Mitral annular motion as a surrogate for left ventricular function: correlation with brain natriuretic peptide levels

Area of Science:

• Cardiology
• Echocardiography
• Cardiac Physiology

Background:

• Pulsed-wave (PW) Doppler tissue velocities of the mitral annulus correlate with Left Ventricular (LV) diastolic and systolic functions.
• Brain natriuretic peptide (BNP) levels are elevated in symptomatic LV dysfunction and correlate with symptom severity and prognosis.

Purpose of the Study:

• To validate mitral annular motion (MAM) assessed by Doppler Tissue Imaging (DTI) and M-mode Echocardiography (MME) as a surrogate for LV function determination.
• To compare the accuracy of DTI and MME in assessing LV function against plasma BNP levels.

Main Methods:

• 133 patients with cardiac pathologies and 20 healthy volunteers underwent echocardiography, including LV ejection fraction (EF) assessment, mitral inflow Doppler, MME, and PW-DTI.
• Mean peak systolic (Sm) and early diastolic (Em) mitral annular velocities by PW-DTI, and mean mitral annular plane systolic excursion (MAPSE) by MME were calculated.
• BNP levels were measured using rapid immunoassay, blinded to the echocardiographic assessment.

Main Results:

• MME-derived MAPSE (<12 mm) showed 89% accuracy for detecting LV EF <50%; PW-DTI-derived Sm (<8 cm/s) showed 94% accuracy.
• BNP levels >75 pg/ml demonstrated 97% accuracy for detecting LV dysfunction (systolic, diastolic, or both).
• Significant correlations were found between BNP levels and Em (r=-0.82), Sm (r=-0.7), MAPSE (r=-0.54), and LVEF (r=-0.64).

Conclusions:

• MME and PW-DTI are valuable for assessing LV function.
• PW-DTI parameters correlate more strongly with plasma BNP levels than MME parameters.
• PW-DTI offers a simple, sensitive, accurate, and reproducible tool for early diagnosis of LV dysfunction.