The goal of this clinical trial study is to test whether a mathematical calculation, using the patient's gender, weight and kidney function, can better predict a patient's heparin goal dose than a flat number of units per patient weight can. Participants will have the first dose of heparin infusion calculated, after which if adjustments are needed, the Hospital's prebuilt table for results driven dosing for this purpose is used. The researchers will compare the time it takes for the participants to get to the desired goal using the patient's information for calculation versus patients in the past who received the medication using the flat rate. The hypothesis is that the patients with enhanced personal data, gender, weight and kidney function, included for the initial dose, will get to their goal lab value sooner and with less chance of delay or overshooting the goal. A quicker time to goal lab value is beneficial to patients in many ways, including earlier treatment of the clot or coronary issue that the patient is experiencing.

Heparin infusions are high-risk medications that must be titrated to effect within a narrow therapeutic anti-Xa range. Prolonging the time to reach the therapeutic range decreases the clinical effectiveness of the infusion and increases the potential for adverse drug events.

The intervention used in this study will be calculating the initial heparin infusion rates described below rather than dosing 18 units/kg/hr for the moderate-intensity protocol and 12 units/kg/hr with a dose cap of 1000 units/hr for the low-intensity protocol.

Moderate-Intensity Protocol (R2 = 0.48) Heparin infusion rate (unit/(kg*hr))=(1004.8-163.5*(1 if female)-4.8*(age in years)+14.6*(actual body weight in kg)-19.3*(BMI in kg/m^2))/(Actual body weight in kg)

Low-Intensity Protocol (R2 = 0.31) Heparin infusion rate (unit/(kg*hr))=(615.5-70.1*(1 if female)-1.7*(age in years)+10.1*(actual body weight in kg)-11.9*(BMI in kg/m^2))/(Actual body weight in kg)

All other components of heparin infusion management will be conducted per Inova Health System standard of care.

Inclusion Criteria:

• Age > 18 years-old
• Diagnosis by the attending physician with one of the following conditions for which anticoagulation with heparin in an Food & Drug Administration approved indication and considered the standard of care:
• Moderate-intensity anti-Xa protocol: new-onset deep vein thrombosis or pulmonary embolism, or mechanical heart valve
• Low-intensity anti-Xa protocol: atrial fibrillation, acute cardiac syndrome, embolic stroke
• Heparin infusion either has not started or has been initiated in the last 120 minutes

Exclusion Criteria:

• Use of extracorporeal membrane oxygenation or ventricular assist devices such as Impella pumps
• Diagnosis of thrombophilia/hypercoagulable state
• Concurrent use of direct-acting oral anticoagulants or low molecular weight heparins
• Baseline anti-Xa > 0.7
• Pregnancy

Data obtained through this study may be provided to qualified researchers with academic interest in doing of Heparin Infusions. Data or samples shared will be coded, with no PHI included. Approval of the request and execution of all applicable agreements (i.e. a material transfer agreement) are prerequisites to the sharing of data with the requesting party.

The information will become available after publication acceptance has been received. This will be available from 6 months post publication and up to 24 months post publication date.

Scientific researchers interested in the study information would need to contact the primary or sub investigator via email. The data requested will be reviewed by the internal research team, any necessary paperwork required at the time by the Inova research team will be shared with the requester. If appropriate paperwork is received by Inova, the data requested will be shared expeditiously