Peripheral ARtery Atherosclerotic DIsease and SlEep disordered breathing (PARADISE) trial - protocol for an observational cohort study.

Background: Peripheral arterial disease (PAD) is in fact a group of disease entities with different symptoms and course but a common underlying cause that is atherosclerosis. Atherosclerosis is known to be aggravated by several cardiovascular risk factors, including obstructive sleep apnea (OSA). Aim: Following paper is a protocol for Peripehral ARtery Atherosclerotic DIsease and SlEep disordered breathing (PARADISE) trial, which aims to describe the prevalence of OSA in PAD patients scheduled for revascularization and to determine the effect of OSA on the procedure outcomes. Methods: PARADISE study in an observational cohort trial. It plans to include 200 consecutive patients hospitalized for revascularisation due to PAD. In every patient an overnight sleep study will be performed for diagnosing the sleep disorders, according to the results of the test, patients will be divided into two groups: group A - patients with OSA; group B - patients without OSA, control group. All patients will be also screened for classical and non-classical cardiovascular risk factors. In some of the patients, during surgery a fragment of atherosclerotic plaque will be collected for further testing. Patients will be followed for 1 year for adverse events and end-points. Primary end-point of the study will be the failure of revascularization defined as recurrence or new onset of the symptoms of the ischemia from the treated region, a need for re-operation or procedure revision or recurrence of ischemia signs on the imaging tests. Discussion: The data obtained will help determine the incidence of obstructive sleep apnea in the population of patients with PAD. Authors expect to show that, as with other cardiovascular diseases associated to atherosclerosis, also in patients with PAD, the incidence of undiagnosed OSA is high and its presence is associated with elevated cholesterol, inflammatory markers, and higher prevalence of arterial hypertension and poor control of other cardiovascular risk factors. In addition, due to increased oxidative stress and vascular endothelial injury associated with OSA, patients afflicted with this condition will not only have more advanced atherosclerotic lesions, and in their histopathological examination their atherosclerotic plaque will exhibit evidence of greater instability and adverse morphology. We also expect to show that in patients with OSA achieving a correct control of cardiovascular risk factors will be more difficult. The study may improve PAD control through assuring better multispecialty care in PAD patients.