Nonpredictive value of fibrosis in dilated cardiomyopathy treated with metoprolol

Therapy with β-adrenergic blocking agents has been advocated as a potential useful approach in heart failure. Recent studies suggest that histologic parameters may be helpful in assessing the effectiveness of β-blocker treatment in dilated cardiomyopathy (DCM). In order to predict the response to β-blockers in DCM, fibrous tissue was evaluated at endomyocardial biopsy (EMB) in 45 patients (pts) with a mean left ventricular ejection fraction of 0.28 ± 0.07, who were successively long-term treated with metoprolol (M) (mean dosage 138 ±26 mg/die). s performed from left (n = 32) or right (n = 13) ventricle by means of a Kingʹs bioptome or the Cordis adaptation of this instrument. fication of fibrous tissue was performed at 9 × magnification and with a computerized morphometric system. Qualitative evaluation at light microscopy distinguished four types of fibrosis: pericellular, perivascular, focal, and endocardial. Volume fraction of fibrous tissue ranged from 1.3 to 35.5% (mean 12.1 ± 9.3%) and was not significantly correlated with any clinical variable considered. 24 ± 12 months of treatment, 25 pts were considered improved (group A), whereas the remaining 20 pts were considered not improved (group B), according to criteria based on ejection fraction, left ventricular end-diastolic diameter, filling pattern at Doppler-Echocardiography, cardiothoracic ratio, NYHA functional class, and exercise duration at ergometric test. fraction of fibrous tissue did not differ significantly between the two groups (group A = 12.1 ± 9.1%; group B = 11.3 ± 9.6%;p = NS). Dominant pericellular type of fibrosis was equally distributed between the two groups (group A = 925 pts, 36%; group B = 1020 pts, 50%), whereas a perivascular and/or focal replacement fibrosis was more frequent in group A (group A = 1020 pts, 50%; group B = 220 pts, 10%; p = .05, OR 5.55 at univariate analysis). At multivariate analysis mean aortic blood pressure was the only variable discriminating the two groups; the type of fibrosis, although not statistically significant, maintained a high value of odds-ratio (5.23). clusion, extent of total fibrosis assessed by EMB may range widely in patients with DCM, is not correlated with the most important clinical variables, and is not predictive of long-term response to β-blocker treatment. Otherwise, prevalent perivascular and/or focal replacement fibrosis could be associated with a higher probability of improvement after long-term β-blocker treatment.