Abstract 2821: Clinical and Echocardiographic Determinants of Left Ventricular Synchrony
Background: Current research on predicting response to cardiac resynchronization therapy suggests quantification of left ventricular (LV) dyssynchrony. However, impact of age, gender and other variables on LV synchrony in healthy individuals is unknown.
Methods: Echocardiography with color tissue Doppler was performed on 122 healthy volunteers (age 19 – 68 years, 64 men). LV systolic and diastolic synchrony were measured as the absolute basal lateral to septal wall delay (LSD) in peak myocardial Sm and Em velocities respectively. Systolic and diastolic synchrony were also measured as the standard deviation of time to 12 regional peak Sm (SDTs) and Em (SDTe) velocities. Mean Sm and Em velocities were calculated from 6 basal segments.
Results: Mean QRS duration was 87 ± 12msec. Mean systolic LSD and SDTs were 57.5 ± 39.7msec and 37.1 ± 17.4msec respectively. Women had significantly higher systolic LSD (74.1 ± 40.2 vs 42.2 ± 32.8msec, p < 0.001) and SDTs (44.5 ± 16.1 vs 30.2 ± 15.7msec, p < 0.001) than men. SDTs was correlated with LV wall stress (r = 0.23, p = 0.01) and mean Sm (r = 0.40, p < 0.001). Gender (p < 0.001) and mean Sm (partial r = -0.31, p < 0.001) independently predicted SDTs (multiple R = 0.51, p < 0.001) whereas only gender independently predicted systolic LSD. Mean diastolic LSD and SDTe were 15.3 ± 15.6msec and 17.3 ± 6.7msec respectively. There were no gender differences in diastolic LSD or SDTe. Diastolic LSD was correlated with mean Em (r = -0.20, p = 0.03), isovolumic relaxation time (IVRT, r = 0.24, p = 0.01), mitral E/A ratio (r = -0.21, p = 0.02), pulmonary S/D ratio (r = 0.23, p = 0.01) and systolic blood pressure (r = 0.22, p = 0.02). Only IVRT independently predicted diastolic LSD. SDTe correlated with age (r = 0.42, p < 0.001), mean Em (r = -0.73, p <0.001), mitral E/A ratio (r =0.40, p <0.001), pulmonary S/D ratio (r =0.42, p <0.001), IVRT (r = 0.51, p < 0.001), systolic blood pressure (r = 0.25, p = 0.005) and LV mass (r = 0.21, p = 0.019). Mean Em (partial r = -0.34, p < 0.001) and IVRT (partial r = 0.31, p = 0.001) independently predicted SDTe (multiple R = 0.58, p < 0.001).
Conclusions: In healthy individuals, 1) women have higher systolic but not diastolic synchrony indices than men; 2) systolic function impacts on systolic synchrony, diastolic function impacts on diastolic synchrony.