Low-molecular-weight heparin for the treatment of patients with mechanical heart valves.
BACKGROUND
The interruption of oral anticoagulant (OAC) administration is sometimes indicated in patients with mechanical heart valves, mainly before noncardiac surgery, non-surgical interventions, and pregnancy. Unfractionated heparin (UH) is currently the substitute for selected patients. Low-molecular-weight heparin (LMWH) offers theoretical advantages over UH, but is not currently considered in clinical guidelines as an alternative to UH in patients with prosthetic valves.


OBJECTIVE
The aim of the present study was to review the data accumulated so far on the use of LMWH in this patient population and to discuss its applicability in common practice.


METHODS
For this paper, the current medical literature on LMWH in patients with mechanical heart valves was extensively reviewed.


RESULTS
There were eight series and six case reports. None of the studies was randomized, and only one was prospective. Data to establish the thromboembolic risk were incomplete. After excluding case reports, the following groups were constructed: (a) short-term administration, after valve insertion (n = 212); (b) short-term, perioperative (noncardiac)/periprocedural (n = 114); (c) long-term, due to intolerance to OAC (n = 16); (d) long-term, in pregnancy (n = 10). The incidence rate of thromboembolism was 0.9% for all the studies and 0.5, 0, 20, and 0% in groups a, b, c, and d, respectively; for hemorrhage, the overall rate was 3.4% (3.8, 2.6, 10, and 0% for the respective groups).


CONCLUSIONS
In patients with mechanical heart valves, short-term LMWH therapy compares favorably with UH. Data on mid- and long-term LMWH administration in these patients are sparse. Further randomized studies are needed to confirm the safety and precise indications for the use of LMWH in patients with mechanical heart valves.
Department of Cardiology, Rabin Medical Center, Petah Tiqva, Israel. shapira_yaron@hotmail.com
Yaron
Y
Shapira
Alex
A
Sagie
Alexander
A
Battler
D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006470:Hemorrhage / Q000139:chemically induced; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D011247:Pregnancy; D013923:Thromboembolism / Q000139:chemically induced
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight