Right ventricular myocardial performance index (RV MPI)
The index of RV myocardial performance, also known as Tei index, is a
marker of both systolic and diastolic RV function and it is calculated
by dividing the total isovolumic time (isovolumic contraction plus
isovolumic relaxation) to the ejection time [19]. It can be measured
using either pulsed-wave Doppler or tissue Doppler, the cut-offs
proposed for abnormal RV MPI being >0.43 using pulsed
Doppler method and >0.54 using tissue Doppler method
[16]. The advantage of RV MPI is that it bypasses the limitations of
the complex RV geometry, as it is derived from time intervals only
[18]; however, irregular rhythms make MPI difficult to calculate
[19].
Vizzardi et al. assessed the prognostic value of RV MPI (calculated with
the pulsed Doppler method) in a cohort of patients with HF and reduced
LVEF, who were prospectively followed for 5 years for a combined
endpoint of cardiac death and readmissions for HF. The authors found
that a RV MPI>0.38 was an independent predictor of adverse
outcome [30]. In a study by Field et al., each 0.1-unit increase in
RV MPI (assessed by pulsed Doppler) was associated with a 16% increased
risk of MACE (defined as death, cardiac transplantation or ventricular
assist device placement) in patients with advanced HF referred for
cardiac resynchronization therapy (CRT) [31]. To our knowledge, no
studies evaluated the prognostic role of TDI-derived RV MPI in HF,
although some authors suggest that tissue Doppler MPI is superior to
pulsed Doppler MPI because it has the advantage of recording all the
time intervals in the same cardiac cycle [32].