Effect of Left Ventricular Outflow Tract Obstruction on Left Atrial Mechanics in Hypertrophic Cardiomyopathy

Table 4

LA volumes and myocardial mechanics.

	Normal controls ()	Nonobstructive HCM ()	Obstructive HCM ()
LA volume indices
(mL/m^2)	38.3 ± 10	54.3 ± 15	63.4 ± 17
(mL/m^2)	22.3 ± 8	40.1 ± 13	49.3 ± 14
(mL/m^2)	13.3 ± 5	28.9 ± 10	36.9 ± 13
Left atrial ejection/emptying fraction (%)	65.0 ± 11	47.2 ± 9	42.3 ± 8
Left ventricular stroke volume (mL/m^2)	54.5 ± 9	52.6 ± 11	55.5 ± 9
Conduit volume	58.4 ± 26	52.3 ± 22	56.4 ± 23
Reservoir function
Expansion index (%)	219.0 ± 113	95.2 ± 36	76.3 ± 23
Longitudinal reservoir strain (%)	39.5 ± 13	17.7 ± 5	14.5 ± 4
SRs (%/sec)	1.37 ± 0.4	0.73 ± 0.2	0.59 ± 0.2
Conduit function
Passive emptying index/fraction (%)	41.6 ± 13	26.4 ± 9	22.3 ± 7
SRe (%/sec)	−0.99 ± 0.5	−0.43 ± 0.2	−0.35 ± 0.2
Booster function
Active emptying index/fraction (%)	39.9 ± 14	28.0 ± 10	25.7 ± 8
Longitudinal booster strain (%)	15.3 ± 7	7.5 ± 3	6.1 ± 2
SRa (%/sec)	−1.05 ± 0.5	−0.58 ± 0.2	−0.44 ± 0.1

SRs: strain rate in systole; SRe: strain rate during passive emptying; SRa: strain rate during active emptying; compared with normal controls; between obstructive and nonobstructive HCM.