Coronary flow reserve and myocardial performance index in newly diagnosed diabetic patients

Background: Patients with diabetes mellitus (DM) are at high risk of left ventricular (LV) dysfunction. A reduction of coronary flow reserve (CFR) has been demonstrated in diabetic patients without coronary artery stenosis. In this study, we investigated the association between LV myocardial diastolic and systolic functions and the CFR in newly diagnosed diabetic patients in the absence of coronary artery disease.

Method: We studied 88 patients (mean age 49 ± 10 years) with newly diagnosed DM and 40 healthy control subjects (mean age 50 ± 9 years). All subjects underwent transthoracic echocardiography. The myocardial performance index (MPI) was determined by using pulsed-wave Doppler. The CFR was calculated as the hyperemic to resting coronary diastolic peak velocities ratio.

Results: Patients with diabetes had significantly longer mitral E-wave deceleration time and higher MPI value than control group (P = 0.023 and P < 0.001, respectively). The mean CFR was lower in diabetic patients compared with controls (P = 0.001). The MPI was significantly correlated with CFR (r = -0.371, P < 0.001), LV ejection fraction (r = -0.274, P = 0.018) E/A ratio (r = -0.244, P = 0.024), and glycosylated hemoglobin (HbA1c) (r = 0.476, P < 0.001). Multivariate regression analysis showed that MPI was independently associated with CFR (β = -0.292, P < 0.0001) and HbA1c level (β = 0.372, P < 0.0001).

Conclusions: The MPI was independently associated with CFR in newly diagnosed diabetic patients. The decrease in CFR may cause LV systolic and diastolic dysfunction in asymptomatic diabetic patients.