Coronary Flow Reserve Research Articles

Abstract 18770: Understanding Patients’ Characteristics and Coronary Microvasculature: Early Insights From First US Coronary Microvascular Dysfunction Registry

Introduction: Coronary angiography falls short in accurately evaluating the coronary microcirculation. Fortunately, a new comprehensive invasive hemodynamic assessment method, which uses coronary flow reserve (CFR) and the index of microvascular resistance (IMR), provides enhanced diagnostic capabilities. Objective: We present our early real-world experience with invasive hemodynamic assessment of the coronary microvasculature in symptomatic patients with non-obstructive coronary artery disease (CAD) from the first US Coronary Microvascular Disease Registry (CMDR). Methods: The CMDR is a prospective, multi-center, standardized registry of patients with angina and non-obstructive CAD who underwent invasive hemodynamic assessment of the coronary microvasculature using the Coroventis CoroFlow Cardiovascular System (Abbott Laboratories, Chicago, Illinois). Comprehensive assessments, including resting full-cycle ratio (RFR), fractional flow reserve (FFR), CFR, and IMR, were performed on all patients. Results: The first 156 patients enrolled in the CMDR were analyzed; their mean age was 62.4 years and 65.6% were female. A substantial proportion (31.8%) of patients presented with a Canadian Cardiovascular Society Angina Score of 3 or 4. CMD was diagnosed in 39 of 154 patients (25.3%), with mean RFR of 0.89±0.43, mean FFR of 0.93±0.08, mean CFR of 1.8±0.9, and mean IMR of 36.26±19.23. None of the patients experienced in-hospital adverse events. Conclusions: Early results from CMDR patients show that invasive hemodynamic assessment of the coronary microvasculature is safe and effective for suspected CMD. Tailored medical therapy for microvascular angina was provided to diagnosed CMD patients. With ongoing patient enrollment, the CMDR aims to contribute valuable insights to the growing evidence base for CMD.

Abstract 15577: Diagnostic Performance of Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography versus Coronary Angiography Fractional Flow Reserve in Estimating Myocardial Blood Flow and Flow Reserve: A Diagnostic Accuracy Meta-Analysis

Introduction: Precisely estimating myocardial blood flow and flow reserve is crucial in diagnosing and managing ischemic heart disease. Coronary angiography fractional flow reserve (FFR) has been a standard tool. However, the recent emergence of Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography (CZT-SPECT) has provided an innovative diagnostic approach. Consequently, a comprehensive comparative analysis of their efficacies in evaluating myocardial blood flow and flow reserve is necessary. Hypothesis: This study aims to determine the diagnostic accuracy of CZT-SPECT compared to coronary angiography FFR in estimating myocardial blood flow and flow reserve. Methods: A systematic search until July 2022 was conducted across databases such as PubMed, Embase, and Web of Science, focusing on studies comparing CZT-SPECT and coronary angiography FFR in the estimation of myocardial blood flow and flow reserve. Utilizing the mada package in R software (version 4.0.3), we conducted diagnostic accuracy analysis by pooling metrics like sensitivity, specificity, false-positive rate estimates, diagnostic odds ratio, and positive and negative Likelihood Ratios (LR), all of which were presented with a 95% Confidence Interval (CI). Results: The meta-analysis incorporated 6 studies with a total patient population of 346. Our findings reveal that CZT-SPECT exhibited a pooled sensitivity of 79.1% (95% CI: 71.8-84.9%, I^2=0) and a specificity of 78.5% (95% CI: 70.4-84.8%, I^2=25.3%). The false-positive rate was 21.5% (95% CI: 15.2-29.6%). Moreover, CZT-SPECT demonstrated a diagnostic odds ratio of 13.75 (95% CI: 7.67-24.65), while the positive likelihood ratio was 3.67 (95% CI: 2.59-5.19), and the negative likelihood ratio stood at 0.26 (95% CI: 0.19-0.37). Conclusions: This study provides valuable insights into the diagnostic accuracy of CZT-SPECT compared to coronary angiography FFR in estimating myocardial blood flow and flow reserve. These findings indicate that while CZT-SPECT shows promising diagnostic potential, its performance is similar to coronary angiography FFR. The results will be instrumental in informing clinical decision-making and shaping future research directions in the field of cardiovascular imaging.

Abstract 17343: Coronary Microvascular Function in Physician Burnout and Job Stress

Background: As a professional group, physicians are at increased risk of burnout and job stress, both of which are associated with an increased risk of coronary heart disease that seems more prevalent among male than female physicians. Aim: This study aimed to examine the association of burnout and job stress with coronary microvascular function, a predictor of major adverse cardiovascular events. Methods: Thirty male physicians with clinical burnout and 30 controls without burnout were included. Burnout was assessed with the Maslach Burnout Inventory and job stress with the effort-reward imbalance and overcommitment questionnaire. All participants underwent myocardial perfusion positron emission tomography to quantify endothelium-dependent (cold pressor test) and endothelium-independent (adenosine challenge) coronary microvascular function. Burnout and job stress were regressed on measures of coronary microvascular function in the same model while adjusting for age and body mass index. Results: Burnout and job stress had significant and independent effects on endothelium-dependent microvascular function. Burnout was positively associated with coronary flow reserve, myocardial blood flow (MBF) response, and hyperemic MBF (r partial: 0.29 to 0.35; p-value: 0.008 to 0.027). Effort-reward ratio (r partial: -0.32 to -0.34; p-value: 0.009 to 0.017) and overcommitment (r partial: -0.29 to -0.35; p-value: 0.008 to 0.027) showed inverse associations with these measures. Conclusions: In male physicians, burnout and high job stress showed opposite effects on coronary microvascular endothelial function. Longitudinal studies are needed to show potential clinical implications. Future studies should include burnout and job stress for a more nuanced understanding of their potential impact on cardiovascular health.

Abstract 13787: Restricted Coronary Flow Reserve of Mental Stress Induced Myocardial Ischemia in Angina and No Obstructive Coronary Artery Disease

Background: The myocardial blood flow (MBF) mechanism in mental stress-induced myocardial ischemia (MSIMI) in angina with no obstructive coronary artery disease (ANOCA) population is unknown. Methods: 13-NH 3 cardiac PET-CT was utilized to assess MBF and perfusion changes under mental stress (ms) and adenosine stress (as) in ANOCA subjects and gender- and age-matched healthy controls. MSIMI was defined as an increase in perfusion defect score of ≥3 points. Results: Among the 126 participants enrolled, ANOCA women showed a significantly higher prevalence of MSIMI compared to the healthy controls (36/84 vs. 1/42, p <0.001). Perfusion defects under ms occurred synchronously however more pronounced in the left anterior descending and right coronary artery territories, consistent with a significantly higher MBF hyperemia in the left circumflex territory. MBF ms shows a close correlation with rate-pressure product (RPP ms ) ( p <0.05 in ANOCA&MSIMI+, ANOCA&MSIMI-, and control groups with r pearson ranging from 0.39-0.65). Although no differences existed in absolute MBF ms values between groups, there were notable increasing trends among the three groups in corrected MBF, which reflected blood flow supply-demand balance (ANOCA&MSIMI+: 0.96±0.23 vs. control group: 1.10±0.29, p =0.020), and in coronary flow reserve (CFR) (ANOCA&MSIMI+: 2.41±0.75 vs. control group: 2.89±0.77, p =0.016). Furthermore, after adjusting for confounding factors, only subjects in ANOCA&MSIMI+ group did not exhibit a corresponding increase in MBF ms matching MBF as . Conclusion: Restricted CFR, indicating impaired coronary microvascular function, and mismatch between myocardial blood supply and demand together constitute the pathogenic mechanism of MSIMI in ANOCA population. More researches are still needed in exploring the brain-heart interaction in MSIMI.

Abstract 13713: Coronary Endothelial Dysfunction and Microvascular Vasospasm in Patients With Postural Orthostatic Tachycardia Syndrome

Background: Postural Orthostatic Tachycardia Syndrome (POTS) is characterized by autonomic dysfunction-related symptoms such as orthostatic intolerance, palpitations, dizziness, and chest pain. The mechanisms driving chest pain in POTS are unclear. Hypothesis: We hypothesized that coronary endothelial dysfunction (ED) and abnormal microvascular reactivity may be a contributor to chest pain in POTS. Methods: Patients (n=6) were diagnosed with POTS or had significant tachycardia despite medical therapy out of 67 patients in our cohort. All patients reported persistent chest pain and were referred for coronary function testing (CFT) to test macro- and micro-vascular function. CFT was performed to test endothelium-dependent and non-endothelium dependent function using graded doses of intracoronary acetylcholine (ACH), and intravenous adenosine (ADO). Coronary Flow Reserve<2.0 and Index of Microvascular Resistance>25 diagnosed coronary microvascular dysfunction. Coronary artery diameter narrowing to ACH (100 mcg) was used to diagnose ED. Epicardial coronary spasm was defined as >90% constriction to ACH. Microvascular spasm was diagnosed by ACH provoked-chest pain and EKG changes in the absence of epicardial spasm. Results: Mean age was 44.1 ± 15.2 years, 67% were female, and all tolerated CFT without complications. POTS symptoms, baseline medications, and CFT results are shown ( Table ). All had an abnormal response to ACH, indicating ED and microvascular spasm. Non-endothelium function was normal in all patients. Anti-anginal medications were changed based on CFT information, with improvement in chest pain with calcium channel blocker use. Conclusion: In all 6 pts, CP was associated with ED and microvascular spasm. Mechanistic links between ED and POTS need further investigation. Given that ED is a prognostic marker associated with recurrent angina hospitalization and events, investigation of therapies that target ED in POTS may be warranted.

Abstract 14662: What Factors Contribute to the Presence of Coronary Microvascular Dysfunction in Patients With Non-Obstructive Coronary Artery Disease?

Introduction: In recent years, there has been growing interest in coronary microvascular dysfunction (CMD). Several risk factors have been discussed as causes of CMD, but there are still many unknowns. Hypothesis: In this study, we evaluated clinical risk factors for CMD in patients with chest pain with non-obstructive coronary artery disease (INOCA). Methods: Sixty-two patients who were able to undergo comprehensive coronary angiography at the time of chest pain screening were included in the study. Patients with a history of heart failure were excluded. Comprehensive angiography excluded patients with organic coronary artery stenosis (%stenosis>50%) and was performed with the spasm provocation test using acetylcholine (ACh) to induce coronary spasm and with a pressure wire to evaluate CMD. Positive coronary spasm was defined as the presence of usual chest pain or electrocardiographic changes and >90% coronary artery constriction on angiograms in response to ACh provocation. In addition, a coronary spasm within one section of the American Heart Association’s classification was defined as a focal spasm. CMD was defined as the presence of coronary flow reserve (CFR) < 2.0 or an index of microcirculatory resistance (IMR) ≥ 25 obtained from a pressure wire. The clinical background leading to CMD was investigated and evaluated by logistic analysis. Results: Of 62 patients with INOCA, 26 (42%) had CMD. The results are shown in the table. Conclusions: These results suggested that factors contributing to CMD in INOCA patients were diverse: women, smoking, focal spasm, and elevated NTproBNP level. It is necessary to identify the cause of CMD before treatment in such patients.

Abstract 17339: Deficiency of Sirtuin 3 in Endothelium Reduces Endothelial-Dependent Relaxation and Impairs Myogenic Response in Coronary and Middle Cerebral Arteries of Mice

Previously, we demonstrated that specific knockout of Sirtuin 3 (Sirt3) in endothelial cells (ECs) impairs coronary flow reserve and diastolic function in mice. So far, the role of endothelial Sirt3 in the coronary arteries remains unexplored. Male and female Sirt3 EC-knockout (Sirt3 EC KO) mice and Sirt3-Lox-P mice at 14-15-month old age were used to assess the roles of endothelial Sirt3 on the microvascular functions. Mouse coronary arteries (CA) and middle cerebral arteries (MCA) were isolated and mounted in a myograph system. Myogenic response was evaluated by increasing perfusion pressure. Ach (Acetylcholine, 1nM-100μM)-induced EC-dependent vasodilation and NO donor SNP (sodium nitroprusside,1nM-10μM)-induced EC-independent vasodilation were examined. Myogenic response was significantly impaired in both CA and MCA of male and female Sirt3 ECKO mice, as evidenced by a lack of constriction while raising perfusion pressure from 10 mmHg to 150 mmHg. Both wall thickness and cross-sectional area were increased in CA and MCA of male and female Sirt3 EC KO mice. The wall to lumen ratio was increased in MCA, but did not change in CA of Sirt3 EC KO mice, compared to SIRT3-Lox-p mice. The wall tension and myogenic tone were significantly decreased in CA and MCA of both male and female Sirt3 EC KO mice. The vessel stiffness was not significantly different between SIRT3EC KO mice and SIRT3-Lox-p mice. In CA, the Ach-induced EC-dependent vasodilation was reduced in both male and female Sirt3 ECKO mice. Intriguingly, the SNP-induced EC-independent vasodilation was significantly reduced in female Sirt3 ECKO mice, but did not observed in male Sirt3 ECKO mice. In MCA, the Ach-induced EC-dependent vasodilation was only impaired in male Sirt3 ECKO mice, but was not observed in female Sirt3 ECKO mice. Whereas, the SNP-induced EC-independent vasodilation was impaired in both male and female Sirt3 EC KO mice as compared to their control SIRT3-Lox-p mice. These data revealed a sex and organ specific role of Sirt3 in EC, i.e. there is more EC-independent dysfunction in female CA, but greater impairment of EC-dependent relaxation in male MCA. Our study demonstrates the critical role of endothelial Sirt3 in maintaining microvascular function in coronary and cerebral arteries.

Abstract 15736: Coronary Angiography Alone Compared With Invasive Coronary Function Testing in Women With Ischemia and No Obstructive Coronary Artery Disease

Introduction: Ischemic heart disease is a leading cause of morbidity and mortality in women. Women frequently suffer from ischemia and no obstructive coronary artery disease (INOCA) which includes phenotypes of coronary microvascular dysfunction (CMD) or coronary vasospasm (VA). Between 30-60% of women referred for invasive angiography have non obstructive coronary arteries, leaving many patients without a definitive diagnosis. Objective: We sought to determine the real-world diagnostic yield of invasive physiological testing in women with INOCA, and to describe downstream care regarding modifications to medical therapy based on the eventual diagnosis. Methods: We included 198 women who underwent either coronary angiography (CA, N=99) alone or coronary function testing (CFT, N=99) comprised of acetylcholine provocation and assessment of coronary flow reserve and the index of microcirculatory resistance. We performed a descriptive retrospective analysis of demographics, pre-procedure diagnostic testing and used logistic regression to compare the findings of angiography, post-procedure diagnosis, and changes to cardiac medications across cohorts. Results: The mean age was 62 ± 10 (CA alone) compared with 57 ± 10 years (CFT). Patients were mostly white (72% CA vs 79% CFT). An angiography-based diagnosis of normal coronary arteries was found in 21% CA alone (N=21) vs 48% in CFT (N=48) and non-obstructive CAD in 79% CA alone (N=78) vs 51% CFT (N=50), p<0.001. Of the women who underwent CFT, 76% (N=75) were diagnosed with a vasomotor disorder stratified by endotype of CMD 34% (n=34), VA 22% (n=22), mixed CMD/VA 10% (N=10) or endothelial dysfunction 20% (N=20). Medications were changed after angiography in 41% in the CA alone group compared to 67% in the CFT group, p<0.001; while medication changes at 30 days occurred in 22% CA alone vs 45% in the CFT group, p<0.001. Conclusions: Our findings demonstrate that women presenting with suspected ischemic heart disease undergoing coronary angiography often received a diagnosis of non-obstructive coronary artery disease; whereas those undergoing CFT were diagnosed with coronary vasomotor disorders. In our institution, medication changes occurred more frequently after a CFT-confirmed diagnosis.

Abstract 12847: The Heart Bus: A Mobile Patient-Centered Approach to Improve Early Diagnosis of Heart Failure in the Community

Introduction: Heart failure with preserved ejection fraction (HFpEF) is associated with poor quality of life and considerable morbidity and mortality risk. Early diagnosis is expected to improve clinical outcomes, but requires imaging and laboratory analyses with frequent hospital visits. We developed a mobile care unit, the Heart Bus, to improve early diagnosis of HF. Methods: The Heart Bus was a 70 m 2 trailer with examination rooms, cardiac ultrasound, exercise testing equipment, a clinical laboratory, and 4 staff. During 2020-2022, the Heart Bus team reached out to the population in local newspapers, via HF patient digital platforms, and visited locations in the West Coast of Sweden. Eligible participants had suspected signs or symptoms of HF. Participants underwent echocardiography and tests for cardiopulmonary exercise, vascular function, adenosine-stress coronary flow reserve, and routine biochemistry and haematology. Molecular and physiological deep phenotyping were also performed in the Heart Bus to facilitate future patient stratification and precision medicine (data to be presented Nov 2023). Results: Of 218 participants screened over 18 months (12/month), 200 were included. Most participants actively reached out to take part. Twenty three participants (11.5%) had HFrEF, 54 (27.0%) had HFmrEF, and 62 (31.0%) had HFpEF; 70 (35.0%) had a previous HF diagnosis. Of the remaining patients, 60 (30.0%) had intermediate risk of HFpEF. The phenotypes of the EF-stratified HF subgroups were similar. However, participants in the HFpEF cohort had more women ( p < 0.001), lower lung volume ( p < 0.01), higher pulse wave velocity ( p < 0.01) and poorer kidney function ( p < 0.05) than those with HFrEF. Conclusions: The Heart Bus mobile clinic identified large numbers of patients with HF and may represent a cost-effective way to early HF diagnosis also for underserved communities, those located remotely, or have other thresholds for admittance to HF clinics.

Characterizing Mechanisms of Ischemia in Patients With Myocardial Bridges.

Myocardial bridges (MBs) are prevalent and can be associated with acute and chronic ischemic syndromes. We sought to determine the substrates for ischemia in patients with angina with nonobstructive coronary arteries and a MB in the left anterior descending artery. Patients with angina with nonobstructive coronary arteries underwent the acquisition of intracoronary pressure and flow during rest, supine bicycle exercise, and adenosine infusion. Coronary wave intensity analysis was performed, with perfusion efficiency defined as accelerating wave energy/total wave energy (%). Epicardial endothelial dysfunction was defined as a reduction in epicardial vessel diameter ≥20% in response to intracoronary acetylcholine infusion. Patients with angina with nonobstructive coronary arteries and a MB were compared with 2 angina with nonobstructive coronary arteries groups with no MB: 1 with coronary microvascular disease (CMD: coronary flow reserve, <2.5) and 1 with normal coronary flow reserve (reference: coronary flow reserve, ≥2.5). Ninety-two patients were enrolled in the study (30 MB, 33 CMD, and 29 reference). Fractional flow reserve in these 3 groups was 0.86±0.05, 0.92±0.04, and 0.94±0.05; coronary flow reserve was 2.5±0.5, 2.0±0.3, and 3.2±0.6. Perfusion efficiency increased numerically during exercise in the reference group (65±9%-69±13%; P=0.063) but decreased in the CMD (68±10%-50±10%; P<0.001) and MB (66±9%-55±9%; P<0.001) groups. The reduction in perfusion efficiency had distinct causes: in CMD, this was driven by microcirculation-derived energy in early diastole, whereas in MB, this was driven by diminished accelerating wave energy, due to the upstream bridge, in early systole. Epicardial endothelial dysfunction was more common in the MB group (54% versus 29% reference and 38% CMD). Overall, 93% of patients with a MB had an identifiable ischemic substrate. MBs led to impaired coronary perfusion efficiency during exercise, which was due to diminished accelerating wave energy in early systole compared with the reference group. Additionally, there was a high prevalence of endothelial and microvascular dysfunction. These ischemic mechanisms may represent distinct treatment targets.

Diseases of the Coronary Microcirculation: Diagnosis and Treatment.

Coronary microvascular dysfunction (CMD) comprises a variety of pathogenic mechanisms that impair the microcirculation of the heart. Clinical studies have shown that 30-50% of patients suffering from myocardial ischemia without significant coronary artery stenosis have CMD. The disease is associated with elevated mortality and poor quality of life. Whenever a patient presents with symptoms of angina pectoris and no underlying disease is detected by the usual methods, CMD should be considered a possible cause. This review is based on publications retrieved by a selective search in PubMed and on current international guidelines and recommendations of specialty societies. The diagnosis of CMD is based on objective evidence of a microvascular origin of symptoms. The guidelines contain a class IIa recommendation for invasive coronary flow reserve and microvascular resistance measurements. Noninvasive tests such as positron emission tomography and cardiac magnetic resonance imaging are less accurate and are given a class IIb recommendation. No high-quality therapeutic trials are available to date, and the treatment of CMD is thus based on that of chronic coronary syndrome. Lifestyle modification is performed to reduce risk factors. Patients with an abnormal coronary flow reserve or elevated microvascular resistance can be treated with an ACE inhibitor or angiotensin receptor blocker. Beta-blockers and calcium channel antagonists can relieve angina pectoris. Statins lower the LDL level and have positive pleiotropic effects. First-line treatment can be supplemented with further medications. Approximately 25% of patients with CMD have symptoms that do not respond to intensive treatment with the currently available modalities. New treatments, including interventional therapies, are being studied. Their long-term benefit remains to be assessed and compared to that of the existing methods.

Regional differences and coronary microvascular dysfunction in heart failure with preserved ejection fraction.

In heart failure with preserved ejection fraction (HFpEF), regional heterogeneity of clinical phenotypes is increasingly recognized, with coronary microvascular dysfunction (CMD) potentially being a common shared feature. We sought to determine the regional differences in clinical characteristics and prevalence of CMD in HFpEF. We analysed clinical characteristics and CMD in 202 patients with stable HFpEF (left ventricular ejection fraction ≥40%) in Finland, Singapore, Sweden, and United States in the multicentre PROMIS-HFpEF study. Patients with unrevascularized macrovascular coronary artery disease were excluded. CMD was assessed using Doppler echocardiography and defined as coronary flow reserve (adenosine-induced vs. resting flow)<2.5. Patients from Singapore had the lowest body mass index yet highest prevalence of hypertension, dyslipidaemia, and diabetes; patients from Finland and Sweden were oldest, with the most atrial fibrillation, chronic kidney disease, and high smoking rates; and those from United States were youngest and most obese. The prevalence of CMD was 88% in Finland, 80% in Singapore, 77% in Sweden, and 59% in the United States; however, non-significant after adjustment for age, sex, N-terminal pro-brain natriuretic peptide, smoking, left atrial reservoir strain, and atrial fibrillation. Associations between CMD and clinical characteristics did not differ based on region (interaction analysis). Despite regional differences in clinical characteristics, CMD was present in the majority of patients with HFpEF across different regions of the world with the lowest prevalence in the United States. This difference was explained by differences in patient characteristics. CMD could be a common therapeutic target across regions.

Continuous vs Bolus Thermodilution to Assess Microvascular Resistance Reserve.

Coronary flow reserve (CFR) and microvascular resistance reserve (MRR) can, in principle, be derived by any method assessing coronary flow. The aim of this study was to compare CFR and MRR as derived by continuous (CFRcont and MRRcont) and bolus thermodilution (CFRbolus and MRRbolus). A total of 175 patients with chest pain and nonobstructive coronary artery disease were studied. Bolus and continuous thermodilution measurements were performed in the left anterior descending coronary artery. MRR was calculated as the ratio of CFR to fractional flow reserve and corrected for changes in systemic pressure. In 102 patients, bolus and continuous thermodilution measurements were performed in duplicate to assess test-retest reliability. Mean CFRbolus was higher than CFRcont (3.47 ± 1.42 and 2.67 ± 0.81 [P< 0.001], mean difference 0.80, upper limit of agreement 3.92, lower limit of agreement-2.32). Mean MRRbolus was also higher than MRRcont (4.40 ± 1.99 and 3.22 ± 1.02 [P< 0.001], mean difference 1.2, upper limit of agreement 5.08, lower limit of agreement-2.71). The correlation between CFR and MRR values obtained using both methods was significant but weak (CFR, r=0.28 [95%CI: 0.14-0.41]; MRR, r=0.26 [95%CI: 0.16-0.39]; P< 0.001 for both). The precision of both CFR and MRR was higher when assessed using continuous thermodilution compared with bolus thermodilution (repeatability coefficients of 0.89 and 2.79 for CFRcont and CFRbolus, respectively, and 1.01 and 3.05 for MRRcont and MRRbolus, respectively). Compared with bolus thermodilution, continuous thermodilution yields lower values of CFR and MRR accompanied by an almost 3-fold reduction of the variability in the measured results.

A Comparison of Dynamic SPECT Coronary Flow Reserve with TIMI Frame Count in the Treatment of Non-Obstructive Epicardial Coronary Patients.

Microvascular dysfunction in patients with non-obstructive epicardial coronary may aggravate patient's symptoms or lead to various clinical events. To investigate the correlation between dynamic single photon emission computed tomography (D-SPECT) derived coronary flow reserve (CFR) and TIMI frame count (TFC) in patients with non-obstructive epicardial coronary patients. Patients with suspected or known stable CAD who were recommended to undergo invasive coronary angiography were prospectively enrolled in this study. Those who had non-obstructive coronary received TIMI frame count (TFC) and D-SPECT. A cut-off value of >40 was defined as slow flow referred to TFC. A total of 47 patients diagnosed with non-obstructive coronary were enrolled. The mean age of patients was 66.09 ± 8.36 years, and 46.8% were male. Dynamic SPECT derived coronary flow reserve (CFR) was significantly correlated with TIMI frame count in 3 epicardial coronary (LAD: r=-0.506, P = 0.0003; LCX: r= -0.532, P = 0.0001; RCA: r= -0.657, P < 0.0001). The sensitivity and specificity of CFR in identifying abnormal TIMI frame count < 40 was 100.0% and 57.6% in LAD, 62.5% and 87.0% in LCX, 83.9% and 75.0% in RCA, respectively. The optimal CFR cut-off values were 2.02, 2.47, and 1.96 among the three vessels. In patients with non-obstructive coronary, CFR derived from D-SPECT was strongly correlated with TFC. This study demonstrates that that CFR may be an alternative non-invasive method for identifying slow flow in non-obstructive coronary.

Coronary Flow Reserve Changes after Angiotensin Receptor-Neprilysin Inhibitor Treatment in Heart Failure with Reduced Ejection Fraction.

Sacubitril/valsartan has been shown to reduce hospital admissions and even mortality for heart failure. In heart failure and acute coronary syndrome, the effects of sacubitril/valsartan have been studied, but the effect on coronary artery flow is not known. We aimed to understand the effect of sacubitril/valsartan on coronary artery flow by using echocardiographic coronary flow reserve (CFR). Thirty-six patients (17 ischemic and 19 non-ischemic) with heart failure with reduced ejection fraction (EF of < 40%) eligible for sacubitril/valsartan treatment and 21 normal controls were recruited. The study group and controls were similar with regard to gender, smoking status, and age distribution (p = 0.874, p = 0.709, and p = 0.765, respectively). Blood pressure, heart rate, 6-minute walk test (6MWT), N terminal pro B type natriuretic peptide (NT-pro-BNP) level, standard echocardiography, from where left anterior descending mid-distal flow was seen, baseline peak diastolic flow rate and 2 minutes after dipyridamole infusion, and hyperemic peak diastolic flow rate were measured, and CFR with echocardiography was assessed prior to and at 6 months after sacubitril/valsartan initiation. Baseline peak diastolic flow rate did not exhibit a significant difference at 6 months (p = 0.143), but hyperemic peak diastolic flow rate, CFR, EF (%), and 6MWD values were significantly increased (all p < 0.001), and New York Heart Association Functional Class, NT-pro-BNP (pg/mL), left ventricule end diastolic diameter (mm), and left ventricule end systolic diameter (mm) values were significantly decreased (all p < 0.001) after sacubitril/valsartan treatment. Sacubitril/valsartan significantly alters coronary blood flow, especially its dynamic features, in patients with heart failure with reduced ejection fraction.

Relation between impaired coronary microvascular circulation and plasma atherogenic index in patients with ankylosing spondylitis

Aim: The coronary flow reserve (CFR) is a sign of endothelial dysfunction and early-stage coronary artery disease (CAD). Plasma atherogenic index (PAI) is related to subclinical CAD and may be used as a predictor of cardiovascular mortality. Our aim is to determine CFR and PAI in patients with AS and to investigate whether PAI can be used in the detection of early stage CAD.&#x0D; Methods: The study population comprised 48 patients, who were diagnosed with AS based on modified New York criteria and 35 healthy volunteers. PAI values were calculated with the formula log 10 triglyceride (TG) / high-density lipoprotein (HDL).&#x0D; Results: No difference was detected between the two groups for the demographic variables, including age, sex and BMI. The comparison of the groups for PAI and CFR demonstrated that PAI levels were observed to be significantly higher and CFR levels were observed to be significantly lower in the AS patients (p=0.01, p

Myocardial perfusion segmentation and partitioning methods in personalized models of coronary blood flow

Abstract In this work we present methods and algorithms for construction of a personalized model of coronary haemodynamics based on computed tomography images. This model provides estimations of fractional flow reserve, coronary flow reserve, and instantaneous wave-free ratio taking into account transmural perfusion ratio indices obtained from perfusion images. The presented pipeline consists of the following steps: aorta segmentation, left ventricle wall segmentation, coronary arteries segmentation, construction of 1D network of vessels, partitioning of left ventricle wall, and personalization of the model parameters. We focus on a new technique, which generates specific perfusion zones and computes transmural perfusion ratio according to the quality of available medical images with a limited number of visible terminal coronary vessels. Numerical experiments show that accurate evaluation of stenosis before precutaneous coronary intervention should take into account both fractional flow reserve indices and myocardial perfusion, as well as other indices, in order to avoid misdiagnosis. The presented model provides better understanding of the background of clinical recommendations for possible surgical treatment of a stenosed coronary artery.

Coronary physiology thresholds associated with microvascular obstruction in myocardial infarction

ObjectivesTo ascertain whether invasive assessment of coronary physiology soon after recanalisation of the culprit artery by primary percutaneous coronary intervention is associated with the development of microvascular obstruction by cardiac...

Performance of a novel artificial intelligence software developed to derive coronary fractional flow reserve values from diagnostic angiograms.

Although invasive measurement of fractional flow reserve (FFR) is recommended to guide revascularization, its routine use is underutilized. Recently, a novel non-invasive software that can instantaneously produce FFR values from the diagnostic angiograms, derived completely from artificial intelligence (AI) algorithms has been developed. We aim to assess the accuracy and diagnostic performance of AI-FFR in a real-world retrospective study. Retrospective, three-center study comparing AI-FFR values with invasive pressure wire-derived FFR obtained in patients undergoing routine diagnostic angiography. The accuracy, sensitivity, and specificity of AI-FFR were analyzed. A total of 304 vessels from 297 patients were included. Mean invasive FFR was 0.86 vs. 0.85 AI-FFR (mean difference: -0.005, P = 0.159). The diagnostic performance of AI-FFR demonstrated sensitivity of 91%, specificity 95%, positive predictive value 83% and negative predictive value 97%. Overall accuracy was 94% and the area under curve was 0.93 (95% CI 0.88-0.97). 105 lesions fell around the cutoff value (FFR = 0.75-0.85); in this sub-group, AI-FFR demonstrated sensitivity of 95%, and specificity 94%, with an AUC of 0.94 (95% CI 88.2-98.0). AI-FFR calculation time was 37.5 ± 7.4 s for each angiographic video. In 89% of cases, the software located the target lesion and in 11%, the operator manually marked the target lesion. AI-FFR calculated by an AI-based, angio-derived method, demonstrated excellent diagnostic performance against invasive FFR. AI-FFR calculation was fast with high reproducibility.

The Relationship between Coronary Flow Reserve and the TyG Index in Patients with Gestational Diabetes Mellitus.

Background and Objectives: Gestational diabetes mellitus (GDM) is a prevalent metabolic disorder characterized by glucose intolerance during pregnancy. The triglyceride glucose (TyG) index, a marker of insulin resistance, and coronary flow reserve (CFR), a measure of coronary microvascular function, are emerging as potential indicators of cardiovascular risk. This study aims to investigate the association between CFR and the TyG index in GDM patients. Materials and Methods: This cross-sectional study of 87 GDM patients and 36 healthy controls was conducted. The participants underwent clinical assessments, blood tests, and echocardiographic evaluations. The TyG index was calculated as ln(triglycerides × fasting glucose/2). CFR was measured using Doppler echocardiography during rest and hyperemia induced by dipyridamole. Results: The study included 87 individuals in the GDM group and 36 individuals in the control group. There was no significant difference in age between the two groups (34.1 ± 5.3 years for GDM vs. 33.1 ± 4.9 years for the control, p = 0.364). The TyG index was significantly higher in the GDM group compared to the controls (p < 0.001). CFR was lower in the GDM group (p < 0.001). A negative correlation between the TyG index and CFR was observed (r = -0.624, p < 0.001). Linear regression revealed the TyG index as an independent predictor of reduced CFR. Conclusions: The study findings reveal a significant association between the TyG index and CFR in GDM patients, suggesting their potential role in assessing cardiovascular risk.