Coronary slow flow and angiography-derived index of microcirculatory resistance as prognostic predictors in patients with angina and normal coronary arteries: a retrospective cohort study.

BACKGROUND: This study aims to investigate prognostic implications of coronary slow flow (CSF) and angiography-derived index of microcirculatory resistance (caIMR) in patients with angina and normal coronary arteries. METHODS: A total of 582 patients were enrolled with angiographically normal coronary arteries. caIMR was calculated using a commercial software. Patients were followed up for a median of 45 months. The primary endpoint was defined as major adverse cardiovascular events (MACEs) comprising death, myocardial infarction and readmission for angina or heart failure. RESULTS: CSF was diagnosed when TIMI grade 2 flow presented in at least one coronary artery. Multivariate analysis indicated TIMI-flow-based determination of CSF was not significantly associated with MACEs [hazard ratio (HR): 2.14; 95% confidence interval (CI): 0.87-5.31; p = 0.099), while caIMR >42 (HR: 2.53; 95% CI: 1.02-6.32; p = 0.047) were independent predictors of MACEs. Incorporation of caIMR improved the area under the curve from 0.587 to 0.642. CONCLUSIONS: caIMR was an independent prognostic factor of long-term cardiovascular events in patients with CSF. Evaluation of caIMR improved the risk stratification of patients with angiographically-normal coronary arteries.

Vericiguat improves cardiac function and microcirculation of a male patient with Fabry disease: A case report.

Fabry disease (FD) is a rare X chromosome-linked disorder and can be easily misdiagnosed. Here, we report the case of a 69-year-old male patient with FD who developed heart failure and showed extremely high pulmonary artery pressure. His initial symptom was recurrent atrial fibrillation. The left and right atrial inner diameters were large, and the ventricular wall was thick. Gene analysis which showed GLA c.215T>C p.Met72Thr mutation and single photon emission computed tomography indicated the diagnosis of FD with coronary microvascular dysfunction. The patient was prescribed anti-heart failure drugs, including vericiguat. Following the treatment, his heart function and microvascular perfusion significantly improved, which might be due to the beneficial effects of vericiguat.

Angiographic Coronary Slow Flow Is Not a Valid Surrogate for Invasively Diagnosed Coronary Microvascular Dysfunction.

BACKGROUND: Ischemia with no obstructive coronary arteries is frequently caused by coronary microvascular dysfunction (CMD). Consensus diagnostic criteria for CMD include baseline angiographic slow flow by corrected TIMI (Thrombolysis In Myocardial Infarction) frame count (cTFC), but correlations between slow flow and CMD measured by invasive coronary function testing (CFT) are uncertain. OBJECTIVES: The aim of this study was to investigate relationships between cTFC and invasive CFT for CMD. METHODS: Adults with ischemia with no obstructive coronary arteries underwent invasive CFT with thermodilution-derived baseline coronary blood flow, coronary flow reserve (CFR), and index of microcirculatory resistance (IMR). CMD was defined as abnormal CFR (<2.5) and/or abnormal IMR (≥25). cTFC was measured from baseline angiography; slow flow was defined as cTFC >25. Correlations between cTFC and baseline coronary flow and between CFR and IMR and associations between slow flow and invasive measures of CMD were evaluated, adjusted for covariates. All patients provided consent. RESULTS: Among 508 adults, 49% had coronary slow flow. Patients with slow flow were more likely to have abnormal IMR (36% vs 26%; P = 0.019) but less likely to have abnormal CFR (28% vs 42%; P = 0.001), with no difference in CMD (46% vs 51%). cTFC was weakly correlated with baseline coronary blood flow (r = -0.35; 95% CI: -0.42 to -0.27), CFR (r = 0.20; 95% CI: 0.12 to 0.28), and IMR (r = 0.16; 95% CI: 0.07-0.24). In multivariable models, slow flow was associated with lower odds of abnormal CFR (adjusted OR: 0.53; 95% CI: 0.35 to 0.80). CONCLUSIONS: Coronary slow flow was weakly associated with results of invasive CFT and should not be used as a surrogate for the invasive diagnosis of CMD.

Local carbachol application induces oral microvascular recruitment and improves gastric tissue oxygenation during hemorrhagic shock in dogs.

Introduction: Hemorrhagic shock is characterized by derangements of the gastrointestinal microcirculation. Topical therapy with nitroglycerine or iloprost improves gastric tissue oxygenation but not regional perfusion, probably due to precapillary adrenergic innervation. Therefore, this study was designed to investigate the local effect of the parasympathomimetic carbachol alone and in combination with either nitroglycerine or iloprost on gastric and oral microcirculation during hemorrhagic shock. Methods: In a cross-over design five female foxhounds were repeatedly randomized into six experimental groups. Carbachol, or carbachol in combination with either nitroglycerine or iloprost were applied topically to the oral and gastric mucosa. Saline, nitroglycerine, or iloprost application alone served as control groups. Then, a fixed-volume hemorrhage was induced by arterial blood withdrawal followed by blood retransfusion after 1h of shock. Gastric and oral microcirculation was determined using reflectance spectrophotometry and laser Doppler flowmetry. Oral microcirculation was visualized with videomicroscopy. Statistics: 2-way-ANOVA for repeated measurements and Bonferroni post-hoc analysis (mean ± SEM; p < 0.05). Results: The induction of hemorrhage led to a decrease of gastric and oral tissue oxygenation, that was ameliorated by local carbachol and nitroglycerine application at the gastric mucosa. The sole use of local iloprost did not improve gastric tissue oxygenation but could be supplemented by local carbachol treatment. Adding carbachol to nitroglycerine did not further increase gastric tissue oxygenation. Gastric microvascular blood flow remained unchanged in all experimental groups. Oral microvascular blood flow, microvascular flow index and total vessel density decreased during shock. Local carbachol supply improved oral vessel density during shock and oral microvascular flow index in the late course of hemorrhage. Conclusion: The specific effect of shifting the autonomous balance by local carbachol treatment on microcirculatory variables varies between parts of the gastrointestinal tract. Contrary to our expectations, the improvement of gastric tissue oxygenation by local carbachol or nitroglycerine application was not related to increased microvascular perfusion. When carbachol is used in combination with local vasodilators, the additional effect on gastric tissue oxygenation depends on the specific drug combination. Therefore, modulation of tissue oxygen consumption, mitochondrial function or alterations in regional blood flow distribution should be investigated.

Impaired retinal oxygen metabolism and perfusion are accompanied by plasma protein and lipid alterations in recovered COVID-19 patients.

The aim of the present study was to investigate retinal microcirculatory and functional metabolic changes in patients after they had recovered from a moderate to severe acute COVID-19 infection. Retinal perfusion was quantified using laser speckle flowgraphy. Oxygen saturation and retinal calibers were assessed with a dynamic vessel analyzer. Arterio-venous ratio (AVR) was calculated based on retinal vessel diameter data. Blood plasma samples underwent mass spectrometry-based multi-omics profiling, including proteomics, metabolomics and eicosadomics. A total of 40 subjects were included in the present study, of which 29 had recovered from moderate to severe COVID-19 within 2 to 23 weeks before inclusion and 11 had never had COVID-19, as confirmed by antibody testing. Perfusion in retinal vessels was significantly lower in patients (60.6 ± 16.0 a.u.) than in control subjects (76.2 ± 12.1 a.u., p = 0.006). Arterio-venous (AV) difference in oxygen saturation and AVR was significantly lower in patients compared to healthy controls (p = 0.021 for AVR and p = 0.023 for AV difference in oxygen saturation). Molecular profiles demonstrated down-regulation of cell adhesion molecules, NOTCH3 and fatty acids, and suggested a bisphasic dysregulation of nitric oxide synthesis after COVID-19 infection. The results of this study imply that retinal perfusion and oxygen metabolism is still significantly altered in patients well beyond the acute phase of COVID-19. This is also reflected in the molecular profiling analysis of blood plasma, indicating a down-regulation of nitric oxide-related endothelial and immunological cell functions.Trial Registration: ClinicalTrials.gov ( https://clinicaltrials.gov ) NCT05650905.

Intracoronary microcatheter indwelling for continuous pumping of low-dose thrombolytic drugs: A new approach to reperfusion in acute myocardial infarction.

Reperfusion therapy of acute myocardial infarction (AMI) refers to physical or chemical recanalization and restoration of blood flow to an occluded coronary artery, and current techniques for reperfusion therapy include intravenous thrombolysis, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The number of patients receiving emergency CABG in the real world is decreasing due to the disadvantages of CABG and the improvement in PCI procedures. Thrombolytic therapy has some disadvantages such as low recanalization rate, high risk of reocclusion and bleeding, and short time window. On the other hand, intracoronary interventional therapy may meet the requirements of "early, complete and persistent" patency of coronary arteries at different time points. However, in the emergency PCI, although thrombus aspiration via a catheter or balloon dilation is performed, residual thrombus with heavy or low TIMI (thrombolysis in myocardial infarction) myocardial perfusion grading is still observed in some patients, suggesting disordered microcirculation. Currently, the treatment of microcirculatory disturbance in emergency PCI mainly employed injection of tirofiban, adenosine, thrombolytic agent or other drugs into the local area via a microcatheter in a short time, all of which can significantly reduce the thrombus load and improve TIMI perfusion. Herein, we report that a microcatheter was indwelled in the coronary artery for continuous pumping of low-dose thrombolytic drugs as reperfusion therapy in 12 patients with acute and subacute MI.

A New Approach to Vascular Screening: Identification of Impaired Vascular Function Using the FMSF Technique.

Arterial blood pressure monitoring plays an important role in preventive medicine, allowing, in selected cases, the identification of vascular dysfunction. In this review, we propose a new non-invasive approach to assessment of the circulatory system, based on its reaction to hypoxia induced by post-occlusive reactive hyperemia (PORH). Three key parameters can be used for vascular screening: the Reactive Hyperemia Response (RHR), which represents the overall reaction of the macro- and microcirculation to transient hypoxia; Hypoxia Sensitivity (HS), which reflects hypoxia-induced activation of myogenic oscillations of the microcirculation; and Normoxia Oscillatory Index (NOI), which characterizes microcirculatory oscillations under normoxia conditions. A method for assessing these parameters, analogous in simplicity to arterial blood pressure measurement, is provided by the Flow Mediated Skin Fluorescence (FMSF) technique. Reference values are proposed based on numerous test measurements.

Increased Angio-Derived Index of Microcirculatory Resistance Within a Timeframe of 30-60 days After COVID-19 Infection.

BACKGROUND AND OBJECTIVES: Chest pain is a relatively long-term symptom that commonly occurs in patients who have contracted COVID-19. The reasons for these symptoms remain unclear, with coronary microvascular dysfunction (CMD) emerging as a potential factor. This study aimed to assess the presence of CMD in these patients by measuring the angio-derived index of microcirculatory resistance (AMR). METHODS: In this cross-sectional case-control study, patients who had chest pain and a history of COVID-19 infection within the preceding 30 to 60 days were included. The control subjects were patients without COVID-19. Demographic, clinical, and echocardiographic data were recorded. Angiographic images were collected for AMR analysis through an angioplus quantitative flow ratio measurement system. Propensity score matching (PSM) was performed to match the two groups. Multivariate logistic regression was used to examine the association between COVID-19 incidence and the increase in AMR (AMR > 285 mmHg*s/m) after correction for other confounders. RESULTS: After PSM, there were 58 patients in each group (the mean age was 66.3 ± 9.04 years, and 55.2% were men). The average time between the onset of COVID-19 infection and patient presentation at the hospital for coronary angiography was 41 ± 9.5 days. Moreover, there was no significant difference in the quantitative flow ratio between the two groups. Patients with COVID-19 had a greater mean AMR (295 vs. 266, p = 0.002). Multivariate logistic regression analysis revealed that COVID-19 (OR = 3.32, 95% CI = 1.50-7.60, p = 0.004) was significantly associated with an increase in AMR. CONCLUSIONS: Long-term COVID-19 patients who experience chest pain without evidence of myocardial ischemia exhibit an increase in AMR, and CMD may be one of the reasons for this increase. COVID-19 is an independent risk factor for an increase in AMR.

Coronary microvascular dysfunction assessment: A comparative analysis of procedural aspects.

BACKGROUND: Full adoption of coronary microvascular dysfunction (CMD) assessment faces challenges due to its invasive nature and concerns about prolonged procedure time and increased contrast and/or radiation exposure. We compared procedural aspects of CMD invasive assessment to diagnostic left heart catheterization (DLHC) in patients with chest pain who were not found to have obstructive coronary artery disease. METHODS: A total of 227 patients in the Coronary Microvascular Disease Registry were compared to 1592 patients who underwent DLHC from August 2021 to November 2023. The two cohorts were compared using propensity-score matching; primary outcomes were fluoroscopy time and total contrast use. RESULTS: The participants' mean age was 64.1 ± 12.6 years. CMD-assessed patients were more likely to be female (66.5% vs. 45.2%, p < 0.001) and have hypertension (80.2% vs. 44.5%, p < 0.001), history of stroke (11.9% vs. 6.3%, p = 0.002), and history of myocardial infarction (20.3% vs. 7.7%, p < 0.001). CMD assessment was safe, without any reported adverse outcomes. A propensity-matched analysis showed that patients who underwent CMD assessment had slightly higher median contrast exposure (50 vs. 40 mL, p < 0.001), and slightly longer fluoroscopy time (6.9 vs. 4.7 min, p < 0.001). However, there was no difference in radiation dose (209.3 vs. 219 mGy, p = 0.58) and overall procedure time (31 vs. 29 min, p = 0.37). CONCLUSION: Compared to DLHC, CMD assessment is safe and requires only slightly additional contrast use (10 mL) and slightly longer fluoroscopy time (2 min) without clinical implications. These findings emphasize the favorable safety and feasibility of invasive CMD assessment.

Cells flowing to attain functionality.

Unraveling the fundamental biological processes underpinning cell functions and behavior remains a key challenge. Researchers working on cell biological processes might want to take a look at microscale cell flow as functionality genesis. This Commentary provides an outlook on how cell-microcirculation interplay promises to lead to exciting insights into the cell biology complexity.

Impact of renal denervation on patients with coronary microvascular dysfunction: study rationale and design.

AIMS: Long-standing hypertension may cause an impairment in microvascular coronary circulation, which is involved in many different cardiac conditions. Renal sympathetic denervation (RDN) has been successfully proven as a valuable therapeutic choice for patients with resistant hypertension; moreover, the procedure looks promising in other settings, such as heart failure and atrial fibrillation, given its ability to downregulate the sympathetic nervous system, which is a recognized driver in these conditions as well as in microvascular dysfunction progression. The aim of this study is to explore the effect of RDN on coronary physiology in patients with ascertained coronary microvascular dysfunction and resistant hypertension. METHODS: This is a multicenter, prospective, nonrandomized, open-label, interventional study. Consecutive patients with resistant hypertension, nonobstructive coronary artery disease (NOCAD) and documented microvascular dysfunction will be enrolled. Patients will undergo RDN by Spyral Symplicity 3 (Medtronic Inc, Minneapolis, Minnesota, USA) and reassessment of coronary microvascular function 6 months after the procedure. Primary endpoint will be the difference in the index of microcirculatory resistance. CONCLUSION: The IMPRESSION study seeks to evaluate if there is any pleiotropic effect of the RDN procedure that results in modulation of microvascular function; if observed, this would be the first evidence showing RDN as a valuable therapy to revert hypertension-related microvascular dysfunction.

The microcirculation in the first days of ICU admission in critically ill COVID-19 patients is influenced by severity of disease.

The objective of this study was to investigate the relationship between sublingual microcirculatory parameters and the severity of the disease in critically ill coronavirus disease 2019 (COVID-19) patients in the initial period of Intensive Care Unit (ICU) admission in a phase of the COVID-19 pandemic where patients were being treated with anti-inflammatory medication. In total, 35 critically ill COVID-19 patients were included. Twenty-one critically ill COVID-19 patients with a Sequential Organ Failure Assessment (SOFA) score below or equal to 7 were compared to 14 critically ill COVID-19 patients with a SOFA score exceeding 7. All patients received dexamethasone and tocilizumab at ICU admission. Microcirculatory measurements were performed within the first five days of ICU admission, preferably as soon as possible after admission. An increase in diffusive capacity of the microcirculation (total vessel density, functional capillary density, capillary hematocrit) and increased perfusion of the tissues by red blood cells was found in the critically ill COVID-19 patients with a SOFA score of 7-9 compared to the critically ill COVID-19 patients with a SOFA score ≤ 7. No such effects were found in the convective component of the microcirculation. These effects occurred in the presence of administration of anti-inflammatory medication.

Tiny clue reveals the general trend: a bibliometric and visualized analysis of renal microcirculation.

BACKGROUND: Renal microcirculation plays a pivotal role in kidney function by maintaining structural and functional integrity, facilitating oxygen and nutrient delivery, and waste removal. However, a thorough bibliometric analysis in this area remains lacking. Therefore, we aim to provide valuable insights through a bibliometric analysis of renal microcirculation literature using the Web of Science database. METHODS: We collected renal microcirculation-related publications from the Web of Science database from January 01, 1990, to December 31, 2022. The co-authorship of authors, organizations, and countries/regions was analyzed with VOSviewer1.6.18. The co-occurrence of keywords and co-cited references were analyzed using CiteSpace6.1.R6 software to generate visualization maps. Additionally, burst detection was applied to keywords and cited references to forecast research hotspots and future trends. RESULTS: Our search yielded 7462 publications, with the American Journal of Physiology-Renal Physiology contributing the most articles. The United States, Mayo Clinic, and Lerman Lilach O emerged with the highest publication count, indicating their active collaborations. 'Type 2 diabetes' was the most significant keyword cluster, and 'diabetic kidney disease' was the largest cluster of cited references. 'Cardiovascular outcome' and 'diabetic kidney diseases' were identified as keywords in their burst period over the past three years. CONCLUSION: Our bibliometric analysis illuminates the contours of nephrology and microcirculation research, revealing a landscape ripe for challenges and the seeds of future scientific innovation. While the trends discerned from the literature emerging opportunities in diagnostic innovation, renal microcirculation research, and precision medicine interventions, their translation to clinical practice is anticipated to be a deliberate process.

Beyond the microcirculation: sequestration of infected red blood cells and reduced flow in large draining veins in experimental cerebral malaria.

Sequestration of infected red blood cells (iRBCs) in the microcirculation is a hallmark of cerebral malaria (CM) in post-mortem human brains. It remains controversial how this might be linked to the different disease manifestations, in particular brain swelling leading to brain herniation and death. The main hypotheses focus on iRBC-triggered inflammation and mechanical obstruction of blood flow. Here, we test these hypotheses using murine models of experimental CM (ECM), SPECT-imaging of radiolabeled iRBCs and cerebral perfusion, MR-angiography, q-PCR, and immunohistochemistry. We show that iRBC accumulation and reduced flow precede inflammation. Unexpectedly, we find that iRBCs accumulate not only in the microcirculation but also in large draining veins and sinuses, particularly at the rostral confluence. We identify two parallel venous streams from the superior sagittal sinus that open into the rostral rhinal veins and are partially connected to infected skull bone marrow. The flow in these vessels is reduced early, and the spatial patterns of pathology correspond to venous drainage territories. Our data suggest that venous efflux reductions downstream of the microcirculation are causally linked to ECM pathology, and that the different spatiotemporal patterns of edema development in mice and humans could be related to anatomical differences in venous anatomy.

Microcirculation-driven mitochondrion dysfunction during the progression of experimental sepsis.

Sepsis is accompanied by a less-known mismatch between hemodynamics and mitochondrial respiration. We aimed to characterize the relationship and time dependency of microcirculatory and mitochondrial functions in a rodent model of intraabdominal sepsis. Fecal peritonitis was induced in rats, and multi-organ failure (MOF) was evaluated 12, 16, 20, 24 or 28 h later (n = 8/group, each) using rat-specific organ failure assessment (ROFA) scores. Ileal microcirculation (proportion of perfused microvessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI)) was monitored by intravital video microscopy, and mitochondrial respiration (OxPhos) and outer membrane (mtOM) damage were measured with high-resolution respirometry. MOF progression was evidenced by increased ROFA scores; microcirculatory parameters followed a parallel time course from the 16th to 28th h. Mitochondrial dysfunction commenced with a 4-h time lag with signs of mtOM damage, which correlated significantly with PPV, while no correlation was found between HI and OxPhos. High diagnostic value was demonstrated for PPV, mtOM damage and lactate levels for predicting MOF. Our findings indicate insufficient splanchnic microcirculation to be a possible predictor for MOF that develops before the start of mitochondrial dysfunction. The adequate subcellular compensatory capacity suggests the presence of mitochondrial subpopulations with differing sensitivity to septic insults.

Optimization of cardiopulmonary bypass prime fluid to preserve microcirculatory perfusion during on-pump coronary artery bypass graft surgery: PRIME study protocol for a double-blind randomized trial.

BACKGROUND: Acute microcirculatory perfusion disturbances and organ edema are important factors leading to organ dysfunction during cardiac surgery with cardiopulmonary bypass (CPB). Priming of the CPB system with crystalloid or colloid fluids, which inevitably leads to hemodilution, could contribute to this effect. However, there is yet no optimal evidence-based strategy for this type of priming. Hence, we will investigate different priming strategies to reduce hemodilution and preserve microcirculatory perfusion. METHODS: The PRIME study is a single-center double-blind randomized trial. Patients undergoing elective coronary artery bypass graft surgery with CPB will be randomized into three groups of prime fluid strategy: (1) gelofusine with crystalloid, (2) albumin with crystalloid, or (3) crystalloid and retrograde autologous priming. We aim to include 30 patients, 10 patients in each arm. The primary outcome is the change in microcirculatory perfusion. Secondary outcomes include colloid oncotic pressure; albumin; hematocrit; electrolytes; fluid balance and requirements; transfusion rates; and endothelial-, glycocalyx-, inflammatory- and renal injury markers. Sublingual microcirculatory perfusion will be measured using non-invasive sidestream dark field video microscopy. Microcirculatory and blood measurements will be performed at five consecutive time points during surgery up to 24 h after admission to the intensive care unit. DISCUSSION: PRIME is the first study to assess the effect of different prime fluid strategies on microcirculatory perfusion in cardiac surgery with CPB. If the results suggest that a specific crystalloid or colloid prime fluid strategy better preserves microcirculatory perfusion during on-pump cardiac surgery, the current study may help to find the optimal pump priming in cardiac surgery. TRIAL REGISTRATION: ClinicalTrials.gov NCT05647057. Registered on 04/25/2023. CLINICALTRIALS: gov PRS: Record Summary NCT05647057, all items can be found in the protocol.

Prognostic Implications of Microvascular Resistance Reserve in Symptomatic Patients With Intermediate Coronary Stenosis.

BACKGROUND: Microvascular resistance reserve (MRR) is a novel index reflecting coronary microcirculatory function, irrespective of epicardial coronary artery stenosis. There is limited evidence regarding whether MRR can be an independent prognostic tool in patients with stable ischemic heart disease (IHD). OBJECTIVES: The aim of this study was to evaluate clinical outcomes according to MRR in patients with stable IHD accompanied with or without significant epicardial coronary artery stenosis. METHODS: The present study included 547 consecutive patients undergoing systematic echocardiographic and invasive physiological assessment for suspected stable IHD. Significant epicardial coronary artery stenosis was defined as fractional flow reserve (FFR) ≤0.80. Coronary microvascular dysfunction (CMD) was defined as MRR ≤3.0. The primary outcome was major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure. RESULTS: Among the study group, 172 patients (31.4%) had FFR ≤0.80, and 200 patients (36.6%) had CMD defined by MRR ≤3.0. MRR showed no significant correlation with FFR (R = -0.031; P = 0.469), but it was significantly correlated with the index of microcirculatory resistance (R = -0.353; P < 0.001), N-terminal pro-B-type natriuretic peptide (R = -0.296; P < 0.001), left ventricular filling pressure (E/e' ratio) (R = -0.224; P < 0.001), and diastolic dysfunction grade (P < 0.001). During a median follow-up period of 3.3 years (Q1-Q3: 2.0-4.5 years), MRR was significantly associated with MACE risk (HR: 1.23 per 1-U decrease; 95% CI: 1.12-1.36; P < 0.001). CMD defined by MRR ≤3.0 was associated with an increased MACE risk for both FFR >0.80 (41.0% vs 26.0%; adjusted HR: 1.59; 95% CI: 1.07-2.35; P = 0.021) and FFR ≤0.80 (34.7% vs 14.8%; adjusted HR: 2.32; 95% CI: 1.12-4.82; P = 0.024). CONCLUSIONS: Decreased MRR was associated with the presence of cardiac diastolic dysfunction as well as increased left ventricular filling pressure. The presence of CMD defined by MRR was independently associated with the risk for a composite of cardiovascular death, myocardial infarction, repeat revascularization, and admission for heart failure in patients with stable IHD, irrespective of significant epicardial coronary artery stenosis. (Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function [DIAST-CMD]; NCT05058833).