Increased circulating levels of malondialdehyde-modified low-density lipoprotein in patients with coronary microvascular dysfunction.

BACKGROUND: Coronary microvascular dysfunction (CMD) is associated with angina symptoms and adverse clinical outcomes in patients without obstructive coronary artery disease (CAD). Malondialdehyde-modified low-density lipoprotein (MDA-LDL) is reportedly a marker of the initiation and acceleration of epicardial coronary atherosclerosis. However, its impact on CMD remains unclear. OBJECTIVE: We aimed to investigate the relationship between CMD and MDA-LDL levels. METHODS: This study included 95 patients who did not receive lipid-lowering medications and had no obstructive CAD. Obstructive CAD was defined as >50 % diameter reduction on coronary angiography or fractional flow reserve of ≤0.80. We retrospectively analyzed coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and MDA-LDL levels. CMD was defined as either CFR <2.0 or IMR ≥25. RESULTS: CMD was observed in 29 (31 %) patients. MDA-LDL levels were significantly higher in patients with CMD than in those without CMD (124.8 ± 37.6 vs. 95.3 ± 29.5 U/L; p < 0.01). Univariable logistic regression analysis indicated a significant relationship between CMD and MDA-LDL levels (odds ratio (OR): 1.03; p < 0.01). In the multivariable model, MDA-LDL levels were significantly associated with CMD (OR: 1.02; p < 0.01). Regression analysis showed a significant correlation between MDA-LDL levels and CFR (r = -0.42, p < 0.01) and IMR (r = 0.35, p < 0.01). In the multiple regression analysis, MDA-LDL levels were independently associated with CFR (ß = -0.30, p < 0.01) and IMR (ß = 0.26, p = 0.02). CONCLUSION: MDA-LDL levels were associated with CMD in patients without obstructive CAD.

The Belgian Registry on Coronary Function Testing (BELmicro Registry): Study Population, Prevalence of Coronary Vascular Dysfunction, and Procedural Safety.

Coronary function testing (CFT) plays a pivotal role in the diagnosis of coronary vascular dysfunction and providing patients with tailored therapy. The Belgian registry on CFT (BELmicro registry) is a prospective, observational, multicenter registry including 14 centers in Belgium. All patients who underwent clinically indicated CFT were included in the registry. Baseline characteristics, CFT data, and clinical outcomes were collected. This analysis aimed to describe the baseline characteristics of a real-world population of patients who underwent CFT, evaluate the prevalence of coronary vascular dysfunction, and assess the safety of CFT in daily clinical practice. Between October 2021 and September 2023, 449 patients were enrolled. The mean age was 65 ± 10 years, and 47.4% of patients were men. A total of 59% of patients had hypertension, 18.7% had diabetes, 69.5% had hypercholesterolemia, and 40.1% had a smoking habit. Angina and nonobstructive coronary arteries (ANOCAs) were identified in 85.1% of the patients. Microvascular physiology assessment was performed in 95.5% of patients, vasoreactivity test in 28.5%, and both in 24.0%. coronary microvascular dysfunction was diagnosed in 23.4% of patients with ANOCA, epicardial vasospasm in 26.3%, and microvascular spasm in 14.9%. Rates of major complications were 0.7% for microvascular physiology assessment and 0% for vasoreactivity test. In conclusion, participants in the BELmicro registry represented a real-world population of patients, characterized by a high burden of cardiovascular risk factors. Coronary microvascular dysfunction and coronary vasospasm were frequent in patients with ANOCA. Performing CFT in daily clinical practice was feasible, with a low rate of complications.

Comparison of Ticagrelor with Clopidogrel on Coronary Microvascular Dysfunction Following Acute Myocardial Infarction Using Angiography-Derived Index of Microcirculatory Resistance.

PURPOSE: This research aimed to assess the impact of ticagrelor and clopidogrel on coronary microvascular dysfunction (CMD) and prognosis following acute myocardial infarction (AMI), using the angiography-derived index of microcirculatory resistance (angio-IMR) as a non-invasive assessment tool. METHODS: In this retrospective study, angio-IMR was performed to evaluate CMD before and after dual antiplatelet therapy (DAPT) with either ticagrelor (90 mg twice daily, n = 184) or clopidogrel (75 mg once daily, n = 72). The primary endpoint is the improvement of CMD evaluated by angio-IMR (delta angio-IMR) following DAPT. Secondary endpoints included myocardial reinfarction and readmission for heart failure during 2-year follow-up. RESULTS: Compared with clopidogrel, ticagrelor exhibited a significantly higher delta angio-IMR [- 3.09 (5.14) versus - 1.99 (1.91), P = 0.008], indicating a superior improvement of CMD with ticagrelor treatment. Multivariate Cox regression indicated that ticagrelor treatment was related to a reduced risk of readmission for heart failure [8 (4.3) versus 9 (12.5), adjusted HR = 0.329; 95% CI = 0.116-0.934; P = 0.018] and myocardial reinfarction [7 (3.8) versus 8 (11.1), adjusted HR = 0.349; 95% CI = 0.125-0.975; P = 0.026]. Furthermore, ticagrelor treatment serves as an independent predictor of readmission for heart failure (HR = 0.322; 95% CI = 0.110-0.943; P = 0.039). CONCLUSION: The results of this study indicate a potential association between ticagrelor treatment and improved CMD, as well as a reduced risk of cardiovascular events, including myocardial reinfarction and readmission for heart failure in AMI patients. Further randomized controlled trials are necessary to confirm the potential benefits of ticagrelor on CMD and cardiovascular prognosis. This clinical trial was registered in www. CLINICALTRIALS: gov (NCT05978726).

Prognostic Value of Coronary Angiography-Derived Index of Microcirculatory Resistance in Non-ST-Segment Elevation Myocardial Infarction Patients.

BACKGROUND: The index of microcirculatory resistance is a reliable measure for evaluating coronary microvasculature, but its prognostic value in patients with non-ST-segment elevation myocardial infarction (NSTEMI) remains unclear. OBJECTIVES: This study aimed to evaluate the prognostic impact of postpercutaneous coronary intervention (PCI) angiography-derived index of microcirculatory resistance (angio-IMR) in patients with NSTEMI. METHODS: The culprit vessel's angio-IMR was measured after PCI in 2,212 NSTEMI patients at 3 sites. The primary endpoint was 2-year major adverse cardiac events (MACEs), defined as a composite of cardiac death, readmission for heart failure, myocardial reinfarction, and target vessel revascularization. RESULTS: The mean post-PCI angio-IMR was 20.63 ± 4.17 in NSTEMI patients. A total of 206 patients were categorized as the high post-PCI angio-IMR group according to maximally selected log-rank statistics. Patients with angio-IMR >25 showed a higher rate of MACEs than those with angio-IMR ≤25 (32.52% vs 9.37%; P < 0.001). Post-PCI angio-IMR >25 was an independent predictor of MACEs (HR: 4.230; 95% CI: 3.151-5.679; P < 0.001) and showed incremental prognostic value compared with conventional risk factors (AUC: 0.774 vs 0.716; P < 0.001; net reclassification index: 0.317; P < 0.001; integrated discrimination improvement: 0.075; P < 0.001). CONCLUSIONS: In patients undergoing PCI for NSTEMI, an increased post-PCI angio-IMR is associated with a higher risk of MACEs. The addition of post-PCI angio-IMR into conventional risk factors significantly improves the ability to reclassify patients and estimate the risk of MACEs. (Angiograph-Derived Index of Microcirculatory Resistance in Patients With Acute Myocardial Infarction; NCT05696379).

Combined risk estimates of diabetes and coronary angiography-derived index of microcirculatory resistance in patients with non-ST elevation myocardial infarction.

BACKGROUND: Diabetes mellitus (DM) and coronary microvascular dysfunction (CMD) increase the risk of adverse cardiac events in patients with non-ST-segment elevation myocardial infarction (NSTEMI). This study aimed to evaluate the combined risk estimates of DM and CMD, assessed by the angiography-derived index of microcirculatory resistance (angio-IMR), in patients with NSTEMI. METHODS: A total of 2212 patients with NSTEMI who underwent successful percutaneous coronary intervention (PCI) were retrospectively enrolled from three centers. The primary outcome was a composite of cardiac death or readmission for heart failure at a 2-year follow-up. RESULTS: Post-PCI angio-IMR did not significantly differ between the DM group and the non-DM group (20.13 [17.91-22.70] vs. 20.19 [18.14-22.77], P = 0.530). DM patients exhibited a notably higher risk of cardiac death or readmission for heart failure at 2 years compared to non-DM patients (9.5% vs. 5.4%, P < 0.001). NSTEMI patients with both DM and CMD experienced the highest cumulative incidence of cardiac death or readmission for heart failure at 2 years (24.0%, P < 0.001). The combination of DM and CMD in NSTEMI patients were identified as the most powerful independent predictor for cardiac death or readmission for heart failure at 2 years (adjusted HR: 7.894, [95% CI, 4.251-14.659], p < 0.001). CONCLUSIONS: In patients with NSTEMI, the combination of DM and CMD is an independent predictor of cardiac death or readmission for heart failure. Angio-IMR could be used as an additional evaluation tool for the management of NSTEMI patients with DM. TRIAL REGISTRATION: URL: https://www. CLINICALTRIALS: gov ; Unique identifier: NCT05696379.

Microcirculatory dysfunction in hypertrophic cardiomyopathy with chest pain assessed by angiography-derived microcirculatory resistance.

Chest pain, a common initial symptom in hypertrophic cardiomyopathy (HCM) patients, is closely linked to myocardial ischemia, despite the absence of significant coronary artery stenosis. This study explored microvascular dysfunction in HCM patients by employing angiography-derived microcirculatory resistance (AMR) as a novel tool for comprehensive assessment. This retrospective analysis included HCM patients with chest pain as the primary symptom and control patients without cardiac hypertrophy during the same period. The AMR was computed through angiography, providing a wire-free and adenosine-free index for evaluating microcirculatory function. Propensity score matching ensured balanced demographics between groups. This study also investigated the correlation between the AMR and clinical outcomes by utilizing echocardiography and follow-up data. After matching, 76 HCM patients and 152 controls were analyzed. While there was no significant difference in the incidence of epicardial coronary stenosis, the AMR of three epicardial coronary arteries was markedly greater in HCM patients. The criterion of an AMR ≥ 250 mmHg*s/m was that 65.7% of HCM patients experienced coronary microvascular dysfunction (CMD). Independent risk factors for CMD included increased left ventricular (LV) wall thickness (OR = 1.209, 95% CI 1.013-1.443, p = 0.036). Furthermore, an AMR_LAD ≥ 250 mmHg*s/m had an increased cumulative risk of the endpoint (log-rank p = 0.023) and was an independent risk factor for the endpoint (HR = 11.64, 95% CI 1.13-120.03, p = 0.039), providing valuable prognostic insights.

Coronary Microvascular Function Assessment using the Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients with ST-segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention.

Background: Studies reporting the status of coronary microvascular function in the infarct-related artery (IRA) after primary percutaneous coronary intervention (PCI) remain limited. This study utilized the coronary angiography-derived index of microcirculatory resistance (caIMR) to assess coronary microvascular function in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary PCI. Methods: We used the FlashAngio system to measure the caIMR after primary PCI in 157 patients with STEMI. The primary endpoint was the occurrence of a major adverse cardiovascular event (MACE), defined as a composite endpoint encompassing cardiac mortality, target vessel revascularization, and rehospitalization due to congestive heart failure (CHF), myocardial infarction (MI), or angina. Results: Approximately 30% of patients diagnosed with STEMI and who experienced successful primary PCI during the study period had a caIMR in the IRA of > 40. The caIMR in the IRA was significantly higher than in the reference vessel (32.9 ± 15.8 vs. 27.4 ± 11.1, p < 0.001). The caIMR in the reference vessel of the caIMR > 40 group was greater than in the caIMR ≤ 40 group (30.9 ± 11.3 vs. 25.9 ± 10.7, p = 0.009). Moreover, the caIMR > 40 group had higher incidence rates of MACEs at 3 months (25.5% vs. 8.3%, p = 0.009) and 1 year (29.8% vs. 13.9%, p = 0.04), than in the caIMR ≤ 40 group, which were mainly driven by a higher rate of rehospitalization due to CHF, MI, or angina. A caIMR in the IRA of > 40 was an independent predictor of a MACE at 3 months (hazard ratio (HR): 3.459, 95% confidence interval (CI): 1.363-8.779, p = 0.009) and 1 year (HR: 2.384, 95% CI: 1.100-5.166, p = 0.03) in patients with STEMI after primary PCI. Conclusions: Patients with STEMI after primary PCI often have coronary microvascular dysfunction, which is indicated by an increased caIMR in the IRA. An elevated caIMR of > 40 in the IRA was associated with an increased risk of adverse outcomes in STEMI patients undergoing primary PCI.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Impact of the use of plaque modification techniques on coronary microcirculation using an angiography-derived index of microcirculatory resistance.

Many lesions in patients undergoing percutaneous coronary intervention (PCI) exhibit significant calcification. Several techniques have been developed to improve outcomes in this setting. However, their impact on coronary microcirculation remains unknown. The aim of this study is to evaluate the influence of plaque modification techniques on coronary microcirculation across patients with severely calcified coronary artery disease. In this multicenter retrospective study, consecutive patients undergoing PCI with either Rotablation (RA) or Shockwave-intravascular-lithotripsy (IVL) were included. Primary endpoint was the impairment of coronary microvascular resistances assessed by Δ angiography-derived index of microvascular resistance (ΔIMRangio) which was defined as the difference in IMRangio value post- and pre-PCI. Secondary endpoints included the development of peri procedural PCI complications (flow-limiting coronary dissection, slow-flow/no reflow during PCI, coronary perforation, branch occlusion, failed PCI, stroke and shock developed during PCI) and 12-month follow-up adverse events. 162 patients were included in the analysis. Almost 80% of patients were male and the left descending anterior artery was the most common treated vessel. Both RA and IVL led to an increase in ΔIMRangio (22.3 and 10.3; p = 0.038, respectively). A significantly higher rate of PCI complications was observed in patients with ΔIMRangio above the median of the cohort (21.0% vs. 6.2%; p = 0.006). PCI with RA was independently associated with higher ΔIMRangio values (OR 2.01, 95% CI: 1.01-4.03; p = 0.048). Plaque modification with IVL and RA during PCI increases microvascular resistance. Evaluating the microcirculatory status in this setting might help to predict clinical and procedural outcomes and to optimize clinical results.

Beyond Coronary Artery Disease: Assessing the Microcirculation.

Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary arteries, nearly half of patients with stable angina and IHD who undergo invasive coronary angiography do not have obstructive epicardial coronary artery disease. Ischemia with nonobstructive coronary arteries is frequently caused by microvascular angina with underlying coronary microvascular dysfunction (CMD). Greater understanding the pathophysiology, diagnosis, and treatment of CMD holds promise to improve clinical outcomes of patients with ischemic heart disease.

Coronary Microvascular Dysfunction: A Guide for Clinicians.

Dysfunction of the coronary microvasculature has become increasingly recognized as an important mechanism of myocardial ischemia in patients without obstructive coronary artery disease. The causes and management of coronary microvascular dysfunction remain poorly understood and are still largely based on extrapolation of epicardial coronary artery disease data. Quantification of myocardial blood flow and flow reserve have improved diagnosis, though important questions remain. In this review, we explain current understanding of the spectrum of pathophysiology of coronary microvascular dysfunction, summarize current diagnostic techniques to assess for coronary microvascular dysfunction, and appraise the limited data on management options specifically for patients with coronary microvascular dysfunction.

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.

Prognostic impact of coronary microvascular dysfunction in patients with atrial fibrillation.

BACKGROUND: Coronary microvascular dysfunction (CMD) is frequently observed in atrial fibrillation (AF), the most commonly sustained arrhythmia. Nevertheless, an in-depth prognostic significance of CMD in AF is lacking. We aimed to provide insight into the predictive impact of CMD assessed by a novel non-invasive coronary angiography-derived index of microcirculatory resistance (caIMR) for major adverse events (MACE) in AF patients. METHOD: This study included patients with AF who underwent invasive coronary angiography due to suspected cardiac ischemia and did not exhibit obstructive epicardial coronary artery disease (≤50 % stenosis). The caIMR was prospectively evaluated, and the optimal cutoff value for predicting MACE was determined through ROC analysis. RESULT: A total of 463 patients with AF were enrolled. During a median of 33 months of follow-up, 111 (23.97 %) patients had MACE endpoints. The best caIMR cutoff value was 39.28. In patients with MACE, both the mean caIMR and the prevalence of elevated caIMR (caIMR>39.28) were significantly higher compared to those without MACE. An elevated caIMR was linked to a higher risk of MACE (log-rank P < 0.001) and emerged as an independent predictor of clinical outcomes (HR: 4.029; 95 % CI: 2.529-6.418; P < 0.001). In addition, the risk of MACE was higher in high caIMR patients with non-paroxysmal AF (log-rank P < 0.001) and no catheter ablation (log-rank P < 0.001). CONCLUSION: Elevated caIMR is common and showed a vital independent prognostic significance in AF patients. In addition to well-known risk factors, assessment of microvascular function can be a feasible approach for early prevention and a therapeutic target in AF patients.

The invasive investigation of INOCA in the coronary catheterization lab.

Over half of all patients with angina have no angiographically demonstratable obstructive coronary disease, with a significant proportion of these patients having undiagnosed microvascular dysfunction and/or vasospastic angina. In chronic coronary syndrome, ischemia with non-obstructive coronary artery disease (INOCA) often remains undiagnosed, or uninvestigated. INOCAmay occur due to vasospastic angina and microvascular dysfunction and require invasive assessment in the coronary catheterization lab. To evaluate INOCA coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR) are used to assess microvascular dysfunction before acetylcholine provocation testing for coronary spasm. This review provides an overview of the invasive investigation of INOCA in the coronary catheterization lab for patients with angina to be optimally managed.

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).

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.

Comprehensive Angiography-Derived Functional Assessment of Epicardial and Microvascular Coronary Disease. Correlation With Non-invasive Myocardial Stress Imaging.

Coronary angiography (CA) is poorly correlated with non-invasive myocardial stress imaging (NSI) and myocardial ischemia is often observed in patients with unobstructed coronary arteries. Moreover, the diagnostic performance of combined epicardial and microcirculatory angiography-derived physiological assessment and its correlation with NSI remains unknown. A total of 917 coronary vessels in 319 patients who underwent both CA and NSI were included in this multicenter observational retrospective analysis. Quantitative flow ratio (QFR) and angiography-derived index of microcirculatory resistance (IMRangio) analyses were performed to estimate coronary epicardial and microcirculatory function respectively. NSI demonstrated evidence of myocardial ischemia in 76% of the cases. IMRangio (36 [22 to 50] vs 29 [21 to 41], p <0.001) was significantly higher and QFR (0.92 [0.78 to 0.99] vs 0.97 [0.91 to 0.99], p <0.001) was significantly lower in vessels subtending ischemic territories. Overall, the diagnostic accuracy of QFR was moderate (area under the curve of receiver operating characteristic [AUCROC] 0.632 [95% confidence interval [CI] 0.589 to 0.674], p <0.0001) but it was higher in patients with normal microcirculatory function (AUCROC = 0.726 [95% CI 0.669 to 0.784], p <0.0001, p Value for AUCROC comparison = 0.009). Combined QFR/IMRangio assessment provided incremental diagnostic performance compared with the evaluation of epicardial or microcirculatory districts in isolation (p Value for AUC comparison <0.0001) and it was able to identify the predominant mechanism of myocardial ischemia in 77% of the patients with positive NSI. Our study suggests the value of a combined angiography-derived assessment of epicardial and microvascular function for the definition of the predominant mechanism of myocardial ischemia in patients with suspected coronary artery disease.

Implementation of Microcirculation Examination in Clinical Practice-Insights from the Nationwide POL-MKW Registry.

Background and Objectives: The assessment of coronary microcirculation may facilitate risk stratification and treatment adjustment. The aim of this study was to evaluate patients' clinical presentation and treatment following coronary microcirculation assessment, as well as factors associated with an abnormal coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) values. Materials and Results: This retrospective analysis included 223 patients gathered from the national registry of invasive coronary microvascular testing collected between 2018 and 2023. Results: The frequency of coronary microcirculatory assessments in Poland has steadily increased since 2018. Patients with impaired IMR (≥25) were less burdened with comorbidities. Patients with normal IMR underwent revascularisation attempts more frequently (11.9% vs. 29.8%, p = 0.003). After microcirculation testing, calcium channel blockers (CCBs) and angiotensin-converting enzyme inhibitors were added more often for patients with IMR and CFR abnormalities, respectively, as compared to control groups. Moreover, patients with coronary microvascular dysfunction (CMD, defined as CFR and/or IMR abnormality), regardless of treatment choice following microcirculation assessment, were provided with trimetazidine (23.2%) and dihydropyridine CCBs (26.4%) more frequently than those without CMD who were treated conservatively (6.8%) and by revascularisation (4.2% with p = 0.002 and 0% with p < 0.001, respectively). Multivariable analysis revealed no association between angina symptoms and IMR or CFR impairment. Conclusions: The frequency of coronary microcirculatory assessments in Poland has steadily increased. Angina symptoms were not associated with either IMR or CFR impairment. After microcirculation assessment, patients with impaired microcirculation, expressed as either low CFR, high IMR or both, received additional pharmacotherapy treatment more often.

[Index of microcirculatory resistance is associated with left ventricular remodeling in patients with acute anterior ST-segment elevation myocardial infarction undergoing emergency primary percutaneous coronary intervention].

OBJECTIVE: To evaluate whether index of microcirculatory resistance (IMR) is associated with left ventricular (LV) remodeling in acute anterior ST elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI). METHODS: This was a single-center retrospective cohort study. The patients with first anterior STEMI who received PPCI from January 2014 to August 2017 in Peking University Third Hospital was enrolled. After PPCI, IMR was measured immediately by using pressure/temperature guidewire. The success rate of IMR measurement was 100%. Also we collected some related clinical data from the medical records and laboratory results. Infarct size [assessed as creatine kinase (CK) peak], echocardiography at baseline and 1 year follow-up were assessed. LV adverse remodeling (LVAR) was defined as ≥20% increase in LV end-diastolic volume (LVEDV). RESULTS: A total of forty-three patients were enrolled, with an average age of (58.7±12.4) years.The patients were divided into two groups as IMR ≤25 and IMR>25 by normal values recommended by previous literature. Compared with IMR ≤25 group, IMR>25 group had a higher percentage of initial thrombolysis in myocardial infraction (TIMI) grade 0 (95.7% vs. 65.0%, P=0.029), higher serum CK peak value [4 090 (383, 15 833)vs. 1 580 (396, 5 583), P=0.004]. The IMR>25 group suffered higher rates of ventricular aneurysm (30.4% vs. 5.0%, P=0.021). There was no difference in LVEDV [(111.0±18.8) mL vs. (115.0±23.6) mL, P=0.503] between the two groups 1 day after MI, but after 1 year, LVEDV in IMR>25 group was significantly higher than in IMR≤25 group [(141.5±33.7) mL vs. (115.9±27.9) mL, P=0.018]. The incidence of LVAR was more significant in IMR>25 group (47.4% vs. 11.8%, P=0.024). Binary Logistics regression showed that IMR [B=0.079, exp(B) (95%CI)=1.082 (1.018－1.149), P=0.011] and serum triglyceride level [B=1.610, exp(B) (95%CI)=5.005 (1.380－18.152), P=0.014] were the predictors of LVAR 1 year after MI. IMR had a good predictive value for LVAR 1 year after MI [area under the curve (AUC)=0.749, P=0.019], IMR>29 was a good cutoff value with sensitivity 81.8% and specificity 68.0%. CONCLUSION: Our study elaborates that immediate measurement of IMR after PPCI in patients with STEMI can reflect the microvascular function.And IMR could be used as a quantitative biomarker to predict LVAR after STEMI.