Purpose:
Tissue Doppler imaging (TDI) M-mode through the mitral leaflet is an easy, fast, and precise method to estimate the cardiac time intervals from one cardiac cycle (Figure). The aim was to evaluate the usability of the cardiac time intervals in predicting major cardiovascular events (MACE) in the general population.
Methods:
In a large community based population study, cardiac function was evaluated in 1,915 participants by both conventional echocardiography and by TDI. The cardiac time intervals, including the isovolumic relaxation time (IVRT), isovolumic contraction time (IVCT), and ejection time (ET) were obtained by TDI M-mode through the mitral leaflet (Figure). IVCT/ET, IVRT/ET and the myocardial performance index (MPI=(IVRT+IVCT)/ET) were calculated.
Results:
During follow-up (median 10.8 years), 383 (20%) participants reached the combined endpoint MACE (ischemic heart disease, heart failure or cardiac death). After multivariable adjustment for clinical predictors and conventional echocardiography, only the combined indexes, including information on both the systolic and diastolic performance (IVRT/ET and MPI), remained significant prognosticators (IVRT/ET: Subdistribution Hazard Ratio (SHR) 1.16 (1.00-1.34), p = 0.047; MPI: 1.11 (1.03-1.23), p = 0.024). Adding IVRT/ET or MPI to a model already including all other echocardiographic parameters resulted in a significant increase in the Harrell’s c-statistics (p<0.05 for both). Finally, when adding IVRT/ET or MPI to the clinical predictors improved reclassification significantly (p<0.05 for both).
Conclusion:
In the general population, the combined cardiac time intervals which include information on both the systolic and diastolic function in one index (IVRT/ET and MPI) are not only powerful and independent predictors of future MACE, but provide additional prognostic information to clinical and conventional echocardiographic measures of systolic and diastolic function.
Cardiac Time Intervals by Tissue Doppler Imaging M-Mode: Normal Values and Association with Established Echocardiographic and Invasive Measures of Systolic and Diastolic Function
