During the 7-day acute admission, she remained asymptomatic from a
cardiac perspective with normal telemetry. The obstetric team reviewed
at least daily, both as a routine and for any maternal pregnancy
concerns. Investigations for fetal wellbeing included a Kleihauer test
and fetal growth ultrasound, both of which were normal. The estimated
foetal weight (EFW) was on the 40th centile, with a
normal amniotic fluid index (AFI) and doppler studies. A
multidisciplinary team (MDT) meeting was undertaken to discuss the
antenatal, intrapartum and postpartum management for this patient. The
consensus management was for elective birth at 37 weeks gestation, with
either a vaginal birth with a modified second stage or caesarean section
considered appropriate, with early regional anaesthesia in either event.
It was considered that for the intervening weeks, aspirin alone would be
suitable anticoagulation, and so the enoxaparin ceased. Given the
increased concern regarding SCAD in the post-partum period, a planned 2
week elective admission postpartum in conjunction with telemetry
monitoring for the first 48 hours was recommended.
The patient was discharged at 34 weeks gestation on 150mg aspirin daily.
She was required to stay within 30 minutes of the hospital and present
if she had any concerns. A further MDT with patient involvement was
undertaken to plan the mode of delivery. After counselling that the
modified second stage would involve an early epidural, telemetry, no
active pushing and a forceps delivery, the patient decided on an
elective caesarean section, for which she was consented and planned for
at 37+1 weeks.
An uncomplicated caesarean section was conducted at 37+1 weeks,
resulting in an uncomplicated delivery of a 2.8kg baby with APGARS of 7
and 7 under combined spinal-epidural (CSE) anaesthetic. She was
commenced on 47.5mg of extended-release metoprolol and 150mg of aspirin
once daily and remained well for the 2-week admission post-delivery. On
discharge, she completed the metoprolol for a further 4 weeks and the
aspirin for a total 12 weeks. Due to the high risk of iatrogenic
dissection with an angiogram, a CTCA and CTA of carotid, vertebral,
subclavian, renal and iliac arteries were conducted to exclude aneurysm
and resolution of the SCAD. This showed normal vessels and SCAD
resolution at 3 months post-partum.
Discussion
Spontaneous coronary artery dissection (SCAD) is an ischaemic event that
occurs with an expanding intramural haematoma between the tunica media
and intima of an artery resulting in separation of the intima-media
complex. This creates a false lumen which in turn compresses the true
lumen of the vessel resulting in ischemia and therefore an acute
coronary syndrome (ACS)3. Amongst the general
population, there is great variation in type of primary presenting ACS
being STEMI, NSTEMI and unstable angina4,5,6. The vast
majority of SCAD presentations (87-95%) occur in women at a mean age of
41 years old, slightly lower than the 45 year mean for SCAD in males,
yet most of these women do not have typical cardiovascular risk
factors7,8. Patients with SCAD are grouped into three
subsets; coronary artherosclerotic disease (CAD), females in the
peripartum period and idiopathic SCAD9.
SCAD is responsible for 25% of myocardial infarctions (MI) antenatally
and 50% of MI’s in the peri- and postpartum
periods10. Patients with pregnancy associated
spontaneous coronary artery dissection (p-SCAD) generally present with a
more severe clinical manifestations when compared with SCAD not
associated with pregnancy. SCAD antepartum is very rare but is
associated with high maternal and fetal
morbidity11,12. As per the Mayo SCAD Registry, SCAD in
pregnancy is more likely to occur postpartum, most likely to be
associated with STEMI, and significantly correlated to multiparity,
infertility treatment and pre-ecclampsia11,13. SCAD
can be associated with connective tissue disorders, vasculitis
polycystic kidney disease and use of particular drugs. Its
pathophysiology in pregnancy is multifactorial, likely due to a
combination of sexual hormones and an increase in shearing force from a
hyperdynamic circulation.
For those presenting with typical or atypical symptoms consistent with
an ACS, investigation typically starts with standard pathology such as
serial troponin levels in addition to serial electrocardiography (ECG)
and echocardiogram. SCAD must be considered among the diagnostic
differentials. This is followed by the diagnostic modality of invasive
coronary angiography for which there is usually significant concern
surrounding fetal radiation. It is estimated that procedural exposure
contributes to approximately 1 in 8000 of childhood cancer
cases14. Unlike classic atherogenic myocardial
infarction, percutaneous intervention (PCI) is not routinely recommended
in SCAD. This is mainly due to the unpredictable nature of PCI and the
high risk of haematoma propagation along the vessel (occurs in
approximately one third of cases)15. Other modalities
such as intravascular ultrasound (IVUS) and optical coherence tomography
(OCT) are fast becoming beneficial in vessel morphology, however, are
typically reserved for cases where the diagnosis is unclear or where
intervention of the lesion may be required15.
The vast majority of antenatal SCAD cases occur in the post-partum
period, therefore data on delivery planning in the context of antenatal
SCAD is very limited. A retrospective cohort study of 54 women showed
that only 4 were diagnosed with SCAD antenatally; only 1 of these women
chose to undergo elective termination, while the other 3 women had
emergency caesarean sections, though the indication for caesarean
delivery was not reported16. Another large case
analysis compiling 120 cases of SCAD in pregnancy in contemporary
literature showed that only 17.5% presented in the
3rd trimester, and 6% in the 2nd
trimester16.
Currently, the preferred treatment for antenatal SCAD is conservative,
however, intervention may be required in the circumstances such as
ongoing or recurrent clinical or ECG-demonstrated ischaemia, cardiogenic
shock requiring support, sustained VT or VF, or a left main coronary
artery dissection17. There is evidence that suggests
any surgical intervention required to stabilise the female patient with
a SCAD in pregnancy, such as PCI and CABG, are best performed
postnatally, and as such if surgical intervention is required then
emergent pre-procedure birth of the baby should be strongly
considered16. Havakuk et.al. found that of the 4 women
who underwent CABG antenatally, 50% experienced intrauterine fetal loss
and the other 50% experienced significant fetal complications. While
there is limited published research on the specifics of delivery
planning and intrapartum management of SCAD in pregnancy, it is a known
ischaemic cardiac event, and therefore principles applied to other
ischaemic cardiac conditions in pregnancy can be extrapolated to SCAD in
pregnancy. In order to achieve rate control, ß1-adrenergic blockers are
the preferred treatment option, in addition to being widely used in
other pregnancy conditions such as hypertension, arrhythmias, mitral
stenosis and Marfan Syndrome10. It is, however,
prudent to consider fetal effects such as bradycardia, hypoglycaemia and
apnoea of the newborn.
It is proposed that the hormonal milieu associated with the pregnant and
post-partum state are partially responsible for p-SCAD. In particular,
high levels of progesterone may contribute to changes in protein
composition, degradation of reticulin, collagen and elastic fibres and
hypertrophy of smooth muscle of the vessel wall18.
This, in combination with the other cardiac haemodynamic changes of
pregnancy, such as increased cardiac output/intravascular volume and
decreased peripheral vascular resistance (which are estrogen mediated),
can ultimately increase the risk of rupture of a weakened vessel
wall16.
It is unclear if the female sex hormones used for contraception increase
the risk of SCAD in a similar way to pregnancy, as they are likely to
only be only part of the mechanism. However, there are at least 7
published cases of women who experienced SCAD in the context of oral
contraceptive pill use, suggesting a possible
association18,19,20. As well as this, other
hyperestrogenic states have been associated with SCAD, such as hepatic
cirrhosis21. Havakuk et al. showed that when compared
to SCAD, women with p-SCAD had a higher risk of persistence and often
progression of SCAD. This was demonstrated in one third of their
population16. This ongoing fragility of the vessel
wall steers the authors to advocate for an individualised discussion
which takes into consideration the possible risk of SCAD recurrence with
contraceptive use and that associated with repeat pregnancy. Further
research into this area would be helpful for this patient cohort.
Conclusion
This case highlights the diagnostic and management dilemmas of SCAD in
pregnancy. It can be a difficult clinical scenario to balance patient
autonomy and safety, particularly on the background of a small evidence
base with limited recommendations for optimal investigations and
delivery modality. This case contributes valuable demographic data to
the rare condition of SCAD intrapartum. Further research into this
unique pregnancy-associated cardiac condition would provide a valuable
contribution to the evidence base for clinicians faced with this
scenario in future.