CardioExchange Archive

An expert weighs in on a case of unexplained VTE in a patient under 50. (see Part I)
 
The rationale for genetic testing in unexplained thrombosis is to gain a better understanding of why VTE occurred and to document risk factors for recurrent events. However, genetic testing in this setting is somewhat controversial. Knowing the possible molecular etiology of VTE might provide some intangible benefits to physicians and patients (e.g., less worry about occult cancer), but it doesn’t necessarily lead to changes in clinical management that improve patient outcomes. Regardless of genotype, patients with a first idiopathic VTE should receive anticoagulation therapy for 6 to 12 months (Ann Intern Med 2007; 146:204). According to a recent systematic review, there are no randomized trials of genetically guided anticoagulation strategies following VTE (Health Technol Assess 2009;13[2]).
 
Decisions about genetic testing in asymptomatic family members must be made on a case-by-case basis. Special considerations include pregnancy, the presence of hypercoagulability risk factors (such as oral contraceptive use and smoking), and the presence of medical conditions that might increase VTE risk (such as cancer). Of particular concern is that pregnant women found to have prothrombotic genotypes could be faced with the decision of whether to receive prophylactic subcutaneous low-molecular-weight heparin (Curr Opin Endocrinol Diabetes Obes 2009; 16:464). Clearly, family members may have a wide range of reactions to the disclosure of genetic information and may need counseling to make appropriate decisions for themselves.
 
Given the lack of data currently supporting the clinical utility of genetic testing for VTE, we must ask ourselves as physicians why we engage in this practice. Are we just searching for an explanation? Do patients and their families value the knowledge that comes from testing? When informed patients do want testing, is it reasonable to expect us to take detailed family histories and provide individualized genetic counseling?