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Collateral vessel development predictive of portal vein thrombosis in patients with cirrhosis

Characteristics of collateral vessels, particularly flow volume in the largest vessel, are predictive factors for developing portal vein thrombosis, according to recent results.

In a retrospective analysis, researchers evaluated data on portal vein thrombosis (PVT) in 150 patients with virus-related cirrhosis, including 133 cases caused by HCV, 16 due to HBV and one patient with HCV and HBV. Participants were observed for a mean of 67.6 months.

Twenty-eight percent of participants developed PVT during the 11-year study, with cumulative incidence rates of 12.8% at 1 year, 20% at 5 years and 38.7% at 8 to 10 years. Vein obstruction was partial in 73.8% of PVT cases and complete in 26.2%, with extrahepatic thrombus in 54.8%, intrahepatic in 19% and both conditions in 26.2%.

While the number of collateral vessels did not differ significantly between patients with and without PVT, thrombotic patients had greater vessel diameter (7.6 mm vs. 3.9 mm; P<.0001), flow velocity (15.6 cm/s vs. 4.9 cm/s; P=.0112) and volume (517.3 mL/min vs. 148.6 mL/min; P<.0001) in the largest vessel. Participants with velocity greater than 10 cm/s had higher cumulative PVT incidence rates at 1, 5 and 10 years than those with a velocity of 10 cm/s or less (19.1% vs. 8.6%; 27% vs. 16.3%; 78.4% vs. 24.7%, respectively; P=.0303 for trend).

Thrombosis improved naturally in 47.6% of cases, did not change in 45.2% and worsened in 7.2%. Patients who experienced improvement had significantly lower largest collateral vessel diameter (3.6 mm vs. 7.7 mm) and flow volume (141.1 mL/min vs. 451.6 mL/min) than patients who did not improve (P<.0001 for both). Multivariate analysis indicated that flow volume at baseline independently increased the risk for thrombosis (HR=3.922; 95% CI, 3.697-4.415).

“The development of collateral vessels was a significant predictive factor for the occurrence of PVT in patients with virus-induced cirrhosis,” the researchers concluded. “However, thrombosis had little influence on prognosis. Whether or not therapeutic intervention for PVT leads to improved long-term survival of patients with cirrhosis is an issue that remains to be solved.”