Peripartum Cardiomyopathy
/What is Peripartum Cardiomyopathy?
Definitions:
Potentially life-threatening pregnancy-associated disease that typically arises in the peripartum period and is marked by left ventricular dysfunction and heart failure - from Arany Z, Elkayan U. Peripartum Cardiomyopathy in Circulation from April 2016.
It’s not a precisely defined entity, because timing can vary.
The US National Heart, Lung, and Blood Institute (NHLBI) in the 1990s defined PPCM as heart failure that develops in the last month of pregnancy or up to 5 months postpartum
This excludes patients that have pre-existing cardiomyopathies, but there are patients who otherwise meet criteria for PPCM who are <36 weeks.
Many definitions require cardiomyopathy to demonstrate reduced LV systolic function, where LVEF < 45%, fractional shortening <30%, or both.
Epidemiology:
Ranges from 1/1000 to 1/4000 live births, but potentially increasing.
Increasing maternal age, preeclampsia, and multiple gestations, which are all risk factors for PPCM.
Also increasing HTN, diabetes, and obesity.
Also just growing recognition of PPCM as a disease entity.
Symptoms/Signs:
Usual symptoms of heart failure:
Ie. fatigue, shortness of breath, increased extremity swelling, sometimes arrhythmias from overstretching of the heart.
Signs on exam:
Evidence of left sided congestion (pulmonary rales), right side congestion (ie. increased JVP and edema)
Elevated BNP (Malhame in Green Journal 2019)
EKG may show non-specific changes like LBBB pattern
Chest Xray: may show pulmonary edema and enlarged cardiac silhouette
Echo: LV dilation of variable degrees, LV systolic dysfunction, RV and bi-atrial enlargement; LVEF < 45%
What causes PPCM?
Older hypothesis: triggered by viral myocarditis
However, a study that looked at endomyocardial biopsies in patients with PPCM and other types of cardiomyopathies, the same proportion of specimens in each group had detectable viral genomes (30%).
Current hypothesis: “two hit” model
Vascular insult - due to antivascular or hormonal effects of late pregnancy and early postpartum period → cardiomyopathy in women with an underlying predisposition.
There is also question of genetic predisposition
High prevalence of pre-eclampsia in women with PPCM suggests a possible shared pathophysiology - perhaps some type of placental angiogenic factor.
How do we manage PPCM?
Prognosis:
50-80% of women with PPCM recover to normal range LVEF (>50%) with most recovery occurring within the first 6 months.
This is pretty good considering that in the early 1970s, the mortality of PPCM was 30-50%.
LV size and EF at time of diagnosis most strongly predict LV recovery.
LVEF <30% and LV end-diastolic diameter > 6 cm are indicative of decreased likelihood of left ventricular recovery and increased risk of mechanical support, transplant, and death.
25% of patients will develop chronic heart failure, and mortality rate is still 6-10% in the United States (depending on follow up defined for mortality rate by study).
Complications
One study found that 2.6% of women with PPCM in the US had cardiogenic shock, 1.5% of them needed mechanical circulatory support, and 0.5% of women underwent cardiac transplantation.
VTE is one of the most common severe complications of PPCM - affect 6.6% of women.
Mechanism: underlying intracardiac thrombosis in PPCM d/t cardiac dilatation and hypocontractility → blood stasis.
Also pregnancy is a hypercoagulable state.
Arrhythmias - can contribute to morbidity and mortality d/t death from VTach.
2.1% of women with PPCM had cardiac arrest and 2.9% underwent implantation of a cardiac device.
Treatment
Few studies performed specifically in women with PPCM, so management strategies are generally extrapolated from other forms of heart failure.
Multidisciplinary care: MFM, anesthesia, and cardiology.
Individualized discussion of delivery timing for optimal maternal-neonatal outcome.
Usually don’t need to do a cesarean.
Hemodynamic shifts may be mitigated by slow epidural and assisted second stage of labor.
Care overall is usually supportive, directed toward managing heart failure symptoms.
Diuresis (but don’t go overboard and cause hypotension)
If hemodynamics permit, beta blockers should be used, with preference of B1 selective ones (ie. metoprolol).
B2 blockers may prompt uterine activity, so better to avoid.
ACE-inhibitors and ARBs are considered contraindicated in pregnancy, but can use them postpartum.
Consider anticoagulation in PPCM if LVEF < 30%
If arrhythmias, may require acute or chronic administration of antiarrythmic drugs.
Cardiac assisted devices - may be indicated if severe depression of LV function or if concerned for rapid deterioration.
After PPCM, future pregnancy:
Avoid future pregnancy if EF fails to improve, as mortality increases up to 50% if EF does not improve!