Impact of continuous positive airway pressure therapy on left atrial function in patients with obstructive sleep apnoea: assessment by conventional and two-dimensional speckle-tracking echocardiography

Abstract

Objective The objective of this study was to evaluate left atrial (LA) function in patients with obstructive sleep apnoea (OSA) receiving continuous positive airway pressure therapy (CPAP), incorporating two-dimensional speckle-tracking echocardiography (2D-STE).

Methods Forty-five control and 117 OSA patients were enrolled in the study. They were categorized into mild, moderate and severe OSA groups according to the apnoea-hypopnoea index (AHI). All patients underwent conventional and 2D-STE. Forty-three patients with AHI greater than 20 were enrolled to receive CPAP therapy for 24 weeks. They underwent echocardiography examination at baseline, after 12 weeks and 24 weeks of CPAP therapy.

Results Severe OSA patients have higher total emptying volume index (EVI) and lower total emptying fraction (EFr) (P < 0.05). LA contractile strain and strain rate values of severe OSA were greater than in the other groups (P < 0.05). Left ventricular filling pressure (E/E’) increased with severity of OSA (P < 0.05). The AHI correlated positively with LA-maximal, -pre-contraction, -minimum volume index, contractile strain and strain rate and E/E’ (P < 0.05). AHI correlated negatively with LA reservoir strain and strain rate, conduit strain and strain rate (P < 0.05). In the compliant CPAP group: (i) reduction in the E/E’ ratio (P < 0.05); (ii) reduction in the LA volume indexes (P < 0.05); (iii) reduction in the LA-total EVI, -active EVI and -active EFr (P < 0.05); (iv) increase in the LA-passive emptying volume and -passive emptying fraction (P < 0.05); (v) increase in the LA reservoir strain, -conduit strain and strain rate (P < 0.05) were observed.

Conclusion LA volumetric and deformation abnormalities in OSA patients can be reversed as early as 12 weeks into CPAP therapy, with progressive improvement in LA anatomical remodelling over 24 weeks as assessed by conventional and 2D-STE.

Key Words:

• Left atrial deformation
• left atrial volume
• obstructive sleep apnoea
• 2-dimensional strain echocardiography
• CPAP therapy