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Heparin Dosing During Percutaneous Coronary Intervention and Obesity
Rolf P Kreutz1, Isaac G Leon1, Eric R Bain1
1Division of Cardiovascular Medicine, Indiana University School of Medicine/Indiana University Health Methodist, Indianapolis, IN.
Insights
Unfractionated heparin dosing for percutaneous coronary intervention varies significantly. Obese patients require lower weight-adjusted heparin doses to achieve target activated clotting time (ACT) levels.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Unfractionated heparin is a standard anticoagulant for percutaneous coronary intervention (PCI).
- Current guidelines suggest weight-based dosing (70-100 U/kg) to reach target activated clotting time (ACT) of 250-300 seconds.
- The effect of severe obesity on heparin dosing and ACT response is not well understood.
Purpose of the Study:
- To investigate the impact of obesity on unfractionated heparin dosing and ACT response during PCI.
- To identify predictors of heparin dose-response variability in patients undergoing PCI.
Main Methods:
- Retrospective analysis of 424 patients undergoing PCI who received unfractionated heparin.
- Data collection included cumulative heparin doses and ACT measurements.
- Multivariate linear regression analysis was used to identify significant covariates affecting ACT.
Main Results:
- Significant variability in heparin dosing was observed, with a mean administration of 103.9 ± 32 U/kg.
- Only 49% of patients achieved the target ACT (≥ 250 s) with the initial recommended dose.
- Obese patients required lower weight-adjusted heparin doses to achieve target ACT.
- Body mass index was the only significant covariate in multivariate analysis for ACT, after accounting for weight-based dosing.
Conclusions:
- There is substantial variability in the therapeutic efficacy of unfractionated heparin during PCI.
- Obesity is associated with a need for lower weight-adjusted heparin doses to achieve therapeutic anticoagulation.
- Current weight-based dosing protocols may require adjustment in obese populations.
Abstract:
Unfractionated heparin is the most common anticoagulant used during percutaneous coronary intervention. Practice guidelines recommend an initial weight-based heparin bolus dose between 70 and 100 U/kg to achieve target activated clotting time (ACT) of 250-300 seconds. The impact of severe obesity on weight-based heparin dosing is not well studied. We performed a retrospective analysis of 424 patients undergoing percutaneous coronary intervention who received heparin for anticoagulation. We collected detailed data on cumulative heparin administration and measured ACT values in this cohort. We performed separate analyses to identify clinical predictors that may affect dose-response curves. There was significant variability in dosing with mean dose of 103.9 ± 32-U/kg heparin administered to achieve target ACT ≥ 250 seconds. Women received higher initial heparin doses when adjusted for weight than men (97.6 ± 31 vs. 89 ± 28 U/kg, P = 0.004), and only 49% of patients achieved ACT ≥ 250 s with the initial recommended heparin bolus dose (70-100 U/kg). Lower heparin dose (U/kg) was required in obese patients to achieve target ACT. In multivariate linear regression analysis with ACT as dependent variable, after inclusion of weight-based dosing for heparin, body mass index was the only significant covariate. In conclusion, there is significant variability in the therapeutic effect of heparin, with a lower weight-adjusted heparin dose required in obese patients.
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