Shortness of breath in clinical practice: A case for left atrial function and exercise stress testing for a comprehensive diastolic heart failure workup

Table 1 Imaging modalities and their correlations with components of atrial function¹

LA function	Volumetric	Spectral Doppler			Tissue Doppler and deformation indexes
	LA volume fraction	Transmitral flow	PV flow	Composite indexes	TDI	Strain (ε)	Strain rate
Global	LA EF [(LAmax - LAmin)/LAmax]	-	-	LAFI	-	-	-
Reservoir	Expansion index [(LAmax - LAmin)/LAmin]	-	S	-	S’	S; total	S
Conduit	Passive EF [(LAmax - LApre-A)/LAmax]	E E/A	D	-	E’	e-pos	E
Contractile (Booster)	Active EF [(LApre-A - LAmin)/LApre-A]	A E/A AFF	PVa	Ejection force (AEF) LAKE	A’	a-neg	A

¹Table modified from Ref[20,22]. ε: Strain; A/A’: Atrial contraction velocity/tissue Doppler velocity; AEF: Atrial ejection force Atrial ejection force = 0.5 × 1.06 g/cm3 × mitral annulus area (peak A velocity). Mass of blood is calculated as the product of the density of blood (ρ = 1.06 g/cm3) and volume of blood passing through mitral annulus; AFF: Atrial filling fraction, the ratio of the velocity time integral of the mitral A wave to the total diastolic transmitral flow; E/E’: Early diastole velocity/tissue Doppler velocity; EF: Emptying fraction; LA: Left atrial; LAEF: Left atrial emptying fraction; LAFI: Left atrial functional index; LAKE: Left atrial kinetic energy; LAmax: Maximum left atrial volume; LAmin: Minimum left atrial volume; neg: Negative; pos: Positive; preA: Preatrial contraction; PV: Pulmonary venous; Pva: Pulmonary venous reversal velocity; S/S’: Ventricular systole velocity/tissue Doppler velocity; TDI: Tissue Doppler imaging.