The impact of renal function on the incidence and prognosis of new-onset atrial fibrillation in acute myocardial infarction

Introduction

Atrial fibrillation (AF) is a frequent complication of acute myocardial infarction (AMI) and is associated with a worse prognosis. Patients with chronic kidney disease are more likely to develop AF. Whether the association between AF and renal function is also true in AMI has never been investigated.

Purpose

The aim of the study was to assess the incidence of new-onset AF according to renal function, estimated at hospital admission, and its relationship with short-term outcome and long-term all-cause mortality in a large real-world cohort of AMI patients.

Methods

We prospectively enrolled 2,445 AMI patients. New-onset AF was recorded during hospitalization. Glomerular filtration rate (eGFR) was estimated at admission and patients were grouped according to their renal function (group 1 [n=1,887]: eGFR>60; group 2 [n=492]: eGFR 60–30; group 3 [n=66]: eGFR<30 ml/min/1.73m2). The primary endpoint was AF incidence. In-hospital and long-term (median 5 years) all-cause mortality were the secondary endpoints.

Results

The AF incidence in the whole population was 10% and it was associated with a higher in-hospital (5% vs. 1%; P<0.0001) and long-term mortality (34% vs. 13%; P<0.0001). The AF incidence was 8%, 16%, 24% in groups 1, 2, 3, respectively (P<0.0001). In each group, in-hospital mortality was higher in AF patients (3.5% vs. 0.5%, 6.5% vs. 3.0%, 19% vs. 8%, respectively; P<0.0001). A similar trend was observed for long-term mortality (20% vs. 9%, 51% vs. 24%, 81% vs. 50%, respectively; P<0.0001). The higher risk for in-hospital and long-term mortality associated with AF in each group was confirmed also after adjustment for major confounders.

Conclusions

The study demonstrates that the incidence of new-onset AF during AMI, as well as its associated in-hospital and long-term mortality, increases in parallel with the severity of renal dysfunction assessed at hospital admission.

Funding Acknowledgement

Type of funding source: Private hospital(s). Main funding source(s): Centro Cardiologico Monzino, IRCCS, Milan, Italy

Activated platelets present high mobility group box 1 to neutrophils, inducing autophagy and promoting the extrusion of neutrophil extracellular traps

BACKGROUND

Increasing evidence implicates both platelets and neutrophils in the formation, stabilization, and growth of peripheral and coronary thrombi. Neutrophil extracellular traps (NETs) play a key role. The early events in the deregulated cross-talk between platelets and neutrophils are poorly characterized.

OBJECTIVES

To identify at the molecular level the mechanism through which platelets induce the generation of NETs in sterile conditions.

PATIENTS/METHODS

The presence of NETs was determined in 26 thrombi from patients with acute myocardial infarction by immunohistochemistry and immunofluorescence and markers of NETs assessed in the plasma. In vitro NET generation was studied in static and in physiological flow conditions.

RESULTS

Coronary thrombi mainly consist of activated platelets, neutrophils, and NETs in close proximity of platelets. Activated platelets commit neutrophils to NET generation. The event abates in the presence of competitive antagonists of the high mobility group box 1 (HMGB1) protein. Hmgb1(-/-) platelets fail to elicit NETs, whereas the HMGB1 alone commits neutrophils to NET generation. Integrity of the HMGB1 receptor, Receptor for Advanced Glycation End products (RAGE), is required for NET formation, as assessed using pharmacologic and genetic tools. Exposure to HMGB1 prevents depletion of mitochondrial potential, induces autophagosome formation, and prolongs neutrophil survival. These metabolic effects are caused by the activation of autophagy. Blockade of the autophagic flux reverts platelet HMGB1-elicited NET generation.

CONCLUSIONS

Activated platelets present HMGB1 to neutrophils and commit them to autophagy and NET generation. This chain of events may be responsible for some types of thromboinflammatory lesions and indicates novel paths for molecular intervention.

Glutathione, vitamin E and oxidative stress in coronary artery disease: relevance of age and gender

BACKGROUND

Observational studies suggest that low levels of antioxidants are associated with high risk for coronary artery disease (CAD). We investigated whether the biomarkers of oxidative balance undergo the same modifications in all CAD patient groups, regardless of gender and age.

MATERIALS AND METHODS

One hundred sixty-eight CAD patients and 107 healthy controls were assayed for plasma levels of reduced glutathione (GSH), alpha- and gamma-tocopherol (alpha- and gamma-T) as endogenous antioxidants. A damage score (DS), representative of oxidative stress status, was calculated. ANCOVA models were used to test the association between antioxidants, DS and CAD and its modulation by age and gender.

RESULTS

The DS was higher in CAD than in controls. GSH levels, were lower in CAD patients (mean +/- SEM: 57.61 +/- 1.87 micromol 10 g(-1) haemoglobin vs. 68.55 +/- 2.23 in controls, P < 0.0006) in males and in older subjects. Levels of other antioxidants exhibited a complex pattern. Overall, no difference was found in alpha- and gamma-T contents between CAD and controls, but lower alpha-T values were observed in CAD females. A significant interaction between CAD status and gender was observed (P = 0.003).

CONCLUSIONS

Our study shows that the involvement of antioxidants in CAD is related to patients' characteristics. These findings may be relevant in planning antioxidant therapies.