Neutrophil Extracellular Trap Components Associate with Infarct Size, Ventricular Function, and Clinical Outcome in STEMI.

BACKGROUND: The relevance of neutrophil extracellular traps (NETs) in acute ST-elevation myocardial infarction (STEMI) is unclear. We explored the temporal profile of circulating NET markers and their associations to myocardial injury and function and to adverse clinical events in STEMI patients. METHODS AND RESULTS: In 259 patients, blood samples were drawn before and after PCI, on day 1, and after 4 months. Double-stranded deoxyribonucleic acid (dsDNA) and myeloperoxidase-DNA (MPO-DNA) were measured in serum by a nucleic acid stain and ELISA. Cardiac magnetic resonance imaging assessed microvascular obstruction (MVO), area at risk, infarct size, myocardial salvage index, left ventricular ejection fraction (LVEF), and change in indexed left ventricular end-diastolic volume (LVEDVi). Clinical events were registered after 12 months. dsDNA and MPO-DNA levels were highest before PCI, with reduced levels thereafter (all p ≤ 0.02). Patients with high vs. low day 1 dsDNA levels (>median; 366 ng/ml) more frequently had MVO, larger area at risk, larger infarct size acutely and after 4 months, and lower myocardial salvage index (all p < 0.03). Moreover, they had lower LVEF acutely and after 4 months, and larger change in LVEDVi (all p ≤ 0.014). High day 1 dsDNA levels also associated with risk of having a large infarct size (>75th percentile) and low LVEF (≤49%) after 4 months when adjusted for gender, time from symptoms to PCI, and infarct localization (OR 2.3 and 3.0, both p < 0.021), and patients with high day 1 dsDNA levels were more likely to experience an adverse clinical event, also when adjusting for peak troponin T (hazard ratio 5.1, p = 0.012). No such observations were encountered for MPO-DNA. CONCLUSIONS: High day 1 dsDNA levels after STEMI were associated with myocardial infarct size, adverse left ventricular remodeling, and clinical outcome. Although the origin of dsDNA could be discussed, these observations indicate a potential role for dsDNA in acute myocardial ischemia. This trial is registered with S-08421d, 2008/10614 (Regional Committee for Medical Research Ethics in South-East Norway (2008)).

Association of IL-8 With Infarct Size and Clinical Outcomes in Patients With STEMI.

BACKGROUND: Little is known about the role of interleukin (IL)-8 in patients with acute ST-segment elevation myocardial infarction (STEMI). OBJECTIVES: The aims of this study were to evaluate, in STEMI patients, the temporal profile of IL-8 and possible associations with left ventricular (LV) function and remodeling, infarct size, microvascular obstruction, myocardial salvage, and future clinical events. METHODS: A total of 258 patients with STEMI were included. Blood samples were drawn before and immediately after percutaneous coronary intervention (PCI), at day 1, and after 4 months. Cardiac magnetic resonance imaging was performed in the acute phase and after 4 months. Clinical events were registered during 12 months' follow-up and all-cause mortality after median 70 months' follow-up. RESULTS: Patients with IL-8 levels greater than the median measured both immediately after PCI and at day 1 had larger final infarct size, lower LV ejection fraction, larger increase in LV end-diastolic volume, and higher frequency of microvascular obstruction. After multivariate adjustment, high IL-8 levels at day 1 were associated with an increased risk of developing a large MI and having reduced LV ejection fraction at 4 months, also after adjustment for peak troponin value. Patients with IL-8 levels in the highest quartile measured at all sampling points were more likely to have a clinical event during the first 12 months after the MI and had lower overall survival during long-term follow-up. CONCLUSIONS: High levels of circulating IL-8 were associated with large infarct size, impaired recovery of LV function, and adverse clinical outcome in patients with STEMI, suggesting IL-8 as a future therapeutic target based on its important role in post-infarction inflammation.

Soluble IL-1 receptor 2 is associated with left ventricular remodelling in patients with ST-elevation myocardial infarction.

BACKGROUND: The inflammatory response following myocardial infarction (MI) is prerequisite for proper healing of infarcted tissue, but can also have detrimental effects on cardiac function. Interleukin (IL)-1α and IL-1ß are potent inflammatory mediators and their bioactivity is tightly regulated by IL-1 receptor antagonist (IL-1ra) and soluble (s) IL-1 receptors (R). We aimed to examine whether levels of soluble regulators of IL-1 signalling are changed during ST-elevation MI (STEMI) and their associations with parameters of cardiac injury and ventricular remodelling. METHODS: Plasma levels of IL-1Ra, sIL-1R1, sIL-1R2 and sIL-1R accessory protein (sIL-1RAcP) were measured by immunoassays in repeated samples from patients with STEMI (n = 255) and compared to healthy controls (n = 65). RESULTS: IL-1Ra, sIL-1R1 and sIL-1R2 levels were all significantly elevated after STEMI, while levels of sIL-1RAcP were lower compared to controls. sIL-1R2 levels (at different time points) correlated positively with C-reactive protein, myocardial infarct size and change in indexed left ventricular end-diastolic and end-systolic volume (LVEDVi and LVESVi) measured by cardiac MR acutely and after 4 months, and negatively with LV ejection fraction. Patients with >median levels of sIL-1R2 in the acute phase were more likely to have increased change in LVEDVi and LVESVi. Importantly, sIL-1R2 remained significantly associated with change in LVEDVi and LVESVi also after adjustment for clinical covariates. CONCLUSION: Levels of sIL-1R2 are independently associated with parameters of LV adverse remodelling following STEMI.

Evaluation of circulating levels of CCN2/connective tissue growth factor in patients with ST-elevation myocardial infarction.

CCN2/Connective tissue growth factor seems to be involved in development of cardiac hypertrophy and fibrosis, but a possible cardioprotective role in left ventricular (LV) remodelling following myocardial infarction has also been suggested. The main objectives of the study were therefore to investigate whether circulating CCN2 levels were associated with infarct size, LV function, adverse remodelling or clinical outcome in two cohorts of patients with ST-elevation myocardial infarction (STEMI). CCN2 was measured in 988 patients 18 hours after PCI and clinical events were recorded after 55 months in the BAMI cohort. In the POSTEMI trial, serial measurements of CCN2 were performed in 258 STEMI patients during index hospitalisation and cardiac magnetic resonance imaging was performed in the acute phase and after 4 months. Clinical events were also recorded. There were no significant associations between levels of CCN2 and infarct size, LV ejection fraction, changes in LV end-diastolic or end-systolic volume, myocardial salvage or microvascular obstruction. There were no significant associations between CCN2 levels and clinical events including mortality, in either of the study cohorts. In conclusion, circulating levels of CCN2 measured in the acute phase of STEMI were not associated with final infarct size, left ventricular function or new clinical events.

Osteoprotegerin levels in ST-elevation myocardial infarction: Temporal profile and association with myocardial injury and left ventricular function.

BACKGROUND: Elevated levels of osteoprotegerin (OPG) have been associated with adverse outcomes in ST-elevation myocardial infarction (STEMI). However, the role of OPG in myocardial injury and adverse remodeling in STEMI patients remains unclear. The aims of this observational cohort study were to evaluate: 1) the temporal profile of OPG during STEMI, 2) possible associations between OPG measured acutely and after 4 months, with infarct size, adverse left ventricular (LV) remodeling, microvascular obstruction (MVO) and myocardial salvage and 3) the effect of heparin administration on OPG levels. METHODS: Blood samples were drawn repeatedly from 272 STEMI patients treated with primary percutaneous coronary intervention (PCI). Cardiac magnetic resonance imaging (CMR) was performed in the acute phase and after 4 months. The effect of heparin administration on OPG levels was studied in 20 patients referred to elective coronary angiography. RESULTS: OPG levels measured acutely were significantly higher than Day 1 and during follow-up. OPG levels were correlated with age. No association was found between early OPG levels and CMR measurements at 4 months. Patients with >median OPG levels measured at Day 1 had larger final infarct size, lower LV ejection fraction (LVEF) at 4 months and higher frequency of MVO. There were no associations between OPG and change in end-diastolic volume or myocardial salvage. OPG remained associated with infarct size and LVEF after adjustment for relevant covariates, except peak troponin T and CRP. A 77% increase in OPG levels following heparin administration was found in patients undergoing elective coronary angiography. CONCLUSIONS: OPG was found to be associated with myocardial injury, but not with LV remodeling or myocardial salvage. The use of OPG as a biomarker in STEMI patients seems to be limited by a strong association with age, confounding effect of heparin administration, and little additive value to established biomarkers.

Effect of ischemic postconditioning on infarct size in patients with ST-elevation myocardial infarction treated by primary PCI results of the POSTEMI (POstconditioning in ST-Elevation Myocardial Infarction) randomized trial.

BACKGROUND: Reduction of infarct size by ischemic postconditioning (IPost) has been reported in smaller proof-of-concept clinical studies, but has not been confirmed in other smaller studies. The principle needs to be evaluated in larger groups of ST-elevation myocardial infarction (STEMI) patients before being implemented in clinical practice. This study assessed the effect of ischemic postcoditioning (IPost) on infarct size in patients with STEMI treated by primary percutaneous coronary intervention (PCI). METHODS AND RESULTS: Patients with first-time STEMI, <6 hours from symptom onset, referred to primary PCI were randomized to IPost or control groups. IPost was administered by 4 cycles of 1-minute reocclusion and 1-minute reperfusion, starting 1 minute after opening, followed by stenting. In the control group, stenting was performed immediately after reperfusion. The primary endpoint was infarct size measured by cardiac magnetic resonance after 4 months. A total of 272 patients were randomized. Infarct size (percent of left ventricular mass) after 4 months (median values and interquartile range) was 14.4% (7.7, 24.6) and 13.5% (8.1, 19.3) in the control group and IPost group, respectively (P=0.18). No significant impact of IPost was found when controlling for baseline risk factors of infarct size in a multivariate linear regression model (P=0.16). The effects of IPost on secondary endpoints, including markers of necrosis, myocardial salvage, and ejection fraction, as well as adverse cardiac events during follow-up, were consistently neutral. CONCLUSIONS: In contrast to several smaller trials reported previously, we found no significant effects of IPost on infarct size or secondary study outcomes. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov Unique identifier: NCT.No.PO1506.

Myocardial salvage is reduced in primary PCI-treated STEMI patients with microvascular obstruction, demonstrated by early and late CMR.

OBJECTIVES: This study evaluates the association between microvascular obstruction and myocardial salvage, determined by cardiac magnetic resonance performed both in the acute stage of myocardial infarction and after 4 months. METHODS: In patients with acute ST-elevation myocardial infarction treated by primary percutaneous coronary intervention, myocardial salvage, infarct size, left ventricular volumes, and ejection fraction were assessed by early (1-4 days) and follow-up (4 months) cardiac magnetic resonance. These variables were related to the presence or absence of microvascular obstruction at early investigation. Myocardial salvage was determined by: (1) myocardium at risk and infarct size measured in the acute stage and (2) myocardium at risk, measured acutely, and infarct size measured after 4 months. Multivariate analyses were performed, adjusting for clinical confounders at baseline. RESULTS: Microvascular obstruction was present in 49 of 94 included patients, (52%). Myocardial salvage was significantly reduced in patients with microvascular obstruction, compared to those without: 23% vs. 38%, measured acutely, and 39.8% vs. 65.4%, after 4 months (p<0.001). The presence of microvascular obstruction was significantly and independently associated with large infarct size, lower left ventricular ejection fraction, and larger left ventricular end-systolic volume. CONCLUSION: The presence of microvascular obstruction demonstrated by cardiac magnetic resonance early after infarction was associated with impaired myocardial salvage. This association was more marked when based on measurement of infarct size after 4 months compared to assessment in the acute stage.

Rationale and design of the POSTEMI (postconditioning in ST-elevation myocardial infarction) study.

Rapid reperfusion of the infarct-related coronary artery is essential in the treatment of acute ST-elevation myocardial infarction (STEMI). Paradoxically, restoration of the blood flow to the ischemic area may result in further injury to the myocardium. This phenomenon is described as 'ischemia/reperfusion injury' and the pathophysiological mechanisms are not fully elucidated. A cardioprotective effect of ischemic postconditioning (short repetitive cycles of reperfusion and re-occlusion) has been demonstrated in experimental studies and in pilot studies on patients with acute STEMI treated with primary percutaneous coronary intervention. We present the study design of the Postconditioning in ST-Elevation Myocardial Infarction (POSTEMI) study, which is a prospective, randomized, open-label clinical trial with blinded endpoint evaluation designed to evaluate the effect of postconditioning on final infarct size. Patients with acute STEMI with symptoms of less than 6 h and proximal or mid-coronary artery occlusion will be included. The primary endpoint is infarct size, assessed by cardiac MRI after 4 months. The secondary endpoints are to evaluate the effect of postconditioning on TIMI myocardial perfusion grade, resolution of ST-segment elevation, release of markers of ischemia, left ventricular function and final infarct size related to the area at risk. A total of 260 patients will be included in the study.