Natural course of inflammatory cardiomyopathies

Abstract

Introduction. Refractory heart failure with a poor prognosis is a key feature of dilated cardiomyopathy. Inflammatory cardiomyopathy, often diagnosed via in vivo subendomyocardial biopsy, is considered a potential precursor to dilated cardiomyopathy. The Dallas criteria, applied to morphometric and electron microscopic studies of biopsy samples, are essential for differentiating the features of various inflammatory stages. Building upon these established diagnostic principles, our study integrates immunohistological analysis with measurements of intramyocardial indices and intracardiac hemodynamics. This comprehensive approach aims to characterize the natural course of inflammatory cardiomyopathy, seeking to improve the understanding of the clinical trajectories and tissue structures that define both inflammatory cardiomyopathy and its progression to dilated cardiomyopathy. Material and methods. The study included 75 patients with inflammatory cardiomyopathies and 75 patients with dilated cardiomyopathies. The following procedures were performed: coronary angioventriculography, repeated subendomyocardial biopsy, immunohistologic analysis, and assessment of intracardiac and intramyocardial hemodynamics. Results. Morphohistologic analysis of inflammatory cardiomyopathies at different stages revealed a maximum of 10-12 lymphocytes, which decreased to only isolated lymphocytes in late stages. In biopsies from early-stage inflammatory dilated cardiomyopathies, the morphologic appearance showed lymphocytic infiltration of the myocardial stroma, vasculitis of intramural arteries and arterioles. The biopsies performed after 36 months showed dystrophic structures, microfocal and diffuse replacement fibrosis, predominantly perivascular, which are indistinguishable from the features of dilated cardiomyopathy. Intracardiac hemodynamic indices in patients with dilated and inflammatory cardiomyopathies did not differ. Similarly, left ventricular regional contractility, as verified by radiopaque ventriculography, was not significantly different. The degree of radiotracer detection on thallium-201 scintigraphy was statistically insignificant between the two conditions. Immune complexes and immunoglobulins G, M, and A in the blood were elevated in both groups, likely as a consequence of heart failure. Conclusions. Morphostructural analysis of biopsies taken from patients with inflammatory dilated cardiomyopathies, at different stages of its natural course reveals the progressive development of dilated cardiomyopathies. These structural changes correlate closely with findings from intracavitary and hemodynamic assessments and measures of regional contractility, supporting a direct link between dilated and inflammatory cardiomyopathies.