Interaction of vitamin K antagonists with heparin affect monitoring by activated clotting times.
J Interv Card Electrophysiol
; 27(2): 89-94, 2010 Mar.
Article
in En
| MEDLINE
| ID: mdl-20087759
ABSTRACT
BACKGROUND:
Unfractionated heparin is recommended during atrial fibrillation (AF) ablation to achieve activated clotting time (ACT) above 250-300 s to prevent clot. Many patients on therapeutic international normalised ratio (INR) undergo AF ablation procedures; however, it is unknown whether they require less heparin to achieve similar ACT levels.METHODS:
During AF ablation, the ACT was measured before and 10 min after administration of i.v. unfractionated heparin in patients with and without anticoagulation. The association of INR, heparin, pre-procedure ACT and body weight with ACT after heparin administration was tested using multivariable linear regression models.RESULTS:
The subjects of this study were 149 patients undergoing AF ablation, among them 40 (27%) with subtherapeutic INR < 2, 79 (53%) with an INR between 2 and 3, and 30 (20%) patients with INR > 3. Baseline ACT was associated with INR (r = 0.33, p < 0.001). After a mean of 8,685 +/- 2,015 U (range, 5,000-15,000 IU) unfractionated heparin, univariate predictors of ACT were baseline INR (p < 0.001), heparin dose (p = 0.012) and baseline ACT (p = 0.027). In the multivariable model, baseline INR (part r = 0.64, p < 0.001) and heparin dose (part r = 0.33, p < 0.001) strongly predicted post-heparin ACT. Estimated from the regression model, the heparin dose reductions by approximately one third in those with an INR of 2-3 and by at least two thirds in those with an INR above 3 may be favourable. Over the following 3 months, no thromboembolism and acute bleeding were observed.CONCLUSION:
The INR was the strongest predictor of post-heparin ACT, even more important than the heparin dose itself. The reduction of heparin dose by one third if INR is between 2-3 and by two thirds if INR is above 3 may be favourable.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Vitamin K
/
Whole Blood Coagulation Time
/
Heparin
/
Artifacts
/
International Normalized Ratio
/
Drug Interactions
Type of study:
Diagnostic_studies
/
Prognostic_studies
Limits:
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
J Interv Card Electrophysiol
Journal subject:
CARDIOLOGIA
Year:
2010
Document type:
Article
Affiliation country:
Switzerland