Utility of the Myocardial Performance Index in a Population with High Prevalences of Obesity, Diabetes, and Hypertension: The Strong Heart Study

Abstract

The myocardial performance index (MPI) introduced by Tei, a Doppler-derived echocardiographic measure that reflects both left ventricular (LV) systolic and diastolic function, has been shown to have prognostic value in several clinical settings, including myocardial infarction and congestive heart failure. There are scant data on the correlates and prognostic value of MPI in a population without overt cardiovascular (CV) disease. We investigated clinical and physiologic correlates of MPI, as assessed from echocardiographic Doppler recordings in 1,862 American Indian participants free of coronary or valvular disease or LV systolic dysfunction in the population-based strong heart study (SHS). We then assessed the prognostic value of MPI for incident CV events, including nonfatal stroke, coronary heart disease, congestive heart failure, and CV death. The study population was 59 +/- 8 years old (66% women); 48% had diabetes, 44% hypertension, and 54% were obese. In univariable analyses, MPI (mean = 0.24 +/- 0.17) showed significant negative associations with creatinine clearance, C-reactive protein (CRP), LV ejection fraction (EF), mitral valve E- and A-wave velocities, cardiac index (CI), stroke index (SI) and stroke index/pulse pressure (SI/PP), and significant positive associations with serum creatinine and total peripheral resistance index (TPRI) (all P < 0.05). There were no significant associations of MPI with hypertension or diabetes status, systolic or diastolic blood pressure, body mass index, hemoglobin A1C or LV mass. After adjusting for age, sex, diabetes, and hypertension, MPI remained weakly but significantly correlated with CRP, EF, CI, SI, SI/PP, mitral E- and A-wave velocities, and TPRI. MPI did not predict fatal and nonfatal CV events (risk ratio 1.06 per unit MPI, 95% C.I. 0.56-2.04; P = 0.85) at a mean follow-up of 7.1 +/- 2.2 years. In a population-based sample of adults with high prevalence of diabetes, hypertension, and obesity but without overt CV disease, MPI has weak associations with clinical and physiologic determinants of cardiac function. Moreover, MPI does not provide prognostic information for CV events in this population. Though conceptually attractive as a global measure of cardiac function, MPI has limited utility in a high-risk population without clinical CV disease.