Transient elastography (TE) by Fibroscan was initially designed as a noninvasive tool to diagnose and stage hepatic fibrosis. Previously, increased liver stiffness (LS) has been shown to reflect liver inflammation from acute hepatitis,[2, 3] congestion from increased central venous pressure, and extrahepatic cholestasis. While food intake has also been previously demonstrated to increase LS, the most recent article by Arena et al. further illustrates the timeframe and pattern of this increase in LS. This is an important finding and has clinical consequences.
In this study, LS was measured after an overnight fast (baseline), followed by 15, 30, 45, 60, and 120 minutes after a standardized meal in 125 chronic hepatitis C (HCV) patients. At least 75% of these patients had a liver biopsy to determine the level of fibrosis, while the other quarter of these patients were considered cirrhotic based on clinical, laboratory, sonographic, and endoscopic criteria. The major findings of this study were a peak LS increase at 30 minutes after a standardized meal (although some patients peaked between 15 and 45 minutes) and the LS returning to baseline after 120 minutes. The impact of a standard meal on LS values (S delta) was shown to be directly proportional to the stage of fibrosis present, with the highest increase in absolute values (not percentage of S delta) found in cirrhosis patients.
Liver TE is performed without consideration of the state of fasting in most institutions. For patients with no fibrosis on TE (F0-F1), this new information will not be clinically relevant, as one would expect lower LS when fasting. In contrast, the findings of this study could potentially impact treatment decisions and management plans for patients with significant fibrosis on TE (F2-F3). HCV patients with an overestimated LS value may not be considered for newer antiviral therapies without a liver biopsy because most trials exclude patients with cirrhosis. Similarly, patients with significant fibrosis misclassified as F4-cirrhotic may undergo unnecessary gastroscopy to screen for esophageal varices every 2 to 3 years. Hence, we suggest that patients classified as F2 or greater fibrosis should have a repeat liver TE after a 2-hour fast to reassess their LS. Moreover, serial LS measurements may be an important consideration to assess disease progression in HCV.
Another interesting aspect of this LS study relates to the dynamic changes in LS with standardized meals. The suggested mechanism of this change was postprandial hyperemia and increase in portal pressure in cirrhosis patients after meals. In this study, the number of cirrhosis patients with esophageal varices on primary prophylaxis with a noncardioselective beta-blocker was not known. Similar to standard meals, whether beta-blocker therapy may potentially be another factor affecting LS remains to be answered. Together with previous work on the influence of central venous pressure on LS, this study again highlights the possibility of using TE as a suitably sensitive noninvasive tool to assess serial changes to parenchymal stiffness.
Jun Liong Chin, M.B., MRCPI, MRCP (U.K.)1 Angelina Farrelly, M.B., B.Ch., BAO1 Grace Chan, MBBS, MRCPI, MRCP (U.K.)1 Suzanne Norris, Ph.D., FRCPI, M.Sc.1 P. Aiden McCormick, M.D., FRCPI, FRCP2
1Department of Gastroenterology and Hepatology GEMS directorate St. James's Hospital Dublin, Ireland
2Liver Unit St., Vincent's University Hospital University College Dublin Dublin, Ireland