Myocardial performance (Tei) index is normal in diastolic and systolic heart failure induced by pressure overload in rats

AIMS: Myocardial performance index (MPI), or Tei index, is a Doppler echocardiographic parameter defined as the sum of the isovolumic contraction and relaxation times divided by the ejection time. It is considered a reliable parameter for global left ventricular function. However, the interpretation of this index is not fully clear in diastolic dysfunction. We measured MPI in a pressure-overload model of rats with severe diastolic with or without systolic dysfunction and examined its usefulness as a parameter for cardiac function in a hypertensive heart failure model. METHODS AND RESULTS: Pressure overload was created by placement of a metal clip around the thoracic aorta [transverse aortic constriction (TAC)] at a weight of 40-50 g. Transthoracic echocardiography including Doppler analysis and invasive left ventricular catheter examination were performed 10 and 20 weeks after TAC (n = 6 for each time point). While left ventricular ejection fraction was over 50% in all TAC animals after 10 weeks (56.3 ± 2.3%), it was below 50% in all TAC animals after 20 weeks (45.4 ± 1.0%). E/E' was significantly larger in the TAC groups at both time points and the time constant τ by Millar catheter was also elevated in the TAC groups. On the other hand, MPI was not different compared with the control groups (10 weeks: 0.47 ± 0.09 vs. 0.44 ± 0.04; 20 weeks: 0.38 ± 0.03 vs. 0.46 ± 0.07). CONCLUSION: MPI is not a reliable parameter for the assessment of contractile function in pressure-overload heart failure. It is normal in diastolic dysfunction with or without preserved ejection fraction.