The proposed new classification of coronary microcirculation as the predictor of the heart failure progression in idiopathic dilated cardiomyopathy.

BACKGROUND: The appropriate condition of the coronary microcirculation is essential for proper cardiac muscle activity. The understanding of the pathological microcirculation changes in different stages of idiopathic dilated cardiomyopathy (IDCM) could provide a reliable background for proper therapeutic decisions and prognosis.

METHODS AND RESULTS: The study population consisted of 116 patients (86.2% males, mean age 50.4±13.2 years) with IDCM and heart failure. In samples from left ventricular endomyocardial biopsy, the coronary microcirculation was evaluated by staining with hematoxylin and eosin, Masson's trichrome, and anti-CD34 antibody. The microvessel density (MVD) was calculated. Also, the electron microscopic evaluation of the extracellular matrix capillaries was performed. Samples were assigned to one of four types according to the microcirculation condition: 1, normal microvessels (MVs) (18 patients); 2, mostly normal, some MVs with slightly decreased lumen diameter and thickened wall, absent/mild intravascular fibrosis, and MVD decrease (37 patients); 3, MVs with moderately decreased lumen diameter and thickened wall, moderate intravascular fibrosis, and MVD decrease (45 patients); and 4, MVs with significantly decreased lumen diameter and thickened wall, significant intravascular fibrosis, and MVD decrease (16 patients). Taking all types of the proposed classification into consideration, in type 4, clinical (incidence of New York Heart Association 3 and 4, dyspnea on exertion, pulmonary congestion) and echocardiographic (left atrial and right ventricular diameter, left ventricular mass and ejection fraction, tricuspid annular plane systolic excursion, early diastolic mitral annular velocity measured at the interventricular-septal annulus [E'med], ratio of early diastolic mitral inflow velocity to E'med) parameters were worst. Only atrial fibrillation, diabetes, tricuspid annular plane systolic excursion, and the type of the microcirculation significantly correlated with the incidence of cardiovascular hospitalizations in the linear regression models.

CONCLUSION: The condition of the coronary microcirculation corresponds with the heart failure progression in patients with IDCM.