Left ventricular torsion in patients with obstructive sleep apnoea before and after continuous positive airway pressure therapy: assessment by two-dimensional speckle tracking echocardiography.

BACKGROUND: The purpose of the present study was to evaluate how obstructive sleep apnoea (OSA) influences left ventricular (LV) torsion and whether nasal continuous positive airway pressure (CPAP) therapy has any impact on LV torsion in OSA patients with established cardiovascular risk factors.
METHODS: LV torsion was assessed by two-dimensional speckle tracking echocardiography (STE) in 162 participants without overt cardiovascular disease. The participants were categorized according to the apnoea-hypopnea index (AHI) as controls and mild, moderate and severe OSA patients. Forty-three patients with AHI greater than 30 were enrolled to receive CPAP therapy for 24 weeks. Twenty-eight patients received CPAP therapy effectively (compliance: 65%). After completion of CPAP therapy, STE was repeated to evaluate LV torsion.
RESULTS: LV torsion was decreased in the severe OSA group compared to mild and moderate OSA but was similar to controls as a result of predominant decrease in apical rotation. AHI had no correlation with LV torsion in moderate OSA but a significant and mild negative correlation with LV torsion in severe OSA. When adjusted for potential confounding variables such as left ventricular mass index, diastolic dysfunction and the presence of hypertension, AHI and E/E' remained significant predictors of LV torsion in OSA patients. LV apical rotation tended to increase after effective CPAP therapy. On the other hand, LV basal rotation decreased significantly.
CONCLUSIONS: LV torsion was altered in OSA patients with varying degrees according to the disease severity. Furthermore, there was no significant change of torsion after 24 weeks of CPAP therapy.