Obstructive sleep apnea and cardiac mechanics: how strain could help us?

Obstructive sleep apnea (OSA) syndrome is the most common sleep-breathing disorder, which is associated with increase cardiovascular morbidity and mortality. OSA increases risk of resistant arterial hypertension, coronary artery disease, heart failure, pulmonary hypertension, and stroke. Studies showed the significant relationship between OSA and cardiac remodeling. The majority of investigations were focused on the left ventricle and its hypertrophy and function. Fewer studies investigated right ventricular structure and function revealing deteriorated diastolic and systolic function. Data regarding left and right ventricular mechanics in OSA patients are scarce and controversial. The results of the studies that were focused on the influence of continuous positive airway pressure and weight reduction on cardiac remodeling revealed favorable effect on left and right ventricular structure and function. Recently published analyses confirmed positive effect of treatment on cardiac mechanics. Deterioration of left and right ventricular mechanics occurs before functional and structural cardiac impairments in the cascade of cardiac remodeling and therefore the assessment of left and right ventricular strain may represent a cornerstone in detection of subtle cardiac changes that develop significantly before other, often irreversible, alterations. Considering the fact that left and right ventricular strains have important predictive value in wide range of cardiovascular diseases, one should consider the evaluation of left and right ventricular strains in the routine echocardiographic assessment at all stages of disease-from diagnosis, during follow-up and evaluation of therapeutic effects. The main aim of this review is to provide the current overview of cardiac mechanics in OSA patients before and after (during) therapy, as well as mechanisms that could be responsible for cardiac changes.