Serum carboxy-terminal propeptide of procollagen type I is a marker of myocardial fibrosis in hypertensive heart disease

Background-This study was designed to investigate whether the serum concent ration of the carboxy-terminal propeptide of procollagen type I (PIP), a ma rker of collagen type I synthesis, is related to myocardial fibrosis in hyp ertensive patients. Methods and Results-The study was performed in 26 patients with essential h ypertension in which ischemic cardiomyopathy was excluded after a complete medical workup. Right septal endomyocardial biopsies were performed in hype rtensive patients to quantify collagen content, Collagen volume fraction (C VF) was determined on picrosirius red-stained sections with an automated im age analysis system. The serum concentration of PIP was measured by specifi c radioimmunoassay. Compared with normotensives, both serum PIP and CVF wer e increased (P<0.001) in hypertensives. A direct correlation was found betw een CVF and serum PIP (r=0.471, P<0.02) in all hypertensives. Histological analysis revealed the presence of 2 subgroups of patients: 8 with severe fi brosis and 18 with nonsevere fibrosis. Serum PIP was higher (P<0.05) in pat ients with severe fibrosis than in patients with nonsevere fibrosis. Using receiver operating characteristic curves, we observed that a cutoff of 127 mu g/L for PIP provided 78% specificity and 75% sensitivity for predicting severe fibrosis with a relative risk of 9.80 (95% CI, 1.19 to 19.30). Conclusions-These results show a strong correlation between myocardial coll agen content and the serum concentration of PIP in essential hypertension. Although preliminary, these findings suggest that the determination of PIP may be an easy and reliable method for the screening and diagnosis of sever e myocardial fibrosis associated with arterial hypertension.