Background: The spectrum of diabetic heart disease involves a progression from normal heart to preclinical left ventricular diastolic and systolic dysfunction followed by overt echocardiographic evidence of left ventricular (LV) dysfunction and finally symptomatic heart failure.
Objective: To compare the value of tissue Doppler imaging (TDI) over the conventional echocardiography in the assessment of early myocardial dysfunction in type 1 diabetics in correlation with serum N-terminal pro-brain natriuretic peptide (NT-pro-BNP), state of metabolic control, and diabetes duration.
Methods: Sixty subjects were included; 40 type 1 diabetics (aged 12-18 years). Twenty matched subjects served as controls. They were subjected to clinical examination with assessment of cardiovascular reflexes for autonomic neuropathy. Laboratory investigations included mean random blood sugar (MRBS), hemoglobin A1c (HbA1c), urinary microalbumin, and serum determination of NT-pro-BNP. Echocardiography for chamber dimensions, systolic and diastolic function, Tie index, and longitudinal myocardial global biventricular function by pulsed TDI of 6 LV walls and right ventricle (RV) free wall.
Results: All diabetics and controls had normal LV dimensions, LV mass index and systolic functions except for higher left ventricular posterior wall (LVPW) in diabetics (P < 0.05). LV and RV diastolic dysfunction diagnosed in 25% of diabetics by conventional Doppler with higher peak A (P < 0.05, P < 0.05) and lower E/A (P < 0.05, P < 0.05) compared to controls. Diabetics had larger Tie index (P < 0.05). TDI showed delayed myocardial relaxation in 52.5% of diabetics with lower LV and RV peak Em (P < 0.05, P < 0.01) and Em/Am (P < 0.01, P < 0.001) compared to controls. NT-pro-BNP was elevated in diabetics (P < 0.01) with best cut-off value = 62.5 Fmol/mL, sensitivity (82%), and specificity (95%) for detection of isolated diastolic dysfunction in diabetics. It was correlated negatively with LV Em (P < 0.05), Em/Am (P < 0.01) and positively with Am (P < 0.01), impaired diastolic velocities were associated with higher HbA1c.
Conclusion: Asymptomatic diabetics had evidence of subtle right and LV dysfunction with delayed myocardial relaxation which was related to metabolic control. Tissue Doppler (TD) has an additional value in evaluating ventricular filling. NT-pro-BNP is considered a sensitive, specific, and predictive marker for diastolic dysfunction.