Collagen remodeling and cardiac dysfunction in patients with hypertrophic cardiomyopathy: The significance of type III and VI collagens

Background: The relationship between the extent of myocardial interstitial fibrosis, the percentage of each type of collagen, and cardiac function in patients with hypertrophic cardiomyopathy (HC) has not been established. Hypothesis: The study aimed to establish that increases in some types of co llagen may correlate with cardiac dysfunction. Methods: Mallory-Azan staining and immunohistochemical staining by the avid in-biofin-complex (ABC) method using anticollagen antibodies were performed on the myocardial biopsy specimens in 35 patients with HC, and the percent age and type of collagen present was determined. Left ventricular (LV) func tion was evaluated by cardiac catheterization and ventriculography. Results: The percentage of myocardial interstitial fibrosis correlated high ly with indices of LV diastolic and systolic function. The amount of type I II collagen correlated significantly with the peak negative dp/dt, the rapi d filling volume/stroke volume, and the ejection fraction (EF). Significant correlations also were noted between the amount of type VI collagen and pe ak negative dp/dt, peak positive dp/dt, and EE Type I collagen did not corr elate with any of the LV function indices, and type IV collagen correlated only with peak ejection rate. Type V collagen did not accumulate substantia lly in the myocardial interstitium. Conclusions: The progression of myocardial interstitial fibrosis in the HC heart adversely impacts both the diastolic and systolic function of the LV. Increases in the percentage of type III and VI collagen correlate with car diac dysfunction.