Kelsey McLaughlin, PhD
Peripartum cardiomyopathy is a condition where a woman develops heart failure near the end of pregnancy or in the early postpartum period. The term 'heart failure' means that the heart is not pumping blood efficiently.
Keep reading to learn more about peripartum cardiomyopathy.
What is peripartum cardiomyopathy?
The European Society of Cardiology defines peripartum cardiomyopathy as heart failure due to reduced ejection fraction that occurs ‘towards the end of pregnancy or in the months following delivery’ in women who have no other existing cardiac conditions. It is essentially unexplained failure of heart function associated with pregnancy. The definition of peripartum cardiomyopathy is vague, as experts do not fully understand what causes this condition and not all women develop the same clinical symptoms.
In women who develop peripartum cardiomyopathy, 70% developed this condition within 3 months of delivery, while 25% developed this condition during pregnancy. Although less common, women can also develop peripartum cardiomyopathy more than 3 months following delivery.
Peripartum cardiomyopathy is a relatively rare disease, impacting approximately 1 out of every 1,000 births in the United States. In certain parts of the world, including Haiti and Northern Nigeria, this condition is much more common, impacting as many as 1 in 100 women. The number of women diagnosed with peripartum cardiomyopathy each year is increasing; it is not clear if this is due to increasing risk factors, or if more women with this condition are being accurately identified and diagnosed.
What does reduced ejection fraction mean?
Let’s think back to our discussion of changes that occur to the maternal cardiovascular system during pregnancy for a moment. In normal pregnancy, women have a large increase in the amount of blood flowing through their circulation to support a healthy pregnancy and fetal growth. To accommodate this increase in blood volume and added stress on the heart, the mother’s heart undergoes changes to become more muscular, increase in size and improve its ability to contract – these changes all support efficient pumping of blood into the circulation.
Ejection fraction is a calculation that represents how efficiently your heart pumps blood into the circulation. The ejection fraction calculation is derived from:
Stroke volume: the volume of blood your heart pumps with each beat
Left ventricular end-diastolic volume: the volume of blood in the left ventricle after the end of diastole, the phase of the cardiac cycle where the heart is relaxing and filling up with blood to pump before the next contraction
The calculation is as follows:
Ejection fraction therefore represents the fraction or percentage of blood that is ejected with each contraction (or beat) of the heart. In pregnant and non-pregnant individuals, a normal ejection fraction is above 50%, meaning that over half of the blood in the left ventricle is pumped into the circulation with each heart beat.
Peripartum cardiomyopathy is characterized as ejection fraction below 45%; this means that only 45% of blood in the left ventricle or less is pumped into the circulation by the heart with each beat. Therefore, there is something interfering with the function of the heart, and it is not pumping blood efficiently.
What causes peripartum cardiomyopathy?
The exact cause of peripartum cardiomyopathy is unknown, however, scientists are getting closer to understanding what contributes to the development of this pregnancy-specific condition.
Peripartum cardiomyopathy has previously been hypothesized to originate from a wide variety of causes, including abnormal cardiovascular adaptation to pregnancy, inflammation of heart muscle (myocarditis), the interaction of fetal cells in the heart and malnutrition. However, these theories are not well supported by data.
More recently, scientists have developed two theories to explain what causes peripartum cardiomyopathy:
Heart damage caused by hormones & proteins
Scientists believe high levels of oxidative stress within the heart muscle may cause peripartum cardiomyopathy. Animal models have determined that increased oxidative stress in the heart increases production of the hormone prolactin. Prolactin is the hormone responsible for stimulating the production of breast milk when women near the end of pregnancy and delivery; it is produced by the pituitary gland, which is located at the base of the brain, and is a main regulator of hormones in the body. However, in women who develop peripartum cardiomyopathy, scientists think that the increased production of prolactin causes damage to the heart and blood vessels, causing them to function abnormally. Scientists are now investigating whether normalizing prolactin levels could be used to prevent or treat peripartum cardiomyopathy.
A protein that may be involved in the development of peripartum cardiomyopathy is called soluble fms-like tyrosine kinase 1, or sFlt-1. During early pregnancy, the placenta releases proteins that promote vasodilation of blood vessels to protect against hypertension (placental growth factor); as the end of pregnancy nears, the placenta releases proteins that cause constriction of blood vessels, potentially to protect against bleeding at delivery. One of these vasoconstrictive proteins is sFlt-1. A small study determined that women with peripartum cardiomyopathy have higher levels of sFlt-1 in the blood, compared to healthy pregnant women; sFlt-1 could therefore be causing damage to the hearts of pregnant women. Interestingly, circulating levels of sFlt-1 are also associated with increased risk of developing preeclampsia, which may explain the link between preeclampsia and peripartum cardiomyopathy.
Together, this data suggests that peripartum cardiomyopathy is a condition characterized by damage to the heart and blood vessels by abnormal levels of oxidative stress of the heart that leads to higher levels of prolactin and sFlt-1.
Peripartum cardiomyopathy has been associated with variation in a number of genes that regulate how the heart, blood vessels and body's muscles work; this means that women who develop this condition may have a genetic sequence in their genome that is different than most of the population. In a German study, 16% of patients with peripartum cardiomyopathy had a family history of cardiomyopathy.
Risk factors for peripartum cardiomyopathy
A number of risk factors have been identified that put women at higher risk of developing peripartum cardiomyopathy, including:
Age: Pregnant women over 30 years of age are at increased risk
Race: Black women are at a 4 times higher risk of developing peripartum cardiomyopathy than white women, and tend to develop more severe symptoms and health impacts
Obesity: Approximately 1 in 4 women who develop peripartum cardiomyopathy are obese
Multiple birth: women pregnant with twins or triplets are at increased risk
Symptoms of peripartum cardiomyopathy
Peripartum cardiomyopathy can be difficult to identify in women, due to the fact that some of the symptoms could be confused for regular pregnancy symptoms. The clinical presentation of peripartum cardiomyopathy can be variable, with some women developing severe symptoms over a short period of time, and other women developing more mild symptoms over a longer period of time.
Symptoms of this condition include:
Shortness of breath, especially when lying flat
Attacks of shortness of breath and coughing that typically occur during the night
Fast heart beat
Rapid weight gain
Testing & investigations for peripartum cardiomyopathy
As peripartum cardiopathy is a condition that impacts the heart and cardiovascular system, doctors will investigate how well the mother’s heart is functioning.
Echocardiograms are used to assess the shape and function of the heart’s chambers through ultrasound and diagnose peripartum cardiomyopathy. Doctors will use echocardiogram to estimate ejection fraction, through measuring left ventricular end-diastolic volume and stroke volume.
Doctors will also check for signs of increased heart rate (tachycardia), checking for increased pressure in blood vessels on the neck (jugular venous pressure), the rate of breathing and any signs of swelling, typically in the lower limbs.
An electrocardiogram can be used to monitor the electrical activity of the heart – women with peripartum cardiomyopathy usually show changes in electrical activity due to changes in cardiac function.
There are no specific biomarkers available to diagnose peripartum cardiomyopathy in women at this time, however, this is an important area of research. Smaller studies have suggested that the hormone brain natriuretic peptide (BNP) could be used as a biomarker for peripartum cardiomyopathy, as women with this condition have higher levels of BNP in their blood. Testing the mother’s blood for sFlt-1 and other biomarkers are also being investigated.
Treatment & management of peripartum cardiomyopathy
Treatment for peripartum cardiomyopathy focuses on normalizing the function of the mom's heart and preventing the progression of this condition. There are limited proven treatments and management strategies for women with peripartum cardiomyopathy – most doctors base their care on personal experience with heart failure in non-pregnant patients.
Doctors will use therapies to reduce swelling and the risk of blood clots, as well as the risk of high blood pressure and heart complications. Wearable defibrillators or cardiac assist devices may also be recommended in women with very severe cardiac symptoms (ejection fraction below 30%).
Few studies have been conducted to investigate novel therapies for women with peripartum cardiomyopathy.
Bromocriptine therapy has been investigated as a strategy to prevent the release of the hormone prolactin. Small studies have determined that bromocriptine improved recovery of the heart in women with peripartum cardiomyopathy. More recently, a multi-centre, randomized clinical trial determined that bromocriptine helped women with peripartum cardiomyopathy recover function of their heart and reduce health complications. Further research is needed to determine any safety concerns associated with bromocriptine use in pregnancy. At this time, the Canadian Cardiovascular Society recommends that bromocriptine not be used for treatment of peripartum cardiomyopathy.
Similar to other pregnancy conditions, doctors must balance both the mother and baby’s health. Women with peripartum cardiomyopathy have higher rates of Caesarean section; babies born to women with peripartum cardiomyopathy have earlier gestational age at delivery and smaller birthweight. This means that women with peripartum cardiomyopathy are most likely delivered earlier than most women due to their condition.However, there is no evidence to suggest that early delivery improves the mother’s symptoms of peripartum cardiomyopathy or improves fetal outcomes.
Approximately 13% of women with peripartum cardiomyopathy experiencing a major adverse event, defined as in-hospital death or health complications that are life threatening or impact health in the long-term. This condition is also associated with increased need for mechanical circulatory support, risk of cardiogenic shock and longer stay in hospital, as well as thromboembolism (blocked blood vessel due to clot).
Peripartum cardiomyopathy is associated with a higher risk of maternal death, leading to maternal death in approximately 1% of women who develop this condition.
Recovery from peripartum cardiomyopathy
By 1 year postpartum, the majority of women (70%) who developed peripartum cardiomyopathy recover, meaning that their ejection fraction returns to a normal levels of above 50%. However, 13% of women experience a major health event or continue to exhibit low ejection fraction, with a 4% mortality rate.
A study of 85 women with peripartum cardiomyopathy determined that there was a 16% mortality rate within 7 years of pregnancy. A number of factors have been identified to impact recovery of peripartum cardiomyopathy, including:
Race: Black women have significantly worse rates of recovery, cardiac transplantation and mortality, compared to white women
Ejection fraction at time of clinical diagnosis: Women who presented with more severe disease during pregnancy were less likely to recover in the postpartum period
Hypertension in pregnancy: Women who had hypertension in pregnancy, as well as peripartum cardiomyopathy, may have improved outcomes, compared to women who did not have high blood pressure during pregnancy
There are no recommendations regarding next pregnancies following a pregnancy complicated by peripartum cardiomyopathy, however, available data suggest that women with a history of peripartum cardiomyopathy who have not fully recovered cardiac function are at high risk of this condition in subsequent pregnancies. Experts recommend treating women with standard heart failure medications and strategies for a minimum of 12 months following after clinical presentation of peripartum cardiomyopathy.
Peripartum cardiomyopathy is a serious condition of pregnancy characterized by reduced ejection fraction. Scientists hypothesize this condition may be due to a combination of increased oxidative stress and the abnormal release the hormone prolactin and protein sFlt-1, causing vascular damage. Further work is needed to develop specific therapies to prevent and manage pregnant women with this condition, as well as more precise diagnostic tests.
Every woman and every pregnancy is unique. Pregnant women should speak to their healthcare provider to ensure maternal and fetal safety. This article is meant to provide readers with current information and opinions. All medical and treatment decisions should be discussed with your healthcare provider.