Tel Aviv, Israel - A new review of pregnancy-related acute MI has revealed that mortality from this condition has fallen considerably over the past decade, probably as a result of improved treatment of MI overall rather than a specific focus on pregnancy-related MI, say the researchers [1].

Dr Arie Roth (Tel Aviv University Sackler School of Medicine, Tel Aviv, Israel) and Dr Uri Elkayam (University of Southern California [USC] Keck School of Medicine, Los Angeles) report the findings of their literature review of pregnancy-related MI in the July 15, 2008 issue of the Journal of the American College of Cardiology. Elkayam, a professor of obstetrics and gynecology and director of the heart-failure program at USC, told heartwire that they performed a similar review of 125 cases in 1995, and this new research is a follow-up to that, comparing outcomes in 103 women with pregnancy-associated MI from 1995 until 2005 with the earlier cases and providing updated advice on how to manage the condition.

"Ten years ago we reported a high incidence of mortality in this patient population. The major change—and the good news—is that mortality from pregnancy-related MI, which was between 20% and 30%, has been reduced now to around 5% to 10%," he noted. And although acute MI is still rare in women of childbearing age, pregnancy increases the risk three to fourfold in this age group, and medical advances enabling more and more older women to conceive and have children mean that the occurrence of pregnancy-related MI is expected to increase further, he says.

"It's extremely important that physicians who take care of women during pregnancy and after delivery be aware of the occasional occurrence of acute MI in pregnancy and not overlook symptoms in these young patients," he stressed.

The major change—and the good news—is that mortality from pregnancy-related MI . . . has been reduced now to around 5% to 10%.

Elkayam expanded upon changes they have found since the prior review. "Last time, we pointed out the fact that some cases [of pregnancy-related MI] were diagnosed late, and the awareness of the possibility of having acute MI at such a young age was not very high. Also, because of the pregnancy, any treatment of MI was not that effective because of concerns and a lack of experience people had in treating MI in pregnancy."

Luckily, diagnosis has progressed, although he does not believe the improvements seen are necessarily a result of an increased awareness of pregnancy-related acute MI per se; rather, the management of acute MI overall has grown considerably better over the past 10 years.

But "a higher number of patients are having angiography, so we have learned more about the mechanisms of acute MI in pregnancy." The big difference [from MI outside of pregnancy] is that almost half of women do not have any atherosclerotic disease, he says. "In almost 30% of cases they had coronary dissection, the incidence of which is multiple-fold higher than in nonpregnant women. Others just had clots and no atherosclerotic disease."

Those who experienced acute MI within 24 hours ante- or postpartum were twice as likely to die as those who had a cardiac event 24 hours or more before labor or afterward—likely because coronary dissection was the primary cause of infarction in the peripartum period (50%). Pregnancy-related spontaneous coronary dissection is likely related to an excess of progesterone, leading to biochemical and structural changes to the vessel wall, say the doctors.

Because the mechanisms leading to acute MI can be very different in pregnancy, it is essential for doctors to make a proper diagnosis, Elkayam notes. "One thing we have learned is that when a women presents with acute MI in pregnancy, particularly around the time of or just after delivery, you need to suspect an unusual cause of MI and try to define the mechanism."

As regards tests, echo is safe during pregnancy, they advise, and exercise testing can also be performed, although they recommend using a submaximal protocol (70% or less of maximal predicted heart rate) with fetal monitoring. And although the use of radiation during pregnancy should be kept to a minimum, the amount of fetal exposure during chest X-ray is "extremely small and should probably be considered safe for use when necessary," they note.

Consideration must also be taken when deciding on appropriate therapy, says Elkayam, as certain treatments could be hazardous during pregnancy. For example, some of the standard medications (eg, ACE inhibitors and warfarin) used to manage acute MI can be harmful to the baby, so their use should take into account potential risks and benefits. There is also limited evidence about the efficacy and safety of other commonly employed strategies, such as thrombolytic therapy, antiplatelet therapy, and drug-eluting stents, Roth and Elkayam note.

They recommend a strategy of primary percutaneous coronary intervention (PCI) for acute-ST-elevation MI during pregnancy, with bare-metal stents, as drug-eluting stent use could be problematic because of the prolonged antiplatelet therapy needed with clopidogrel. Thrombolytic therapy should be considered a second choice, as it has risks.

And because half of all women they reviewed did have atherosclerotic disease, Elkayam said it is important for physicians to register risk factors in pregnant women—for example, a family history of premature heart disease—and act accordingly. The incidence of risk factors has risen in this current report compared with the older review, he noted—perhaps due to the increased incidence of smoking in young women and also due to the increasing age of the women—72% were over 30 and 38% over 35.

"We felt it was important to reexamine the literature about acute MI related to pregnancy and provide updated recommendations for the diagnosis and management of heart attack in this group of women. It's been encouraging to see improvement in patient outcomes over the past 10 years, and we hope the guidelines presented in this paper will further increase awareness about acute MI in pregnancy."

"The message is that young women can have heart disease and MI. It's rare—you don't see it a lot—but people need to recognize the fact that this needs to be included in a differential diagnosis," he concluded.