Tei index – myocardial performance index (MPI) is the ratio of the time spent in isovolumetric activity divided by the time spent in ventricular ejection . In other words, it is the sum of isovolumic contraction and relaxation times divided by the ejection time .
MPI = (ICT + IRT) / ET ICT: isovolumic contraction time; IRT: isovolumic relaxation time; ET: ejection time
Myocardial performance index has an inverse relation with global ventricular function in that increasing values indicate worsening global ventricular function. There is good correlation between Doppler derived myocardial performance index and cath derived invasive measures as well as with the clinical outcome. Myocardial performance index has different normal ranges for different age groups and for the left and right ventricles, though it is roughly a little more than one third.
Advantages of myocardial performance index
Simple to estimate
Not affected by geometry
Assesses global function
Down sides of MPI
Variation with heart rate, age and body surface area, and rhythm
Nonspecific – unable to differentiate between systolic and diastolic dysfunction. There could also be pseudo-normalization due to this.
Tei index is used mainly in amyloidosis, dilated cardiomyopathy, and ischemic heart disease . MPI values are independent of blood pressure, heart rate, afterload, preload and atrioventricular (AV) valve regurgitation. Pseudonormalization of diastolic function can be differentiated with estimation of MPI .
A prolonged Tei index – Myocardial performance index of more than 1.14 has been shown to be a powerful and independent predictor of poor clinical outcome in patients with severe left ventricular dysfunction and symptomatic heart failure .
Yasushige Shingu, Paulo Amorim, T Dung Nguyen, Friedrich W Mohr, Michael Schwarzer, Torsten Doenst. Myocardial performance (Tei) index is normal in diastolic and systolic heart failure induced by pressure overload in rats. Eur J Echocardiogr. 2010 Dec;11(10):829-33.
Kishore J Harjai, Luis Scott, K Vivekananthan, Eduardo Nunez, Ravi Edupuganti. The Tei index: a new prognostic index for patients with symptomatic heart failure. J Am Soc Echocardiogr. 2002 Sep;15(9):864-8.