Patients with reduced calf muscle pump function (rCPF) may be at an increased risk for venous thromboembolism (VTE) compared with those without rCPF, according to the authors of a research article published in Blood. The authors suggested, furthermore, that these findings may aid in risk stratification for VTE.

Previous research suggests that rCPF is associated with chronic venous insufficiency, poor wound healing, and all-cause mortality. CPF can also be quantified using venous plethysmography.

While immobility is a known factor in the development of deep vein thrombosis and pulmonary embolism, a physiological understanding of these connections is lacking. As rCPF may predict venous stasis even in ambulatory patients, evaluation of this metric may help to predict risk of VTE. For this population-based cohort study, researchers evaluated patient data to determine any causal link between rCPF and VTE.

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Data from previous venous plethysmography obtained from the from the Mayo Clinic Gonda Vascular Laboratory were evaluated. Overall, of the 1532 patients included, 591 had normal CPF, 353 had unilateral rCPF, and 588 had bilateral rCPF. The overall median age was 63.9 years, 1056 (68.9%) patients were female, and the median BMI was 28.8. Patients with a prior VTE were not included.

The median follow-up was 11.7 years (range, 0-22); VTE was noted in 5.7% (87) of patients overall. Compared with patients with bilateral normal CPF, patients with bilateral rCPF had an unadjusted hazard ratio (HR) for VTE of 2.0 (95% CI, 1.2-3.4). After adjusting for age, body mass index, and Charlson Comorbidity Index score, however, the HR for VTE was 1.68 (95% CI, 0.98-2.89)—showing that the lower level of the confidence interval was below 1.

An evaluation of individual patient legs in those with rCPF vs normal CPF showed an adjusted HR for ipsilateral deep vein thrombosis of 1.71 (95% CI, 1.03-2.84).

Patients in both the bilateral rCPF and unilateral rCPF groups had a higher risk of mortality, compared with those with normal CPF (both P <.001).

“In this population-based study of Olmsted County residents with no prior VTE, rCPF as measured by venous plethysmography was associated with increased risk for VTE, particularly lower extremity proximal [deep vein thrombosis],” the authors wrote. “CPF may be a useful measurement to incorporate into VTE risk stratification models.”


Houghton DE, Ashrani A, Liedl D, et al. Reduced calf muscle pump function is a risk factor for venous thromboembolism: a population-based cohort study. Blood. 2021;137(23):3284-90. doi:10.1182/blood.2020010231