HDL May Be Protective Against Recurrent Venous Thrombosis

ORLANDO -- High-density lipoproteins, which are known protectors against arterial atherothrombosis, also appear to protect against recurrent venous thrombosis, Dr. Sabine Eichinger reported at the annual meeting of the American Society of Hematology.

In a prospective study of 772 patients with a first episode of spontaneous venous thromboembolism, the relationship between plasma lipoprotein parameters and recurrence of venous thrombosis was evaluated. Of the 772 patients, 100 (13%) had recurrent venous thromboembolism during an average follow-up of 4 years.

Compared with the patients who did not have a recurrence, those patients who had a recurrence showed significantly lower mean plasma levels of apolipoprotein A-I, a major component of HDL (1.12 vs. 1.23 mg/mL), said Dr. Eichinger, who is a professor extraordinarius at the Medical University of Vienna.

The relative risk of recurrence in this study population was found to be 0.87 for each increase of 0.1 mg/mL in plasma apolipoprotein A-I. For those patients who had apolipoprotein A-I levels above the 67th percentile of the study population, compared with those with lower levels, the relative risk of recurrence was 0.51. Further, the HDL cholesterol levels and the HDL particle concentrations in the plasma of patients who had recurrence were lower, compared with those in patients without recurrence, according to Dr. Eichinger.

Although HDL is known to protect against arterial atherothrombosis, venous thrombosis is a clinically distinct entity, particularly regarding thrombus appearance, pathogenic mechanisms, and therapeutic approaches.

Although it was believed that HDL is protective against recurrent venous thrombosis as a result of its multiple antithrombotic and anti-inflammatory actions, this had not been previously shown, she explained.

The findings may have implications for the assessment of venous thrombosis recurrence risk; measurement of HDL parameters may be useful for predicting risk.

The findings also suggest that drugs that increase HDL might be useful for reducing the risk of venous thrombotic events, she concluded.