Chronic Myocardial Ischemia Research Articles

Differential but Complementary HIF1α and HIF2α Transcriptional Regulation.

Effective vascular regeneration could provide therapeutic benefit for multiple pathologies, especially in chronic peripheral artery disease (PAD) and myocardial ischemia. The hypoxia inducible factors (HIFs) mediate the cellular transcriptional response to hypoxia and regulate multiple processes that are required for angiogenesis to ultimately restore perfusion and oxygen supply. In endothelial cells, both HIF1α and HIF2α are known to contribute to this role; however, the extent and individual roles of each of these HIFα remain unclear. To characterize the individual roles of HIFα, we sequenced the transcriptional outputs of stabilized forms of HIF1α and HIF2α, where they regulated 701 and 1,454 genes, respectively. HIF1α transcription primarily regulated metabolic reprogramming, whereas HIF2α exerted a larger role in regulating angiogenic extracellular signaling, guidance cues, and extracellular matrix remodeling factors. Furthermore, HIF2α almost exclusively regulated a large and diverse subset of transcription factors and coregulators that contribute to its diverse roles in hypoxia. Further understanding of how HIFs regulate cellular processes in hypoxia and angiogenesis could offer new avenues to modulate physiological angiogenesis to enhance revascularisation in ischemic conditions and other pathologies.

Abstract 350: Brown Adipose Tissue, a Novel Mechanism to Induce both Angiogenesis and Arteriogenesis

Brown adipose tissue (BAT) is known to protect metabolism, but the extent to which it mediates angiogenesis and cardioprotection, the goal of this investigation, is not known. The Regulator of G Protein Signaling 14 (RGS14) knockout (KO) mouse is unique in that it not only extends longevity, but also enhances several aspects of healthful aging, i.e., protects against diabetes, obesity, exercise intolerance and increased brown adipose tissue by 47% compared with wild type littermates (WT). However, less is known about its role in cardioprotection. Accordingly we examined the effects of chronic myocardial ischemia after 1 and 3 weeks of permanent coronary artery occlusion (CAO) in 3-4 month old RGS14 KO and their WT. Scar size after 3 weeks CAO, determined by histology, was decreased by 33±5% in RGS14 KO, which was only possible in the face of permanent CAO if angiogenesis/arteriogenesis developed in the RGS14 KO mice hearts. Indeed, both angiogenesis assessed by Ki 67 endothelial cell staining and arteriogenesis, assessed by Ki 67 arteriole staining, more than doubled compared with WT. This was associated with a 206±25.5% increase in VEGF in the RGS14 KO hearts compared with WT. We then examined the role of BAT by using a simulated BAT KO, i.e., BAT was transplanted from the RGS14 KO to WT. In the WT with BAT transplants VEGF was increased by 90%. Infarct size, assessed as the fraction of area at risk, was lower, p<0.05, in the BAT transplants (27±2.8%), compared with infarct size in RGS14 KO donors (44±1.9%), a value similar to that observed in WT without the BAT transplant (46±1.0%). Thus, brown adipose tissue appears to be a novel mechanism to induce both angiogenesis and arteriogenesis, resulting in vascular protection from ischemia.

Diagnostic accuracy of postmortem computed tomography, magnetic resonance imaging, and computed tomography-guided biopsies for the detection of ischaemic heart disease in a hospital setting.

The autopsy rate worldwide is alarmingly low (0-15%). Mortality statistics are important, and it is, therefore, essential to perform autopsies in a sufficient proportion of deaths. The imaging autopsy, non-invasive, or minimally invasive autopsy (MIA) can be used as an alternative to the conventional autopsy in an attempt to improve postmortem diagnostics by increasing the number of postmortem procedures. The aim of this study was to determine the diagnostic accuracy of postmortem magnetic resonance imaging (MRI), computed tomography (CT), and CT-guided biopsy for the detection of acute and chronic myocardial ischaemia. We included 100 consecutive adult patients who died in hospital, and for whom next-of-kin gave permission to perform both conventional autopsy and MIA. The MIA consists of unenhanced total-body MRI and CT followed by CT-guided biopsies. Conventional autopsy was used as reference standard. We calculated sensitivity and specificity and receiver operating characteristics curves for CT and MRI as the stand-alone test or combined with biopsy for detection of acute and chronic myocardial infarction (MI). Sensitivity and specificity of MRI with biopsies for acute MI was 0.97 and 0.95, respectively and 0.90 and 0.75, respectively for chronic MI. MRI without biopsies showed a high specificity (acute: 0.92; chronic: 1.00), but low sensitivity (acute: 0.50; chronic: 0.35). CT (total Agatston calcium score) had a good diagnostic value for chronic MI [area under curve (AUC) 0.74, 95% confidence interval (CI) 0.64-0.84], but not for acute MI (AUC 0.60, 95% CI 0.48-0.72). We found that the combination of MRI with biopsies had high sensitivity and specificity for the detection of acute and chronic myocardial ischaemia.

Glycogen synthase kinase 3β inhibition reduces mitochondrial oxidative stress in chronic myocardial ischemia

ObjectivesGlycogen synthase kinase 3β (GSK-3β) inhibition has been reported to increase microvascular density and improve myocardial blood flow in a porcine model of chronic myocardial ischemia and metabolic syndrome. Inhibition of GSK-3β can also be cardioprotective by modulating fibrosis signaling and mitochondrial-induced apoptosis. We hypothesized GSK-3β inhibition would have a beneficial effect on myocardial fibrosis and oxidative stress in a porcine model of chronic myocardial ischemia and metabolic syndrome. MethodsPigs were fed a high fat diet for 4 weeks followed by placement of an ameroid constrictor to the left circumflex coronary artery. Three weeks later animals received either no drug or a GSK-3β inhibitor. The diets and placebo/GSK-3β inhibition were continued for an additional 5 weeks, the pigs were then euthanized, and the myocardial tissue was harvested. Collagen expression was analyzed via Picrosirius staining. Oxidative stress was analyzed via Oxyblot analysis. Protein expression was analyzed via Western blot. ResultsGSK-3β inhibition was associated with decreased collagen expression and oxidative stress in the ischemic and nonischemic myocardial tissue compared with control. There was a decrease in profibrotic proteins transforming growth factor-β, p-SMAD2/3, and matrix metalloproteinase-9, and in proapoptotic and oxidative stress proteins, apoptosis inducing factor, the cleaved caspase 3/caspase 3 protein ratio and phosphorylated myeloid cell leukemia sequence-1 in the GSK-3β inhibited group compared with the control. ConclusionsIn the setting of metabolic syndrome and chronic myocardial ischemia, inhibition of GSK-3β decreases collagen formation and oxidative stress in myocardial tissue. GSK-3β inhibition might be having this beneficial effect by downregulating transforming growth factor-β/SMAD2/3 signaling and decreasing mitochondrial induced cellular stress.

Patient-controlled oral analgesia for acute abdominal pain: A before-and-after intervention study on pain intensity and use of analgesics

AimTo compare the use of patient-controlled oral analgesia with nurse-controlled analgesia for patients admitted to hospital with acute abdominal pain. The primary outcome measure was pain intensity. The secondary outcome measures were the use of analgesics and antiemetics. BackgroundInadequate pain management of patients with acute abdominal pain can occur during hospital admission. Unrelieved acute pain can result in chronic pain, stroke, bleeding and myocardial ischemia. MethodsA before-and-after intervention study was conducted in an emergency department and a surgical department with three subunits. Data were collected from medical charts and analyzed using chi-squared and Kruskal–Wallis tests. ResultsA total of 170 patients were included. The median pain intensity score, using the numeric ranking scale, was 2.5 and 2 on Day 2 (p = 0.10), 2 and 2 on Day 3 (p = 0,40), 2.5 and 0 on Day 4 (p = 0.10), 2 and 0 on Day 5 (p = 0.045) in the control and intervention group, respectively. The percentage of patients receiving analgesics was 93 and 86 on Day 2 (p = 0.20), 91 and 75 on Day 3 (p = 0.02), 89 and 67 on Day 4 (p = 0.009) and 80 and 63 on Day 5 (p = 0.39). The use of antiemetics was similar in the two groups. ConclusionPatient-controlled oral analgesia significantly reduced the numerical ranking pain scale score on Day 5 and the consumption of analgesics on Days 3 and 4 after hospital admission. Patient-controlled oral analgesia is feasible as pain management for patients, but only with minor impact on experienced pain intensity and use of analgesics.

Panax Quinquefolium Saponins Attenuate Myocardial Dysfunction Induced by Chronic Ischemia

Background/Aims: Previous studies in rat models of myocardial ischemia showed that Panax quinquefolium saponins (PQS) could attenuate ischemic/reperfusion injury, increase vessel density and improve cardiac function. In the current study, we examined whether PQS could attenuate myocardial dysfunction in a swine model of chronic myocardial ischemia (CMI). Methods: CMI was established in Bama mini-pigs by placing amroid constrictor on the left anterior descending artery (LAD). Starting from 2 months after the surgery, pigs randomly received PQS (30 mg/kg/day), atorvastatin (1.5 mg/kg/day), or no drug for one month (n=6). A group of pigs receiving sham surgery was included as an additional control. Glucose utilization was assessed with positron emission tomography-computer tomography (PET-CT). Cardiac function was assessed with echocardiography. Myocyte size, nuclear density, and arteriolar density were examined in tissue section obtained from the ischemia area. Potential molecular targets of PQS were identified using proteomic analysis with isobaric tags for relative and absolute quantitation (iTARQ) and network pharmacology. Results: In comparison to the sham controls, pigs implanted with ameroid constrictor had decreased ventricular wall motion, left ventricular ejection fraction (LVEF), and glucose utilization. PQS significantly increased cardiac function and glucose utilization. Arteriole density and myocyte nuclear density were increased. Myocyte diameter was decreased. PQS also attenuated the CMI-induced change of protein expression profile. The effects of atorvastatin were generally similar to that of PQS. However, PQS attenuated the reduction of left ventricular systolic WT induced by CMI more robustly than atorvastatin. Conclusion: The results from the current study supports the use of PQS in patients with coronary artery disease.

Effects of Salvia miltiorrhiza extract with supplemental liquefied calcium on osteoporosis in calcium-deficient ovariectomized mice

BackgroundExtracts from Salvia miltiorrhiza Bunge have been used in traditional Asian medicine to treat coronary heart disease, chronic renal failure, atherosclerosis, myocardial infraction, angina pectoris, myocardial ischemia, dysmenorrheal, neurasthenic insomnia, liver fibrosis and cirrhosis. The aim of the study was to investigate the anti-RANK signal effect of the combination of S.miltiorrhiza Bunge (SME) and liquefied calcium (LCa) supplement with ovariectomized (OVX-SML) mice, a osteoporosis animal model. Results were compared to 17β-estradiol (E2) treatment.MethodsA total of 70 female ICR strain mice (7 weeks) were randomly divided into 10 groups with 7 mice in each group as follows: (1) sham-operated control mice (sham) received daily oral phosphate-buffered-saline (PBS) of equal volumes through oral administration. (2) OVX mice received a daily oral administration of PBS (OVX). (3) OVX mice treated daily with 50 mg/kg b.w./ day of SME (4) with 100 mg/kg b.w./day of SME or (5) with 200 mg/kg b.w./day of SME via oral administration. (6) OVX mice treated daily with 50 mg/kg b.w./day of SML (7) with 100 mg/kg b.w./day of SML or (8) with 200 mg/kg b.w./day of SML via oral administration. (9) OVX mice treated daily with 10 ml/kg b.w./day of LCa (10) OVX mice received i.p. injections of 17β-estradiol (E2) (0.1 mg/kg b.w./day) three times per week for 12 weeks.Resultsmicro-CT analysis revealed that oral administration of SML inhibited tibial bone loss, sustained trabecular bone state, and ameliorated bone biochemical markers. In addition, SML administration compared to SEM and LCa reduced serum levels of RANKL, osteocalcin and BALP through increased serum levels of OPG and E2 in OVX mice. SML also had more beneficial effects on protection of estrogen-dependent bone loss through blocking expression of TRAF6 and NFTAc1 and produces cathepsin K and calcitonin receptor to develop osteoclast differentiation.ConclusionThese data suggest that S. miltiorrhiza Bunge combined with liquefied calcium supplement has an inhibitory activity in OVX mice. This result implies the possibility of a pharmacological intervention specifically directed toward a disease such as osteoporosis where decreased bone strength increases the risk of a broken bone.

ЗВИВИСТІСТЬ ВІНЦЕВИХ АРТЕРІЙ В ДІАГНОСТИЦІ ПОРУШЕНЬ КОРОНАРНОЇ ГЕМОДИНАМІКИ

Обговорене діагностичне значення звивистості вінцевих артерій (ВА), її прогностична роль у виникненні хронічної ішемії міокарда, гострого порушення коронарного кровообігу та ішемічної хвороби серця (ІХС) у пацієнтів без ангіографічних ознак атеросклеросклерозу (АС) стінки судин.
 Мета дослідження: вивчення ролі звивистої конфігурації ВА в порушенні коронарного кровообігу.
 Матеріали і методи. У дослідження включені 816 пацієнтів без змін конфігурації ВА і 588 - у яких виявлено звивистість ВА. Обстеження проводили з використанням загальноклінічних методів дослідження, електрокардіографії, ехокардіографії (ЕХО–КГ), велоергометрії, коронаровентрикулографії (КВГ), стрес-векторехокардіографії (стрес–ВЕХО–КГ).
 Результати. У пацієнтів з звивистими ВА, за відсутності ангіографічних ознак їх гемодинамічно значущого стенозу, виявляли типовий больовий синдром, клінічні ознаки стенокардії напруження та хронічної недостатності кровообігу. У пацієнтів з ангіографічними ознаками гемодинамічно значущого стенозу звивистість ВА зумовлювала збільшення частоти виникнення аневризми лівого шлуночка.
 Висновки. Звивистість ВА є фактором, здатним спричинити порушення перфузії міокарда, що створює підґрунтя для несприятливого прогнозу перебігу ІХС, незалежно від наявності АС ВА.
 Ключові слова: ішемічна хвороба серця; звивистість вінцевих артерій; порушення коронарної гемодинаміки.

Evaluation of relationship between myocardial injury and left ventricular mechanical dyssynchrony using 99Tcm-MIBI myocardial perfusion SPECT and 18F-FDG myocardial metabolic PET imaging

Objective To investigate the relationship between myocardial injury and damage of mechanical synchrony in the left ventricle of patients with ischemic cardiomyopathy (ICM) using 99Tcm-MIBI MPI and gated 18F-FDG myocardial metabolic PET imaging. Methods A total of 113 ICM patients (100 males, 13 females; average age (58±10) years) underwent 99Tcm-MIBI MPI and gated 18F-FDG myocardial metabolic PET imaging from July 2015 to December 2015 in Fu Wai Hospital were retrospectively analyzed. Three-point scoring system was used for quantitative assessment of myocardial ischemia and myocardial infarction in each segment. Total ischemic score (TIS) and total scar score (TSS) of 17 segments were calculated in each patient. The phase bandwidth (BW) and phase SD were derived from phase analysis. Pearson correlation analysis and logistic regression analysis were used. Results TSS were correlated with BW and SD in all 93 patients with myocardial infarction (r values: 0.517, 0.470, both P 0.05). Logistic regression analysis showed that the number of myocardial infarction segments and TSS were associated with mechanical dyssynchrony. Conclusion Myocardial infarction is the main factor of left ventricular mechanical dyssynchrony in ICM patients, but chronic myocardial ischemia has no significant influence on mechanical dyssynchrony. Key words: Myocardial ischemia; Myocardial contraction; Myocardial perfusion imaging; Tomography, emission-computed, single-photon; Positron-emission tomography; Technetium Tc 99m sestamibi; Deoxyglucose

Steerable Induction of the Thymosin β4/MRTF-A Pathway via AAV-Based Overexpression Induces Therapeutic Neovascularization.

Viral vectors have been frequently used in a variety of preclinical animal models to deliver genetic constructs into tissues. Among the vectors used, adeno-associated viral vectors (AAVs) may be targeted to specific tissues, depending on the serotype used. Moreover, they show robust expression for prolonged periods of time and have a low immunogenic potential. Furthermore, AAVs, unlike other vector systems, only display a low rate of genomic integration. However, to ensure efficient transgene production, expression is typically driven by constitutively active promoters, such as the cytomegalovirus (CMV) promoter. Tetracyclin responsive promoters represent a promising alternative to unregulated promoters. The present study compares AAVs encoding either constitutively active CMV or tet-off promoter regions in the preclinical models of hindlimb and chronic myocardial ischemia. Therapeutically, mediators regulating vessel maturation, specifically thymosin beta 4 (Tβ4) and the downstream signaling molecule myocardin-related transcription factor A (MRTF-A) as well as the endothelial activator angiopoietin-2 (Ang2) were overexpressed via AAVs using both promotors. In the model of rabbit hindlimb ischemia, temporary (tet-off) expression of Tβ4 improved capillary density, collateralization, and perfusion in the ischemic hindlimb, with no detectable difference to constitutive Tβ4 overexpression. Similarly, constitutive overexpression of MRTF-A alone was able to improve capillarization, collateralization and perfusion. Temporary expression of Ang2 for 7 days further increased capillary density and pericyte coverage compared with MRTF-A alone, without further improving collateralization or perfusion. In the pig model of chronic myocardial ischemia constitutive expression of Tβ4 for 4 weeks induced capillary and collateral growth similarly to a pulsed expression (2 day expression per week for 3 weeks). Taken together these findings demonstrate for two models of preclinical interventions that temporary gene expression may lead to similar results as constitutive expression, highlighting the potential of controlled temporary gene expression for induction of vascular growth as a therapeutic approach.

Low-intensity pulsed ultrasound enhances angiogenesis and ameliorates contractile dysfunction of pressure-overloaded heart in mice.

IntroductionChronic left ventricular (LV) pressure overload causes relative ischemia with resultant LV dysfunction. We have recently demonstrated that low-intensity pulsed ultrasound (LIPUS) improves myocardial ischemia in a pig model of chronic myocardial ischemia through enhanced myocardial angiogenesis. In the present study, we thus examined whether LIPUS also ameliorates contractile dysfunction in LV pressure-overloaded hearts.Methods and resultsChronic LV pressure overload was induced with transverse aortic constriction (TAC) in mice. LIPUS was applied to the whole heart three times in the first week after TAC and was repeated once a week for 7 weeks thereafter (n = 22). Animals in the control groups received the sham treatment without LIPUS (n = 23). At 8 weeks after TAC, LV fractional shortening was depressed in the TAC-Control group, which was significantly ameliorated in the TAC-LIPUS group (30.4±0.5 vs. 36.2±3.8%, P<0.05). Capillary density was higher and perivascular fibrosis was less in the LV in the TAC-LIPUS group than in the TAC-Control group. Myocardial relative ischemia evaluated with hypoxyprobe was noted in the TAC-Control group, which was significantly attenuated in the TAC-LIPUS group. In the TAC-LIPUS group, as compared with the control group, mRNA expressions of BNP and collagen III were significantly lower (both P<0.05) and protein expressions of VEGF and eNOS were significantly up-regulated associated with Akt activation (all P<0.05). No adverse effect related to the LIPUS therapy was noted.ConclusionsThese results indicate that the LIPUS therapy ameliorates contractile dysfunction in chronically pressure-overloaded hearts through enhanced myocardial angiogenesis and attenuated perivascular fibrosis. Thus, the LIPUS therapy may be a promising, non-invasive treatment for cardiac dysfunction due to chronic pressure overload.

Pathological characteristics of the heart and coronary artery from elderly heart failure patients with preserved ejection fraction and coronary artery disease

Objective: To analyze the pathological feathers of the heart in elderly (60-99 years old) heart failure patients with preserved ejection fraction (HFpEF) and coronary artery disease (CAD) and to explore the misdiagnosis and missed diagnosis rates. Method: This retrospective study included 154 HFpEF (left ventricular ejection fraction (LVEF)≥50%) cases and 49 heart failure with reduced ejection fraction (HFrEF) (LVEF≤40%) cases aged 60-99 years old out of 1 485 consecutive autopsy cases. Pathological changes of the heart and coronary artery were compared between patients with HFpEF and HFrEF. The misdiagnosis and missed diagnosis rates of HFpEF were analyzed based on pathological examination. Results: Patients with HFpEF were older than those with HFrEF ((85.7±7.4) vs. (82.9±7.8) years old, P=0.017). Among all the cases, CAD was diagnosed in 105 (68.2%) HFpEF patients and 38 (77.6%) HFrEF patients. Compared with patients with HFrEF, HFpEF patients displayed less acute myocardial infarction (12.3%(19/154) vs. 59.2%(29/49), P<0.01) and more chronic myocardial ischemia (18.2%(28/154) vs. 6.1%(3/49), P=0.041). 51.9% (80/154) HFpEF and 71.4% (35/49) HFrEF patients (P=0.017) displayed >50% left anterior descending artery stenosis. Prevalence of >75% coronary arterial stenosis (51% (25/49) vs. 20.1%(31/154), P<0.001) and more than one vessel lesions (55.1%(27/49) vs. 33.8%(52/154), P=0.008) were significantly higher in HFrEF patients than in HFpEF patients. The misdiagnosis rate of CAD in HFpEF was 63.3% (31/49). Among HFpEF, the missed diagnosis rate of acute myocardial infarction was 57.9% (11/19) and the missed diagnosis rate of old myocardial infarction was 57.7% (45/78). Conclusions: CAD and chronic myocardial ischemia are common in elderly patients with HFpEF. Chronic myocardial ischemia may play an important role in the development of HFpEF of elderly CAD patients. Among HFpEF patients, the misdiagnosis rate of CAD and missed diagnosis rate of myocardial infarction are high, so the accurate evaluation of myocardial ischemia status is of great importance.

P4914LNA-based miR92a inhibition induces therapeutic neovascularization in a pig model of chronic myocardial ischemia

P4914LNA-based miR92a inhibition induces therapeutic neovascularization in a pig model of chronic myocardial ischemia

Safety and efficacy of percutaneous intramyocardial bone marrow cell injection for chronic myocardial ischemia: Long-term results.

Intramyocardial injection of bone marrow cells (BMC) in refractory angina patients with chronic myocardial ischemia has shown to be safe and improve clinical status during short-term follow-up. However, scarce data are available on long-term (>12 months) safety and efficacy. Therefore, the occurrence of clinical events and the long-term clinical effects of intramyocardial BMC injection were evaluated in patients with chronic myocardial ischemia up to 10 years after treatment. Patients (n = 100, age 64 ± 9 years, male 88%) with chronic myocardial ischemia who underwent intramyocardial BMC injection between 2004 and 2010 were evaluated. During yearly outpatient clinic visits, the occurrence of clinical events was documented. In addition, clinical status was assessed according to the Canadian Cardiovascular Society (CCS) score and quality of life was measured using the Seattle Angina Questionnaire. These parameters were evaluated at baseline and during the first year, followed by cross-sectional long-term follow-up which was performed in 2011 and 2014. No adverse events considered related to the procedure occurred during 10 years of follow-up. Observed annual mortality rate and annual myocardial infarction rate were 3.8% and 1.9% per year, respectively. When compared to baseline, CCS class and quality of life remained significantly better during 5-year follow-up after BMC treatment (both P < 0.05). The present long-term follow-up study shows that intramyocardial BMC injection in patients with chronic myocardial ischemia is safe and improves both angina complaints and quality of life up to 5 years after BMC treatment.

Abstract 251: Lna- Mediated Mir-92a Inhibition Induces Therapeutic Neovascularization in a Pig Model of Chronic Myocardial Ischemia

miRNA are post-transcriptional gene regulators which modulate RNA silencing and gene expression. In chronic myocardial ischemia, miRNA are altered and dysregulated. MiR92a inhibition in a mouse model of LAD occlusion led to improved neovascularisation and reduced infarct sizes. We aimed to investigate this therapeutic effect of miR92a- inhibition in a pig model of chronic myocardial ischemia. Methods: In pigs (n=5/group) reduction stent graft implantation in the circumflex artery led to a gradual occlusion of the vessel within 28 days (d28) after intervention. Using selective pressure-regulated retroinfusion the nucleic acid-modified antisense miR92a (LNA-92a; 5 mg/KG heart weight) was injected 28 days post implantation. The global myocardial function (Ejection Fraction (EF)) and the left end-diastolic pressure (LVEDP) were obtained at day 28 and 56. At day 56 after stent implantation regional myocardial function (subendocardial segmentshortning) as well as post mortem angiographies for collateral growth were analyzed. For the histological quantification the ischemic tissue was stained for PECAM-1 positive cells (capillaries) and for NG2- positive cells (vessel maturation, pericyte coverage). Results: The regionally applied locked nucleic acid-modified anti-sense miR-92a significantly reduced miR-92a expression in the heart and enhanced capillary coverage in the ischemia. Improved collateral growth (3±1 control vs. 6±1 in LNA-92a treated hearts) and distal perfusion of the occluded coronary artery (Rentrop score: 1.3±0.2 control vs. 2.4±0.2 in LNA-92a treated hearts) was seen after miR-92a inhibition. Moreover the increased LVEDP at day 28 (control: 16±1 mmHg vs. LNA-92a 15±1mmHg) was reduced after regional miRNA-92a inhibition (control: 16±1 mmHg vs. LNA-92a 15±1mmHg) and EF clearly increased after LNA-92a application (39±4% vs. 25±2 % in control). Regional myocardial function, obtained in the ischemic area under increased heart rate, was significantly improved after miR-92a inhibition (SES at hear rate 150bpm: 7±3 % of non-ischemic in control vs. 70±11 %% of non-ischemic in LNA-92a treated animals). Conclusion: Even single application of LNA-92a was able to reduce ischemia dependent impaired myocardial function

Chronic Myocardial Ischemia Leads to Loss of Maximal Oxygen Consumption and Complex I Dysfunction

Cardiomyocytes rely heavily on mitochondrial energy production through oxidative phosphorylation. Chronic myocardial ischemia may cause mitochondrial dysfunction and affect ATP formation. Metabolic changes due to ischemia alters cardiac bioenergetics and hence myocardial function and overall bioenergetic state. Here, we evaluate differences in functional status of respiratory complexes in mitochondrial isolates extracted from leftatrial appendage tissue (LAA) from patients undergoing cardiac surgery, with and without chronic ischemia. Mitochondrial isolates were extracted from LAA in ischemic coronary artery bypass grafting patients (n = 8) and non-ischemic control patients (n= 6) undergoing other cardiac surgery (valve repair/replacement). Coupling and electron transport chain assays were performed using Seahorse XFe 96 (Agilent Technologies, Santa Clara, CA) analyzer. Oxygen consumption rates were measured to calculate respiration states. Respiratory control rate (RCR) in ischemic patients was significantly lower than control patients (6.17± 0.27 vs 7.11 ± 0.31, respectively; p < 0.05). This is the result of minimal, non-significant state 3ADP and state 4O changes in chronic ischemia. Complex I respiration is diminished in ischemic tissue (99.1 ± 14.9 vs 257.8 ± 65.2 in control; p < 0.01). Maximal complex I/II respiration ratio was significantly lower in ischemic patients (58.9% ± 5.5% vs 90.9% ± 8.8%; p < 0.05), a difference that was also seen in complex I/IV ratios (p < 0.05). There was no significant difference in complex II/IV ratios between groups. Ischemic patients have aberrant mitochondrial function, highlighted by a lowered RCR. All ratios involving complex I were affected, suggesting that the insufficient ATP formation is predominantly due to complex I dysfunction. Complex II and IV respiration may be impaired as well, but to a lesser extent.

Effects of Alcohol on Postoperative Adhesion Formation in Ischemic Myocardium and Pericardium

Postoperative formation of adhesions increases risk of complications during cardiac reoperations. We previously demonstrated that swine supplemented with vodka had a significant reduction in adhesions at sternotomy after previous thoracotomy. This follow-up study was conducted to determine reproducibility and the mechanism for adhesion reduction in swine supplemented with ethanol. An ameroid constrictor was placed in the left circumflex in 14 male Yorkshire swine to induce chronic myocardial ischemia through left minithoracotomy. Animals were supplemented postoperatively with ethanol (45 g ETOH, n= 7) or sucrose (80 g SUC, n= 7) for 7 weeks, followed by a reoperative median sternotomy. The ETOH group had significantly fewer adhesions, thinner pericardial thickness, decreased intramyocardial fibrosis, and decreased myocardial collagen deposition compared with the SUC group. In the myocardium, ETOH animals had decreased expression of proadhesion proteins focal adhesion kinase, paxillin, integrin-β1, transforming growth factor-β1 and phosphorylated SMAD and increased expression of adhesion breakdown proteins matrix metalloproteinase (MMP) 1, MMP2, MMP3, and MMP9 compared with SUC animals. However in the pericardium, ETOH animals had increased expression of proadhesion proteins focal adhesion kinase, paxillin, phosphorylated paxillin, vinculin, integrin-β1, tumor necrosis factor-α, transforming growth factor-β, and phosphorylated SMAD3, and decreased expression of adhesion breakdown proteins MMP1, MMP3, MMP9, and plasmin compared with SUC animals. Alcohol supplementation substantially reduced postoperative pericardial adhesion formation, attenuated pericardial thickening, and reduced myocardial fibrosis in response to chronic ischemia. Alcohol supplementation modulates adhesion protein and MMP/tissue inhibitor of metalloproteinase expression, favoring a profile associated with reduced pericardial adhesions. These results suggest that the myocardium is the driving factor in reducing pericardial adhesions and mediating the postoperative healing process.

Resveratrol-Mediated Expression of KLF15 in the Ischemic Myocardium is Associated with an Improved Cardiac Phenotype.

Myocardial infarction results in physiological derangements that lead to structural and functional alterations to the myocardium. In addition, oxidative stress potentiates cardiac remodeling and drives disease progression. Unfortunately, treatment with antioxidants in clinical trials have failed to show any therapeutic benefits despite the positive results reported in animal studies, which warrants further investigation into their mechanism(s) of action. Accordingly, the aim of this study was to elucidate a previously unknown mechanism of action for the antioxidant, resveratrol, in the treatment of the ischemic heart. Male Sprague-Dawley rats underwent four weeks of chronic myocardial ischemia with or without daily resveratrol treatment (10mg/kg/day). The expression and signaling of Krüppel-like factor 15 (KLF15) were determined by immunoblot and qPCR analyses, respectively. Chronic myocardial ischemia reduced the protein expression of KLF15. In parallel, mRNA transcripts of KLF15 gene targets actively involved in cardiac remodeling were robustly increased in untreated hearts. Importantly, daily treatment with resveratrol stimulated KLF15 expression, which was associated with attenuated gene expression and an improved cardiac phenotype. Additionally, we describe a novel role for KLF15 in the regulation of redox homeostasis. Based on our current findings, it appears that resveratrol treatment induces KLF15 expression, which may, in part, explain its therapeutic efficacy to improve the cardiac phenotype following ischemic injury.

Improvement of Subjective Well-Being by Ranolazine in Patients with Chronic Angina and Known Myocardial Ischemia (IMWELL Study).

IntroductionWe aimed to assess if ranolazine would improve angina symptoms among patients with documented myocardial ischemia.MethodsEligible subjects had chronic stable angina and at least one coronary stenosis with fractional flow reserve (FFR) ≤0.80 or at least one chronic total occlusion (CTO) without attempted revascularization. Subjects were randomized to oral ranolazine 500 mg twice daily for 1 week, then ranolazine 1000 mg twice daily for 15 weeks versus matching placebo. The primary end point was change in angina at 16 weeks as assessed by the Seattle Angina Questionnaire (SAQ).ResultsBetween September 2014 and January 2016, 25 subjects were randomized to ranolazine versus 25 to placebo. The most common reason for eligibility was CTO (72%), while the remainder had myocardial ischemia documented by low FFR. The mean FFR was 0.57 ± 0.12. Sixty-eight percent of subjects were on two or more anti-angina medications at baseline. Study medication was discontinued in 32% (eight of 25) of the ranolazine group versus 36% (nine of 25) of the placebo group. By intention-to-treat, 46 subjects had baseline and follow-up SAQ data completed. Ranolazine was not associated with an improvement in angina compared with placebo at 16 weeks. The results were similar among 33 subjects that completed study medication. The incidence of ischemia-driven hospitalization or catheterization was 12% (three of 25) of the ranolazine group versus 20% (five of 25) in the placebo group (p > 0.05).ConclusionsIn subjects with chronic stable angina and documented myocardial ischemia, ranolazine did not improve angina symptoms at 16 weeks.FundingGilead.Clinical trial registrationThe study was registered at ClinicalTrials.gov (NCT02265796).

Comparison of the Therapeutic Effects of Acupuncture at PC6 and ST36 for Chronic Myocardial Ischemia.

We aimed to compare the differences of the effects on chronic myocardial ischemia (MI) of acupuncture at PC6 and ST36. The chronic MI model of minipigs was created by implanting an Ameroid constrictor on the left anterior descending coronary artery (LAD) and then two weeks' acupuncture was stimulated at PC6 or ST36, respectively. The results showed that both acupoints' stimulation decreased the serous cardiac troponin T (cTnT) and ischemia modified albumin (IMA) significantly and improved the ischemic ECG changes. The amplitude of pathological Q wave in the PC6 group decreased more significantly than that of the ST36 group. The cardiovascular magnetic resonance imaging (cMRI) results showed that the decreased left ventricular ejection fraction (LVEF) was not improved obviously in both groups. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) enlarged progressively even after acupuncture. The left ventricular wall mass (LVWM) in the ST36 group increased more obviously than that of the PC6 group, which paralleled the decreasing angiotensin II (Ang II) concentration in the plasma. These results suggested that acupuncture at PC6 or ST36 was effective for protecting the myocardium from chronic ischemic injury, and the effect of PC6 seemed to be better.