Table 2.
Summary of international recommendations for the management of anticoagulation in parturients with mechanical heart valves.6,11 aPTT, activated partial thromboplastin time; INR, international normalised ratio; LMWH, low-molecular-weight heparin; UFH, unfractionated heparin; VKA, vitamin K antagonist.
| Organisation | First trimester | Second and third trimesters |
|---|---|---|
| European Society of Cardiology 20186 | Warfarin dose <5 mg day−1 | Warfarin dose <5 mg day−1 |
| Continuation of VKA should be considered; monitor INR every one or two weeks or switch to dose-adjusted i.v. infusion of UFH (aPTT ≥2 control) or LMWH twice-daily regimen dose adjusted to weight may be considered. | Monitor INR every two weeks. VKA recommended for all women until 36 weeks. |
|
| Give LMWH initially in-hospital with daily anti-Xa levels until target anti-Xa achieved, then weekly monitoring of post-dose anti-Xa level may be considered between 6 and 12 weeks. | ||
| Target anti-Xa level 4–6 h post-dose 0.8–1.2 IU ml−1 (1–1.2 IU ml−1 for right-sided or mitral valve and 0.8–1.2 IU ml−1 for aortic valve). Monitor trough (pre-dose) anti-Xa level with dose adjustment to maintain trough level at >0.6 IU ml−1. | ||
| Warfarin dose >5 mg day−1 | Warfarin dose >5 mg day−1 | |
| Monitor INR every two weeks. A switch to adjusted-dose i.v. UFH or LMWH should be considered between 6 and 12 weeks as stated. | VKA should be considered for all women until 36 weeks, or | |
| Continuation of VKA may be considered between 6 and 12 weeks after fully informed consent. | LMWH with anti-Xa level monitoring (both peak and trough levels) with dose adjustment may be considered in women after patient information and consent. | |
| Any changes in the anticoagulation regimen during pregnancy should take place in hospital. | ||
| American College of Cardiology/American Heart Association 202011 | Warfarin dose ≤5 mg day−1 | Warfarin dose ≤5 mg day−1 |
| Can continue warfarin in the first trimester after discussion of all the risks and benefits, or LMWH at least twice-daily regimen dose adjusted to weight and monitoring of post-dose anti-Xa level may be considered between 6 and 12 weeks. Target anti-Xa level 4–6 h post-dose 0.8–1.2 IU ml−1 with weekly monitoring. | Can be continued | |
| Warfarin dose >5 mg day−1 | Warfarin dose >5 mg day−1 | |
| LMWH at least twice-daily regimen dose adjusted to weight and weekly monitoring of post-dose anti-Xa level. Target anti-Xa level 4–6 h (post-dose) 0.8–1.2 IU ml−1 with weekly monitoring or switch to adjusted-dose UFH (aPTT ≥2 control as an i.v. infusion) if LMWH not available or cost prohibitive. | LMWH twice-daily regimen dose adjusted to weight and weekly monitoring of post-dose anti-Xa level may be considered. Target anti-Xa level 4–6 h post-dose 0.8–1.2 IU ml−1. For whom dose-adjusted LMWH is unavailable, warfarin can be continued. | |
| Low-dose aspirin 75 mg may be considered if needed for other indications (e.g. pre-eclampsia). |