Myocardial performance index (Tei index): evaluating its application to myocardial infarction.

impairment of left ventricular (LV) systolic and diastolic dysfunction to various degrees. These functions are energetically and tightly coupled: 1) at the cellular level, since adenosine triphosphate is a substance essential for both active contraction and relaxation; 2) at the myocardial level, because regional wall motion asynchrony influences global LV diastolic function (contraction-relaxation axis); and 3) at the hemodynamic level, because systolic function indirectly affects LV filling pressures. Conventional echocardiographic indices that are routinely applied for the estimation of cardiac function face a number of limitations. The ejection fraction, the most reliable estimator of systolic function, is prone to significant inaccuracies when the elliptical cardiac chamber is transformed to a spherical one. On the other hand, transmitral flow, which is the most frequent method for evaluation of diastolic function, is dependent on age, heart rate, as well as loading conditions. Taking into account all the above, we could hypothesize that measurement of a more complex parameter, capable of estimating combined systolic and diastolic performance and independent of the limitations mentioned previously, could be more advantageous than the isolated measurement of either systolic or diastolic parameters in the evaluation of the global LV function of MI patients. Quite recently, a method with these properties has been developed: the myocardial performance index, or Tei index, which was first applied in 1995 in patients with dilated cardiomyopathy and with cardiac amyloidosis.