Importance of left ventricular activation in determining myocardial performance (Tei) index: comparison with total isovolumic time.

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.