From the Guidelines

Receiving Lovenox (enoxaparin) before a heart catheterization is generally not recommended as it increases bleeding risk during the procedure.

The decision to continue or discontinue Lovenox before a heart catheterization should be made on a case-by-case basis, taking into account the patient's individual risk factors for bleeding and thrombosis.
According to the most recent guidelines, enoxaparin is preferred to unfractionated heparin (UFH) in certain settings, such as pre-hospital fibrinolysis 1.
However, in the context of heart catheterization, the risk of bleeding associated with enoxaparin must be carefully weighed against its potential benefits.

Typically, Lovenox should be discontinued at least 12-24 hours before a planned cardiac catheterization, with the exact timing depending on kidney function and dosage.
For patients on therapeutic doses (1 mg/kg twice daily or 1.5 mg/kg once daily), a 24-hour window is often preferred, while for prophylactic doses (40 mg daily), 12 hours may be sufficient.
If a patient is already taking Lovenox for a condition like deep vein thrombosis, pulmonary embolism, or acute coronary syndrome, they should inform their cardiologist immediately.
The catheterization team will need to balance the patient's thrombotic risk against bleeding risk, and in emergency situations, procedures may still proceed with reversal agents available.

Lovenox works by inhibiting factor Xa in the coagulation cascade, which prolongs the time it takes blood to clot - beneficial for preventing clots but problematic during procedures requiring vascular access.

The 2012 ACCF/AHA focused update of the guideline for the management of patients with unstable angina/non-ST-elevation myocardial infarction recommends discontinuing enoxaparin 12 to 24 hours before coronary artery bypass grafting (CABG) 1.
The 2020 position paper of the Acute Cardiovascular Care Association (ACCA) of the ESC recommends the pre-hospital use of enoxaparin as a first-line therapy, or UFH if enoxaparin is not available, during the transfer for primary percutaneous coronary intervention (PPCI) 1.

From the Research

The use of enoxaparin before heart catheterization has been studied in various clinical settings 2, 3, 4.
Enoxaparin has been shown to be effective in preventing venous thromboembolism and reducing the rate of deaths and serious cardiac events in patients with acute coronary syndromes 2, 3.
However, the use of enoxaparin before heart catheterization may also increase the risk of bleeding complications, particularly at the access site 5, 3, 4.
A study published in 2003 found that 4.2% of patients who received enoxaparin before cardiac catheterization developed severe late enoxaparin-associated hemorrhagic or vascular complications at the femoral arterial puncture site 5.
Another study published in 2006 found that enoxaparin was associated with more bleeding events, including access site bleeding and mild bleeding, compared to unfractionated heparin in patients undergoing percutaneous coronary intervention 3.
A substudy of the TRANSFER-AMI trial found that enoxaparin was associated with similar efficacy compared to unfractionated heparin, but with more minor bleeding, in high-risk patients with ST-elevation myocardial infarction undergoing early or late transfer for cardiac catheterization after fibrinolysis 4.

Enoxaparin may increase the risk of bleeding complications, particularly at the access site, when used before heart catheterization 5, 3, 4.
The efficacy and safety of enoxaparin compared to unfractionated heparin in patients undergoing heart catheterization may depend on the individual patient's risk factors and the specific clinical setting 2, 3, 4.
More research is needed to fully understand the benefits and risks of using enoxaparin before heart catheterization 6, 5, 2, 3, 4.