Heparin Rebound Phenomenon in Acute Coronary Syndromes: Advantage of Low Molecular Weight Heparins

Heparin rebound phenomenon was named to illustrate unstable angina pectoris (UAP) reactivation after stopping heparin. Reinfarction clustering, as well as sharp increase of both thrombin production and activity in the early hours after heparin abandoning have been described (after thrombolysis), which has been partially attributed to heparin rebound. The aim of the study was to show importance of problem of heparin rebound, to suggest possible directions of its avoidance and to present our own initial results with low molecular weight heparin (LMWH) Nadroparin in this context, because data on these topics have been completely lacking in our literature. Total number of pts analyzed was 45 (27 men, 18 women), average age 59.4 ± 4.3, all of them with gastric protection with H2 blocker. With close inhospital follow-up there was no heparin rebound phenomenon had negative result found, which might be related to the solid duration of therapy. In addition to careful heart rate and blood pressure control, adequate antithrombin therapy seem to improve their prognosis. Side effects were only minor haemorrhages: 5 injection site ecchymoses and 1 gingival haemorrhage, while 39 pts experienced no manifest bleeding, including 9 pts with ulcer history. There are some practical suggestions to reduce heparin-rebound phenomenon: 1) to decrease prothrombotic tendencies in the blood, unrelated to heparin; 2) to improve therapy with standard heparin and to 3) to use newer antithrombotic drugs. We conclude that prevalence of heparin rebound can be lowered probably with adequate duration and dose of standard and LMWH, together with other suggested actions to decrease coagulation and platelet activation. Literature and own data suggest low incidence of heparin rebound phenomenon with enough long LMWH usage. They may be given with easily, with low bleeding rates, and without a need for aPTT monitoring. Thus, LMWHs for a few weeks seems justified in pts at high rethrombosis risk.