AFISBIO - Atrial Fibrillation in Relationship to Sleep Quality and Plasma Biomarkers.

AFib is the most common sustained arrhythmia, associated with an increased risk of stroke, heart failure, and mortality. Despite the high prevalence, AFib may be asymptomatic and consequently subclinical. Detection of subclinical AFib is highly challenging as only a minority of the patients is diagnosed during a standard examinations with a 12 - lead ECG or a 24h ECG Holter monitoring. Documented AFib causes 15% of ischemic strokes, however approximately 25% of ischemic strokes is of an unknown etiology. It is believed that undetected subclinical AFib is responsible for these strokes. There is also evidence that asymptomatic AFib is associated with a higher incidence of strokes in comparison to symptomatic AFib.

Due to the fact that the standard ECG examination is not sufficient for AFib detection, various ECG screening methods have been introduced. Intermittent short ECG recording seems to be more effective than 24-hour Holter ECG in the detection of the arrhythmia however, it is not known whether it is superior to the 7 - day ECG Holter monitoring.

Plasmatic biomarkers might be of a paramount importance in the diagnostic management.

Several plasmatic biomarkers were tested to find an association with AFib. Perhaps the most studied ones were the natriuretic peptides that showed to be significantly increased in patients with AFib. Similarly, high sensitivity troponins are elevated in patients with the AFib. Another marker of left atrial stretching and also of ionotropic effects is apelin. Patients with lone AFib showed a significantly decreased levels of this peptide. Conflicting results were shown in studies with inflammatory biomarkers such as high sensitivity CRP Parameters reflecting thrombogenesis were also found to be associated with the arrhythmia. Fibrinogen and fibrin D-dimer were significantly increased in paroxysmal AFib. Finally, in the last years, the circulating micro RNAs emerged as a promising biomarker of AFib, having important function in suppression of messenger RNA responsible for thrombogenesis and ionotropic functions.

The weakness of the mentioned studies is, that the biomarkers were usually tested in patients with a few comorbidities. So, it is not known whether these biomarkers are specific for AFib "per se" or whether they just reflect pathophysiological mechanisms like inflammation, fibrogenesis or left atrium stretching that is also present in other cardiovascular diseases. Furthermore, the AFib cohorts were often not matched with the control groups adding more uncertainty. To clarify these questions, we designed a study where plasmatic biomarkers will be studied in high risk cohort of patients with AFib having several cardiovascular comorbidities. These patients will be subsequently matched with a control group according to the age, gender and the cardiovascular comorbidities.