Study of Atherosclerotic Risk Factors and Oxidative Stress in Atrial Fibrillation. Relation to Cardiovascular Events

Atrial fibrillation (AF) is the most common cardiac arrhythmia that is associated with a high risk of cardiovascular events and increased morbidity and mortality. Cardiovascular events are prevalently localized in the cerebral circulation in which AF is responsible for ischemic stroke. Clinical characteristics of ischemic stroke from AF are almost severe and thromboembolism is considered the most important cause. Thus, ischemic stroke is deemed to origin from thrombus formation generated in the left atrium with ensuing embolism in the cerebral circulation.

Patients with AF are typically associated with different risk factors of atherothrombosis including, overall, hypertension which may be detected in about 70-80% of the population; other risk factors are diabetes and dyslipidemia. This accounts for instrumental evidence of systemic atherosclerosis associated to AF. Thus, signs of atherosclerosis have been detected in the thoracic aorta, as represented by aortic plaque assessed by trans-esophageal echocardiography; patients with complex aortic plaque had fourfold increased rate of stroke compared to plaque-free patients.

Metabolic syndrome (MetS) is a constellation of atherosclerotic risk factors including, according to the modified National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII), hypertension, low HDL, impaired glycaemic control, hypertriglyceridemia and central obesity as assessed by waist circumference; the presence of MetS is associated with an increased risk of developing cardiac and cerebral ischemic events.

An higher risk to develop atrial fibrillation (AF) has been well recognized in patients with MetS. In a prospective, community-based, observational cohort study with annual health check-up 28449 subjects without AF the age-adjusted rates of AF were higher in subjects with compared to those without metabolic syndrome during a mean follow-up of 4.5 years.

Few studies reported on the prevalence of MetS in AF population are still lacking. Some data can be inferred from studies regarding recurrence of AF after catheter ablation reporting a prevalence ranging from 18.8% to 49.4% . The only population study so far published included 741 chinese patients and reported a prevalence of the MetS in AF of 46.3%. Taking into account the thresholds of waist circumference recommended by international societies for different ethnic groups, it is unclear if such prevalence can be extrapolated to population of western countries.