The role of myocardial blood volume in the pathophysiology of angina with non-obstructed coronary arteries: The MICORDIS study.

BACKGROUND: Angina with Non-Obstructed Coronary Arteries (ANOCA) involves abnormal vasomotor responses. While reduced coronary flow is an established contributor to myocardial hypoxia, myocardial blood volume (MBV) independently regulates myocardial oxygen uptake but its role in ANOCA remains unclear. OBJECTIVES: We hypothesized that reduced MBV contributes to ANOCA, and associates with insulin resistance in ANOCA. METHODS: MBV in ANOCA patients was compared to age- and sex-matched healthy controls. ANOCA patients underwent coronary angiography with invasive coronary function testing (CFT) to identify vasospasm and coronary microvascular dysfunction. In all subjects MBV was quantified at baseline, during hyperinsulinemia and during dobutamine-induced stress using myocardial contrast echocardiography (MCE). The hyperinsulinemic-euglycemic clamp was used to assess insulin resistance. RESULTS: Twenty-eight ANOCA patients (21% men, 56.8 ± 8.6 years) and 28 healthy controls (21% men, 56.5 ± 7.0 years) were included. During CFT 11% of patients showed epicardial vasospasm, 39% microvascular vasospasm, 25% coronary microvascular dysfunction, and 11% of patients had a negative CFT. ANOCA patients had significant lower insulin-sensitivity (p < 0.01). During MCE, ANOCA patients showed a significantly lower MBV at baseline (0.388 vs 0.438 mL/mL, p = 0.04), during hyperinsulinemia (0.395 vs 0.447 mL/mL, p = 0.02), and during dobutamine-induced stress (0.401 vs 0.476 mL/mL, p = 0.030). CONCLUSIONS: In ANOCA patients MBV is diminished at baseline, during hyperinsulinemia and dobutamine-induced stress in the absence of differences in microvascular recruitment. These findings support the presence of capillary rarefaction in ANOCA patients. ANOCA patients showed metabolic insulin resistance, but insulin did not acutely alter myocardial perfusion.

Relationship between peripheral and intracoronary blood flow in patients with angina and non-obstructive coronary arteries.

Background: Coronary vasomotor dysfunction, an important underlying cause of angina and non-obstructive coronary arteries (ANOCA), encompassing coronary vasospasm, coronary endothelial dysfunction and/or coronary microvascular dysfunction, is clinically assessed by invasive coronary function testing (ICFT). As ICFT imposes a high burden on patients and carries risks, developing non-invasive alternatives is important. We evaluated whether coronary vasomotor dysfunction is a component of systemic microvascular endothelial and smooth muscle dysfunction, and can be detected using laser speckle contrast analysis (LASCA). Methods: Forty-three consecutive ANOCA patients underwent ICFT, with intracoronary acetylcholine, adenosine, and flow measurements, to assess coronary vasomotor dysfunction. Cutaneous microvascular function was assessed using LASCA, combined with vasodilators acetylcholine, sodium-nitroprusside and insulin and using EndoPAT, by measuring the reactive hyperemia index (RHI). Results: Of the 43 included ANOCA patients (79% women, 59±9 years), 38 patients had coronary vasomotor dysfunction, including 28 with coronary vasospasm, 26 with coronary endothelial dysfunction and 18 with coronary microvascular dysfunction, with overlapping endotypes. Patients with and without coronary vasomotor dysfunction had similar peripheral flow responses to acetylcholine, insulin, and RHI. In contrast, coronary vasomotor dysfunction was associated with lower peripheral flow responses to sodium-nitroprusside (p<0.001). An absolute flow response to sodium-nitroprusside of 83.95APU resulted in 86.1% sensitivity and 80.0% specificity for coronary vasomotor dysfunction (area under the ROC curve: 0.883; p=0.006). Conclusions: This study provides evidence of a systemic vascular smooth muscle dysfunction in ANOCA patients with coronary vasomotor dysfunction, and diagnostic value of peripheral microvascular function testing as non-invasive tool for detecting coronary vasomotor dysfunction.

Digital consults in heart failure care: a randomized controlled trial.

Guideline-directed medical therapy (GDMT) has clear benefits on morbidity and mortality in patients with heart failure; however, GDMT use remains low. In the multicenter, open-label, investigator-initiated ADMINISTER trial, patients (n = 150) diagnosed with heart failure and reduced ejection fraction (HFrEF) were randomized (1:1) to receive usual care or a strategy using digital consults (DCs). DCs contained (1) digital data sharing from patient to clinician (pharmacotherapy use, home-measured vital signs and Kansas City Cardiomyopathy Questionnaires); (2) patient education via a text-based e-learning; and (3) guideline recommendations to all treating clinicians. All remotely gathered information was processed into a digital summary that was available to clinicians in the electronic health record before every consult. All patient interactions were standardly conducted remotely. The primary endpoint was change in GDMT score over 12 weeks (ΔGDMT); this GDMT score directly incorporated all non-conditional class 1 indications for HFrEF therapy with equal weights. The ADMINISTER trial met its primary outcome of achieving a higher GDMT in the DC group after a follow-up of 12 weeks (ΔGDMT score in the DC group: median 1.19, interquartile range (0.25, 2.3) arbitrary units versus 0.08 (0.00, 1.00) in usual care; P < 0.001). To our knowledge, this is the first multicenter randomized controlled trial that proves a DC strategy is effective to achieve GDMT optimization. ClinicalTrials.gov registration: NCT05413447 .

Explainable machine learning using echocardiography to improve risk prediction in patients with chronic coronary syndrome.

Aims: The European Society of Cardiology guidelines recommend risk stratification with limited clinical parameters such as left ventricular (LV) function in patients with chronic coronary syndrome (CCS). Machine learning (ML) methods enable an analysis of complex datasets including transthoracic echocardiography (TTE) studies. We aimed to evaluate the accuracy of ML using clinical and TTE data to predict all-cause 5-year mortality in patients with CCS and to compare its performance with traditional risk stratification scores. Methods and results: Data of consecutive patients with CCS were retrospectively collected if they attended the outpatient clinic of Amsterdam UMC location AMC between 2015 and 2017 and had a TTE assessment of the LV function. An eXtreme Gradient Boosting (XGBoost) model was trained to predict all-cause 5-year mortality. The performance of this ML model was evaluated using data from the Amsterdam UMC location VUmc and compared with the reference standard of traditional risk scores. A total of 1253 patients (775 training set and 478 testing set) were included, of which 176 patients (105 training set and 71 testing set) died during the 5-year follow-up period. The ML model demonstrated a superior performance [area under the receiver operating characteristic curve (AUC) 0.79] compared with traditional risk stratification tools (AUC 0.62-0.76) and showed good external performance. The most important TTE risk predictors included in the ML model were LV dysfunction and significant tricuspid regurgitation. Conclusion: This study demonstrates that an explainable ML model using TTE and clinical data can accurately identify high-risk CCS patients, with a prognostic value superior to traditional risk scores.

Digital Solutions to Optimize Guideline-Directed Medical Therapy Prescriptions in Heart Failure Patients: Current Applications and Future Directions.

PURPOSEOF REVIEW: Guideline-directed medical therapy (GDMT) underuse is common in heart failure (HF) patients. Digital solutions have the potential to support medical professionals to optimize GDMT prescriptions in a growing HF population. We aimed to review current literature on the effectiveness of digital solutions on optimization of GDMT prescriptions in patients with HF. RECENT FINDINGS: We report on the efficacy, characteristics of the study, and population of published digital solutions for GDMT optimization. The following digital solutions are discussed: teleconsultation, telemonitoring, cardiac implantable electronic devices, clinical decision support embedded within electronic health records, and multifaceted interventions. Effect of digital solutions is reported in dedicated studies, retrospective studies, or larger studies with another focus that also commented on GDMT use. Overall, we see more studies on digital solutions that report a significant increase in GDMT use. However, there is a large heterogeneity in study design, outcomes used, and populations studied, which hampers comparison of the different digital solutions. Barriers, facilitators, study designs, and future directions are discussed. There remains a need for well-designed evaluation studies to determine safety and effectiveness of digital solutions for GDMT optimization in patients with HF. Based on this review, measuring and controlling vital signs in telemedicine studies should be encouraged, professionals should be actively alerted about suboptimal GDMT, the researchers should consider employing multifaceted digital solutions to optimize effectiveness, and use study designs that fit the unique sociotechnical aspects of digital solutions. Future directions are expected to include artificial intelligence solutions to handle larger datasets and relieve medical professional's workload.

Comparison of the Diagnostic Yield of Intracoronary Acetylcholine Infusion and Acetylcholine Bolus Injection Protocols During Invasive Coronary Function Testing.

Coronary endothelial dysfunction (CED) and coronary artery spasm (CAS) are causes of angina with no obstructive coronary arteries in patients. Both can be diagnosed by invasive coronary function testing (ICFT) using acetylcholine (ACh). This study aimed to evaluate the diagnostic yield of a 3-minute ACh infusion as compared with a 1-minute ACh bolus injection protocol in testing CED and CAS. We evaluated 220 consecutive patients with angina and no obstructive coronary arteries who underwent ICFT using continuous Doppler flow measurements. Per protocol, 110 patients were tested using 3-minute infusion, and thereafter 110 patients using 1-minute bolus injections, because of a protocol change. CED was defined as a <50% increase in coronary blood flow or any epicardial vasoconstriction in reaction to low-dose ACh and CAS according to the Coronary Vasomotor Disorders International Study Group (COVADIS) criteria, both with and without T-wave abnormalities, in reaction to high dose ACh. The prevalence of CED was equal in both protocols (78% vs 79%, p = 0.869). Regarding the endotypes of CAS according to COVADIS, the equivocal endotype was diagnosed less often in the 3 vs 1-minute protocol (24% vs 44%, p = 0.004). Including T-wave abnormalities in the COVADIS criteria resulted in a similar diagnostic yield of both protocols. Hemodynamic changes from baseline to the low or high ACh doses were comparable between the protocols for each endotype. In conclusion, ICFT using 3-minute infusion or 1-minute bolus injections of ACh showed a similar diagnostic yield of CED. When using the COVADIS criteria, a difference in the equivocal diagnosis was observed. Including T-wave abnormalities as a diagnostic criterion reclassified equivocal test results into CAS and decreased this difference. For clinical practice, we recommend the inclusion of T-wave abnormalities as a diagnostic criterion for CAS and the 1-minute bolus protocol for practicality.

Impact of sex on the assessment of the microvascular resistance reserve.

BACKGROUND: The microvascular resistance reserve (MRR) is an innovative index to assess the vasodilatory capacity of the coronary circulation while accounting for the presence of concomitant epicardial disease. The MRR has shown to be a valuable diagnostic and prognostic tool in the general coronary artery disease (CAD) population. However, considering the fundamental aspects of its assessment and the unique hemodynamic characteristics of women, it is crucial to provide additional considerations for evaluating the MRR specifically in women. AIM: The aim of this study was to assess the diagnostic and prognostic applicability of the MRR in women and assess the potential differences across different sexes. METHODS: From the ILIAS Registry, we enrolled all patients with a stable indication for invasive coronary angiography, ensuring complete physiological and follow-up data. We analyzed the diagnostic value by comparing differences between sexes and evaluated the prognostic value of the MRR specifically in women, comparing it to that in men. RESULTS: A total of 1494 patients were included of which 26% were women. The correlation between MRR and CFR was good and similar between women (r = 0.80, p < 0.005) and men (r = 0.81, p < 0.005). The MRR was an independent and important predictor of MACE in both women (HR 0.67, 0.47-0.96, p = 0.027) and men (HR 0.84, 0.74-0.95, p = 0.007). The optimal cut-off value for MRR in women was 2.8 and 3.2 in men. An abnormal MRR similarly predicted MACE at 5-year follow-up in both women and men. CONCLUSION: The MRR seems to be equally applicable in both women and men with stable coronary artery disease.

Digital consults to optimize guideline-directed therapy: design of a pragmatic multicenter randomized controlled trial.

AIMS: Many heart failure (HF) patients do not receive optimal guideline-directed medical therapy (GDMT) despite clear benefit on morbidity and mortality outcomes. Digital consults (DCs) have the potential to improve efficiency on GDMT optimization to serve the growing HF population. The investigator-initiated ADMINISTER trial was designed as a pragmatic multicenter randomized controlled open-label trial to evaluate efficacy and safety of DC in patients on HF treatment. METHODS AND RESULTS: Patients (n = 150) diagnosed with HF with a reduced ejection fraction will be randomized to DC or standard care (1:1). The intervention group receives multifaceted DCs including (i) digital data sharing (e.g. exchange of pharmacotherapy use and home-measured vital signs), (ii) patient education via an e-learning, and (iii) digital guideline recommendations to treating clinicians. The consults are performed remotely unless there is an indication to perform the consult physically. The primary outcome is the GDMT prescription rate score, and secondary outcomes include time till full GDMT optimization, patient and clinician satisfaction, time spent on healthcare, and Kansas City Cardiomyopathy Questionnaire. Results will be reported in accordance to the CONSORT statement. CONCLUSIONS: The ADMINISTER trial will offer the first randomized controlled data on GDMT prescription rates, time till full GDMT optimization, time spent on healthcare, quality of life, and patient and clinician satisfaction of the multifaceted patient- and clinician-targeted DC for GDMT optimization.

Prognostic Implications of Individual and Combinations of Resting and Hyperemic Coronary Pressure and Flow Parameters.

Background: Coronary pressure- and flow-derived parameters have prognostic value. Objectives: This study aims to investigate the individual and combined prognostic relevance of pressure and flow parameters reflecting resting and hyperemic conditions. Methods: A total of 1,971 vessels deferred from revascularization after invasive pressure and flow assessment were included from the international multicenter registry. Abnormal resting pressure and flow were defined as distal coronary pressure/aortic pressure ≤0.92 and high resting flow (1/resting mean transit time >2.4 or resting average peak flow >22.7 cm/s), and abnormal hyperemic pressure and flow as fractional flow reserve ≤0.80 and low hyperemic flow (1/hyperemic mean transit time <2.2 or hyperemic average peak flow <25.0 cm/s), respectively. The clinical endpoint was target vessel failure (TVF), myocardial infarction (MI), or cardiac death at 5 years. Results: The mean % diameter stenosis was 46.8% ± 16.5%. Abnormal pressure and flow were independent predictors of TVF and cardiac death/MI (all P < 0.05). The risk of 5-year TVF or MI/cardiac death increased proportionally with neither, either, and both abnormal resting pressure and flow, and abnormal hyperemic pressure and flow (all P for trend < 0.001). Abnormal resting pressure and flow were associated with a higher rate of TVF or MI/cardiac death in vessels with normal fractional flow reserve; this association was similar for abnormal hyperemic pressure and flow in vessels with normal resting distal coronary pressure/aortic pressure (all P < 0.05). Conclusions: Abnormal resting and hyperemic pressure and flow were independent prognostic predictors. The abnormal flow had an additive prognostic value for pressure in both resting and hyperemic conditions with complementary prognostic between resting and hyperemic parameters.

The impact of valvular heart disease in patients with chronic coronary syndrome.

Background: The European Society of Cardiology 2019 Guidelines on chronic coronary syndrome (CCS) recommend echocardiographic measurement of the left ventricular function for risk stratification in all patients with CCS. Whereas CCS and valvular heart disease (VHD) share common pathophysiological pathways and risk factors, data on the impact of VHD in CCS patients are scarce. Methods: Clinical data including treatment and mortality of patients diagnosed with CCS who underwent comprehensive transthoracic echocardiography (TTE) in two tertiary centers were collected. The outcome was all-cause mortality. Data were analyzed with Kaplan-Meier curves and Cox proportional hazard analysis adjusting for significant covariables and time-dependent treatment. Results: Between 2014 and 2021 a total of 1,984 patients with CCS (59% men) with a median age of 65 years (interquartile range [IQR] 57-73) underwent comprehensive TTE. Severe VHD was present in 44 patients and moderate VHD in 325 patients. A total of 654 patients (33%) were treated with revascularization, 39 patients (2%) received valve repair or replacement and 299 patients (15%) died during the median follow-up time of 3.5 years (IQR 1.7-5.6). Moderate or severe VHD (hazard ratio = 1.33; 95% CI 1.02-1.72) was significantly associated with mortality risk, independent of LV function and other covariables, as compared to no/mild VHD. Conclusions: VHD has a significant impact on mortality in patients with CCS additional to LV dysfunction, which emphasizes the need for a comprehensive echocardiographic assessment in these patients.

Sex differences in prevalence and outcomes of the different endotypes of chronic coronary syndrome in symptomatic patients undergoing invasive coronary angiography: Insights from the global ILIAS invasive coronary physiology registry.

BACKGROUND AND AIMS: The management of chronic coronary syndrome (CCS) is informed by studies predominantly including men. This study investigated the relationship between patients sex and different endotypes of CCS, including sex-specific clinical outcomes. METHODS: In patients with CCS undergoing coronary angiography, invasive Fractional Flow Reserve (FFR) and Coronary Flow Reserve (CFR) were measured. Patients were stratified into groups: 1) obstructive coronary artery disease (oCAD) (FFR≤0.80, no revascularization), 2) undergoing revascularization, 3) non-obstructive coronary artery disease with coronary microvascular dysfunction (CMD) (FFR>0.80, CFR≤2.5), and 4) non-obstructive coronary artery disease without CMD (FFR>0.80 and CFR>2.5). RESULTS: 1836 patients (2335 vessels) were included, comprising 1359 (74.0%) men and 477 (26.0%) women. oCAD was present in 14.1% and was significantly less prevalent in women than in men (10.3% vs 15.5%, respectively p < 0.01). Revascularization was present in 30.9% and was similarly prevalent in women and men (28.2% vs. 31.9%, respectively p = 0.13). CMD was present in 24.2% and was significantly more prevalent in women than men (28.6% vs 22.6%, respectively p < 0.01). Normal invasive measurements were found in 564 patients (33.0% women vs 30.0% men, p = 0.23). Male sex was associated with an increased risk of target vessel failure compared to women (HR.1.89, 95% CI 1.12-3.18, p = 0.018), regardless of CCS-endotype. CONCLUSIONS: Sex differences exist in the prevalence and outcomes of different endotypes of CCS in symptomatic patients undergoing invasive coronary angiography. In particular, oCAD (and subsequent revascularization) were more prevalent in men. Conversely, CMD was more prevalent in women. Overall, men experienced a worse cardiovascular outcome compared to women, independent of any specific CCS endotype.

Changes in microvascular resistance following percutaneous coronary intervention - From the ILIAS global registry.

BACKGROUND: Microvascular resistance (MR) has prognostic value in acute and chronic coronary syndromes following percutaneous coronary intervention (PCI), however anatomic and physiologic determinants of the relative changes of MR and its association to target vessel failure (TVF) has not been investigated previously. This study aims to evaluate the association between changes in MR and TVF. METHODS: This is a sub-study of the Inclusive Invasive Physiological Assessment in Angina Syndromes (ILIAS) registry which is a global multi-centre initiative pooling lesion-level coronary pressure and flow data. RESULTS: Paired pre-post PCI haemodynamic data were available in n = 295 vessels out of n = 828 PCI treated patients and of these paired data on MR was present in n = 155 vessels. Vessels were divided according to increase vs. decrease % in microvascular resistance following PCI (ΔMR % ≤ 0 vs. ΔMR > 0%). Decreased microvascular resistance ΔMR % ≤ 0 occurred in vessels with lower pre-PCI fractional flow reserve (0.67 ± 0.15 vs. 0.72 ± 0.09 p = 0.051), coronary flow reserve (1.9 ± 0.8 vs. 2.6 ± 1.8 p < 0.0001) and higher hyperemic microvascular resistance (2.76 ± 1.3 vs. 1.62 ± 0.74 p = 0.001) and index of microvascular resistance (24.4 IQ (13.8) vs. 15. 8 IQ (13.2) p = 0.004). There was no difference in angiographic parameters between ΔMR % ≤ 0 vs. ΔMR > 0%. In a cox regression model ΔMR % > 0 was associated with increased rate of TVF (hazard ratio 95% CI 3.6 [1.2; 10.3] p = 0.018). CONCLUSION: Increased MR post-PCI was associated with lesions of less severe hemodynamic influence at baseline and higher rates of TVF at follow-up.

The role and implications of left atrial fibrosis in surgical mitral valve repair as assessed by CMR: the ALIVE study design and rationale.

Background: Patients with mitral regurgitation (MR) commonly suffer from left atrial (LA) remodeling. LA fibrosis is considered to be a key player in the LA remodeling process, as observed in atrial fibrillation (AF) patients. Literature on the presence and extent of LA fibrosis in MR patients however, is scarce and its clinical implications remain unknown. Therefore, the ALIVE trial was designed to investigate the presence of LA remodeling including LA fibrosis in MR patients prior to and after mitral valve repair (MVR) surgery. Methods: The ALIVE trial is a single center, prospective pilot study investigating LA fibrosis in patients suffering from MR in the absence of AF (identifier NCT05345730). In total, 20 participants will undergo a CMR scan including 3D late gadolinium enhancement (LGE) imaging 2 week prior to MVR surgery and at 3 months follow-up. The primary objective of the ALIVE trial is to assess the extent and geometric distribution of LA fibrosis in MR patients and to determine effects of MVR surgery on reversed atrial remodelling. Implications: This study will provide novel insights into the pathophysiological mechanism of fibrotic and volumetric atrial (reversed) remodeling in MR patients undergoing MVR surgery. Our results may contribute to improved clinical decision making and patient-specific treatment strategies in patients suffering from MR.

Effect of allogeneic adipose tissue-derived mesenchymal stromal cell treatment in chronic ischaemic heart failure with reduced ejection fraction - the SCIENCE trial.

AIMS: The aim of the SCIENCE trial was to investigate whether a single treatment with direct intramyocardial injections of adipose tissue-derived mesenchymal stromal cells (CSCC_ASCs) was safe and improved cardiac function in patients with chronic ischaemic heart failure with reduced ejection fraction (HFrEF). METHODS AND RESULTS: The study was a European multicentre, double-blind, placebo-controlled phase II trial using allogeneic CSCC_ASCs from healthy donors or placebo (2:1 randomization). Main inclusion criteria were New York Heart Association (NYHA) class II-III, left ventricular ejection fraction (LVEF) <45%, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels >300 pg/ml. CSCC_ASCs or placebo (isotonic saline) were injected directly into viable myocardium. The primary endpoint was change in left ventricular end-systolic volume (LVESV) at 6-month follow-up measured by echocardiography. A total of 133 symptomatic HFrEF patients were included. The treatment was safe without any drug-related severe adverse events or difference in cardiac-related adverse events during a 3-year follow-up period. There were no significant differences between groups during follow-up in LVESV (0.3 ± 5.0 ml, p = 0.945), nor in secondary endpoints of left ventricular end-diastolic volume (-2.0 ± 6.0 ml, p = 0.736) and LVEF (-1.6 ± 1.0%, p = 0.119). The NYHA class improved slightly within the first year in both groups without any difference between groups. There were no changes in 6-min walk test, NT-proBNP, C-reactive protein or quality of life the first year in any groups. CONCLUSION: The SCIENCE trial demonstrated safety of intramyocardial allogeneic CSCC_ASC therapy in patients with chronic HFrEF. However, it was not possible to improve the pre-defined endpoints and induce restoration of cardiac function or clinical symptoms.

Combined use of hyperemic and non-hyperemic pressure ratios for revascularization decision-making: From the ILIAS registry.

OBJECTIVE: The aim of this study is to evaluate the diagnostic and prognostic value of non-hyperaemic Pd/Pa and to determine its additional value when combined with the gold standard hyperaemic pressure ratio (FFR) to guide revascularization. METHODS: In a large, multi-center, retrospective registry, we included a total of 2141 patients with a clinical indication for coronary angiography providing physiological data in 2726 vessels. A classification was made based on the FFR (cut-off value: 0.80) and non-hyperaemic Pd/Pa (cut-off value: 0.92) values and the primary outcome was target-vessel failure (TVF) at 5-year follow-up. RESULTS: Mean age was 63 ± 10.0 and 75% of the study population were men. Regression analysis showed an overall good correlation between FFR and non-hyperaemic Pd/Pa (r = 0.73, p < 0.005) and discordance was present in 17% of the vessels. Resting Pd/Pa was independently associated with TVF at 5-year follow-up (HR 0.08, 95%CI: 0.02-0.27; p < 0.005). The risk for TVF was the lowest in vessles with concordant normal pressure ratio's, with the highest risk in vessels with any abnormal pressure ratio in which revascularization was deferred. In these vessels, there was no difference in risk for TVF between the discordant and concordant abnormal values. CONCLUSION: Abnormal pressure ratios in both non-hyperemic and hyperemic conditions portend important prognostic value. Combined application of FFR and non-hyperemic Pd/Pa efficiently identifies those vessels with concordant normal resting and hyperemic pressure ratios of which long-term clinical outcomes are excellent. These data lead to hypothesize that the decision to defer revascularization should potentially be based on combined non-hyperemic and hyperemic pressure ratios. CLINICAL TRIAL REGISTRATION: Inclusive Invasive Physiological Assessment in Angina Syndromes Registry (ILIAS Registry), NCT04485234.

Infective endocarditis in developing countries: An update.

Introduction: Despite advances in diagnostic and treatment, morbidity and mortality due to infective endocarditis (IE) has not decreased. There is a discrepancy in epidemiology of IE between developed and developing countries. Over the last years, increased early detection and consequently prevalence of rheumatic heart disease (RHD) and congenital heart disease (CHD) which are considered predisposing conditions for IE, is noted. Here, we present a review of literature on IE in developing countries. Methods: We conducted a systematic literature search of IE studies in developing countries through PubMed and Embase. We have divided the studies into two groups: studies published before 2015 (group 1) and studies ≥ 2015 (group 2). The outcome was defined as a difference in epidemiology, microbiology, treatment, and mortality over time. The Scale for Assessment of Narrative Review Articles guidelines was applied. Findings: In total, 16 studies were included. The total number of IE cases was 1,098 and 1,505 in groups 1 and 2, respectively. We compared 4/7 cohorts from group 1 (n = 789) with 5/9 cohorts from group 2 (n = 636). Six studies were not included in the comparison because they were interacting between the two cohorts. Males predominated in all studies. Rheumatic heart disease was higher in group 1 than in group 2 (42.3% vs. 30.3%, p < 0.001) while for CHD there was no change (17.6% vs. 16.7%, p = 0.672). Streptococci infections was lower in group 1 than group 2 (26.2% vs. 37.7%, p < 0.001). The proportion of Staphylococcus aureus was 15.3% in group 1 and 23.6% in group 2, p < 0.001. Negative blood culture (NBC) was higher in group 1 than in group 2 (42.2% vs. 34.1%, p = 0.002). Patients in group 1 received more surgery than in group 2 (38.8% vs. 28.8%, p < 0.001). Mortality was similar in the two groups (20.9% vs. 22.3%, p = 0.518). Conclusion: This review shows a scarcity of studies on IE in developing countries. Rheumatic heart disease and congenital heart disease are common predisposing conditions. Other risk factors are prosthetic valves, degenerative valve disease (DVD), intravenous drug use, and human immunodeficiency virus infection. While the proportion of IE cases caused by Streptococcus and Staphylococcus has increased, the number of NBC and patients getting surgery has decreased. Mortality has not changed over time. Timely diagnosis and management of patients with RHD and CHD and comprehensive management of IE are warranted.

Metabolic Maturation Increases Susceptibility to Hypoxia-induced Damage in Human iPSC-derived Cardiomyocytes.

The development of new cardioprotective approaches using in vivo models of ischemic heart disease remains challenging as differences in cardiac physiology, phenotype, and disease progression between humans and animals influence model validity and prognostic value. Furthermore, economical and ethical considerations have to be taken into account, especially when using large animal models with relevance for conducting preclinical studies. The development of human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) has opened new opportunities for in vitro studies on cardioprotective compounds. However, the immature cellular phenotype of iPSC-CMs remains a roadblock for disease modeling. Here, we show that metabolic maturation renders the susceptibility of iPSC-CMs to hypoxia further toward a clinically representative phenotype. iPSC-CMs cultured in a conventional medium did not show significant cell death after exposure to hypoxia. In contrast, metabolically matured (MM) iPSC-CMs showed inhibited mitochondrial respiration after exposure to hypoxia and increased cell death upon increased durations of hypoxia. Furthermore, we confirmed the applicability of MM iPSC-CMs for in vitro studies of hypoxic damage by validating the known cardioprotective effect of necroptosis inhibitor necrostatin-1. Our results provide important steps to improving and developing valid and predictive human in vitro models of ischemic heart disease.

Prognostic Impact of Coronary Flow Reserve in Patients With Reduced Left Ventricular Ejection Fraction.

Background Intracoronary physiologic indexes such as coronary flow reserve (CFR) and left ventricular ejection fraction (LVEF) have been regarded as prognostic indicators in patients with coronary artery disease. The current study evaluated the association between intracoronary physiologic indexes and LVEF and their differential prognostic implications in patients with coronary artery disease. Methods and Results A total of 1889 patients with 2492 vessels with available CFR and LVEF were selected from an international multicenter prospective registry. Baseline physiologic indexes were measured by thermodilution or Doppler methods and LVEF was recorded at the index procedure. The primary outcome was target vessel failure, which was a composite of cardiac death, target vessel myocardial infarction, or clinically driven target vessel revascularization over 5 years of follow-up. Patients with reduced LVEF <50% (162 patients [8.6%], 202 vessels [8.1%]) showed a similar degree of epicardial coronary artery disease but lower CFR values than those with preserved LVEF (2.4±1.2 versus 2.7±1.2, P<0.001), mainly driven by the increased resting coronary flow. Conversely, hyperemic coronary flow, fractional flow reserve, and the degree of microvascular dysfunction were similar between the 2 groups. Reduced CFR (≤2.0) was seen in 613 patients (32.5%) with 771 vessels (30.9%). Reduced CFR was an independent predictor for target vessel failure (hazard ratio, 2.081 [95% CI, 1.385-3.126], P<0.001), regardless of LVEF. Conclusions CFR was lower in patients with reduced LVEF because of increased resting coronary flow. Patients with reduced CFR showed a significantly higher risk of target vessel failure than did those with preserved CFR, regardless of LVEF. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04485234.