SummaryBackgroundRemote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months.MethodsWe did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed.FindingsBetween Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91–1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed.InterpretationRemote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI.FundingBritish Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden.

Background-The effect of β-blockers on infarct size when used in conjunction with primary percutaneous coronary intervention is unknown. We hypothesize that metoprolol reduces infarct size when administered early (intravenously before reperfusion). Methods and Results-Patients with Killip class II or less anterior ST-segment-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention within 6 hours of symptoms onset were randomized to receive intravenous metoprolol (n=131) or not (control, n=139) before reperfusion. All patients without contraindications received oral metoprolol within 24 hours. The predefined primary end point was infarct size on magnetic resonance imaging performed 5 to 7 days after STEMI. Magnetic resonance imaging was performed in 220 patients (81%). Mean±SD infarct size by magnetic resonance imaging was smaller after intravenous metoprolol compared with control (25.6±15.3 versus 32.0±22.2 g; adjusted difference, −6.52; 95% confidence interval, −11.39 to −1.78; P=0.012). In patients with pre-percutaneous coronary intervention Thrombolysis in Myocardial Infarction grade 0 to 1 flow, the adjusted treatment difference in infarct size was −8.13 (95% confidence interval, −13.10 to −3.16; P=0.0024). Infarct size estimated by peak and area under the curve creatine kinase release was measured in all study populations and was significantly reduced by intravenous metoprolol. Left ventricular ejection fraction was higher in the intravenous metoprolol group (adjusted difference, 2.67%; 95% confidence interval, 0.09-5.21; P=0.045). The composite of death, malignant ventricular arrhythmia, cardiogenic shock, atrioventricular block, and reinfarction at 24 hours in the intravenous metoprolol and control groups was 7.1% and 12.3%, respectively (P=0.21). Conclusions-In patients with anterior Killip class II or less ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention, early intravenous metoprolol before reperfusion reduced infarct size and increased left ventricular ejection fraction with no excess of adverse events during the first 24 hours after STEMI.

Many CVRF-free middle-aged individuals have atherosclerosis. LDL-C, even at levels currently considered normal, is independently associated with the presence and extent of early systemic atherosclerosis in the absence of major CVRFs. These findings support more effective LDL-C lowering for primordial prevention, even in individuals conventionally considered at optimal risk. (Progression of Early Subclinical Atherosclerosis [PESA] Study; NCT01410318).

Contrary to the accepted view, myocardial edema during the first week after ischemia/reperfusion follows a bimodal pattern. The initial wave appears abruptly upon reperfusion and dissipates at 24 h. Conversely, the deferred wave of edema appears progressively days after ischemia/reperfusion and is maximal around day 7 after reperfusion.

The β1-adrenergic-receptor (ADRB1) antagonist metoprolol reduces infarct size in acute myocardial infarction (AMI) patients. The prevailing view has been that metoprolol acts mainly on cardiomyocytes. Here, we demonstrate that metoprolol reduces reperfusion injury by targeting the haematopoietic compartment. Metoprolol inhibits neutrophil migration in an ADRB1-dependent manner. Metoprolol acts during early phases of neutrophil recruitment by impairing structural and functional rearrangements needed for productive engagement of circulating platelets, resulting in erratic intravascular dynamics and blunted inflammation. Depletion of neutrophils, ablation of Adrb1 in haematopoietic cells, or blockade of PSGL-1, the receptor involved in neutrophil–platelet interactions, fully abrogated metoprolol's infarct-limiting effects. The association between neutrophil count and microvascular obstruction is abolished in metoprolol-treated AMI patients. Metoprolol inhibits neutrophil–platelet interactions in AMI patients by targeting neutrophils. Identification of the relevant role of ADRB1 in haematopoietic cells during acute injury and the protective role upon its modulation offers potential for developing new therapeutic strategies.

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The introduction of the PKP2 R735X mutation into mice resulted in an exercise-dependent ARVC phenotype. The R735X mutation appears to function as a dominant-negative variant. This novel system for AAV-mediated introduction of a mutation into wild-type mice has broad potential for study of the implication of diverse mutations in complex cardiomyopathies.

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