Cardiac time intervals and the association with 2D-speckle-tracking, tissue Doppler and conventional echocardiography: the Thousand&1 Study.

Abstract

Cardiac time intervals (CTI) are prognostic above and beyond conventional echocardiographic measures. The explanation may be that CTI contain information about both systolic and diastolic measures; this is, however, unknown. The relationship between the CTI and systolic and diastolic function assessed by conventional, tissue Doppler (TDI) and speckle-tracking echocardiography (STE) was investigated. CTI and echocardiographic measurements, including conventional, STE, and TDI echocardiography, were studied in 1088 type 1 diabetes patients without known heart disease randomly selected from the out-patient clinic at Steno Diabetes Center. The CTI were obtained by TDI M-mode through the mitral leaflet and included the isovolumic relaxation time (IVRT), isovolumic contraction time (IVCT), and the myocardial performance index (MPI=(IVRT+IVCT)/ejection time). Standardized beta-values were assessed. Both systolic and diastolic measures associated with CTI. Conventional measures: left ventricular ejection fraction (stand. beta): MPI -0.34, IVRT 0.24, and IVCT -0.21, all p<0.001. For the TDI measures, the most significant association was found with e': MPI (stand. beta: -0.30, p<0.001) and IVRT (-0.35, p<0.001) but no association with IVCT -0.05, p=0.1). Speckle-tracking derived measures were in general strongly associated with the cardiac time intervals. Thus, global longitudinal strain and MPI (-0.38, p<0.001), IVRT (-0.23, p<0.001), and IVCT (-0.10, p<0.001); and global longitudinal strain rate e and MPI (-0.40, p<0.001), IVRT (-0.42, p<0.001), and IVCT (-0.04, p=0.11). CTI, in particular MPI and IVRT, associate with both systolic and diastolic myocardial function assessed by conventional and newer echocardiographic measures. This may possibly help to explain the prognostic significance of CTI.