Abstract 2141: Left Ventricular Diastolic Dyssynchrony Derived from Strain Rate Imaging Is Related to Impaired Relaxation and Increased Stiffness in Patients with Dilated Cardiomyopathy
Background: Abnormal left ventricular (LV) relaxation is associated with altered loading conditions and nonuniformities such as dyssynchrony. However, the relations between diastolic dyssynchrony and LV function are unclear. We applied strain rate (SR) imaging derived from tissue Doppler imaging to examine whether LV diastolic dyssynchrony adversely affects LV relaxation or LV stiffness in dilated cardiomyopathy.
Methods: Conventional echocardiography and SR imaging were performed in 19 patients with dilated cardiomyopathy (51.2±13.2 years) and 16 controls(45.3±15.1 years). Systolic strain (ϵsys), peak systolic SR (SRsys), and early diastolic SR (SRdia) were obtained from eight LV segments. The coefficient of variation (CV) for ϵsys, SRsys , and SRdia values for the eight LV segments of each subject was calculated. LV pressure was simultaneously recorded with a high-fidelity micromanometer. The abundance of mRNAs for intracellular Ca2+ regulatory proteins in LV biopsy specimens was measured by quantitative RT-PCR.
Results: The ϵsys, SRsys, and SRdia were smaller in patients with dilated cardiomyopathy than in controls (9.9±3.6 vs. 17.6±2.5%, p<0.0001; 0.57±0.22 vs. 1.03±0.23 s−1, p<0.0001; 0.84±0.36 vs. 1.53±0.43 s−1, p<0.001, respectively). The CV for ϵsys (0.19±0.055 vs. 0.14±0.035, p<0.0005) or SRdia (0.095±0.041 vs. 0.055±0.015, p<0.0001) was greater in patients with dilated cardiomyopathy than in controls. Both ϵsys (r=0.55, p<0.05) and the CV of ϵsys (r= 0.39, p<0.05) were correlated with LV end-diastolic pressure. The CV of SRdia was correlated with the pressure half-time, LV end-diastolic pressure, LV ejection fraction, and SERCA2 mRNA abundance (r=0.55, p<0.005; r=0.47, p<0.05; r= −0.46, p<0.05; r= −0.52, p<0.05, respectively).
Conclusions: LV diastolic dyssynchrony is associated with impaired LV relaxation, down-regulation of SERCA2 mRNA, and increased LV stiffness in dilated cardiomyopathy. Analysis of diastolic dyssynchrony may provide important insight into regional and global diastolic LV function.