Patients with heart failure (HF) are particularly vulnerable to the development of venous thromboembolism (VTE) and its related complications of pulmonary embolism and right ventricular failure. To improve our understanding of the clinical characteristics, prophylaxis, and initial management of patients with HF and deep vein thrombosis (DVT), we compared 685 patients with a history of HF with 3,890 patients without HF in a prospective registry of 5,451 consecutive patients with ultrasound-confirmed DVT. We excluded 876 patients for whom data regarding HF status were incomplete. Patients with HF had an increased frequency of co-morbid conditions such as neurologic disease including stroke (33% vs 26%, p = 0.0002), acute lung disease including pneumonia (31% vs 15%, p <0.0001), and acute coronary syndrome (11% vs 4%, p <0.0001) contributing to a higher medical acuity than in patients without HF. Furthermore, patients with HF were more likely to have VTE risk factors of immobilization (53% vs 42%, p <0.0001), acute infection (33% vs 27%, p = 0.01), and chronic obstructive pulmonary disease (29% vs 12%, p <0.0001). Patients with and without HF and DVT had a high frequency of recent hospitalization (48% vs 47%, p = 0.96). Fewer than 12 of patients with HF (46%) who subsequently developed DVT received any VTE prophylaxis. In conclusion, the combination of higher medical acuity, increased frequency of VTE risk factors, and low rate of VTE prophylaxis presents a "triple threat" to patients with HF.