Sunday, 20 May 2012

Myocardial infarction(MI) in pregnancy

Ischaemic Heart Disease(IHD) in Pregnancy

Prevalence of IHD in pregnancy is 1:10,000
Incidence of Myocardial infarction  in pregnancy is 7.5:100,000
Over all mortality rate is 37%

Risk factors
Family history of myocardial infarction before age 60
History of chronic hypertension
Kawasaki disease,
Hypertrophic cardiomyopathy
Cocaine use

Atherosclerosis accounts for less than 50% of cases but dissection of coronary arteries is relatively common.

ECG changes in normal pregnancy.There could be left-axis deviation and non-specific ST and T wave
changes.Serial ECG is important in diagnosis.

Chest X ray-enlargement of the heart, straightening of the left
heart border, and increased vascular markings are features observed in myocardial infarction.

CK-MB correlates with non pregnant state but  the usage is limited in labour and postpartum period.

Troponin-I is the marker of choice as the level is not affected by pregnancy,labour or obstetric anaesthesia.

Echocardiography helps to check abnormal ventricular wall motion.

Differential diagnosis
1.Acute pulmonary embolism
2.Aortic dissection

Management of MI is similar to non pregnant patients

Setting : Coronary care unit

5.Beta blockers

Multidisciplinary care -cardiologist,obstetrician,anaesthesiologist

Primary PCI(percutaneous coronary intervention) is the treatment of choice but if it isn't feasible thrombolysis should be considered.

Anti coagulation is considered if embolus is demonstrated in angiography,otherwise risk of thrombolysis slightly outweighs the benefit.

Tissue plasminogen activator
Large molecular weight Tissue plasminogen activator wouldn't cross the placenta but there is a risk of premature labour and haemorrhage.

There is no reports linking to congenital defects.
Minimal amount crosses placenta,so no fibrinolytic effects on fetus.


It isn't teratogenic in animal studies.It isn't known whether it crosses placenta but there are proteinase inhibitors in the placenta which inactivates urokinase.

angioplasty and systemic and local thrombolytic therapy has been
described.'Fragile'nature of coronary vessels in pregnancy should be kept in mind when considering angioplasty or angiography.

Radiation exposure to fetus during cardiac catheterisation & interventional procedure is less than 0.01 Gy

Use of clopidogrel also seems to be safe.


Caesarean section is only indicated for Obstetric reasons . It doesn't improve the survival.Second can be limited with forceps.

Delivery with in the first two weeks after ischaemic heart disease should be avoided if possible.ECG monitoring should be done in labour.Epidural analgesia is recommended.

Third stage -avoid ergometrine as it can cause coronary spasm

Good outcomes have been reported from subsequent pregnancies in patients with left ventricular aneurysm and also in patients who suffered cardiac arrest during MI.

Future pregnancy

There is no evidence to suggest that pregnancy predisposes for another episode of MI but if the aetiology had been a coronary embolus the risk of recurrence should be carefully considered.

Poor prognostic features
1.Left ventricular dysfunction
2.Persistence of ischaemia

Statins should be discontinued preconception as there is a risk of fetal anomalies(CNS &Limb defects)

Useful article

1.Nelson-Piercy C. Handbook of Obstetric Medicine, Second Edition. 2nd ed. Taylor & Francis; 2001.
2.Swiet MD. Medical Disorders in Obstetric Practice. 4th ed. Wiley-Blackwell; 2002

3.Fayomi O, Nazar R. Acute myocardial infarction in pregnancy: a case report and subject review. Emerg Med J. 2007 Nov 1;24(11):800-801.