The sGC-cGMP Signaling Pathway as a Potential Therapeutic Target in Doxorubicin-Induced Heart Failure: A Narrative Review.

The anti-cancer agent doxorubicin (DOX) has high cardiotoxicity that is linked to DOX-mediated increase in oxidative stress, mitochondrial iron overload, DNA damage, autophagy, necrosis, and apoptosis, all of which are also associated with secondary tumorigenicity. This limits the clinical application of DOX therapies. Previous studies have attributed DOX-mediated cardiotoxicity to mitochondrial iron accumulation and the production of reactive oxygen species (ROS), which seem to be independent of its anti-tumor DNA damaging effects. Chemo-sensitization of soluble guanylate cyclase (sGC) in the cyclic guanosine monophosphate (cGMP) pathway induces tumor cell death despite the cardiotoxicity associated with DOX treatment. However, sGC-cGMP signaling must be activated during heart failure to facilitate myocardial cell survival. The sGC pathway is dependent on nitric oxide and signal transduction via the nitric oxide-sGC-cGMP pathway and is attenuated in various cardiovascular diseases. Additionally, cGMP signaling is regulated by the action of certain phosphodiesterases (PDEs) that protect the heart by inhibiting PDE, an enzyme that hydrolyses cGMP to GMP activity. In this review, we discuss the studies describing the interactions between cGMP regulation and DOX-mediated cardiotoxicity and their application in improving DOX therapeutic outcomes. The results provide novel avenues for the reduction of DOX-induced secondary tumorigenicity and improve cellular autonomy during DOX-mediated cardiotoxicity.

Long-Term Clinical Effects of Carotid Intraplaque Neovascularization in Patients with Coronary Artery Disease.

OBJECTIVE: To investigate the predictive value of intraplaque neovascularization (IPN) for cardiovascular outcomes. MATERIALS AND METHODS: We evaluated 217 patients with coronary artery disease (CAD) (158 men; mean age, 68 ± 10 years) with a maximal carotid plaque thickness ≥ 1.5 mm for the presence of IPN using contrast-enhanced ultrasonography. We compared patients with (n = 116) and without (n = 101) IPN during the follow-up period and investigated the predictors of major adverse cardiovascular events (MACE), including cardiac death, myocardial infarction, coronary artery revascularization, and transient ischemic accident/stroke. RESULTS: During the mean follow-up period of 995 ± 610 days, the MACE rate was 6% (13/217). Patients with IPN had a higher maximal thickness than those without IPN (2.86 ± 1.01 vs. 2.61 ± 0.84 mm, p = 0.046). Common carotid artery-peak systolic velocity, left ventricular mass index (LVMI), and ventricular-vascular coupling index were significantly correlated with MACE. However, on multivariate Cox regression analysis, increased LVMI was independently related to MACE (p < 0.05). The presence of IPN could not predict MACE. CONCLUSION: The presence of IPN was related to a higher plaque thickness but could not predict cardiovascular outcomes better than conventional clinical factors in patients with CAD.

Reduced Coronary Flow Reserve Is Associated with Impaired Ventricular-vascular Interaction in Patients with Obstructive Sleep Apnea.

Background and Objectives: Obstructive sleep apnea (OSA) is associated with cardiac and arterial damage and adverse cardiovascular outcomes. We aimed to determine whether coronary flow reserve (CFR), which represents microvascular dysfunction, might be associated with the ventricular-vascular coupling index (VVI), which represents the afterload-adjusted contractility in patients with OSA. Methods: We enrolled 281 patients (257 males; mean age, 43±11 years) with newly diagnosed OSA. Transthoracic echocardiography was performed, and adenosine-associated CFR was measured in the left anterior descending coronary artery. We evaluated the differences between the patients with normal CFR ≥2.5 and reduced CFR <2.5. VVI was calculated using the effective arterial elastance (Ea) and left ventricular (LV) end-systolic elastance (Ees) as follows: 10×Ea/Ees. Results: The normal CFR group (n=214) showed increased Ees (7.28±2.31 vs. 8.14±2.33 mmHg/mL, p=0.016) and preserved VVI (3.17±1.53 vs. 2.78±1.20, p=0.044) compared with the reduced CFR group (n=67). There were no differences in LV dimension, LV ejection fraction, left atrial-volume index, E/e', left atrial strain and LV global longitudinal strain between the 2 groups (all p>0.05). CFR was significantly correlated to Ees (r=0.139; p=0.023) and VVI (r=-0.137; p=0.025). Conclusions: Reduced CFR is associated with decreased Ees and impaired VVI in OSA patients. It suggests the necessity of more intensive observation in OSA patients with reduced CFR to improve cardiovascular outcomes.

Substance-P Prevents Cardiac Ischemia-Reperfusion Injury by Modulating Stem Cell Mobilization and Causing Early Suppression of Injury-Mediated Inflammation.

BACKGROUND/AIMS: Therapies using stem/progenitor cells have been experimentally and clinically investigated to regenerate damaged hearts. Substance-P (SP) induces bone marrow (BM) stem cell mobilization and suppresses inflammation in ischemic injuries. This study investigated the role of SP in BM stem cell mobilization and immune responses for tissue repair after ischemic-reperfusion injury (IRI), in comparison with that of granulocyte colony-stimulating factor (GCSF). METHODS: SP was intravenously injected into IRI rats and its affect was evaluated by determining colony forming efficiency, immune cell/ cytokine profiles, histological changes, and heart function through echocardiography. RESULTS: In the rat cardiac IRI model, SP suppressed IRI-mediated tumor necrosis factor-α induction, but increased the levels of interleukin-10, CD206+ monocytes, and regulatory T cells in the blood; reduced myocardial apoptosis at day 1 post-IRI; and markedly stimulated colony forming unit (CFU)-e and (CFU)-f cell mobilization. Efficacy of SP in the recovery of cardiac function after IRI was demonstrated by increased cardiac contractility, accompanied by reduced infarction sizes and fibrosis, and increased revascularization of vessels covered with alpha smooth muscle actin. These effects of SP were confirmed in an acute myocardial infarction (AMI) model. All effects mediated by SP were superior to those mediated by GCSF. CONCLUSION: Systemic injection of SP decreased early inflammatory responses and promoted stem cell mobilization, leading to a compact vasculature and improved cardiac function in cardiac IRI and AMI.

The pharmacodynamics of low and standard doses of ticagrelor in patients with end stage renal disease on hemodialysis.

BACKGROUND: Patients with end-stage renal disease (ESRD) on maintenance hemodialysis (HD) respond poorly to clopidogrel. We assessed the utility of low-dose ticagrelor in ESRD patients on maintenance HD. METHODS: In this single-center, prospective, randomized pharmacodynamic study, 52 ESRD patients on HD were prescribed clopidogrel (300mg loading dose [LD], then 75mg daily), standard-dose ticagrelor (180mg LD, then 90mg twice daily), or low-dose ticagrelor (90mg LD, then 90mg daily) for 14days. Platelet function was evaluated before and after therapy via light transmittance aggregometry and the VerifyNow™ P2Y12 assay. RESULTS: The adenosine diphosphate (ADP)-induced maximal extent of platelet aggregation differed significantly between the low-dose ticagrelor and clopidogrel groups (ANCOVA, p=0.04 after stimulation with 5µmol/L ADP; p<0.01 after stimulation with 20µmol/L ADP). Inhibition of platelet aggregation increased significantly in the order of clopidogrel, low-dose ticagrelor, and standard-dose ticagrelor, as revealed by adjusted intergroup comparison analysis (ANCOVA, p=0.04 after stimulation with 5µmol/L ADP; p=0.005 after stimulation with 20µmol/L ADP). The rates of onset of the antiplatelet effect curves from 0 to 5h after administration of the LDs were greater in the standard- and low-dose ticagrelor groups than in the clopidogrel group. Significant sequential reductions in P2Y12 reaction units were noted, in the following order: clopidogrel, low-dose ticagrelor, and standard-dose ticagrelor (ANCOVA, p<0.001). No bleeding occurred in the low-dose ticagrelor group. CONCLUSIONS: Low-dose ticagrelor afforded greater platelet inhibition than did clopidogrel in ESRD patients on HD.

Close look at the experiences of patients enrolled in a clinical trial of acupuncture treatment for atrial fibrillation in Korea: a qualitative study nested within a randomised controlled trial.

OBJECTIVE: To explore the experiences of patients with atrial fibrillation (AF) in the context of a prospective, two-parallel-armed, participant-blinded and assessor-blinded sham-controlled randomised trial. DESIGN: A nested qualitative study within an ongoing randomised controlled trial to explore acupuncture's antiarrhythmic effects on drug refractory acupuncture in persistent atrial fibrillation (AF) (ACU-AF trial). PARTICIPANTS: Participants were recruited using purposeful sampling and a maximum variation strategy with regard to treatment allocation (treatment or control) and protocol completion (completion or non-completion). SETTING: This was a single-centre in-depth interview qualitative study conducted at a tertiary-level university hospital in Seoul, Republic of Korea. RESULTS: Data saturation was reached after 8 participants. Thematic analysis identified that most patients were not aware of their condition until medical check-up; physician referral was the main reason for trial participation, and patients had high expectations regardless of previous acupuncture experiences. Patients tended to depend on their physicians' opinions because they felt helpless of their condition. No one questioned their assigned treatment groups and generally believed acupuncture treatment was different for cardiovascular diseases. A few patients expressed disappointment in the strict and rigid protocols, in which most practitioners refrained from explaining their acupuncture procedures. CONCLUSIONS: For cardiovascular patients their physician's advice was one of the biggest reasons for enrolling in the acupuncture trial therefore relying on standard recruitment methods may not be effective. Fortunately both real and sham acupuncture groups in our sample were receiving treatment as intended, but in the future, designing a more pragmatic trial (better reflecting clinical settings, expanding the inclusion criteria and using more treatment points) will allow researchers to better explore the comprehensive effects of acupuncture. The findings of this study will allow researchers to improve the currently ongoing ACU-AF trial and to further help interpretation of main trial outcomes once the trial is completed. TRIAL REGISTRATION NUMBER: NCT02110537.

Exenatide Prevents Morphological and Structural Changes of Mitochondria Following Ischaemia-Reperfusion Injury.

BACKGROUND: Exenatide exerts cardioprotective effects by attenuating ischaemic reperfusion (IR) injury, possibly through activating the opening of mitochondrial ATP-sensitive potassium channels. We used atomic force microscopy (AFM) to investigate changes in mitochondrial morphology and properties in order to assess exenatide-mediated cardioprotection in IR injury. METHODS: We used an in vivo Sprague-Dawley rat IR model and ex vivo Langendorff injury model. In the left anterior descending artery (LAD) occlusion model, animals were randomly divided into three groups: sham-operated rats (Sham, n=5), IR-injured rats treated with placebo (IR, n=6), and IR-injured treated with exenatide (IR + EXE, n=6). For the Langendorff model, rats were randomly divided into two groups: IR injury with placebo (IR, n=4) and IR injury with exenatide (IR+EXE, n=4). Morphological and mechanical changes of mitochondria were analysed by AFM. RESULTS: Exenatide pre-treatment improved cardiac function as evidenced by improvement in echocardiographic results. The ratio of infarct area (IA) to risk area (RA) was significantly reduced in exenatide-treated rats. According to AFM, IR significantly increased the area of isolated mitochondria, indicative of mitochondrial swelling. Treatment with exenatide reduced the mitochondrial area and ameliorated the adhesion force of mitochondrial surfaces. CONCLUSIONS: Exenatide pre-treatment improves morphological and mechanical characteristics of mitochondria in response to IR injury in a rat model. These alterations in mitochondrial characteristics appear to play a cardioprotective role against IR injury.

Roles of High-Density Lipoprotein Cholesterol in Patients With Acute Myocardial Infarction.

Many observational studies showed hogh-density lipoprotein cholesterol (HDL-C) is a strong inverse predictor of cardiovascular (CV) outcome. However, recent large clinical trials evaluating therapies to raise HDL-C level in those already on statin therapy have been discouraging. This complexity is not well-known.A total of 28,357 acute myocardial infarction (AMI) patients were enrolled in the Korea Acute Myocardial Infarction Registry (KAMIR), which was a prospective, multicenter, nationwide, web-based database of AMI in Korea. From this registry, we evaluated 3574 patients with AMI who have follow-up HDL-C level to investigate its association with clinical outcomes. The primary endpoint was the relationship between follow-up change in HDL-C and a 12-month composite of major adverse cardiac events (MACEs).Patients with initial HDL-C ≥ 40 mg/dL showed significantly lower rates of 12-month MACEs, especially cardiac and all-cause mortalities (P < 0.001). When patients were stratified into 4 groups according to the change of HDL-C, patients with decreasing HDL-C showed significantly higher rates of 12-month MACEs as comparable with patients with increasing HLD-C. A multivariate analysis indicated that HDL-C level was a significant predictor of CV events (hazard ratio, 1.38; 95% confidence interval, 1.12-1.71) after correcting for confounding variables.The follow-up change in HDL-C level was significantly related with CV outcomes in patients with AMI.

The Dose-Dependent Organ-Specific Effects of a Dipeptidyl Peptidase-4 Inhibitor on Cardiovascular Complications in a Model of Type 2 Diabetes.

OBJECTIVE: Although dipeptidyl peptidase-4 (DPP-4) inhibitors have been suggested to have a non-glucoregulatory protective effect in various tissues, the effects of long-term inhibition of DPP-4 on the micro- and macro-vascular complications of type 2 diabetes remain uncertain. The aim of the present study was to investigate the organ-specific protective effects of DPP-4 inhibitor in rodent model of type 2 diabetes. METHODS: Eight-week-old diabetic and obese db/db mice and controls (db/m mice) received vehicle or one of two doses of gemigliptin (0.04 and 0.4%) daily for 12 weeks. Urine albumin excretion and echocardiography measured at 20 weeks of age. Heart and kidney tissue were subjected to molecular analysis and immunohistochemical evaluation. RESULTS: Gemigliptin effectively suppressed plasma DPP-4 activation in db/db mice in a dose-dependent manner. The HbA1c level was normalized in the 0.4% gemigliptin, but not in the 0.04% gemigliptin group. Gemigliptin showed a dose-dependent protective effect on podocytes, anti-apoptotic and anti-oxidant effects in the diabetic kidney. However, the dose-dependent effect of gemigliptin on diabetic cardiomyopathy was ambivalent. The lower dose significantly attenuated left ventricular (LV) dysfunction, apoptosis, and cardiac fibrosis, but the higher dose could not protect the LV dysfunction and cardiac fibrosis. CONCLUSION: Gemigliptin exerted non-glucoregulatory protective effects on both diabetic nephropathy and cardiomyopathy. However, high-level inhibition of DPP-4 was associated with an organ-specific effect on cardiovascular complications in type 2 diabetes.

Mycophenolate Mofetil Ameliorates Diabetic Nephropathy in db/db Mice.

Chronic low-grade inflammation is an important factor in the pathogenesis of diabetic complication. Mycophenolate mofetil (MMF) has an anti-inflammatory effect, inhibiting lymphocyte proliferation. Previous studies showed attenuation of diabetic nephropathy with MMF, but the underlying mechanisms were unclear. This study aimed to identify the effect of MMF on diabetic nephropathy and investigate its action mechanisms in type 2 diabetic mice model. Eight-week-old db/db and control mice (db/m mice) received vehicle or MMF at a dose of 30 mg/kg/day for 12 weeks. MMF-treated diabetic mice showed decreased albuminuria, attenuated mesangial expansion, and profibrotic mRNA expressions despite the high glucose level. The number of infiltrated CD4(+) and CD8(+) T cells in the kidney was significantly decreased in MMF-treated db/db mice and it resulted in attenuating elevated intrarenal TNF-α and IL-17. The renal chemokines expression and macrophages infiltration were also attenuated by MMF treatment. The decreased expression of glomerular nephrin and WT1 was recovered with MMF treatment. MMF prevented the progression of diabetic nephropathy in db/db mice independent of glycemic control. These results suggest that the effects of MMF in diabetic nephropathy are mediated by CD4(+) T cell regulation and related cytokines.

Effect of onion peel extract on endothelial function and endothelial progenitor cells in overweight and obese individuals.

OBJECTIVES: Acute or chronic intake of polyphenol-rich foods has been reported to improve endothelial function. Quercetin, found abundantly in onion, is a potent antioxidant flavonoid. The aim of this study was to investigate whether consumption of onion peel extract (OPE) improves endothelial function in healthy overweight and obese individuals. METHODS: This was a randomized double-blind, placebo-controlled study. Seventy-two healthy overweight and obese participants were randomly assigned to receive a red, soft capsule of OPE (100 mg quercetin/d, 50 mg quercetin twice daily; n = 36 participants) or an identical placebo capsule (n = 36) for 12 wk. Endothelial function, defined by flow-mediated dilation (FMD), circulating endothelial progenitor cells (EPCs) by flow cytometry, and laboratory test were determined at baseline and after treatment. RESULTS: Baseline characteristics and laboratory findings did not significantly differ between the two groups. Compared with baseline values, the OPE group showed significantly improved FMD at 12 wk (from 12.5 ± 5.2 to 15.2 ± 6.1; P = 0.002), whereas the placebo group showed no difference. Nitroglycerin-mediated dilation did not change in either group. EPC counts (44.2 ± 25.6 versus 52.3 ± 18.6; P = 0.005) and the percentage of EPCs were significantly increased in the OPE group. When FMD was divided into quartiles, rate of patients with endothelial dysfunction defined as lowest quartile (cutoff value, 8.6%) of FMD improved from 26% to 9% by OPE. CONCLUSION: Medium-term administration of OPE an improvement in FMD and circulating EPCs.

Platelet reactivity after receiving clopidogrel compared with ticagrelor in patients with kidney failure treated with hemodialysis: a randomized crossover study.

BACKGROUND: Patients with kidney failure treated with maintenance hemodialysis (HD) are poor responders to clopidogrel. More beneficial platelet-inhibiting strategies in HD patients therefore are required. STUDY DESIGN: Single-center, prospective, randomized, crossover study. SETTING & PARTICIPANTS: 25 HD patients in Seoul, Korea. INTERVENTION: Patients were randomly assigned to receive clopidogrel (300mg loading, 75mg once daily for maintenance dose) or ticagrelor (180mg loading, 90mg twice daily for maintenance dose) for 14 days, and after a 14-day washout period, crossover treatment for another 14 days. All patients received aspirin (100mg/d). OUTCOMES & MEASUREMENTS: Platelet function was evaluated predosing and at 1, 5, and 48 hours and 14 days after the first loading dose. During the offset phase, platelet function was assessed at 1 hour and 2, 4, and 14 days after the last dose by light transmittance aggregometry and the VerifyNow P2Y12 assay, and patients were genotyped for the CYP2C19*2 allele. Maximal extent of aggregation, inhibition of platelet aggregation (IPA), P2Y12 reaction units (PRUs), and percentage of inhibition were evaluated. We performed per-protocol analysis, excluding patients who did not complete the protocol. RESULTS: 9 patients did not complete the protocol (7 patients due to adverse events; 2, nonadherence). Higher IPA occurred with ticagrelor than with clopidogrel at 1, 5, and 48 hours and 14 days after loading. By 5 hours after loading, a greater proportion of patients in the ticagrelor group than in the clopidogrel group achieved IPA>50% (75% vs 12%, respectively; P<0.05) and IPA>70% (44% vs 0%, respectively; P<0.05). Rates (slope) of onset and offset of the antiplatelet effect were faster in patients receiving ticagrelor than for those receiving clopidogrel (P<0.05). Regardless of CYP2C19*2 allele, the ticagrelor group had significantly lower PRUs at all times than the clopidogrel group. LIMITATIONS: Single-center study with a small number of patients, not a double-blind study, and not intention-to-treat analysis. CONCLUSIONS: Ticagrelor may result in more rapid and greater platelet inhibition than clopidogrel in patients with kidney failure receiving HD.

Impact of lysophosphatidylcholine on survival and function of UEA-1(+)acLDL (+) endothelial progenitor cells in patients with coronary artery disease.

Lysophosphatidylcholine (LPC) generated from oxidized low-density lipoprotein by lipoprotein-associated phospholipase A2 plays a key role in plaque inflammation and vulnerability. Endothelial progenitor cells (EPCs) can repair injured endothelium and exert anti-inflammatory effects of vulnerable plaque. We study the impact and mechanisms of LPC on UEA-1 and acLDL binding EPCs (UEA-1(+)acLDL(+) EPCs). UEA-1(+)acLDL(+) EPCs from coronary artery disease (CAD) patients were cultured and exposed to LPC at different concentrations and different timepoints. We determined the significant concentration (40 µM). UEA-1(+)acLDL(+) EPCs were preincubated for 30 min with pravastatin (20 µM) with LY249002, a specific inhibitor of the Akt signaling pathway, and exposed for 24 h to LPC 40 µM. The survival, migration, adhesion, and proliferation of UEA-1(+)acLDL(+) EPCs were assessed. To examine the mechanisms of LPC toxicity and pravastatin effects, phosphorylated Akt and endothelial nitric oxide synthase (eNOS) levels and the ratio of Bcl-2/Bax protein expression were assessed. LPC induced apoptosis and impaired migration and adhesion of UEA-1(+)acLDL(+) EPCs significantly. The detrimental effects of LPC were attenuated by pravastatin. However, when UEA-1(+)acLDL(+) EPCs were pretreated with pravastatin and LY249002, a specific inhibitor of the Akt signaling pathway, simultaneously, the beneficial effects of pravastatin were abolished. Furthermore, LPC suppressed Akt and eNOS phosphorylation and increased Bcl-2/Bax expression. The effects of LPC on Akt/eNOS and Bcl-2/Bax activity were reversed by pravastatin. In conclusion, LPC inhibited UEA-1(+)acLDL(+) EPCs survival and impaired its functions, and these were attributable to inhibition of the Akt/eNOS and Bcl-2/Bax pathway. Pravastatin reversed the detrimental action of LPC. These findings suggest that LPC inhibition can be a possible strategy for CAD through EPC revitalization.

Effect of platelet reactivity, endothelial function, and inflammatory status on outcomes in patients with stable angina pectoris on clopidogrel therapy.

Although high on-treatment platelet reactivity (HTPR) is an important predictor of clinical outcomes in patients undergoing coronary stenting, it is unknown whether endothelial dysfunction and HTPR are associated. We examined the platelet function, peripheral vascular function, endothelial progenitor cell (EPC) number, platelet activation markers, high-sensitivity C-reactive protein (hs-CRP) level, and clinical outcomes in patients receiving chronic clopidogrel therapy. We consecutively enrolled 91 patients who underwent follow-up angiography because of chest discomfort. All patients took aspirin and clopidogrel for an average of 498 ± 138 days. Platelet reactivity was assessed by light transmittance aggregometry (maximal platelet aggregation by 5 µmol/L of adenosine diphosphate ≤50% in group 1 [optimal response] and >50% as group 2 [HTPR]). Flow-mediated dilation of the brachial artery and brachial-ankle pulse wave velocity (PWV), numbers of EPCs isolated from peripheral blood, platelet activation markers (soluble CD40 ligand and soluble P-selectin), and hs-CRP levels were assessed before follow-up angiography. There were no significant differences in baseline characteristics and previous percutaneous coronary intervention (PCI) data between groups 1 (n = 59) and 2 (n = 32). Group 2 showed poorer flow-mediated dilation (6.1 ± 4.1% vs 12.9 ± 6.2%, p <0.001), pulse wave velocity (1925.4 ± 362.2 vs 1571.0 ± 306.5 ms, p <0.001), and lower circulating EPCs by flow cytometry (21.9 ± 14.7 vs 65.2 ± 30.1 per 10 fields, p <0.001) compared with group 1. Significantly higher levels of soluble CD40 ligand, soluble P-selectin, and hs-CRP were observed in group 2. In multivariate analysis, elevated hs-CRP level, but not HTPR, was independently associated with repeated PCI. In patients with angina, HTPR was associated endothelial dysfunction and elevated hs-CRP, although elevated hs-CRP level was significantly associated with poorer outcomes.

Cardioprotective effects of exenatide in patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention: results of exenatide myocardial protection in revascularization study.

OBJECTIVE: Experimental evidence suggests that exenatide, a glucagon-like peptide 1 receptor analogue, has significant cardiovascular protective effects in various conditions. We examined whether routine use of exenatide at the time of primary percutaneous coronary intervention would reduce infarct size in patients with ST-segment-elevation myocardial infarction. APPROACH AND RESULTS: Fifty-eight patients with ST-segment-elevation myocardial infarction and thrombolysis in myocardial infarction flow 0 were enrolled in the study and randomly assigned to receive either exenatide or placebo (saline) subcutaneously. Infarct size was assessed by measuring the release of creatine kinase-MB and troponin I during 72 hours and by performing cardiac magnetic resonance imaging at 1 month after infarction. Routine and speckle tracking echocardiography was performed at initial presentation and at 3 days and 6 months after primary percutaneous coronary intervention. The exenatide and control groups had similar results with respect to ischemia time, demographic characteristics, and ejection fraction before primary percutaneous coronary intervention. The releases of creatine kinase-MB and troponin I were significantly reduced in the exenatide group. In 58 patients evaluated with cardiac magnetic resonance, the absolute mass of delayed hyperenhancement was significantly reduced in the exenatide group as compared with the control group (12.8±11.7 versus 26.4±11.6 g; P<0.01). At 6 months, the exenatide group showed a significantly lower value of E/E' with improved strain parameters. No significant adverse effects of exenatide administration were detected. CONCLUSIONS: In patients with ST-segment-elevation myocardial infarction, adjunctive exenatide therapy with primary percutaneous coronary intervention was associated with reduction of infarct size and improvement of subclinical left ventricular function.

Effect of myocardial protection of intracoronary adenosine and nicorandil injection in patients undergoing non-urgent percutaneous coronary intervention: a randomized controlled trial.

BACKGROUND: Several studies have demonstrated that adenosine and nicorandil protect the myocardium against angioplasty-related myocardial injury. We conducted a prospective study to investigate the myocardial protective effects of combination therapy with intracoronary adenosine and nicorandil. METHODS: We enrolled 213 consecutive patients with stable or unstable angina who were scheduled for non-urgent PCI for de-novo coronary lesions. Patients were randomized into group I (control saline, n=55), group II (adenosine 50 µg, n=54), group III (nicorandil 4 mg, n=54), or group IV (adenosine-nicorandil combination, n=50). Serial assessments of CK-MB were used to assess myocardial necrosis before and after PCI. The primary endpoint was the incidence of myocardial necrosis (elevation of CK-MB), and the secondary endpoints were the changes in serum CK-MB and cTnI levels and the incidence of post-procedural myocardial infarction (MI). RESULTS: No significant differences were observed among the four groups with regard to baseline or angiographic characteristics. No major adverse events related to adenosine and nicorandil were observed. There were no significant differences in the incidence of post-procedural myocardial necrosis among the four groups (10.9, 14.8, 14.8, and 14.0%, respectively, p=0.9). There were no significant differences in the incidence of post-procedural MI among groups (p=0.6). In multivariate regression analysis, multivessel stenting, median stent length, and the presence of a compromised side branch were independent predictors of myonecrosis. CONCLUSIONS: Pretreatment with intracoronary adenosine, nicorandil, or the combination of the two drugs did not reduce the incidences of myocardial necrosis or MI after non-urgent PCI in patients with low-risk angina pectoris.

Preventive effects of exenatide on endothelial dysfunction induced by ischemia-reperfusion injury via KATP channels.

OBJECTIVE: The purpose of this study was to evaluate whether exenatide administration can prevent impairment in endothelium-dependent vasodilatation induced by ischemia-reperfusion (IR) injury and whether this effect is mediated by K(ATP) channel opening. METHODS AND RESULTS: In a double-blind, placebo-controlled, crossover design, 20 volunteers were randomly assigned to 2 groups: subcutaneous exenatide (10 µg) or placebo administration. At 30 minutes after the study drug administration, endothelium-dependent flow-mediated dilatation (FMD) of the radial artery was measured before and after IR (15 minutes of ischemia at the level of the brachial artery followed by 15 minutes of reperfusion) injury. Seven days later, both groups were crossed over and received the other treatment (ie, placebo or exenatide) and underwent the same protocol. Pre-IR radial artery diameter, FMD, and baseline radial artery diameter after IR injury were similar between 2 groups (P=no significant difference). After placebo administration, IR significantly blunted FMD (before IR: 12.0±6.23%; after IR: 4.6±3.57%, P=0.02). Exenatide prevented this impairment (FMD before IR: 15.0±7.14%; FMD after IR: 15.0±5.96%, P=no significant difference; P<0.001 compared with placebo). In a separate protocol, this protective effect was completely abolished by pretreatment with glibenclamide (glyburide, 5 mg), a blocker of K(ATP) channels (n=7; FMD before IR: 12.0±2.2%; after IR: 3.2±2.1%, P<0.001). CONCLUSIONS: The present study demonstrates that subcutaneous exenatide protects IR-induced endothelial dysfunction through opening of K(ATP) channels in human IR injury model.