Sleep Apnea and Left Atrial Phasic Function in Heart Failure With Reduced Ejection Fraction

Area of Science:

• Cardiology
• Sleep Medicine
• Pulmonary Medicine

Background:

• Heart failure with reduced ejection fraction (HFrEF) is a complex condition often comorbid with sleep apnea.
• Distinguishing between obstructive sleep apnea (OSA) and central sleep apnea (CSA) is crucial as they may differentially impact cardiac function.
• Left atrial (LA) phasic function plays a vital role in diastolic filling and overall cardiac hemodynamics.

Purpose of the Study:

• To investigate the differences in phasic left atrial (LA) function between patients with HFrEF experiencing obstructive sleep apnea (OSA) and central sleep apnea (CSA).
• To determine the independent association of OSA and CSA severity with specific components of LA function.

Main Methods:

• Utilized data from the Adaptive Servo Ventilation for Therapy of Sleep Apnea in Heart Failure (ADVENT-HF) trial.
• Included 132 patients with HFrEF (left ventricular ejection fraction ≤ 45%) and an apnea-hypopnea index (AHI) ≥ 15 events/hour, in sinus rhythm.
• Quantified LA reservoir (expansion index), conduit (passive emptying index), and booster (active emptying index) functions using 2D echocardiography.

Main Results:

• Patients with CSA demonstrated significantly reduced LA reservoir, conduit, and active emptying functions compared to those with OSA.
• Central AHI, but not obstructive AHI, was independently associated with impaired LA reservoir and conduit function.
• The relationship between CSA severity and LA function was distinct from that of OSA severity.

Conclusions:

• All three components of phasic LA function are significantly diminished in HFrEF patients with CSA compared to those with OSA.
• The severity of CSA, independently of OSA, is inversely related to LA reservoir and conduit function.
• Impaired LA phasic function may be a consequence of, or contribute to the exacerbation of, central sleep apnea in HFrEF patients.