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Pregnancy-associated acute MI requires special considerations
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Results from a new study call attention to the differences between pregnancy-associated acute MI and acute MI in nonpregnant women.
Uri Elkayam, MD, from the University of Southern California Keck School of Medicine, and colleagues published a review of 150 cases of pregnancy-associated acute MI between 2006 and 2011. The mean age of the patients was 34 years.
Focus on left anterior descending artery
Data on the type of acute MI were available for 139 cases. Three-quarters presented with STEMI. The majority of women developed acute MI during the third trimester of pregnancy or in the postpartum period. The myocardial infarct mostly involved the anterior wall of the left ventricle (69%).
Uri Elkayam
One hundred twenty-nine patients had coronary angiography, which demonstrated coronary dissection in 43%, atherosclerotic disease in 27%, a clot without angiographic evidence for atherosclerotic disease in 17%, and normal coronary anatomy in 11%, according to the results. About three-quarters of women with coronary dissection presented during the postpartum period (73%) and the third trimester (21%).
In contrast, coronary dissection is implicated in only 0.28% to 1.1% of acute MI cases in the nonpregnant population, Elkayam, a member of the Cardiology Today Editorial Board, and colleagues wrote.
The low rate of atherosclerotic CAD was likely due to the younger age of the women, according to the researchers. The most common CV risk factors included smoking (25%), hyperlipidemia (20%), hypertension (15%), type 2 diabetes (9%) and a family history of CAD (9%).
Acute MI secondary to coronary dissection usually occurred in late pregnancy or postpartum and often involved the left anterior descending artery or the left main segment.
“Multivessel involvement in a large proportion of these cases in the present study and in previous studies supports generalized rather than localized vessel wall changes in pregnancy,” the researchers wrote. “Although the exact pathophysiology of [coronary dissection] related to pregnancy remains unclear, hormonal and hemodynamic changes have been proposed as potential causes. The association between pregnancy-associated [coronary dissection] and hormonal changes may be supported by a relatively high incidence of hormonal therapy reported in nonpregnant women who developed [coronary dissection].”
The high rate of the left anterior descending artery or the left main segment involvement may be because “the left coronary system experiences a significant decline in blood flow during systole, accompanied by a marked increase in diastolic pressure, leading to a significant rise in both oscillatory shear stress and wall stress,” they wrote.
In addition, 54% of patients had left ventricular ejection fraction <40%, which the researchers attributed to involvement of the anterior wall in the left ventricle.
Treatment differences
Because the mechanisms of pregnancy-associated acute MI often differ from MI in the nonpregnant population, some recommendations for treatment of MI may differ for pregnant women.
As a result of these findings, Elkayam and colleagues made the following recommendations:
- Many women with pregnancy-associated MI have normal coronary anatomy or coronary dissection, so the risks of thrombolytic therapy may outweigh the benefits and it should not be given if the cause of MI is not known.
- There is a high incidence of iatrogenic coronary dissection secondary to intracoronary contrast injection and mechanical interventions, therefore invasive treatment approaches should be limited to high-risk patients and “mechanical coronary manipulations should be limited to cases in which potential benefits clearly outweigh the risk.”
- Guideline-recommended antiplatelet therapy is desirable, but women should be informed that there is little information about the safety of those drugs for the fetus.
Disclosure: The researchers report no relevant financial disclosures.
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