Myocardial Ischemia Research Articles

Abstract Mo052: Electrocardiographic behavior, arrhythmias, and mortality in two calcium management strategies (cytoplasmic and mitochondrial) in hearts under ischemia.

Background: The disruption of calcium homeostasis in ischemic hearts is determinant for triggering the arrhythmic phenomena and death. Interventions that act on calcium levels in cytoplasm and mitochondria might interrupt or minimize these outcomes. Trisulfate disaccharide (TD) acts by accelerating the sodium-calcium exchanger, decreasing cytosolic calcium levels. Ruthenium red (RuR) is a mitochondrial uniporter inhibitor that blocks calcium influx into mitochondria. Both agents can be useful in calcium overload elicited by myocardial ischemia (MI), modifying electrocardiographic (EKG) parameters that predict arrhythmia, arrhythmic phenomena, and cell death. Objectives: To compare the behavior of Tp-Te and QTc EKG intervals, arrhythmia rates, and mortality in ischemic hearts under the action of TD and RuR. Materials and Methods: Adult Wistar rats (n=24) were divided in 3 groups, i.e, Control: MI with no treatment (n=8), TD: MI treated with TD 0.2 mg/kg IV (n=8), and RuR:MI treated with RuR 1 mg/kg IV (n=8). Rats were monitored by EKG and submitted to surgical MI by ligation of anterior descending artery during 10 minutes followed by reperfusion thereafter. The Tp-Te and QT intervals were analyzed before and at 10 minutes of ischemia and 10 minutes after the onset of reperfusion. The incidence of arrhythmias and mortality were determined throughout the recording time. Results: The Tp-Te and QTc intervals increased during ischemia in all groups (Control, TD and RuR), which were normalized after 10 minutes reperfusion only in TD group. The observed arrhythmias (atrioventricular block, ventricular tachycardia, and torsade of pointes) had a higher incidence in the control group and the lower incidences, with statistically significant differences, were achieved in TD and RuR groups, whose incidence was similar in these both groups. Sustained arrhythmias led to a 50% mortality in the control group and 25% in RuR group. No mortality in TD group was observed. Conclusion: The strategy of decreasing cytosolic calcium levels by the action of TD has proved to be more effective than the blockade of mitochondrial calcium uptake by RuR, with further normalization of EKG parameters predictors of mortality, and absence of sustained arrhythmias and mortality, suggesting that the management of cytosolic calcium levels is more effective than only the management of mitochondrial calcium in MI model.

Abstract Tu145: Exploring Naltrindole’s hypercontracture attenuating effects during myocardial ischemia via a novel mechanism that produces cardioprotective effects in myocardial ischemia/reperfusion injury

Introduction: Previously, naltrindole (NTI) produced robust cardioprotective effects (e.g.~80% reduction of infarct size) in both ex-vivo (2.5-5µM) and in-vivo (3.75-7.5 mg/kg) rat myocardial ischemia-reperfusion (MIR) injury models. Additionally, we recently showed that NTI 100-200µM attenuated phorbol 12-myristate 13-acetate (PMA) induced polymorphonuclear leukocytes (PMNs) superoxide (SO) release by a novel mechanism of action (MOA) devoid of opioid receptors. Hypothesis: We hypothesize NTI’s novel MOA is a reduction of intracellular calcium (Ca 2+ ). Testing this hypothesis, we conducted isolated perfused MIR assays using KB-R7943(KB). KB is known to reduce intracellular Ca 2+ via inhibition of reverse mode Na + /Ca 2+ exchanger and, therefore, should attenuate myocardial ischemic hypercontracture, infarct size, and left ventricular end diastolic pressure (LVEDP). We predict that both NTI and KB will improve LVEDP and decrease infarct size compared to vehicle (dH 2 O) control and naloxone (NX) used as a negative control. Methods: Hearts were isolated from anesthetized male Sprague Dawley (SD) rats (~300g). We then infused NTI 1.25-5µM, KB 10-20µM, or NX 10µM for 5 min into perfused hearts, just prior to global I(30min)/R(45min). Cardiac left ventricular function was measured via a pressure transducer and infarct size using 1% triphenyltetrazolium chloride staining in the MIR assay. Data were analyzed using ANOVA and Fishers post-hoc analysis, with p<0.05 considered statistically significant. Results: MIR assay: NTI 5µM, 2.5µM, 1.25µM and KB 20 µM reduced infarct size (4.8±3%, n=5, p<0.05), (6.8±0.8%, n=6, p<0.05), (12.2±3%, n=5), and (2.9±2%, n=5, p<0.05) respectively compared to vehicle (14.1±2%, n=9) and NX 10µM controls (18±3%, n=3). NTI 5 µM and KB 20 µM had significantly improved LVEDP to (32.4±11%, n=5, p<0.05) and (22.8±4%, n=5, p<0.05) respectively compared to vehicle control (72.4±6%, n=9) and NX 10µM controls (54.2±8%, n=3) Conclusion: Both NTI (2.5µM, 5µM) and KB (20µM) reduced infarct size and improved LVEDP. The novel MOA of NTI may be mediated via a reduction in intracellular Ca 2+ during myocardial ischemia. The infarct reducing effect of NTI can benefit patients undergoing elective PCI, CABG, and transplant procedures.

Abstract Tu136: HIF-1α a novel therapeutic target to reduce Cardiac Ischemia Reperfusion Injury during AMI

Acute myocardial infarction (AMI) is a major cause of mortality worldwide. In preclinical models of AMI, using a trans-valvular pump (TVP) to reduce left ventricular (LV) workload for 30 minutes before reperfusion reduces infarct size by 50%. The mechanisms underlying the cardioprotective effect of LV unloading remain poorly understood. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive transcription factor that activates cardioprotective signaling pathways, improves cell survival and mitochondrial function during myocardial ischemia. We hypothesized that LV unloading limits myocardial injury by activating hypoxia inducible factor 1-a (HIF-1α). To explore the effect of LV unloading on HIF-1α stabilization during ischemia, we performed left anterior descending artery (LAD) occlusion for a total of 120 minutes in adult swine in the presence and absence of LV unloading and further 180 minutes of reperfusion was performed following 120 minutes of LAD occlusion. Trans-valvular unloading activation significantly decreased infarct size both during ischemia (IS/AAR: 4.78±4 % vs 1.5±3%) and post reperfusion when compared ischemia alone and IR alone groups (36.04±8.39 % vs 16.02±3.52 %, p<0.0001) respectively. Interestingly, HIF-1α stabilization is significantly reduced with LV unloading during ischemia and significantly increased post reperfusion in the infarct zone of the swine model of AMI. To test whether HIF1a is necessary for cardioprotection with LV unloading, adult swine were treated with intracoronary delivery of the HIF-1α inhibitor (2-methoxyestradiol; 2ME) before reperfusion. Compared to TVP activation for 30 minutes before reperfusion, addition of 2ME abolished the cardioprotective effect of TVP resulting in increased infarct size (16.03% vs 35.86% p<0.03) and decreased HIF-1a stabilization. Stabilizing HIF-1α post-reperfusion by using a well know HIF-1a stabilizing agent Roxadustat, immediately before reperfusion significantly decreased infarct size in both with and without TVP groups compared to IRI alone. Treatment with Roxadustat also preserved mitochondrial function and increased RISK signaling. We report the novel finding that stabilizing HIF-1a activity before reperfusion plays a critical role in reducing Infarct size in preclinical model of AMI.

The prognostic impact of unplanned invasive coronary angiography following coronary artery bypass grafting.

Myocardial ischaemia following coronary artery bypass grafting (CABG) is a potentially devastating complication. Nevertheless, the incidence, aetiology and prognostic relevance of unplanned coronary angiography (uCAG) remain understudied. We aimed to investigate the prevalence and outcome of patients undergoing urgent, uCAG in the postoperative period following CABG. We screened all patients undergoing isolated elective CABG in an academic referral centre between 2016 and 2021 and identified patients undergoing uCAG within 30 days of surgery. For uCAG patients, a distinction was made between patients undergoing re-revascularization (REV) and patients receiving conservative management (CON). The primary outcomes were 30-day mortality and unadjusted and adjusted long-term survival. Secondary outcomes were the indication for and prevalence of uCAG and urgent revascularization. Of the 1918 patients undergoing isolated CABG, 78 individuals needed uCAG (4.1%), of whom 45 underwent immediate revascularization (REV group; 2.3% overall, 57% within the uCAG group, median age 69.9 years) and 33 were treated conservatively (CONS group; 1.7% overall, 42% within the uCAG group, median age 69.1 years). Patients undergoing uCAG (n = 78) had a higher 30-day mortality than patients not undergoing uCAG (n = 1840, 30-day mortality: 9.0% vs 0.4%, P < 0.001). Long-term survival was significantly decreased in patients undergoing uCAG in both unadjusted (hazard ratio 2.20, 95% confidence interval 1.30-3.73) and EuroSCORE-, age- and sex-adjusted models (hazard ratio uCAG 2.03, 95% confidence interval 1.16-3.56). Unplanned postoperative coronary angiography is performed in 4.1% of isolated CABG procedures, and patients in need of such urgent invasive evaluation are subjected to decreased short- and long-term survival.

Abstract Mo106: Inhibition of microRNA-200c promotes regeneration of the ischemic injured myocardium through activation of developmental pathways

Ischemic injury and adverse post-infarction myocardial remodeling are major causes of heart failure worldwide. Strategies designed to offset cell death with cardiomyocyte regeneration have, to date, not translated to routine clinical practice. Mir-200c modulates the transcripts of cardiogenic transcription factors (TFs) Tbx5 , Gata4 , Mef2c to promote myocyte maturation. We hypothesized that inhibition of mir-200c activity would result in postnatal myocyte de-differentiation and replication sufficient to ameliorate post-infarction decompensation after ischemic injury. To test this hypothesis, we preformed left coronary ligation on Wild-Type (WT) and transgenic mice expressing an RNA inhibitor against miR-200c ( PMIS-C ). Echocardiographic left ventricular (LV) ejection fraction (EF) fell from 88.41 ± 1.08% (WT) and 90% ± 1.42% ( PMIS-C ) (p=NS) to 28% ± 11.55% (WT) and 36% ± 9.35% at 1 day post injury (DPI) (p =NS). At 21DPI, LVEF was 27% ± 4.31% (WT) and 64% ± 4.25% ( PMIS-C ) [p ≤ 0.0001]. Post-infarction LV chamber dilation was reversed in PMIS-C mice (1.136 ± 0.19 v 0.67 ± 0.06 p ≤ 0.004 LV Vol/mass). By 9 WPI, PMIS-C heart function within non-significantly levels of sham and function prior to injury. These results indicated that inhibiting miR-200c following ischemic injury can recover cardiac function and prevent LV dilation. Moreover, trichrome stain showed a decrease in fibrosis 3 WPI (WT: 57% ± 17.46 v PMIS-C : 12% ± 3.01 p ≤ 0.001) and 9 WPI. To understand the mechanism causing this phenomenon, we analyzed expression of cardiac progenitor markers. Fold change in expression of TFs Tbx5, Gata4, Mef2c, and Isl1 were increased at 1 and 3 DPI in PMIS-C . At 1 WPI, PMIS-C border zone CMs express markers of a “progenitor-like” cell state seen during cardiogenesis. Conclusions: Inhibiting miR-200c abrogates post-infarction LV remodeling and significantly restores LV systolic function. Ongoing studies are investigating the therapeutic use of PMIS-C through delivery via AAV and nanoparticles.

Abstract Mo033: Circulating Long Noncoding RNA Expression Signature Predicts Adverse Cardiovascular Outcomes in Patients with Coronary Artery Disease

Background: Patients with coronary artery disease (CAD) have increased risks of subsequent major adverse cardiovascular events (MACE). Currently, there are no reliable tools to predict recurrent MACE in CAD patients. Objective: To determine if circulating long noncoding RNA (lncRNA) expression signature predicts recurrent MACE in CAD patients. Methods: As part of the Taiwan Biosignature Study, this prospective nested case-control study included 168 CAD patients who experienced MACE during the follow-up and another 108 CAD patients who remained free of MACE after a≥24-month follow-up. Plasma lncRNAs were profiled to determine their prognostic values for MACE in CAD patients. Results: Initially, RNA sequencing in 59 CAD patients (41 with recurrent MACE) revealed that a total of 124 plasma lncRNAs were dysregulated in CAD patients with recurrent MACE. Subsequent analyses showed that the expression signature of these lncRNAs classified CAD patients with vs. without recurrent MACE with an accuracy of 93%. Elevated levels of plasma lnc-NCF1-1, BRE-AS1, lnc-ZFAT-6, lnc-SLC46A3-5, lnc-CXCL3-2 and lnc-EBF3-4 were associated with increased risks of recurrent MACE. Additional studies in the remaining 217 CAD patients (127 with recurrent MACE) validated that increased plasma levels of lnc- NCF1-1, BRE-AS1, lnc-ZFAT-6, and lnc-EBF3-4 were significant predictors of recurrent MACE. In addition, lnc-SCORE, an index calculated from MACE-associated plasma lncRNA levels, was shown to be a strong independent predictor (adjusted HR, 2.70 [95% CI 1.78-4.09]) of recurrent MACE in CAD patients. BRE-AS1 and lnc-ZFAT-6 , two endothelium-enriched MACE-associated lncRNAs, were specifically dysregulated in cardiomyopathy of ischemic, but not of non-ischemic, origin, suggesting their potential contribution to the development of myocardial ischemia. Moreover, knocking BRE-AS1 reversed hypoxia-induced upregulation of VCAM-1 in human aortic endothelial cells, suggesting its functional contribution to vascular inflammation upon ischemia. Conclusions: This study shows the prognostic roles of circulating lncRNAs in predicting recurrent MACE in CAD patients. Endothelium-enriched lncRNA BRE-AS1 is involved in ischemia-induced vascular inflammation.

Successful percutaneous coronary intervention in a congenital single right coronary artery with acute myocardial infarction: A case report and literature review.

Single coronary artery (SCA) is a rare coronary artery malformation. SCA combined with atherosclerotic plaques can cause severe and widespread myocardial ischemia and infarction, leading to hemodynamic instability and even sudden death. A 48-year-old Chinese man was admitted for treatment of persistent chest tightness and panic for 5 hours. The patient was a lorry driver with high work intensity and mental stress, with body mass index of 33.78, history of smoking and alcohol consumption, but no history of hypertension and diabetes. Admission examination showed Troponin was 183.083 µg/L and CK-MB value was >300 µg/L. The patient was diagnosed with a congenital single right coronary artery (RCA) with acute myocardial infarction (AMI) by coronary angiography (CAG). Due to atherosclerotic plaques rupture, a complete occlusion of the proximal RCA with thrombolysis in myocardial infarction grade 0 of distal blood flow were found. The patient was treated with thrombus aspiration and thrombolytic therapy by percutaneous coronary intervention under the support of intra-aortic balloon pump. Postoperative the chest tightness and panic were relieved, and CAG revealed that the proximal thrombus of the RCA was reduced, and distal blood flow was restored to thrombolysis in myocardial infarction grade 3. After 2 weeks of intensive antithrombotic and lipid-regulating drug therapy, the patient was successfully discharged. Follow-up for 6 months, the patient was able to live and work normally without experiencing chest tightness and chest pain. Computed tomography angiography (CTA) confirmed a congenital single RCA with patent lumen and no severe stenosis. The congenital single RCA is very rare, and it is fatal in conjunction with acute coronary syndrome. Early detection and appropriate treatment is critical for AMI patient with single RCA. CAG is the gold standard for diagnosis of single RCA, and CTA is a necessary to describe the anatomical course of abnormal coronary arteries.

Abstract Tu135: FYCO1 ameliorates cardiac remodeling in response to ischemia by amplifying autophagic flux

Background: Dysregulation of autophagy is known to have detrimental effects on cardiac remodeling. FYCO1, a novel regulator of autophagy mediates the transport of autophagosomes, thereby amplifying autophagic flux. Here, we investigate the impact of FYCO1 on myocardial healing via autophagy modulation. Methods: FYCO1-Tg mice crossed with RFP-EGFP-LC3 reporter mice (FYCO1-TGxRGFP) were utilized to analyze autophagic flux via confocal microscopy following permanent ligation of the left anterior descending artery (LAD) to induce myocardial ischemia. Autophagy activity was evaluated via Western blot of p62 and LC3 II. Macrophage infiltration and apoptosis was assessed by immunofluorescence microscopy, while Masson's Trichrome staining detected fibrosis and infarct size. Cardiac function was determined by echocardiography. Results: FYCO1-TGxRGFP mice displayed significantly enhanced autophagic flux post MI, as evidenced by increased p62 (WT LAD: 2,9±0,4; TG LAD:4,0±0,5) and LC3 II (WT LAD: 1,6±0,2; TG LAD:14,0±1,4) protein levels. Confocal microscopy revealed an accumulation of autolysosomes in WT mice 30 days post MI (WT autophagosomes: 1±0,4; WT autolysosomes: 38,6±3,8), contrasting with the sustained ratio of autophagosomes to autolysosomes in FYCO1-TGxRGFP mice (TG autophagosomes:43,3±5,1; TG autolysosomes: 73,5±12,4), implying the preservation of adequate autophagic flux. FYCO1 overexpression reduced macrophage infiltration into the border zone post MI (WT LAD: 132,4 ±14,3; TG LAD: 18,91±3,7 and inhibited apoptosis induction shown by cleaved caspase7 activity (WT LAD: 64,6±10,1; TG LAD: 9,2±2,1). Moreover, FYCO1-TGxRGFP mice exhibited significantly reduced fibrosis (WT:19,6±1,8%; TG:10,6±1,6%) and infarct size (WT:34,5 ±3,9%; TG:5,5±2%) in the left ventricle (LV), accompanied by marked improvements in global heart function post MI (EF WT: 32,7±3,2%; TG: 56,4±3,9%) compared to WT mice. Conclusion: In conclusion, FYCO1 mitigates adverse consequences of ischemic injury via induction of autophagy and a previously unrecognized role in modulating inflammation in response to myocardial infarction.

Abstract We037: GPC3-mediated metabolic rewiring of diabetic mesenchymal stromal enhances their cardioprotective functions via pyruvate kinase M2 activation

Background: Mesenchymal stromal cells (MSC) represent promising stem cell therapy for treating cardiovascular diseases. Diabetes affects the functional capability of MSC and impedes cell-based therapy. However, the impact of diabetes on MSC myocardial reparative activity, metabolic fingerprint, and the mechanism of dysfunction is still poorly understood. Therefore, our study aimed to understand the molecular basis of diabetes-induced MSC functions and their metabolic mechanism, and potential metabolic reprogramming of diabetic MSC to reverse these dysfunctions may represent a strategy to enhance cell-based therapeutics for myocardial repair in diabetic patients. Hypothesis: Our central hypothesis is that increased Glypican-3 (GPC3) mediates diabetic MSC dysfunction and diminishes energy metabolism; metabolic reprogramming of diabetic MSC with GPC3 knockdown restored diabetic MSC reparative and therapeutic activities in post-MI cardiac repair. Methods: MSCs were isolated from the bone marrow of mice from db/+ non-diabetic (WT-MSC) and diabetic mice (db/db-MSC) to compare the MSC metabolic profiles and consequent reparative function. We investigated the effect of GPC3 knockdown on db/db-MSC energy metabolism, immunosuppression, angiogenic potential in vitro, and therapeutic potential for ischemic cardiac tissue repair. Results: Intra-myocardial transplantation of db/db-MSC into the ischemic myocardium of mice does not confer cardiac benefit post-MI. The seahorse metabolic flux assays and 13 C glucose tracing studies identified defective energy metabolism in db/db-MSC. Furthermore, we found that GPC3, a heparan sulfate proteoglycan, is highly upregulated in db/db-MSC. GPC3 knockdown-db/db-MSC restored their energy metabolism, immunomodulation, and angiogenesis. Intramyocardial injection of GPC3 metabolically reprogrammed-db/db-MSC confers cardiac benefit post-MI. Conclusion: Our findings indicate that metabolic rewiring using GPC3 may be used to restore the metabolic state and functions of db/db-MSC for cell therapy applications.

Abstract We049: Cell-Specific Metabolic Labelling Identifies hiPSC-CM Proteome In Vitro and In Vivo Post-Transplantation

Background: Human induced pluripotent stem cells (hiPSCs) and their derived cardiomyocytes (hiPSC-CMs) have been used for cell-based therapies for myocardial regeneration. Underlying paracrine signals derived from these hiPSC-CMs have been shown to play a critical role in improving the function of the ischemic myocardium. However, characterization of the transplanted cell proteome in vivo has been challenging due to the lack of tools to distinguish cell-specific proteome in a complex multicellular microenvironment. Methods: To establish cell-specific proteome labelling, we adopted the biorthogonal non-canonical amino acid tagging (BONCAT) system in hiPSCs. We expressed the mutant mouse tRNA synthetase gene, “L274GmMetRS” in hiPSCs (L274G-hiPSCs) using lentiviral transduction to enable incorporation of the non-canonical amino acid azidonorleucine (Anl) in these cells. We assessed the pluripotency and trilineage differentiation potential of the L274G-hiPSCs in vitro and in vivo (teratoma formation assay). Furthermore, we validated the cell-specific Anl incorporation in the L274G-hiPSC-CMs both in vitro (co-culture) and in vivo (post-transplantation). Results: Our studies showed that the L274G-hiPSCs could efficiently differentiate into all the three germ lineages and can be used to track the cell-specific proteome in their differentiated progenies, including L274G-hiPSC-CMs. Furthermore, immunostaining and western blots showed cell-specific BONCAT in L274G-hiPSC-CMs both in co-cultures (in vitro) and post-transplantation (in vivo). Conclusion: The newly-established L274G-hiPSC line can be used to track cell-specific proteome of hiPSC-CMs in vitro and in vivo, to characterize cell-specific proteomic responses and delineate mechanisms underlying cell therapies.

Abstract We066: Macropinocytosis is essential for macrophage activation in acute ischemia.

Macrophages (Mφ) play central roles in inducing the robust inflammatory response to acute ischemia and promoting anti-inflammatory actions necessary for myocardial repair. The broad range of functional repertoire stems from Mφ plasticity dictated by their interaction with the dynamic ischemic milieu. The limited understanding of such interactions contributes to the lack of means to mitigate inflammatory injury in MI patients. We hypothesize that the dynamic Mφ plasma membrane-mediated process macropinocytosis (MP) is essential for Mφ’s activation and function evolvement in ischemia. By MP, Mφs engulf large amounts of soluble contents from the ischemic environment, and the macropinosomes formed from MP become signaling hubs of DAMP (Damage-Associated Molecular Pattern)-PRR (Pattern Recognition Receptor). We aim to determine if ischemia activates MP in Mφs, the signaling pathways that MP promotes, and the role of this process in post-ischemia repair. The rationale is based on our data demonstrating only soluble DAMP (sDAMP), not tissue debris, activates Mφs . We tested our hypothesis using the murine MI model and bone marrow-derived Mφs (BMDM) and used unpaired t-tests for statistical analyses. We uncover that ischemia markedly increases MP in Mφs; blocking MP by the inhibitors or siRNA-mediated knock-down of the Na+H+ exchanger abolished the production of potent cytokines such as IL1β from Mφs in vitro and in vivo . Furthermore, MP activates NF-κB and MAP kinase triggered by sDAMP and ischemia, critical pathways to produce inflammatory cytokine and chemokine. Intriguingly, mTORC1 activation in BMDM and Mφs in the ischemic myocardium depends on MP. These data suggest MP organizes the activation signal and the pathway required for metabolic rewiring in inflammatory Mφs. Suppressing MP at the earlier stage of ischemia (72h) when sDAMP is abundant in the ischemic tissue significantly reduces mortality and improves cardiac function. In conclusion, we identify MP functionalizes the danger signals in bulk and integrates activation signals with metabolic rewiring to promote and sustain the inflammatory function. Targeting MP is better equipped to reduce inflammatory injury as it modifies the dynamic interaction of Mφs with the ischemic environment.

Lipid-Lowering Medication and Outcomes After Anatomical and Functional Imaging in Suspected Coronary Artery Disease.

Anatomical and functional imaging identify different phenotypes of coronary artery disease (CAD) that may have implications for lipid-lowering medication (LLM). The aim of this study was to assess the associations between LLM and long-term outcomes after combined anatomical and functional imaging in patients with suspected obstructive CAD. Consecutive patients (n=1,973; 41% men; median age: 63 years) underwent coronary computed tomography angiography (CTA) because of suspected CAD. Patients in whom obstructive CAD was not ruled out by CTA underwent ischemia testing by positron emission tomography. Data on LLM purchases were collected until 2 years, and the combined endpoints of death, myocardial infarction, and unstable angina pectoris were assessed at a median of 6.7 years. After imaging, LLM was used by 24% of patients with no CAD, 51% of patients with nonobstructive CAD, 72% of patients with obstructive CAD on CTA without myocardial ischemia, and 91% of patients with myocardial ischemia. The use of LLM decreased during follow-up, with 77% of patients with myocardial ischemia using LLM for 2 years. The use ofLLM was associated with a lower annual rate of adverse events in patients with myocardial ischemia (6.1% vs 2.8%; P= 0.032) or obstructive CAD without myocardial ischemia (2.9% vs 1.4%; P = 0.004) but not in patients with nonobstructive CAD (1.5% vs 1.4%; P = 0.89) or no CAD (0.3% vs 0.3%; P = 0.68). The CAD phenotype defined by anatomical and functional imaging guides the use of LLM. The presence of myocardial ischemia and anatomical obstructive coronary lesions were associated with a long-term outcome benefit from LLM.

Myocardial ischemia in patients with mild-to-moderate aortic stenosis: Interaction with cardiac remodeling and adverse events

BackgroundThe association between aortic valve stenosis (AVS) and myocardial perfusion abnormalities has been incompletely characterized. We sought to assess the predictors of myocardial ischemia in patients with mild-to-moderate AVS, and its relationship with long-term prognosis. MethodsEighty-nine patients with mild-to-moderate AVS (peak velocity between 2.6 and 4.0 m/second and aortic valve area > .6 cm2/m2), preserved left ventricular (LV) function, and either normal coronary arteries (28 patients) or non-obstructive coronary artery disease (<50% stenosis; 61 patients) were individuated. Myocardial perfusion imaging was performed using a cadmium–zinc–telluride camera, and the summed difference score (SDS) was computed. The presence of either LV hypertrophy (LVH) (LV mass index [LVMI] > 115 g/m2 [males] or 95 g/m2 [females]) or concentric LV remodeling (relative wall thickness: >.42) was determined at two-dimensional echocardiography. ResultsForty (45%) and 49 (55%) patients had mild and moderate AVS, respectively. Fifty (56%), 17 (19%), and 22 (25%) patients had normal LV geometry, concentric LV remodeling, and LVH, respectively. An interaction between LV remodeling and inducible ischemia was revealed with progressively higher values of SDS in patients with normal LV geometry (3 ± 3), concentric remodeling (4 ± 2), and LVH (7 ± 2) (P < .001).Accordingly, a moderate correlation existed between LVMI and SDS values (R: .67; P < .001). After a median follow-up of 84 ± 47 months, 27 adverse events were recorded, including 19 AV replacements and 8 deaths. On multivariable analysis, the presence of LVH (hazard ratio [HR]: 6.46; 95% confidence interval [CI]: 2.09–20.00; P = .001) and a higher SDS (HR: 1.41; 95% CI: 1.15–1.75; P = .001) were the two independent predictors of AE. ConclusionsIn patients with mild-to-moderate AVS, myocardial ischemia correlates with the severity of adverse LV remodeling. Patients with LVH and ischemia are at increased risk of AE.

Neutrophil Percentage to Albumin Ratio as a Predictor for Coronary Slow Flow Phenomenon in Patients with Myocardial Ischemia with No Obstructive Coronary Arteries.

Accumulating evidences suggest that low-grade inflammatory response plays a key role in the pathophysiology of coronary slow flow phenomenon (CSFP). As a new hematological inflammatory indicator, the neutrophil percentage to albumin ratio (NPAR) and its role in the occurrence and development of CSFP remains unclear. In this study, we aimed to investigate the predictive value of NPAR in the presence of CSFP in patients with myocardial ischemia and no obstructive coronary arteries (INOCA). In total, 1323 individuals with INOCA were included in this study. 85 patients developed CSFP were included in the CSFP group. 1:2 age-and sex-matched patients were selected from the absence of CSFP, with normal blood flow, as the control group. Clinical characteristics, laboratory parameters, and angiographic findings were compared between groups. NPAR was also calculated to explore its relationship with CSFP. NPAR was significantly higher in the CSFP patients than in the controls (19.3±2.5 vs 16.7±1.8, p<0.001). The NPAR increased with the number of coronary arteries involved in CSFP. Multivariate logistic regression analysis showed that an elevated NPAR level was an independent predictor of CSFP (OR 1.915, 95% CI 1.612-2.275, P < 0.001). The ROC curve showed that when NPAR was > 17.39, the sensitivity and specificity were 90.6% and 78.8%, respectively, and the area under the ROC curve (AUC) was 0.860 (95% CI: 0.811-0.909, P < 0.001). The AUC of neutrophil percentage was 0.845 (95% CI: 0.794-0.897, p < 0.001), and that of albumin was 0.808 (95% CI: 0.753-0.864, p < 0.001). Elevated NPAR levels are an independent predictor of CSFP in patients with INOCA. NPAR could improve the predictive value of CSFP compared with neutrophil percentage or albumin ratio alone.

Comparative Analysis of the Feasibility of Myocardial Blood Flow Index Versus CT-FFR in the Diagnosis of Suspected Coronary Artery Disease.

Using fluid dynamic modeling, noninvasive fractional flow reserve (FFR) derived from coronary computed tomography angiography (CCTA) data provides better anatomic and functional information than CCTA, with a high diagnostic and discriminatory value for diagnosing hemodynamically significant lesions. Myocardial blood flow index (MBFI) based on CCTA is a physiological parameter that reflects myocardial ischemia. Thus, exploring the relationship between computed tomography derived fractional flow reserve (CT-FFR) and MBFI could be clinically significant. This study aimed to investigate the relationship between CT-FFR and MBFI and to analyze the feasibility of MBFI differing from CT-FFR in diagnosing suspected coronary artery disease (CAD). Data from 61 patients (35 males, mean age: 59.2 10.02 years) with suspected CAD were retrospectively analyzed, including the imaging data of CCTA, CT-FFR, and data of invasive coronary angiography performed within one week after hospitalization. CT-FFR and MBFI were calculated, and the correlation between MBFI or CT-FFR and invasive coronary angiography (ICA) was evaluated. Using ICA (value 0.70) as the gold standard and determining the optimal cutoff value via a diagnostic test, the diagnostic performance of MBFI or CT-FFR was evaluated. MBFI and CT-FFR were negatively correlated with ICA (r = -0.3670 and -0.4922, p = 0.0036 and 0.0001, respectively). Using ICA (value of 0.70) the gold standard, the optimal cutoff value was 0.115 for MBFI, and the area under the curve (AUC) was 0.833 (95% confidence interval [CI]: 0.716-0.916, Z = 5.357, p 0.0001); using ICA (value of 0.70) the gold standard, the optimal cutoff value was 0.80 for CT-FFR, and the area under the curve (AUC) was 0.759 (95% CI: 0.632-0.859, Z = 3.665, p = 0.0002). No significant difference was observed between the AUCs of CT-FFR and MBFI (Z = 0.786, p = 0.4316). MBFI based on CCTA can be used to evaluate myocardial ischemia similar to CT-FFR in suspected CAD; however, it should be noted that CT-FFR is a functional index based on the anatomical stenosis of the coronary artery, whereas MBFI is a physiological index reflecting myocardial mass remodeling.

A Case Report of a 44-Year-Old Middle-Aged Woman with Acute Chest Pain

&lt;p&gt;胸痛是臨床常見的主訴，鑑別診斷必須配合心電圖，並優先考量會猝死的心血管疾病。本篇個案是一位44歲的中年女性，因急性胸痛至急診就醫，經連續追蹤心電圖與抽血檢驗，診斷為非ST節段上升之急性冠心症(non ST-elevation acute coronary syndrome, NSTE-ACS)，心導管冠狀動脈攝影檢查結果合乎自發性冠狀動脈剝離(spontaneous coronary artery dissection, SCAD)的變化。本文之目的在強調無冠狀動脈疾病危險因子的中年女性發生急性冠心症，須考慮SCAD的可能性。SCAD的病因為冠狀動脈內膜撕裂，血流進入血管內壁產生血腫，當假腔壓迫冠狀動脈血流會使心肌缺血而導致胸痛的症狀，與冠狀動脈阻塞型心肌梗塞成因不同，故治療與處理的方式有不同之處，必須視臨床病人情況做謹慎的評估，以降低侵入性治療的風險。照顧個案期間藉由最少的侵入性檢查給予正確診斷，並配合適當的藥物治療，達成緩解病人症狀、預防合併症與復發的治療目的。藉由這篇病例報告，希望醫護人員對照顧自發性冠狀動脈剝離的病人有更多的認知。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Chest pain is a common clinical complaint. Electrocardiograms must be included in diagnosis, and the priority should be given to cardiovascular diseases that may lead to sudden death. The case described here is a 44-year-old middle-aged woman who presented to the emergency room with unendurable chest pain. After continuous follow-up ECG and blood tests, she was diagnosed with non-ST-elevation acute coronary syndrome (NSTE-ACS). The result of coronary angiography correspond to sponta-neous coronary artery dissection (SCAD). The purpose of this article is to emphasize the possibility of SCAD in acute coronary syndrome in middle-aged women without coronary artery disease risk fac-tors. SCAD is characterized by intimal tear, intramural hematoma, and false lumen formation, which can obstruct coronary blood flow and cause myocardial ischemia with chest pain. Since the etiology of SCAD is different from obstructive coronary artery myocardial infarction, their medical treatments must be carefully evaluated through clinical patient conditions to reduce the risks of invasive proce-dure. In this case, early and correct diagnosis was made to reduce invasive procedure, and appropriate medication therapy were applyed to achieve the purpose of relieving the patient&amp;rsquo;s symptoms, prevent-ing complications and recurrence. Through this case report, it is hoped that healthcare professionals will improve awareness of caring for patients with spontaneous coronary artery dissection.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Gastrodin exerts perioperative myocardial protection by improving mitophagy through the PINK1/Parkin pathway to reduce myocardial ischemia-reperfusion injury

BackgroundAlthough blood flow is restored after treatment of myocardial infarction (MI), myocardial ischemia and reperfusion (I/R) can cause cardiac injury, which is a leading cause of heart failure. Gastrodin (GAS) exerts protective effects against brain, heart, and kidney I/R. However, its pharmacological mechanism in myocardial I/R injury (MIRI) remains unclear. PurposeGAS regulates autophagy in various diseases, such as acute hepatitis, vascular dementia, and stroke. We hypothesized that GAS could repair mitochondrial damage and regulate autophagy to protect against MIRI. Study designMale C57BL/6 mice and H9C2 cells were subjected to I/R and hypoxia-reoxygenation (H/R) injury after GAS administration, respectively, to assess the impact of GAS on cardiomyocyte phenotypes, heart, and mitochondrial structure and function. The effect of GAS on cardiac function and mitochondrial structure in patients undergoing cardiac surgery has been observed in clinical practice. MethodsThe effects of GAS on cardiac structure and function, mitochondrial structure, and expression of related molecules in an animal model of MIRI were evaluated using immunohistochemical staining, enzyme-linked immunosorbent assay (ELISA), transmission electron microscopy, western blotting, and gene sequencing. Its effects on the morphological, molecular, and functional phenotypes of cardiomyocytes undergoing H/R were observed using immunohistochemical staining, real-time quantitative PCR, and western blotting. ResultsGAS significantly reduces myocardial infarct size and improves cardiac function in MIRI mice in animal models and increases cardiomyocyte viability and reduces cardiomyocyte damage in cellular models. In clinical practice, myocardial injury was alleviated with better cardiac function in patients undergoing cardiac surgery after the application of GAS; improvements in mitochondria and autophagy activation were also observed. GAS primarily exerts cardioprotective effects through activation of the PINK1/Parkin pathway, which promotes mitochondrial autophagy to clear damaged mitochondria. ConclusionGAS can promote mitophagy and preserve mitochondria through PINK1/Parkin, thus indicating its tremendous potential as an effective perioperative myocardial protective agent.

Delta troponin does not distinguish acute coronary syndrome in emergency department patients with renal impairment and an initial positive troponin.

In emergency department (ED) patients with renal impairment, troponin concentrations can be positive without myocardial ischemia. When there is clinical concern for acute coronary syndrome (ACS), guidelines recommend obtaining a delta troponin measurement to identify acute myocardial injury. However, evidence supporting the use of delta troponin to rule in or out ACS in patients with renal impairment and initial elevated troponin levels is limited. This retrospective, observational study assessed the diagnostic value of a 20% delta troponin cutoff in the prediction of ACS events in ED patients (estimated glomerular filtration rate [eGFR]<60mL/min/1.72 m2) with renal impairment, clinical concern for ACS, and an initial positive troponin concentration using either conventional troponin (cTnT) or high-sensitivity troponin (hsTnT). Clinical concern for ACS was based on initial ED physician-reported diagnoses. Patients with an initial diagnosis of ST-elevation myocardial infarction were not included. A positive initial troponin was identified at a threshold of ≥0.06ng/mL for cTnT and ≥52ng/L for hsTnT, and delta troponin measurements were obtained within 24h of the initial troponin. The primary composite outcome, termed ACS event, included (1) cardiac-related mortality, (2) coronary revascularization (or its recommendation), or a (3) clinically diagnosed type-1 myocardial infarction within 6 weeks of the ED presentation. Sensitivities, specificities, negative predictive values, positive predictive values, and negative and positive likelihood ratios were calculated for these 6-week ACS events. A total of 608 ED patients with renal impairment, an initial positive troponin, and clinical concern for ACS were included in the study. Of these patients, 234 had an initial positive cTnT (median eGFR 18mL/min/1.72 m2) and 374 had an initial positive hsTnT (median eGFR 25mL/min/1.72 m2). The overall ACS event rate was 38% in the cTnT group and 33% in the hsTnT group. In those with a negative delta, the 6-week ACS event rate was 32% when using cTnT, compared to 24% using hsTnT. Conversely, a positive delta was associated with an ACS event rate of 47% when cTnT was utilized versus 61% when hsTnT was utilized. In this study, approximately one-third of ED patients with renal impairment who had an initial positive troponin and clinical concern for ACS developed ACS events at 6 weeks. A delta troponin did not appear to provide clinically meaningful assistance in the prediction or exclusion of 6-week ACS events in this cohort.

Coronary Atherosclerotic Plaque Burden Assessment by Computed Tomography and Its Clinical Implications.

Recent studies have demonstrated that coronary plaque burden carries greater prognostic value in predicting adverse atherosclerotic cardiovascular disease outcomes than myocardial ischemia, thereby challenging the existing paradigm. Advances in plaque quantification through both noncontrast and contrast-enhanced computed tomography (CT) methods have led to earlier and more cost-effective detection of coronary disease compared with traditional stress testing. The 2 principal techniques of noninvasive coronary plaque quantification assessment are coronary artery calcium scoring by noncontrast CT and coronary CT angiography, both of which correlate with disease burden on invasive angiography. Plaque quantification from these imaging modalities has shown utility in risk stratification and prognostication of adverse cardiovascular events, leading to increased incorporation into clinical practice guidelines and preventive care pathways. Furthermore, due to their expanding clinical value, emerging technologies such as artificial intelligence are being integrated into plaque quantification platforms, placing more advanced measures of plaque burden at the forefront of coronary plaque evaluation. In this review, we summarize recent clinical data on coronary artery calcium scoring and coronary CT angiography plaque quantification in the evaluation of adverse atherosclerotic cardiovascular disease in patients with and without chest pain, highlight how these methods compare to invasive quantification approaches, and directly compare the performance characteristics of coronary artery calcium scoring and coronary CT angiography.

Tissue-Based Predictors of Impaired Right Ventricular Strain in Coronary Artery Disease: A Multicenter Stress Perfusion Study.

Right ventricular (RV) dysfunction is known to impact prognosis, but its determinants in coronary artery disease are poorly understood. Stress cardiac magnetic resonance (CMR) has been used to assess ischemia and infarction in relation to the left ventricle (LV); the impact of myocardial tissue properties on RV function is unknown. Vasodilator stress CMR was performed in patients with known coronary artery disease at 7 sites between May 2005 and October 2018. Myocardial infarction was identified on late gadolinium enhancement-CMR, and infarct transmurality was graded on a per-segment basis. Ischemia was assessed on stress CMR based on first-pass perfusion and localized by using segment partitions corresponding to cine and late gadolinium enhancement analyses. RV function was evaluated by CMR-feature tracking for primary analysis with a global longitudinal strain threshold of 20% used to define impaired RV strain (RVIS); secondary functional analysis via RV ejection fraction was also performed. A total of 2604 patients were studied, among whom RVIS was present in 461 patients (18%). The presence and magnitude of RVIS were strongly associated with LV dysfunction, irrespective of whether measured by LV ejection fraction or wall motion score (P<0.001 for all). Regarding tissue substrate, regions of ischemic and dysfunctional myocardium (ie, hibernating myocardium) and infarct size were each independently associated with RVIS (both P<0.001). During follow-up (median, 4.62 [interquartile range, 2.15-7.67] years), 555 deaths (21%) occurred. Kaplan-Meier analysis for patients stratified by presence and magnitude of RV dysfunction by global longitudinal strain and RV ejection fraction each demonstrated strong prognostic utility for all-cause mortality (P<0.001). RVIS conferred increased mortality risk (hazard ratio, 1.35 [95% CI, 1.11-1.66]; P=0.003) even after controlling for LV function, infarction, and ischemia. RVIS in patients with known coronary artery disease is associated with potentially reversible LV processes, including LV functional impairment due to ischemic and predominantly viable myocardium, which confers increased mortality risk independent of LV function and tissue substrate.