Effect of dobutamine on the left ventricular combined myocardial performance index and B-type natriuretic peptide in symptomatic heart failure patients

ABSTRACT

Congestive heart failure is related to contraction and relaxation abnormalities of the ventricle. Isolated analysis of either mechanism may not be reflective of overall cardiac dysfunction [Recently, a new non invasive Doppler derived index; myocardial performance index [MPI] or total ejection isovolumic index [TEI], which incorporates both systolic and diastolic myocardial performance has been proposed]. It is defined as the sum of isovolumic contraction time [ICT]and isovolumic relaxation time [IRT]divided by ejection time [ET]. In the present study, TEI index was compared with conventional echocardiographic/ Doppler parameters .and plasma B-type natriuretic peptide [BNP] levels in 30 patients with NYHA class 11-1V heart failure, before and after low dose dobutamine stress echocardiography [DSE], which has become accepted in the evaluation of cardiac functional reserve. The mean resting value of the TEI index was significantly higher in patients with advanced NYHA functional class IV [0.94 +/- 0.14] compared with those in class 111[0.78 +/- 0.2] and class 11 [0.61=0.02]. There was a significant negative correlation between TEI index with LVEF [r= -0.39, p< 0.05] and FS [r= -0.34, p<0.05]. The mean resting value of BNP in HF patients was significantly higher than that in controls, and its highest value was in patients in NYHA functional class IV [288 +/- 137.9pg/ml]. Inotropic challenge with dobutamine resulted in a marked improvement of the TEI index [% change -19.9; p< 0.05], and a shortening of the ICT [% change -17.31; p < 0.05] and the IRT [% change -17.01; P<0.05] and an insignificant increase of the ET. The myocardial contractile reserve [MCR] - defined as increment of more than 20% of resting left ventricular ejection fraction - showed significant improvement [% change +23.25; p< 0.05]. We concluded that TEI index is a simple and reproducible measure of cardiac function. It is a sensitive indicator of the effect of inotropic stimulation on global left ventricular function. Larger scale use of this protocol that combined TEI index, BNP and low dose DSE might be useful in HF, as it complements the information provided by other variables used in the diagnosis and functional assessment of heart failure