Search

A best evidence topic was written according to a structured protocol in order to identify the mode of anticoagulation that has the best safety profile for both the mother and the foetus in pregnant patients with mechanical prosthetic heart valves. A total of 281 papers were identified using the reported search, of which eight represented the best evidence to answer the clinical question. The authors, date, journal, study type, population, main outcome measures and results are tabulated. The reported measures were foetal mortality, maternal mortality, congenital abnormalities and embryopathy, and maternal thromboembolic and haemorrhagic complications. The medical orthodoxy has warned of the combination of oral anticoagulation and pregnancy due to the well-documented warfarin embryopathy. Yet only one of the reported papers identified a greater incidence of foetal aberrations among warfarin use, with the highest reported rate being 6.4% and two of the assessed papers reporting no embryopathy at all. Foetal mortality with oral anticoagulation use ranged from 1.52 to 76%. All reported publications demonstrated a superior maternal outcome with warfarin use, with a range of thromboembolic events from 0 to 10% in comparison with 4 to 48% where heparin was used. Thus, it is concluded that warfarin is a more durable anticoagulant with a better maternal outcome despite it carrying a greater foetal risk. Although, in contrast to previous teaching, the risks of embryopathy are not the major drawback of oral anticoagulation. Heparin is consistently less effective, but may be preferred for the superior foetal outcome. Heparin usage during the first trimester reduces the foetal risk but is still associated with an adverse maternal outcome. While the focus for clinicians looking after pregnant women with mechanical heart valves may be to prevent maternal thromboembolic complications, the overriding concern for many women is to avoid any harm to their unborn child, even when this places their health at risk. Thus women with mechanical heart valves must be fully informed of the risks involved with different anticoagulation for an informed decision to be made.

We addressed the question of whether or not the currently available evidence base supports heparinization in the context of a patient requiring cardiovascular support with an intra-aortic balloon pump (IABP). A best evidence topic was written according to a previously defined structured protocol. A literature search returned 443 papers, 3 of which were deemed relevant. Jiang et al. randomized 153 patients requiring IABP to heparin or no heparin, matched for age, sex and comorbidities. There was no significant difference in limb ischaemia; however, incidence of bleeding was significantly increased in the heparinized group (14.1 vs 2.4%). One cohort study compared two management strategies of IABP in which patients either received heparin universally or selectively with heparin only given for certain pre-defined indications. They reported increased bleeding with universal heparinization (39.2 vs 31.8%) but similar other complication rates. Another cohort study in which patients with IABP were initially treated with glycoprotein IIb/IIIa antagonists only, reported bleeding and ischaemia rates within accepted ranges for heparinized patients. The use of anticoagulation with IABP is intended to reduce the risk of thrombus, thromboembolus or limb ischaemia whilst generating an increased risk of bleeding as a side-effect. The aforementioned studies demonstrate that omitting or implementing a selective use strategy of heparinization during IABP counterpulsation can significantly decrease the incidence of bleeding without an increase in ischaemic events. One study also performed angiography prior to IABP insertion on some of their patients, selecting the less diseased side to insert the IABP. Current evidence on this topic is sparse, especially as relates to patients in the context of cardiothoracic surgery. Just one study specifically looked at surgical patients. However, the existing data suggest that it is safe to omit heparinization when using IABP counterpulsation. The decision to heparinize should be weighed in the context of other indications or contraindications rather than being an automatic response to the use of IABP.