Tei Index (Myocardial Performance Index) in Echocardiography

The Tei index, also known as the Myocardial Performance Index (MPI), is a simple, reproducible echocardiographic parameter that integrates systolic and diastolic ventricular function into a single numerical value. It is widely used for both left and right ventricular functional assessment and is relatively independent of heart rate and ventricular geometry.

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What Is the Tei Index?

The Tei index reflects global ventricular performance by combining time intervals from Doppler echocardiography.

Formula:

\text{Tei Index (MPI)} = \frac{\text{IVCT} + \text{IVRT}}{\text{ET}}

Where:

IVCT = Isovolumic contraction time

IVRT = Isovolumic relaxation time

ET = Ejection time

A higher Tei index indicates worse ventricular function.

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How Is Tei Index Measured on Echocardiography?

1. Pulsed-Wave Doppler Method (Conventional)

Place PW Doppler at mitral inflow (LV) or tricuspid inflow (RV)

Measure interval ‘a’ = time from end of one inflow to onset of the next inflow

(includes IVCT + ET + IVRT)

Measure interval ‘b’ = ventricular ejection time from LVOT or RVOT

Calculate:

\text{Tei Index} = \frac{a - b}{b}

2. Tissue Doppler Imaging (TDI) Method

Place TDI sample at mitral annulus (LV) or tricuspid annulus (RV)

Measure:

IVCT

IVRT

ET directly from annular velocity waveform

Less affected by loading conditions and heart rate variability

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Normal Values

Ventricle Normal Tei Index

Left ventricle ≤ 0.40

Right ventricle ≤ 0.43

Values above these thresholds suggest global ventricular dysfunction.

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Clinical Applications

Heart failure (HFrEF and HFpEF)

Dilated cardiomyopathy

Ischemic heart disease

Pulmonary hypertension (RV MPI)

Congenital heart disease

Valvular heart disease

Post–myocardial infarction prognosis

The Tei index correlates with mortality, hospitalization, and adverse outcomes in multiple cardiac conditions.

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Advantages of Tei Index

Simple and quick to obtain

Combines systolic and diastolic function

Geometry-independent

Useful when EF is difficult to assess

Applicable to both LV and RV

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Limitations

Affected by significant valvular regurgitation

Less reliable in atrial fibrillation

Load-dependent in extreme preload/afterload states

Requires accurate Doppler alignment

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Key Echo Pearls

↑ Tei index = worse global ventricular function

Normal EF does not exclude abnormal MPI

Particularly useful in RV assessment, where EF estimation is challenging

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Take-Home Message

The Tei index (MPI) is a robust, Doppler-derived echocardiographic parameter that provides a global snapshot of ventricular performance, complementing conventional systolic and diastolic indices and enhancing risk stratification in everyday echo practice.

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