Relation of myocardial histomorphometric features and left ventricular contractile reserve assessed by high‐dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy

Abstract

This study was designed to determine the relationship between histomorphometric features and contractile reserve assessed by high-dose dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy. Twenty-four consecutive patients (21 men, aged 43.4+/-8.7 years) with idiopathic dilated cardiomyopathy underwent dobutamine stress echocardiography. Wall motion score index, ejection fraction, cardiac power output and end-systolic pressure/volume ratio were used as indices of left ventricular contractility. Left ventricular endomyocardial biopsy specimens (3-5 per patient) were routinely processed and stained with Masson trichrome, interstitial fibrosis and myocyte diameter were calculated quantitatively. Myocyte diameter and interstitial fibrosis showed strongest correlation with change in wall motion score index (r=-0.667, p<0.001, and r=-0.567, p=0.004, respectively), followed by change in ejection fraction (r=-0.603, p=0.002, and r=-0.467, p=0.021, respectively). Interstitial fibrosis showed no correlation with change of cardiac power output and end-systolic pressure/volume ratio, whereas myocyte diameter was associated with change of both indices (r=-0.565, p=0.004, and r=-0.455, p=0.025). Contractile reserve elicited by high-dose dobutamine is strongly related to the degree of histological disruption in patients with idiopathic dilated cardiomyopathy.