Cardiac disease is becoming increasingly recognised in pregnancy,1 and is the highest cause of maternal death in Australia contributing to 14.3% of maternal mortality.1,2 In New Zealand 8.5% of maternal deaths are the result of cardiac conditions.3 This, coupled with the rising average age and body mass index of patients is culminating in an increased burden of cardiovascular risk within obstetric medicine.4 Overall, indirect maternal deaths are decreasing, yet cardiac disease remains unchanged and is the most common cause.5 Recent guidelines published by the European Society of Cardiology recommend that pregnant women with cardiac disease are seen in a specialised centre by a multidisciplinary “pregnancy heart team”.1 Wellington Regional Hospital is a tertiary unit that provides a multidisciplinary service for the lower North Island of New Zealand, which consists of an obstetrician, cardiologists, anaesthetists and midwives. The multidisciplinary team convenes monthly to discuss referred patients, arrange outpatient investigations and clinic appointments and formulate an overall care plan.

We set out to define the range and severity of cardiac disease in pregnant women seen by the team over a two-year period, as well as the maternal and neonatal morbidity and mortality compared with the background obstetric population.

Methods

Clinical records were reviewed retrospectively for all patients reviewed by the multidisciplinary team from January 2016 to December 2017. An electronic list of all women reviewed by the multidisciplinary team is maintained, and this was used to retrieve electronic records, including referral letters, obstetric, anaesthetic and cardiology clinic letters. Discharge summaries, neonatal intensive care unit (NICU) admissions and midwifery databases were utilised to identify maternal morbidity and mortality (including intensive care unit admission, cardiac events) and neonatal morbidity (NICU admission) or mortality.

The patients’ ages and ethnicities were recorded according to Ministry of Health guidelines for reporting ethnicity.6 Rates of instrumental delivery and caesarean section delivery were recorded and compared against the hospital average using binomial tests. We also recorded the indication for referral and the severity of cardiac disease, ranked by the modified World Health Organization (mWHO) criteria as set out in the 2018 European Society of Cardiology Guidelines for Management of Cardiovascular Disease in Pregnancy.1,7 Patients with mWHO score of I (ie, not at increased risk of mortality and no/mild increased risk of morbidity) were not included in the analysis.

Ethical approval was obtained locally from the hospital’s Audit and Research Committee prior to commencing. Confidentiality and privacy of patient notes was ensured by the authors.

Results

Over the two-year period, 72 patients were reviewed by the multidisciplinary team, including 31 patients (43.1%) referred from other district health boards in New Zealand. The three most common referral reasons were arrythmia (n=20, 27.8%), congenital anomalies (n=19, 26.4%) and palpitations (n=10, 13.9%). The full list of cardiac conditions that prompted referral are shown in Table 1. Fifty-three of these patients (73.6%) were found to have increased risk of mortality and morbidity (ie, mWHO score II or higher) and were included for further analysis. Fifty-two of these patients (98.1%) delivered in Wellington Hospital.

Severity of disease according to mWHO scores is shown in Figure 1. Modified WHO scoring categorised 33% (n=24) of patients as at small increased risk (mWHO score II), 21% (n=15) as intermediate increased risk (mWHO score II-III) and 4% (n=3) of patients at significantly increased risk (mWHO score III).1,7

Patients were most frequently seen in the second trimester (n=26, 49.1%); with two (3.8%) being seen preconceptually; 15 (28.3%) in the first trimester; and 10 (18.9%) in the third trimester. The most common investigations ordered by the team included echocardiography for 45 women (84.9%), Holter monitor for 15 (28.3%) women and magnetic resonance imaging for 11 (20.8%) women.

Documented preconceptual counselling by either a cardiologist or obstetrician could be found for 12 patients (22.6%). A specific plan around delivery was devised for 37 patients (69.8%).

Of the 52 patients delivering at Wellington hospital, no significant maternal morbidity or mortality was found. Age at delivery ranged from 16 to 41 with median 31.5 years. The ethnic distribution of these patients (according to Ministry of Health guidelines for reporting ethnicity6) was 49.1% (n=26) New Zealand European, 20.8% (n=11) New Zealand Māori, 11.3% (n=6) Pacific, 11.3% (n=6) Other Asian, 3.8% (n=2) Other European, 1.9% (n=1) Indian and 1.9% (n=1) other. The majority (52.8%, n=28) of these women were primiparous. The mode of delivery was caesarean section for 28.8% (n=15) (hospital average 32.4%, p=0.350), instrumental delivery for 19.2% (n=10) (hospital average 10.8%, p=0.049) and spontaneous vaginal birth for 51.9% (n=27) (hospital average 56.8%)8. Six neonates (11.5%) required NICU admission (hospital average 16.5%).

Table 1: Cardiac indications for multidisciplinary review among pregnancy women 2016–17. Modified WHO score as per the European Society of Cardiology 2018 Guidelines for Cardiovascular Disease in Pregnancy.1

‍Figure 1: Modified WHO classification of maternal cardiovascular risk.11

Discussion

We have demonstrated that cardiac disease among pregnant women is an important aspect of obstetric care in the catchment region of Wellington Hospital, New Zealand, warranting multidisciplinary input. The team comprising obstetricians, cardiologists, anaesthetists and midwives advised specific delivery plans for the majority of these patients, and despite an increased instrumental delivery rate, we did not demonstrate any increased maternal or neonatal mortality or morbidity compared with the background obstetric population.

A multidisciplinary approach is a core tenet of the management of complex medical conditions in general. This is particularly applicable to cardiovascular disease in pregnancy due to the increased physiological demands throughout pregnancy and the puerperium. In our centre, multidisciplinary review plays an important role in identifying and managing women at risk of morbidity and mortality. Over a two-year period, a significant number of women were identified at increased risk using the mWHO scoring systems. The 2018 ESC Guidelines recommend that women with mWHO score II–III or higher are managed at a referral hospital, and that women with mWHO score II or lower are managed at their local hospital. Only 18 women (25% of referrals) met this criteria, however, these guidelines are not necessarily applicable to regional New Zealand, where cardiology, neonatal, anaesthesia and intensive care services are not necessarily available or appropriate to manage complex cardiology and obstetric complications. While some lower-risk patients were appropriately reviewed by the multidisciplinary team, 26% of referrals were found to have mWHO score of I (ie, no/minimal increased risk) and could likely have been managed in a general antenatal clinic.The prevalence and distribution of cardiac disease in pregnancy is geographically and temporally heterogeneous.9 For example, one previous study in South Africa reported that among pregnant women with cardiac disease, 84% had valvular or rheumatic disease (compared with only 9% of women referred to our service), while only 9% had congenital heart disease (compared with 26% in our study10). This highlights the importance of local audit to identify the burden of cardiac disease among the relevant population, and allow for services targeted to this group.

Māori and Pacific women are overrepresented in this group (14.8% and 9.8% compared with the district health board catchment area 10% and 7% respectively8). District health boards need to ensure equity and accessibility to tertiary-level services, which cover large geographical areas and may require patients to travel long distances. This includes providing culturally acceptable services, support with travel, accommodation and assistance with costs for carers and whānau.

Pregnant women with cardiac disease were more likely to require instrumental delivery, however, caesarean section rates were not shown to be different to the background population. This is expected, as delivery plans for women with cardiac disease frequently involve a shortened second stage of labour to decrease the physiological demands of delivery. We did not observe a difference in neonatal admissions as a result of this compared to the general population.

One issue raised by this study is the lack of documented preconceptual counselling, with over three quarters of higher-risk women not having any documented discussion. Our records did not include out of area consultations or consultations with non-hospital practitioners (ie, general practitioners and specialists in the private sector). Preconceptual counselling is a vital part of wholistic care for women of child-bearing age with complex medical comorbidities. A second issue is that there was no defined referral protocol for the service, and therefore there was a wide variation in referrals, ranging from severe disease to palpitations without evidence of arrhythmia. Specific referral criteria are being developed (to be made available via the Health Pathways system). The team will also aim to produce well-documented shared delivery plans between the patient, lead maternity carer and multidisciplinary team for all patients. It is also likely that some women with cardiac disease were managed through general obstetric antenatal clinics without involvement of the multidisciplinary team.

There were no serious adverse outcomes in this cohort of high-risk patients. While our retrospective observational study cannot conclude that the multidisciplinary team is responsible for this, the observation is encouraging. The centralisation of care of these patients does improve the ability of our clinicians to provide high-quality care.

Cardiovascular disease needs to be a key focus for maternity care delivery in well-resourced countries such as New Zealand. We have demonstrated that in our catchment area the number of pregnant women affected by cardiovascular disease warrants a centralised multidisciplinary team approach; we provide encouraging results that this approach can ensure these women have similar obstetric outcomes to the general obstetric population. We plan further, prospective study on this topic with a particular emphasis on communication with primary care, contraception access, preconception counselling and risk factor modification.

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