Inflammatory single nucleotide polymorphisms and the risk of atrial fibrillation: a case control study

Genetic Factors Altering Immune Responses in Atrial Fibrillation: JACC Review Topic of the Week

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide and is associated with a range of adverse clinical outcomes. Accumulating evidence points to inflammatory processes resulting from innate immune responses as a cornerstone in AF pathogenesis. Genetic and epigenetic factors affecting leukocytes have been identified as key modulators of the inflammatory response. Inherited variants in genes encoding proteins involved in the innate immune response have been associated with increased risk for AF recurrence and stroke in AF patients. Furthermore, acquired somatic mutations associated with clonal hematopoiesis of indeterminate potential, leukocyte telomere shortening, and epigenetic age acceleration contribute to increased AF risk. In individuals carrying clonal hematopoiesis of indeterminate potential, myocardial monocyte-derived macrophage shift toward a proinflammatory phenotype may precipitate AF. Further studies are needed to better understand the role of genetic regulation of the native immune response in atrial arrhythmogenesis and its therapeutic potential as a target for personalized medicine.

Atrial fibrillation detected by continuous electrocardiographic monitoring using implantable loop recorder to prevent stroke in individuals at risk (the LOOP study): Rationale and design of a large randomized controlled trial

Atrial fibrillation (AF) increases the rate of stroke 5-fold, and AF-related strokes have a poorer prognosis compared with non-AF-related strokes. Atrial fibrillation and stroke constitute an intensifying challenge, and health care organizations are calling for awareness on the topic. Previous studies have demonstrated that AF is often asymptomatic and consequently undiagnosed. The implantable loop recorder (ILR) allows for continuous, long-term electrocardiographic monitoring with daily transmission of arrhythmia information, potentially leading to improvement in AF detection and stroke prevention.

METHODS

The LOOP study is an investigator-initiated, randomized controlled trial with 6,000 participants randomized 3:1 to a control group or to receive an ILR with continuous electrocardiographic monitoring. Participants are identified from Danish registries and are eligible for inclusion if 70years or older and previously diagnosed as having at least one of the following conditions: hypertension, diabetes mellitus, heart failure, or previous stroke. Exclusion criteria include history of AF and current oral anticoagulation treatment. When an AF episode lasting ≥6minutes is detected, oral anticoagulation will be initiated according to guidelines. Expected follow-up is 4years. The primary end point is time to stroke or systemic embolism, whereas secondary end points include time to AF diagnosis and death.

CONCLUSION

The LOOP study will evaluate health benefits and cost-effectiveness of ILR as a screening tool for AF to prevent stroke in patients at risk. Secondary objectives include identification of risk factors for the development of AF and characterization of arrhythmias in the population. The trial holds the potential to influence the future of stroke prevention.

Does Inflammation Have a Role in the Pathogenesis of Cardiac Syndrome X? A Genetic-Based Clinical Study With Assessment of Multiple Cytokine Levels

We compared Turkish patients with cardiac syndrome X (CSX) and controls with respect to serum pro- and anti-inflammatory cytokine levels, as well as the single-nucleotide polymorphisms located in the promoter regions of their related genes. This study included 111 consecutive patients angiographically diagnosed with CSX and 111 healthy controls with similar demographic characteristics. Serum interleukin (IL) 6, tumor necrosis factor α (TNF-α), and IL-10 levels were measured, and the genotypes of the patients and controls were determined using standard methods. Serum IL-6 and IL-10 levels were significantly higher in the CSX group than in the control group ( P < .01, respectively). Serum TNF-α level was lower in the CSX group than in the control group ( P < .001). On the other hand, participants with CSX and healthy controls were not significantly different with respect to the genotype distributions of IL-6, TNF-α, and IL-10 genes. As a result of our study, both pro-inflammatory and anti-inflammatory cytokines may play a role in the pathogenesis of CSX. In contrast, the studied gene polymorphisms did not influence CSX pathogenesis.