Cardiovascular disorders associated with obstructive sleep apnea.

Epidemiological, longitudinal and therapeutic studies have produced convincing evidence that obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular morbidity and mortality. The strongest evidence supports an independent causal link between OSA and arterial hypertension. OSA may be independently associated with an increased risk for ischemic heart disease, stroke, arrhythmias and mortality. It remains to be determined whether OSA is an independent cause of congestive heart failure and pulmonary hypertension. Confounders and methodological biases are the main reasons for the lack of definitive conclusions in causality studies. Longitudinal studies, adequately powered randomized controlled studies and therapeutic studies involving well-defined participants are all needed to definitively answer the questions surrounding the relationship between OSA and clinical cardiovascular outcomes, comorbidities and intermediate pathogenic mechanisms. OSA is a modifiable risk factor: continuous positive airway pressure administration, the gold standard treatment of OSA, may reduce the early signs of endothelial dysfunction and atherosclerosis, and improve cardiovascular outcomes, such as the mortality related to cardiovascular events, blood pressure, nonfatal coronary events and cardiac function in heart failure patients. However, cardiac patients may not display the typical signs and symptoms of OSA, such as an excessive body mass index and sleepiness. This fact, and the cardiovascular risk associated with OSA, underlines the need for collaborative guidelines to define a diagnostic strategy specifically oriented toward the evaluation of OSA in cardiovascular patients.