Anticoagulation therapy decreases proximal DVT and PE, increases bleeding after calf DVT

Therapeutic anticoagulation therapy decreased already-low rates of proximal deep vein thrombosis and pulmonary embolism among patients with isolated calf DVT, according to the results of a single-center retrospective study.

However, patients treated with therapeutic anticoagulation experienced increased risk for bleeding.

“Despite their common occurrence, optimal management of acute isolated calf DVT is relatively poorly understood,” Garth H. Utter, MD, MSc, associate professor of surgery at University of California Davis Health System, and colleagues wrote. “Approaches include no treatment or monitoring (particularly if the calf DVT is asymptomatic and provoked and the risk factors are transient), follow-up with serial imaging and therapeutic anticoagulation of varied duration.”

Research has shown that anticoagulation reduced risk for thrombus propagation; however, recent literature reviews concluded the methodologic quality of available research is low.

Utter and colleagues evaluated the association between therapeutic anticoagulation and reduced likelihood of proximal DVT and PE among patients treated at the University of California Davis Medical Center.

Researchers identified 384 patients (57.8% men; mean age, 60 years) who had an isolated calf DVT from 2010 to 2013 and who had not received prior therapeutic anticoagulation.

From the cohort, physicians intended to treat 243 patients with therapeutic anticoagulation for their isolated calf DVT. The other 141 patients received no treatment and represented the control cohort.

However, one patient in the therapeutic arm refused treatment and two patients in the control arm subsequently received treatment for other circumstances (atrial fibrillation and upper-extremity DVT).

Anticoagulation therapy included warfarin (75.2%), low–molecular-weight heparin (17.7%), continuous heparin infusion (6.2%), rivaroxaban (Xarelto, Janssen; 0.4%) and bivalirudin (0.4%).

Radiographically confirmed proximal DVT or PE within 180 days of calf DVT diagnosis served as the primary endpoint.

Secondary endpoints included bleeding episodes; death; and a composite of proximal DVT, PE or death.

Total incidence of proximal DVT appeared low for the therapeutic and control arms (1.6% vs. 5%). PE incidence also was low in both arms (1.6% vs. 4.3%).

Adjusted analysis showed patients in the therapeutic arm experienced decreased risk for DVT or PE (OR = 0.33; 95% CI, 0.12-0.87), but increased risk for bleeding (OR = 4.87; 95% CI, 1.37-17.3).

In a subgroup analysis based on location of calf DVT, researchers analyzed the likelihood of developing proximal DVT among patients with original DVT in the axial vein (therapeutic, n = 160; control, n = 83) or muscular branch vein (therapeutic, n = 132; control, n = 83).

Patients with muscular branch vein DVT experienced decreased likelihood of proximal DVT or PE with therapeutic anticoagulation (OR = 0.12; 95% CI, 0.03-0.53). However, the association did not reach statistical significance for patients with axial vein DVT.

Researchers acknowledged that the retrospective, observational nature of the analysis may have limited findings.

“The decision to administer therapeutic anticoagulation to patients with isolated calf DVTs should weigh the risks and benefits for a given patient,” Utter and colleagues wrote. “Bleeding episodes, although infrequently life threatening, were clearly associated with therapeutic anticoagulation in our study and in one instance, an unforeseen hemorrhagic stroke directly caused death.”

The important question — whether bleeding or clotting is worse — remains to be answered, Xuan-Binh D. Pham, MD, surgeon, and Christian de Virgilio, MD, FACS, vice chair of education, both in the department of surgery at Harbor-University of California, Los Angeles Medical Center, wrote in an accompanying editorial.

“A cautionary finding was that the risk for significant bleeding associated with anticoagulation was 9%, which was a fourfold higher rate than among controls and included one death,” they wrote. “Utter and colleagues provide further evidence that anticoagulation should strongly be considered in patients with provoked muscular branch DVT, because some calf DVT clearly can propagate and lead to PE.” – by Nick Andrews

Disclosure: The researchers report no relevant financial disclosures.