Mechanisms of cardiac dysfunction in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality, largely as a result of myocardial anomalies. Numerous mechanisms cause OSA-related myocardial damage. The majority are initiated as a result of OSA-induced, chronic, intermittent hypoxia. The most-important mechanisms that lead to myocardial damage are increased sympathetic activity, endothelial dysfunction, systemic inflammation, oxidative stress, and metabolic anomalies. All these mechanisms promote the development of hypertension, which is common in patients with OSA. Hypertensive cardiomyopathy and coronary heart disease, as well as obesity-related, diabetic, and tachycardia-induced cardiomyopathies, are also associated with OSA. Left ventricular hypertrophy, myocardial fibrosis, atrial dilatation, and left ventricular systolic and diastolic dysfunction in patients with OSA explain the association of the disease with these clinical outcomes. The gold-standard treatment for OSA, nasal continuous positive airway pressure (CPAP), might improve cardiac symptoms and hemodynamic parameters in patients with the disease. However, large clinical trials are required to improve our understanding of the cardiac consequences of OSA, and determine the effect of treatment, particularly CPAP, on myocardial damage in symptomatic patients and primary prevention of cardiovascular disorders.