Fixed vs weight-based heparin dosing in stable patients undergoing diagnostic coronary physiology studies

Unfractionated heparin (UFH) is routinely used during coronary angiography, but the optimal dosing strategy for diagnostic coronary physiology procedures such as fractional flow reserve or microvascular assessment in stable patients remains unclear. While weight-based dosing is standard in percutaneous coronary intervention, a fixed-dose approach may simplify workflow.

To compare bleeding and thromboembolic outcomes between fixed-dose and weight-based UFH during diagnostic coronary physiology procedures without percutaneous coronary intervention.

We conducted a retrospective single-center study of 128 patients undergoing fractional flow reserve or microvascular testing from January 2021 to February 2024. Patients received either fixed-dose (5000 IU) or weight-based (70-100 IU/kg) UFH. The primary outcome was a composite of thromboembolic complications: Radial artery occlusion, stroke, or periprocedural myocardial infarction. Secondary outcomes included bleeding (Bleeding Academic Research Consortium criteria), association with patient characteristics, access site, and length of stay.

Of 128 patients, 78 received fixed-dose and 50 received weight-based UFH. No thromboembolic events occurred in either group. Bleeding (all Bleeding Academic Research Consortium 1-2) occurred in 15% overall, with no significant difference between groups (15% vs 12%, P = 0.47). No significant association between bleeding and patient age, sex, weight, body mass index, access site, antiplatelet, or anticoagulant use. Median hospital stay was 1 day in both groups.

In this exploratory study, a fixed 5000 IU UFH regimen appeared to be a safe and practical alternative to weight-based dosing in diagnostic coronary physiology procedures. Larger prospective studies are warranted to confirm these findings.