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Congestive heart failure and outpatient risk of venous thromboembolism: a retrospective, case-control study
M D Howell1, J M Geraci, A A Knowlton
1Cardiology Section, Department of Medicine, Houston Veterans Affairs Medical Center and Baylor College of Medicine, Houston, TX 77030, USA.
Insights
Congestive heart failure (CHF) significantly increases the risk of venous thromboembolism in outpatients. This risk escalates with declining ventricular function, particularly with ejection fractions below 20%.
Area of Science:
- Cardiology
- Vascular Medicine
- Internal Medicine
Background:
- Congestive heart failure (CHF) is a known risk factor for venous thromboembolism (VTE), but direct evidence is limited.
- The relationship between left ventricular dysfunction and VTE risk in outpatients requires further investigation.
Purpose of the Study:
- To determine if CHF due to left ventricular dysfunction is an independent risk factor for acute VTE in outpatients.
- To assess if worsening ventricular function correlates with increased VTE risk.
Main Methods:
- A case-control study was conducted involving 106 deep vein thrombosis (DVT) cases and 603 controls admitted to a VA hospital.
- Patients were matched for admission month and controls were admitted for diabetes mellitus or infection.
- Logistic regression models were used to analyze the association between CHF, ejection fraction (EF), and VTE, adjusting for established risk factors.
Main Results:
- CHF was identified as an independent predictor of VTE in the logistic regression model.
- A significant inverse relationship was observed between EF and VTE risk.
- An EF < 20% was associated with a high odds ratio (OR) of 38.3 for VTE.
Conclusions:
- Congestive heart failure is an independent risk factor for venous thromboembolism.
- The risk of VTE markedly increases as the ejection fraction decreases in CHF patients.
- Anticoagulation therapy may be beneficial for selected CHF patients at high risk for VTE.
Abstract:
Although CHF has been considered a risk factor for venous thromboembolism, this has not been directly studied. We hypothesized that congestive heart failure would increase the risk of venous thromboembolism in an outpatient population, and that this risk would increase as patients' ventricular function worsened. We conducted a case-control study to examine whether CHF due to left ventricular dysfunction was an independent risk factor for acute venous thromboembolism in outpatients, once established risk factors such as recent surgery and prior venous thromboembolism are taken into account. We reviewed 106 cases of DVT and 603 controls, admitted for diabetes mellitus or infection, matched for month of admission at a VA hospital. Assignment of a diagnosis of venous thromboembolism required a definitive test, as did classification as CHF. In a logistic regression model CHF was an independent predictor of venous thromboembolism. A second logistic regression model showed that the risk of venous thromboembolism increased as the ejection fraction (EF) decreased, with an EF < 20 associated with a venous thromboembolism OR of 38.3 (95% CI 9.6, 152.5). CHF is an independent risk factor for venous thromboembolism, and the risk increases markedly as the EF decreases. These results support the use of anticoagulation in selected patients with CHF.