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Continuous positive airway pressure ameliorates sleep-induced subclinical left ventricular systolic dysfunction: demonstration by two-dimensional speckle-tracking echocardiography.

AIMS
We hypothesized that continuous positive airway pressure (CPAP) therapy could improve sleep-induced left ventricular (LV) dysfunction in patients with obstructive sleep apnoea syndrome (OSA). The aim of this study was to investigate the effects of CPAP therapy on LV systolic dysfunction during overnight sleep in patients with OSA using two-dimensional speckle-tracking echocardiography (2DSTE).


METHODS AND RESULTS
2D LV short-axis and apical views were acquired before and immediately after overnight sleeping in 32 patients with OSA and normal LV ejection fraction. Using 2D strain software, three-principal strains were measured. In a subset of 14 OSA patients who received chronic CPAP therapy, identical measurements were repeated 3 months after the therapy. Although no significant changes in global radial and circumferential strain were noted, global longitudinal strain was significantly reduced after overnight sleeping (-19.1 +/- 2.0) compared with before sleep (-20.7 +/- 1.8, P < 0.001). After CPAP therapy, improvements in apnoea-hypopnoea index and minimal oxygen saturation were accompanied by the disappearance of longitudinal strain reduction during overnight sleep.


CONCLUSION
Repetitive obstructive apnoea produces acute impairment of LV longitudinal function, suggesting the development of subendocardial ischaemia. CPAP therapy not only decreases the severity of OSA, but also ameliorates sleep-induced longitudinal LV dysfunction, which can be assessed by 2DSTE.