Evaluation of sleep apnea subdiagnosis and its potential causes in patients with cardiovascular diseases in a Tertiary Cardiology Center

Abstract

Obstructive Sleep Apnea (OSA) is a condition characterized by partial or complete upper airway obstruction resulting in transient episodes of reduced intrathoracic pressure, intermittent hypoxia, and sleep fragmentation. Recent studies suggest that OSA is independently associated with several clinical conditions such as hypertension, arrhythmias, and heart failure as well as consistently related to an increased risk of fatal and nonfatal cardiovascular events. Despite this evidence suggesting the impact of OSA on several cardiovascular diseases and unfavorable outcomes, the OSA underdiagnosis in Cardiology seems to be very common in clinical practice. A few studies have evaluated the frequency of patients with OSA and underdiagnosis in Cardiology. Potential explanations for this underdiagnosis seem to be multiple: lack of medical training in Sleep Medicine, reluctance to accept OSA as a potential cardiovascular risk factor, lack of definitive evidence regarding the role of OSA in promoting cardiovascular diseases, difficult access to information and updated physicians as well as the difficulty of access to the population to the OSA treatment. Although all these potential causes are known in the general population, no studies have evaluated the relative importance of these among Cardiologists. Thus, this study aims to evaluate consecutively the risk of OSA in different populations with cardiac disease (hypertension, coronary disease, arrhythmias, valvular heart disease, and heart failure) in patients of the Heart Institute (InCor), HCFMUSP. We hypothesized that even patients at high risk for OSA are usually not screened/approached and consequently treated accordingly. Based on our hypothesis, we will do an analysis of potential explanations interrogating residents and attending physicians responsible for the care of these patients. From July 2012 to July 2013, will be recruited 500 patients of both sexes aged e 18 years attended by five groups of sub-specialties of cardiology (hypertension, coronary disease, arrhythmias, valvular heart disease, and heart failure). For each group, we will evaluate approximately 100 patients. All patients will be evaluated by a single researcher, who will perform surveys in patients immediately after the medical consultation. After receiving explanations about the project and signing the consent form, patients will fill out a form with personal data, assessment of medical history, and current medications. The same investigator will perform anthropometric measurements (body mass index, neck circumference, and waist circumference) and apply the Berlin questionnaire (questionnaire that assesses the risk of OSA) and Epworth sleepiness scale (questionnaire that assesses the degree of sleepiness). In order to perform an internal validation of the Berlin questionnaire for the screening of OSA, we will perform a portable sleep monitoring (ApneaLink, ResMed) in a sample of 50 cases (10 patients per group - five high-risk patients and 5 patients with low risk for OSA by the Berlin questionnaire).(AU)