Antithrombin activity during the period of percutaneous coronary revascularization: relation to heparin use, thrombotic complications and restenosis.
OBJECTIVE
This study evaluated changes in antithrombin (AT) activity around the time of percutaneous transluminal coronary revascularization (PTCR) with unfractionated heparin anticoagulation and the effects these changes had on major thrombotic complications of PTCR.


BACKGROUND
Heparin is used during PTCR to prevent thrombosis. However, heparin, a cofactor for AT, causes AT activity to fall. AT activity <70% is associated with thrombosis. There is a prothrombotic state after heparin discontinuation that has not been well explained.


METHODS
Antithrombin activity was sampled at the start and end of PTCR and the next two mornings in 250 consecutive patients. We recorded occurrence of major thrombotic events, defined as 1) major thrombotic complications of PTCR; 2) major in-lab thrombus formation; or 3) subacute occlusion. Discriminant analysis was employed to evaluate the relationship of AT activity to these events. Change in AT activity and its relationship to heparin was evaluated. Evidence of restenosis at six months was obtained.


RESULTS
There were 14 major thrombotic events. Antithrombin activity <70% was strongly (p = 0.006) associated with these events. The AT activity fell significantly through the morning after PTCR when 21% of patients had AT activity <70%; AT activity did not normalize until >20 h after heparin discontinuation. Pre-PTCR use of heparin led to lower AT activity in proportion to duration of heparin use. There was no relationship between AT activity and restenosis.


CONCLUSIONS
Low AT activity may contribute to major thrombotic complications of PTCR. The way heparin is used before and after PTCR is important to development of low AT activity.
Matthai
W H
WH
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, USA. william_matthai@uphs.upenn.edu
Kurnik
P B
PB
Groh
W C
WC
Untereker
W J
WJ
Siegel
J E
JE
D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D000925:Anticoagulants / Q000627:therapeutic use; D000991:Antithrombins / Q000187:drug effects / Q000378:metabolism*; D017023:Coronary Angiography; D003327:Coronary Disease / Q000097:blood / Q000000981:diagnostic imaging / Q000628:therapy; D003328:Coronary Thrombosis / Q000097:blood / Q000209:etiology* / Q000517:prevention & control; D005260:Female; D005500:Follow-Up Studies; D006493:Heparin / Q000627:therapeutic use; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome
D000925:Anticoagulants; D000991:Antithrombins; D006493:Heparin