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Importance of left ventricular activation in determining myocardial performance (Tei) index: comparison with total
Alison M Duncan1, Darrel P Francis, Michael Y Henein
1Department of Echocardiography, The Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK. a.duncan@ic.ac.uk
Insights
The Tei index is not a reliable measure of intrinsic heart function, as it is heavily influenced by ventricular activation. Total isovolumic time (t-IVT) offers a more accurate assessment of mechanical changes in various cardiac conditions.
Area of Science:
- Cardiology
- Echocardiography
- Cardiac Physiology
Background:
- The Tei index is widely used to assess combined systolic and diastolic function.
- A need exists for an index of intrinsic myocardial contraction and relaxation independent of activation abnormalities.
- This study investigates the Tei index's validity in patients with normal activation, left bundle branch block (LBBB), and varying left ventricular (LV) cavity sizes, with or without coronary artery disease (CAD).
Purpose of the Study:
- To evaluate whether the Tei index accurately reflects intrinsic myocardial function.
- To compare the Tei index with total isovolumic time (t-IVT) in assessing cardiac function under different conditions.
- To determine the influence of ventricular activation, LV cavity size, and CAD on these indices.
Main Methods:
- Doppler echocardiography was used to measure the Tei index and t-IVT.
- The study included 32 controls and 124 patients with conditions including CAD, non-ischaemic dilated cardiomyopathy (DCM), and ischaemic DCM, with and without LBBB.
- Analysis compared index values between groups and assessed predictive accuracy.
Main Results:
- Both Tei index and t-IVT were significantly prolonged in patients with LBBB and DCM.
- T-IVT demonstrated higher predictive accuracy than the Tei index for identifying LBBB.
- The Tei index's accuracy for DCM decreased when LBBB was excluded; CAD did not affect either index.
Conclusions:
- The Tei index is primarily determined by ventricular activation, not intrinsic myocardial function or cavity size.
- T-IVT is more sensitive to activation, independent of cavity size and CAD, making it a potentially more accurate measure of mechanical consequences.
- T-IVT may be a superior index for evaluating ventricular activation's mechanical impact in diverse cardiac pathologies.
Background:
The Tei index is commonly used as a measure of "combined systolic and diastolic function". A sensitive and specific index of intrinsic myocardial contraction and relaxation would be independent of abnormal activation. We aimed to determine whether the Tei index fulfils this criterion in patients with normal activation or left bundle branch block (LBBB), normal or dilated left ventricular (LV) cavities, with or without coronary artery disease (CAD).
Methods:
We studied 32 controls and 124 patients; 49 had CAD and normal LV size (11 LBBB), 27 had non-ischaemic dilated cardiomyopathy (DCM, 11 LBBB), and 48 had ischaemic DCM (17 LBBB). Tei index (isovolumic contraction time+isovolumic relaxation time/ejection time) and total isovolumic time (t-IVT: [60-(total ejection time+total filling time]) were measured using Doppler echocardiography.
Results:
Tei index and t-IVT were prolonged in LBBB (by 0.6 and 9.1 s/min, P<0.001). T-IVT identified LBBB with greater predictive accuracy than Tei index (sensitivity 97% vs. 90%, specificity 93% vs. 91%, P<0.05). Tei index and t-IVT were also prolonged in DCM (by 0.2 and 3.1 s/min, both P<0.001). Although Tei index identified DCM with sensitivity 71%, this fell to 53% when LBBB was excluded (P<0.05). CAD had no effect on Tei index or t-IVT.
Conclusions:
The Tei index is not a measure of intrinsic myocardial systolic and diastolic function, since its main determinant is ventricular activation rather than cavity size. T-IVT, however, is more sensitive to activation, is unrelated to cavity size or CAD, and may thus be a more accurate measure of the mechanical consequences of ventricular activation in a variety of cardiac conditions.
