (p = 0.020). The factors that correlated with a CFR < 2.0 included the echocardiograph index E/e' (p = 0.013), which showed a weak but positive correlation with the CFR (r = 0.268, p = 0.013). Conversely, the factors correlated with an IMR ≥ 25 included RAS inhibitor usage (p = 0.018) and smoking (p = 0.042). Assessment of the risk of CMD according to sex revealed that smoking (p = 0.036) was the only factor associated with CMD in men, whereas the left ventricular mass index (p = 0.010) and low glycated haemoglobin levels (p = 0.012) were associated with CMD in women. Our results indicated that smoking status and EM use were associated with CMD. The risk of CMD differed between the two CMD components and sex. Although these factors should be considered when treating CMD, smoking cessation remains important. In addition, CMD assessment should be performed carefully when EM is used after ACh provocation. Further validation of our findings using prospective studies and large registries is warranted.

Evaluation of coronary microvascular dysfunction using magnetocardiography: A new application to an old technology

BackgroundIn patients with angina and non-obstructive coronary artery disease (ANOCA), diagnosis of coronary microvascular dysfunction (CMD) remains an unmet need. Magnetocardiography (MCG), is a rest-based, non-invasive scan that can detect weak electrophysiological changes that occur at the early phase of ischemia. ObjectiveThis study assessed the ability of MCG to detect CMD in ANOCA patients as compared to reference standard, invasive coronary flow reserve (CFR). MethodsPatients with ANOCA and invasive coronary physiologic assessment using intracoronary flow measurements with Doppler and thermodilution methods were enrolled. CMD was defined dichotomously as an invasive CFR < 2.0 by Doppler or thermodilution assessment. Noninvasive 36-channel 90-s MCG scan was performed and quantitative assessment of four distinct MCG features was completed. We evaluated the diagnostic performance of 2 or more abnormal MCG features to detect CMD in the overall cohort and performed a subgroup analysis in the subset of patients with Doppler CFR assessment. ResultsAmong 79 ANOCA patients, 25 were CMD positive and 54 patients were CMD negative by CFR. Using invasive CFR as reference, MCG had an ROC AUC of 0.66 with a sensitivity of 68 % and specificity of 65 % for the detection of CMD. In the subgroup with Doppler CFR assessment, MCG had an ROC AUC of 0.76 with a sensitivity of 75 % and specificity of 77 %. ConclusionsIn ANOCA patients, MCG demonstrates the ability to detect CMD using a 90-second non-invasive scan without the need for an intravenous stressor or ionizing radiation. Further investigations are needed to validate an MCG-based diagnostic pathway for CMD.

Significant Association of Serum Albumin With the Severity of Coronary Microvascular Dysfunction Using Dynamic CZT-SPECT.

Both low serum albumin (SA) concentration and coronary microvascular dysfunction (CMD) are risk factors for the development of heart failure (HF). We hypothesized that SA concentration is associated with myocardial flow reserve (MFR) and implicated in pathophysiological mechanism of HF. We retrospectively studied 454 patients undergoing dynamic cardiac cadmium-zinc-telluride myocardial perfusion imaging from April 2018 to February 2020. The population was categorized into three groups according to SA level (g/dL): Group 1: >4, Group 2: 3.5-4, and Group 3: <3.5. Myocardial blood flow (MBF) and myocardial flow reserve (MFR, defined as stress/rest MBF ratio) were compared. The mean age of the whole cohort was 66.2 years, and 65.2% were men. As SA decreased, stress MBF (mL min-1 g-1) and MFR decreased (MBF: 3.29 ± 1.03, MFR: 3.46 ± 1.33 in Group 1, MBF: 2.95 ± 1.13, MFR: 2.51 ± 0.93 in Group 2, and MBF: 2.64 ± 1.16, MFR: 1.90 ± 0.50 in Group 3), whereas rest MBF (mL min-1 g-1) increased (MBF: 1.05 ± 0.42 in Group 1, 1.27 ± 0.56 in Group 2, and 1.41 ± 0.61 in Group 3). After adjusting for covariates, compared with Group 1, the odds ratios for impaired MFR (defined as MFR < 2.5) were 3.57 (95% CI: 2.32-5.48) for Group 2 and 34.9 (95% CI: 13.23-92.14) for Group 3. The results would be similar if only regional MFR were assessed. The risk prediction for CMD using SA was acceptable, with an AUC of 0.76. Low SA concentration was associated with the severity of CMD in both global and regional MFR as well as MBF.

Comparative effectiveness of positron emission tomography and single-photon emission computed tomography myocardial perfusion imaging for predicting risk in patients with cardiometabolic disease

BackgroundThe epidemiology of coronary artery disease (CAD) has shifted, with increasing prevalence of cardiometabolic disease and decreasing findings of obstructive CAD on myocardial perfusion imaging (MPI). Coronary microvascular dysfunction (CMD), defined as impaired myocardial flow reserve (MFR) by positron emission tomography (PET), has emerged as a key mediator of risk. We aimed to assess whether PET MFR provides additive value for risk stratification of cardiometabolic disease patients compared with single-photon emission computed tomography (SPECT) MPI. MethodsWe retrospectively followed patients referred for PET, exercise SPECT, or pharmacologic SPECT MPI with cardiometabolic disease (obesity, diabetes, or chronic kidney disease) and without known CAD. We compared rates and hazards of composite major adverse cardiovascular events (MACEs) (annualized cardiac mortality or acute myocardial infarction) among propensity-matched PET and SPECT patients using Poisson and Cox regression. Normal SPECT was defined as a total perfusion deficit (TPD) of <5%, reflecting the absence of obstructive CAD. Normal PET was defined as a TPD of <5% plus an MFR of ≥2.0. ResultsAmong 21,544 patients referred from 2006 to 2020, cardiometabolic disease was highly prevalent (PET: 2308 [67%], SPECT: 9984 [55%]) and higher among patients referred to PET (P < 0.001). Obstructive CAD findings (TPD > 5%) were uncommon (PET: 21% and SPECT: 11%). Conversely, impaired MFR on PET (<2.0) was common (62%). In a propensity-matched analysis over a median 6.4-year follow-up, normal PET identified low-risk (0.9%/year MACE) patients, and abnormal PET identified high-risk (4.2%/year MACE) patients with cardiometabolic disease; conversely, those with normal pharmacologic SPECT remained moderate-risk (1.6%/year, P < 0.001 compared to normal PET). ConclusionsCardiometabolic disease is common among patients referred for MPI and is associated with a heterogenous level of risk. Compared with pharmacologic SPECT, PET with MFR can detect nonobstructive CAD including CMD and can more accurately discriminate low-risk from higher-risk individuals.

A Plant-Based Diet Prevented Coronary Microvascular Dysfunction (CMD) Independent of Hypertension in a Similar Manner to Gut Microbiota Depletion

A Plant-Based Diet Prevented Coronary Microvascular Dysfunction (CMD) Independent of Hypertension in a Similar Manner to Gut Microbiota Depletion

Prognostic Value of Coronary Microvascular Dysfunction Assessed by Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients With ST-Segment Elevation Myocardial Infarction.

CaIMR is proposed as a novel angiographic index designed to assess microcirculation without the need for pressure wires or hyperemic agents. We aimed to investigate the impact of caIMR on predicting clinical outcomes in STEMI patients. One hundred and forty patients with STEMI who received PCI in Putuo Hospital of Shanghai from October 2021 to September 2022 were categorized into CMD and non-CMD groups according to the caIMR value. The baseline information, patient-related examinations, and the occurrence of MACE at the 12-month follow-up were collected to investigate risk factors in patients with STEMI. We divided 140 patients with STEMI enrolled into two groups according to caIMR results, including 61 patients diagnosed with CMD and 79 patients diagnosed with non-CMD. A total of 21 MACE occurred during the 1 year of follow-up. Compared with non-CMD group, patients with CMD showed a significantly higher risk of MACE. A multivariate Cox regression model was conducted for the patients, and it was found thatcaIMR was a significant predictor of prognosis in STEMI patients (HR: 8.921). Patients with CMD were divided into culprit vascular CMD and non-culprit vascular CMD, and the result found that culprit vascular CMD was associated with the incidence of MACE (OR: 4.75) and heart failure (OR: 7.50). CaIMR is a strong predictor of clinical outcomes and can provide an objective risk stratification for patients with STEMI. There is a strong correlation among leukocyte index, the use of furosemide, Killips classification, and clinical outcomes.

CORONARY MICROVASCULAR DYSFUNCTION IN PATIENTS AFTER URGENT PERCUTANEOUS CORONARY INTERVENTION DUE TO ACUTE CORONARY SYNDROME

Background. Possible cause of residual myocardial ischemia after urgent PCI during ACS is coronary microvascular dysfunction. Aim: To study the frequency of coronary microvascular dysfunction in patients who underwent urgent PCI due to ACS. Materials and methods. The study included 38 participants with ACS. These patients underwent urgent PCI. After 28 days patients underwent echocardiography with intravenous dipyridamole. Coronary microvascular dysfunction was determined by an CFR less than 2. Quality of life was measured by the severity of angina using the SF-36 and SAQ questionnaires, respectively. To compare the results of the study, a cohort of 20 patients who underwent elective PCI without coronary microvascular dysfunction (CFR≥2) were selected. Results.About 2/3 of patients had complaints of shortness of breath, as the equivalent of angina pectoris, during routine physical exertion. In 83.3% patients presence of coronary microvascular dysfunction, was proven. Quality of life due to the SAQ and SF-36 questionnaires were significantly lower among patients, who underwent urgent PCI. Conclusion.The results of the work showed that 83.3% of patients after urgent PCI for ACS were diagnosed with coronary microvascular dysfunction.

Coronary microvascular dysfunction in patients with Takotsubo syndrome

BackgroundThe pathophysiology of Takotsubo syndrome (TTS) remains incompletely understood. While coronary microvascular dysfunction (CMD) is a potential pathophysiologic mechanism, evidence is limited. ObjectivesWe sought to evaluate CMD in patients with TTS. MethodsConsecutive patients diagnosed with TTS were included and underwent coronary angiography with invasive microvascular function evaluation, including fractional flow reserve, Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR), and Resistive Reserve Ratio (RRR). Patients had an echocardiography evaluation during their index admission and at approximately 6 weeks. ResultsThirty patients were included (mean age 74 ±9, 90 % female). Twenty-five patients (83 %) had at least one abnormal coronary microvascular function parameter. Abnormal parameters included CFR<2.5 in 20 patients (67 %), IMR>25 in 18 patients (60 %), and RRR<3.5 in 25 (83 %). Longer time from symptoms to angiography correlated with a higher CFR (r = 0.51, P<0.01), and had an area under the receiver operating characteristic curve of 0.793 (95 % CI 0.60-0.98) for pathologic CFR. Patients with emotional trigger had a lower rate of pathologic IMR compared with non-emotional trigger (36 % vs 81 %, p = 0.01). Follow up echocardiography performed at a median of 1.5 months (IQR 1.15-6) showed an improvement in left ventricular ejection fraction for all patients (from mean of 40 % to 57 %). ConclusionCMD was present in most patients with TTS. The role of microvascular function in TTS may vary according to the clinical presentation and RRR may be more sensitive for the diagnosis of CMD in TTS.

ENAMPT is a novel therapeutic target for mitigation of coronary microvascular disease in type 2 diabetes

Aims/hypothesisIndividuals with diabetes are at high risk of cardiovascular complications, which significantly increase morbidity/mortality. Coronary microvascular disease (CMD) is recognised as a critical contributor to the increased cardiac mortality observed in people with diabetes. Therefore, there is an urgent need for treatments that are specific to CMD. eNAMPT (extracellular nicotinamide phosphoribosyltransferase) is a damage-associated molecular pattern and TLR4 ligand, whose plasma levels are elevated in people with diabetes. This study was thus designed to investigate the pathogenic role of intracellular nicotinamide phosphoribosyltransferase (iNAMPT) and eNAMPT in promoting the development of CMD in a preclinical murine model of type 2 diabetes.MethodsAn inducible type 2 diabetic mouse model was generated by a single injection of low-dose streptozocin (75 mg/kg, i.p.) combined with a high-fat diet for 16 weeks. The in vivo effects of i/eNAMPT inhibition on cardiac endothelial cell (CEC) function were evaluated by using Nampt+/− heterozygous mice, chronic administration of eNAMPT-neutralising monoclonal antibody (mAb) or use of an NAMPT enzymatic inhibitor (FK866).ResultsAs expected, diabetic wild-type mice exhibited significantly lower coronary flow velocity reserve (CFVR), a determinant of coronary microvascular function, compared with control wild-type mice. eNAMPT plasma levels or expression in CECs were significantly greater in diabetic mice than in control mice. Furthermore, in comparison with diabetic wild-type mice, diabetic Nampt+/− heterozygous mice showed markedly improved CFVR, accompanied by increased left ventricular capillary density and augmented endothelium-dependent relaxation (EDR) in the coronary artery. NAMPT inhibition by FK866 or an eNAMPT-neutralising mAb significantly increased CFVR in diabetic mice. Furthermore, administration of the eNAMPT mAb upregulated expression of angiogenesis- and EDR-related genes in CECs from diabetic mice. Treatment with either eNAMPT or NAD+ significantly decreased CEC migration and reduced EDR in coronary arteries, partly linked to increased production of mitochondrial reactive oxygen species.Conclusions/interpretationThese data indicate that increased i/eNAMPT expression contributes to the development of diabetic coronary microvascular dysfunction, and provide compelling support for eNAMPT inhibition as a novel and effective therapeutic strategy for CMD in diabetes.Graphical

Obesity and diabetes in heart disease in women

Heart disease remains a major health threat in women. Cardiometabolic risk factors such as obesity and diabetes differentially and adversely impact heart disease risk. Although obstructive coronary artery disease is an important cause of ischemic heart disease in women and is prognostic, women are more likely to have angina and myocardial ischemia without obstructive atherosclerosis, which has been attributed to coronary microvascular dysfunction (CMD). Heart failure with preserved ejection fraction (HFpEF) is another condition that predominates in women. CMD and HFpEF are both associated with cardiometabolic risk factors that are prevalent in women. Women are also more likely to have additional risk-enhancing conditions such as autoimmune dysfunction, chronic inflammation, and sex-specific hormonal factors that adversely influence risk. In this review, we focus on cardiometabolic risk factors of obesity and diabetes in heart disease in women, including ischemic heart disease from CMD, HFpEF, and arrythmias. Team-based care to focus on cardiometabolic risk reduction is needed to alter adverse heart disease outcomes in women. Identification, education, treatment, and active surveillance of these dysmetabolic risk factors are imperative in the primary and secondary prevention of heart disease in women.

Epicardial adipose tissue attenuation on computed tomography in women with coronary microvascular dysfunction: A pilot, hypothesis generating study

BackgroundPatients with myocardial ischemia without obstructive coronary artery disease often have coronary microvascular dysfunction (CMD) and associated increased risk of cardiovascular (CV) events and anginal hospitalizations. Epicardial adipose tissue (EAT) covers much of the myocardium and coronary arteries and when dysfunctional, secretes proinflammatory cytokines and is associated with CV events. While oxidative stress and systemic inflammation are associated with CMD, the relationship between EAT and CMD in women is not well known. MethodsWomen diagnosed with CMD (n = 21) who underwent coronary computed tomography with coronary artery calcium (CAC) scoring were compared to a reference group (RG) of women referred for CAC screening for preventive risk assessment (n = 181). EAT attenuation (Hounsfield units (HU)) was measured adjacent to the proximal right coronary artery, along with subcutaneous adipose tissue (SCAT). Two-sample t-tests with unequal variances were utilized. ResultsMean age of the CMD group was 56 ± 8 years and body mass index (BMI) was 31.6 ± 6.8 kg/m2. CV risk factors in the CMD group were prevalent: 67 % hypertension, 44 % hyperlipidemia, and 33 % diabetes. Both CMD and RG had similar CAC score (25.86 ± 59.54 vs. 24.17 ± 104.6; p = 0.21. In the CMD group, 67 % had a CAC of 0. Minimal atherosclerosis (CAD-RADS 1) was present in 76 % of women with CMD. The CMD group had lower EAT attenuation than RG (−103.3 ± 6.33 HU vs. −97.9 ± 8.3 HU, p = 0.009, respectively). There were no differences in SCAT attenuation. Hypertension, smoking history, age, BMI, and CAC score did not correlate with EAT in either of the groups. ConclusionsWomen with CMD have decreased EAT attenuation compared to RG women. EAT-mediated inflammation and changes in vascular tone may be a mechanistic contributor to abnormal microvascular reactivity. Clinical trials testing therapeutic strategies to decrease EAT may be warranted in the management of CMD.

Coronary Microvascular Dysfunction in Women

Coronary Microvascular Dysfunction in Women

Investigating Electrocardiographic Abnormalities in Patients With Coronary Microvascular Dysfunction

Investigating Electrocardiographic Abnormalities in Patients With Coronary Microvascular Dysfunction

Effects of age on microvascular function in patients with normal coronary arteries.

It has been suggested that coronary microvascular function decreases with age, irrespective of the presence of epicardial atherosclerosis. Our aim is to quantitatively investigate the effects of age on microvascular function in patients with normal coronary arteries. In 314 patients with angina with no obstructive coronary artery disease (ANOCA), microcirculatory function was tested using the continuous thermodilution method. In 305 patients, the association between age and both resting and hyperaemic myocardial blood flow (Q), microvascular resistance (Rμ), absolute coronary flow reserve (CFR) and microvascular resistance reserve (MRR) was assessed. In addition, patients were divided into 3 groups to test for differences based on age quartiles (≤52 years [24.9%], 53-64 years [49.2%], ≥65 years [25.9%]). The mean age was 59±9 years with a range from 22 to 79 years. The mean resting Q (Qrest) was not different in the 3 age groups (88±34 mL/min, 82±29 mL/min, and 86±38 mL/min, R2=0.001; p=0.62). A trend towards a decreasing mean hyperaemic Q (Qmax) was observed with increasing age (223±79 mL/min, 209±84 mL/min, 200±80 mL/min, R2=0.010; p=0.083). The mean resting Rμ (Rμ,rest) were 1,204±460 Wood units (WU), 1,260±411 WU, and 1,289±455 WU (p=0.23). The mean hyperaemic Rμ (Rμ,hyp) increased significantly with advancing age (429±149 WU, 464±164 WU, 503±162 WU, R2=0.026; p=0.005). Consequently, MRR decreased with age (3.2±1.2, 3.1±1.0, 2.9±0.9; p=0.038). This trend was present in both the patients with (n=121) and without (n=184) coronary microvascular dysfunction (CMD). There is an age-dependent physiological increase in minimal microvascular resistance and decrease in microvascular function, which is represented by a decreased MRR and is independent of atherosclerosis. The age-dependent decrease in MRR was present in both patients with and without CMD and was most evident in patients with smooth coronary arteries.

Estimation of renal functional reserve in patients with preserved renal function and coronary microvascular dysfunction

Estimation of renal functional reserve in patients with preserved renal function and coronary microvascular dysfunction

Coronary microvascular dysfunction and myocardial area at risk assessed by cadmium zinc telluride single photon emission computed tomography after primary percutaneous coronary intervention in acute myocardial infarction patients

Coronary microvascular dysfunction and myocardial area at risk assessed by cadmium zinc telluride single photon emission computed tomography after primary percutaneous coronary intervention in acute myocardial infarction patients