September 2, 2014

BARCELONA, Spain -- September 2, 2014 -- Mechanical heart valves increase risks during and after pregnancy, according to a study presented at the 2014 Annual Meeting of the European Society of Cardiology (ESC).

The study found that 1.4% of pregnant women with a mechanical heart valve died and 20% lost their baby during pregnancy.

The Registry of Pregnancy and Cardiac Disease (ROPAC) is an ongoing worldwide registry that includes pregnancies in women with any type of structural cardiovascular disease. It is part of the ESC’s EORP programme.

“Cardiac disease is the leading causes of maternal mortality in both developed and developing countries,” said Roos-Hesselink, MD, Erasmus University Medical Center Rotterdam, Rotterdam, the Netherlands. “Pregnancy induces haemodynamic changes such as an increase of cardiac output, stroke volume, and heart rate and demands for an adequate adaptation of the heart. While the normal healthy heart is able to adjust, a structural abnormal heart may be less capable to address these physiological changes, with subsequent increase of maternal and foetal morbidity.”

“Pregnancy induces not only a hemodynamic burden but also a hyper-coagulable state,” she added. “We studied the effect of mechanical prosthetic heart valves on maternal and foetal outcomes. We also examined which anticoagulation regimes were used and what impact they had.”

From January 2008 until now, the ROPAC registry has enrolled more than 3 500 pregnant women with structural heart disease, aortic pathology or pulmonary hypertension from 132 centres in 48 countries. Data presented at ESC was on pregnancy in the 212 women with mechanical prosthetic heart valves.

The researchers found that 1.4% of pregnant women with a mechanical heart valve died during pregnancy. Nearly 16% of women had a miscarriage before 24 weeks of pregnancy while 2.8% of women lost the fetus after 24 weeks. Haemorrhagic events occurred in 23% of women and thrombotic events in 6.1%.

“Pregnant women with mechanical valve prostheses are at particularly high risk of thrombotic complications, of which thrombosis of the mechanical valve is very serious and occurred in 10 patients (4.7%),” said Dr. Roos-Hesselink. “They also have a significantly higher mortality (1.4%) during pregnancy compared to the other women with heart disease in the registry (0.2%).”

The researchers found that just 80% of women with a mechanical valve had a live birth. This was significantly lower than the proportion of live births in women in the registry with a tissue valve (98%) or with no prosthetic valve (98%).

A variety of anticoagulation regimes were used during the trimesters of pregnancy (<14 weeks, 14 to 36 weeks, 36 weeks to delivery). The most popular regimen, used in 43% of women, was heparin followed by a vitamin K antagonist (VKA), followed by heparin. A further 21% of women were given heparin during all 3 trimesters, while 20% of women received a VKA during the first 2 trimesters and heparin in the third. The latter regime was associated with significantly higher late fetal mortality (16%) than the other 2 regimens (~3%).

“Effective anticoagulation is essential to prevent thrombotic complications and mortality in pregnant women with mechanical heart valves,” said Dr. Roos-Hesselink. “However, this inevitably carries an increased risk of haemorrhagic events, particularly during delivery. We found that if vitamin K antagonists are used for anticoagulation in the first trimester there is a significantly increased of late fetal loss. There was no clear difference between the 3 most common anticoagulation regimes in haemorrhagic and thrombotic complications.”

“Pregnancy can be a hazardous situation for women with a mechanical valve prosthesis,” she added. “Women who need a valve replacement should be told about the pregnancy associated risks, particularly when it is time to choose the type of valve.”

SOURCE: European Society of Cardiology

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