Ultrasonic Backscatter and Serum Marker of Cardiac Fibrosis in Hypertensives

Abstract

Elevations in the serum concentration of the carboxy-terminal propeptide of procollagen type I (PIP) >127 &mgr;g/L have been found to predict severe myocardial fibrosis in hypertensive patients. This study was designed to assess whether ultrasonic reflectivity, evaluated by a real-time integrated backscatter analysis, was related to the severity of myocardial fibrosis as estimated by serum PIP. Thirty-four subjects were included in the study. Serum PIP was measured by specific radio immunoanalysis. Backscatter cyclic variation and maximal intensity were measured in 6 regions throughout the left ventricle. The subjects were divided into 3 groups: 14 normotensives with PIP <127 &mgr;g/L (group 1), 12 hypertensives with PIP <127 &mgr;g/L (group 2), and 8 hypertensives with PIP >127 &mgr;g/L (group 3). The highest cyclic variation was found in group 1 and the lowest in group 3 (5.78±0.25 versus 4.70±0.33 dB, P <0.05), with intermediate values in group 2 (5.10±0.27 dB). No differences in maximal intensity were found among the 3 groups of subjects. Using receiver operating characteristics curves, we observed that a cutoff of 2.90 dB for cyclic variation measured in the apex provided 75% sensitivity and 63% specificity for predicting PIP >127 &mgr;g/L in hypertensives, with a relative risk of 2.50 (95% CI, 0.72 to 34.70). These results show an association between diminished cyclic variation of backscatter and increased serum concentration of PIP in hypertension. Thus, the combination of these 2 parameters may be useful for the diagnosis of severe myocardial fibrosis associated with hypertension.