Left atrial function in patients with mitral valve regurgitation

Area of Science:

• Cardiology
• Cardiac Physiology
• Echocardiography

Background:

• Degenerative mitral regurgitation (MR) significantly impacts cardiac function.
• Left atrial (LA) function is crucial for diastolic filling and overall cardiac performance.
• Understanding LA mechanics in MR is vital for assessing disease severity and prognosis.

Purpose of the Study:

• To evaluate left atrial (LA) function and myocardial mechanics in patients with degenerative mitral regurgitation (MR).
• To correlate LA volumetric and strain parameters with MR severity and left ventricular (LV) filling pressures.

Main Methods:

• Prospective study including 80 patients with degenerative MR and 20 controls.
• Three-dimensional transthoracic echocardiography used to measure LA and right atrial (RA) volumes at different cardiac cycle phases.
• LA strain and strain rate assessed using vector velocity imaging; LV filling pressures evaluated via E/E' ratio.

Main Results:

• Patients with severe MR exhibited increased LV filling pressures (E/E': 16 ± 4 vs. 10 ± 3).
• LA volumes (LAVmax, LAVmin, LAVpre-A) increased with MR severity.
• LA active stroke volume (SV) initially increased with LA preload (LAVpre-A) but then decreased, indicating impaired contractility beyond a certain point.
• LA late negative strain decreased with increasing MR volume, correlating positively with LA active emptying fraction.

Conclusions:

• Left atrial (LA) contractility (active SV) demonstrates a biphasic response to increased LA preload (LAVpre-A) in degenerative MR.
• The observed decrease in LA contractility may relate to the Frank-Starling mechanism's descending limb or altered afterload.
• Right atrial (RA) function remained comparable between MR patients and controls.