Objective: To investigate the value of myocardial performance index (MPI) in assessing LV function in patients with primary hypertension (HP).
Methods: We studied 130 patients with HP (mean age 54.9±13.3 years)and 155 healthy control subjects (mean age 52.4±11.6 years). MPI was determined by tissue doppler imaging using the following formula: MPI=(isovolumic contraction time + isovolumic relaxation time)/ ejection time. The HP group was divided into hypertrophy subgroup( LVMI≥115 g/m(2) in males, or ≥95 g/m(2) in females) and normal mass subgroup(LVMI <115 g/m(2) in males, or<95 g/m(2) in females).
Results: MPI was significantly different in control group, normal mass subgroup and hypertrophy subgroup(0.72±0.23 vs. 0.54± 0.17 vs. 0.45±0.11, P<0.001). Hypertrophy subgroup had significant higher MPI than normal mass subgroup(P =0.046), and both the groups had significant higher MPI than control group(all P<0.001). MPI was positively associated with age(r=0.369,P<0.001), Left ventricular end diastolic diameter(r=0.169, P<0.05), Sm(r=-0.211, P<0.001) and Em(r=-0.383, P<0.001) in control group. In multiple linear regression analysis, MPI was independently related to age (β=0.492, t=7.222,P<0.001) in control group. Among the HP patients, MPI was positively associated with left atrial area (r=0.293, P<0.001),intra ventricular septum(IVS) diameter (r=0.453, P<0.001), LVMI (r=0.453, P<0.001), relative wall thickness(r=0.458, P<0.001), and negatively associated with Sm(r=-0.414, P<0.001), Em(r=-0.508, P<0.001), left ventricular ejection fraction (r=-0.305, P<0.001) in bivariate analysis. In the multiple linear regression analysis, MPI was independently related to Em (β=0.401, t=4.256,P<0.001) and IVS diameter (β=-0.365, t=-3.878,P<0.001) in the HP patients.
Conclusion: The HP patients had elevated MPI, especially in the ones with LV hypertrophy. Tissue doppler imaging (TDI) derived MPI could be a useful index to evaluate the overall cardiac function in HP patients.