Left ventricular torsion abnormalities in patients with obstructive sleep apnea syndrome: an early sign of subclinical dysfunction

BACKGROUND: Previous echocardiographic studies using tissue Doppler imaging (TDI) and speckle tracking imaging (STI) have demonstrated that obstructive sleep apnea syndrome (OSAS) patients may develop subclinical left ventricular (LV) systolic and diastolic dysfunction. Our purpose was to evaluate the impact of OSAS on LV torsion dynamics and aortic stiffness by using TDI and STI echocardiography. METHODS: Forty-two patients with OSAS and no comorbidities were studied. They were classified into mild and severe OSAS according to the apnea-hypopnea index (AHI). Thirty-five healthy subjects were selected as controls. Fifteen patients with severe OSAS underwent chronic nocturnal nasal continuous positive airway pressure (CPAP) therapy. Standard echocardiographic parameters were assessed. Global LV longitudinal strain (LS), radial and circumferential strain were determined by STI. Averaged LV rotation and rotational velocities from the base and apex were obtained and used for calculation of LV torsion (LVtor). Mitral annular velocities and aortic wall velocities and strain (AoS) were also obtained by TDI. RESULTS: Severe OSAS had decreased LS compared with control subjects. LVtor increased significantly in severe OSAS compared to normals (p<.001) as a result of a predominant increase in apical rotation and was independently related to AHI and AoS in a multiple stepwise linear regression model. The group treated with CPAP had a significant decrease in LVtor and aortic stiffness index and significant increase in LS and AoS. CONCLUSIONS: LVtor, LS and AoS were identified as parameters demonstrating an association between LV dysfunction, aortic stiffness and severity of OSAS independently of other possible factors or comorbidities.