Different microcirculatory and interstitial matrix patterns in idiopathic dilated cardiomyopathy and Chagas' disease: a three dimensional confocal microscopy study

Objective-To analyse the morphological aspects of the extracellular matrix and microcirculation to clarify whether chronic Chagas' cardiopathy (CCC) i s an accurate model to study the pathogenesis of idiopathic dilated cardiom yopathy (IDCM). Design-Thick histological myocardial sections were prepared to analyse coll agen, and microcirculation was examined during confocal laser and light mic roscopy. Setting-The specimens were prepared at the pathology service of the Heart I nstitute of Sao Paulo, Brazil. Patients-Nine control hearts, eight IDCM hearts, and 10 CCC hearts were stu died after necropsy. Main outcome measures-The number of collagen struts per 100x field, the are a of fibrosis (%), and the diameters of arterioles and capillaries were mea sured in each heart to establish outcome. Results-A smaller number (mean (SD)) of collagen struts was seen in the hea rts in the IDCM group (9.1 (4.1)) than in the control (22.4 (3.2)) (p < 0.0 5) or CCC (15.7 (7.4)) (p > 0.05) groups. Fibrosis was greater in the CCC h earts (13.8 (10.5)%) than in the IDCM hearts (5.9 (6.6)%) (p > 0.05). Major increases in arteriole (65.4 (9.9) mu m) and capillary (9.9 (1.7) mu m) di ameters were seen in the CCC hearts but not in the IDCM hearts (arteriole d iameter 40.3 (7.9) mu m; capillary diameter 7.9 (1.3) mu m) Conclusions-Hearts demonstrating CCC and IDCM present different extracellul ar and microvessel alterations. This suggests that distinct pathogenic mech anisms are responsible for each condition and that CCC is not an effective model to study IDCM.