Integrated backscatter as a fibrosis marker in the metabolic syndrome: association with biochemical evidence of fibrosis and left ventricular dysfunction

AIMS: Myocardial fibrosis is an important contributor to heterogeneity of left ventricular (LV) dysfunction in the metabolic syndrome (MS). Comparison of strain with calibrated integrated backscatter (cIB) and serological fibrosis markers could provide a means to understand the association of cardiac function with markers of fibrosis. METHODS AND RESULTS: We studied 172 patients with MS (age 50 ± 13 years) and 61 healthy controls in a prospective, cross-sectional study. Echocardiographic evaluation included myocardial velocities and deformation, and calibrated cIB. Procollagen type III amino-terminal propeptide (PIIINP) and procollagen type I carboxy-terminal propeptide (PICP) were measured from serum. MS patients demonstrated LV systolic and diastolic function, and myocardial echodensity disturbances, as well as elevated serum PIIINP and PICP levels. For most functional variables, calibrated cIB in the basal septum was the strongest determinant of impaired LV performance, independent of higher procollagen levels, LV mass index, age, body mass index, creatinine level, and C-reactive protein. Patients with increased abdominal fat deposit (assessed by the waist-to-hip ratio) presented higher levels of procollagen peptides and septal calibrated cIB, and with more profound LV dysfunction as indicated by lower myocardial deformation and early diastolic velocity, and higher E/e'. CONCLUSION: Myocardial echodensity is a stronger correlate of LV systolic and diastolic dysfunction in MS, than circulating procollagen peptides. Both fibrosis and LV function abnormalities are increased at a higher waist-to-hip ratio, which might provide a rationale for the implementation of intensified therapy in this subset of patients.