Correlation of Myocardial Performance Index with Serum Nt-Probnp Levels in Asymptomatic Type 2 Diabetes Mellitus

Abstract

Background: Type 2 diabetes mellitus (T2DM) may cause progressive myocardial injury before heart failure symptoms or a reduction in left ventricular ejection fraction becomes evident. The myocardial performance index (MPI) integrates systolic and diastolic time intervals, whereas N-terminal pro-B-type natriuretic peptide (NT-proBNP) reflects myocardial wall stress. Their relationship may provide a pragmatic strategy for identifying subclinical diabetic cardiac dysfunction.

Methods: This single-centre cross-sectional observational study included 80 adults with asymptomatic T2DM. Clinical characteristics, body mass index, duration of diabetes, blood pressure and glycated haemoglobin (HbA1c) were recorded. Doppler echocardiography was used to determine MPI, left ventricular ejection fraction (LVEF) and diastolic dysfunction grade. Serum NT-proBNP was measured by the institution's standardized laboratory method. Correlation analysis assessed relationships between MPI and NT-proBNP, age, HbA1c, diastolic dysfunction and LVEF. Receiver operating characteristic (ROC) analysis evaluated NT-proBNP for detecting abnormal MPI (>=0.40).

Results: Mean age was 57.3 +/- 8.4 years; 48 participants (60.0%) were male, 67 (83.75%) were obese and mean diabetes duration was 7.9 +/- 2.8 years. Abnormal MPI was present in 59 of 80 patients (73.8%), while 59 of 80 (73.75%) had diastolic dysfunction; no participant had LVEF <50%. Mean NT-proBNP increased stepwise from 54.1 +/- 7.3 pg/mL in normal MPI to 150.3 +/- 10.7 pg/mL in severe MPI abnormality (p<0.001). MPI correlated strongly with NT-proBNP (r=0.926), HbA1c (r=0.854), diastolic dysfunction grade (r=0.845) and age (r=0.782), and inversely with LVEF (r=-0.716); all reported p values were <0.001. NT-proBNP >=66 pg/mL identified abnormal MPI with an AUC of 0.982 (95% CI 0.962-1.000), 95.3% sensitivity and 90.5% specificity.

Conclusion MPI is a simple, non-invasive marker of early global cardiac dysfunction in asymptomatic patients with T2DM and shows excellent correlation with serum NT-proBNP levels. Combined use of echocardiographic and biochemical markers may improve early cardiovascular risk stratification.