Cardiac Disease in Pregnancy

Cardiac disease is the leading cause of indirect maternal death in the UK.

Epidemiology and MBRRACE-UK / CMACE Findings

• Cardiovascular disease accounts for approximately 26% of pregnancy-related deaths; mortality has not improved in 20 years
• Leading causes: cardiomyopathy (especially peripartum cardiomyopathy), myocardial infarction / ischaemic heart disease, aortic dissection, sudden arrhythmic death
• Substandard care identified in more than 50% of cardiac deaths — symptoms are often missed or misattributed to normal pregnancy
• All women with cardiac disease need MDT management: obstetrician, cardiologist, anaesthetist
• Red flag symptoms: chest pain, breathlessness at rest, orthopnoea, paroxysmal nocturnal dyspnoea, syncope, palpitations with dizziness

Modified WHO (mWHO) Risk Classification

mWHO I — no detectable increased maternal mortality

• Uncomplicated small PDA, VSD, ASD; repaired simple lesions
• Isolated atrial or ventricular ectopics
• Mild pulmonary stenosis; mitral valve prolapse without significant regurgitation
• Management: cardiology review in pregnancy

mWHO II — small increased mortality, moderate increased morbidity

• Unoperated ASD or VSD; repaired tetralogy of Fallot; most arrhythmias
• Mild left ventricular impairment (EF 45–54%)
• Hypertrophic cardiomyopathy without obstruction
• Native or bioprosthetic valve disease (mild–moderate)
• Management: follow-up each trimester; delivery in a hospital with cardiac services

mWHO II–III — significantly increased risk

• Moderate LV impairment (EF 30–44%); previous peripartum cardiomyopathy with recovered LV
• Mechanical valve; systemic right ventricle (corrected TGA); Fontan circulation
• Unrepaired cyanotic heart disease; moderate mitral stenosis; severe asymptomatic aortic stenosis
• Management: expert counselling, monthly/bimonthly cardiology review, delivery in a specialist cardiac centre, individualised delivery plan

mWHO III — significantly increased mortality / severe morbidity

• Severe LV impairment (EF < 30%) or NYHA III–IV
• Previous PPCM with residual LV impairment
• Severe mitral stenosis; moderate–severe symptomatic aortic stenosis
• Marfan syndrome with aorta 40–45 mm; bicuspid aortic valve with aorta 45–50 mm
• Management: intensive monitoring, delivery in a tertiary cardiac surgical centre

mWHO IV — pregnancy contraindicated

• Pulmonary arterial hypertension of any cause (mortality 30–50%)
• Severe systemic ventricular dysfunction (EF < 30% or NYHA III–IV)
• Severe mitral stenosis; severe symptomatic aortic stenosis
• Marfan syndrome with aorta > 45 mm; bicuspid aortic valve with aorta > 50 mm
• Native severe coarctation
• Maternal mortality 25–50%. If pregnancy occurs, discuss termination; if continued, care in a specialist centre only

Peripartum Cardiomyopathy (PPCM)

Definition: heart failure secondary to LV systolic dysfunction developing in the last month of pregnancy to 5 months postpartum, with no other identifiable cause. Echo: EF < 45%, fractional shortening < 30%, LVEDD > 2.7 cm/m².

Risk factors: advancing maternal age, multiparity, multiple pregnancy, pre-eclampsia (strong association), gestational hypertension, obesity, Afro-Caribbean ethnicity, tocolytic therapy, family history.

Presentation: dyspnoea, orthopnoea, PND, peripheral oedema, palpitations. Symptoms mimic normal pregnancy — maintain a high index of suspicion. May present with cardiogenic shock or arrhythmia.

Management:

• Antenatal: loop diuretics, vasodilators (hydralazine/nitrates), beta-blockers (carvedilol)
• Postnatal: add ACE inhibitors (contraindicated antenatally)
• Anticoagulation with LMWH — high thrombotic risk
• Severe: inotropes, mechanical support (IABP, VAD), transplant. Bromocriptine may have a role (specialist decision)

Prognosis: approximately 50% recover LV function within 6 months. Mortality 5–10% at 1 year. High recurrence risk in subsequent pregnancy if LV has not recovered — contraindicate future pregnancy if impairment persists.

Acute Coronary Syndrome

• Incidence 3–6 per 100,000 deliveries and rising; mortality 5–11%, highest peripartum. Risk 3–4× higher than non-pregnant
• Spontaneous coronary artery dissection (SCAD) is the most common aetiology in pregnancy; also coronary thrombosis, atherosclerosis, spasm, embolism
• Pregnancy-specific risk factors: pre-eclampsia, gestational diabetes, postpartum period
• Women more likely to present atypically. Troponin I is unaffected by pregnancy — use it for diagnosis. Minor ECG ST changes can be normal in pregnancy
• Coronary angiography is not contraindicated and is the gold standard; PCI preferred over thrombolysis
• Aspirin and beta-blockers safe; avoid statins; clopidogrel usable but stop before delivery
• Delivery individualised, often vaginal with a shortened second stage

Valvular Heart Disease

Mitral stenosis — most common rheumatic lesion in pregnancy. Fixed output cannot accommodate the increased cardiac output. Risks: pulmonary oedema, AF, thromboembolism. Severe if valve area < 1.5 cm² or gradient > 10 mmHg. Beta-blockers to keep heart rate < 90 bpm, diuretics for congestion, digoxin only if AF, balloon valvotomy if medical therapy fails, anticoagulate if AF / large left atrium / prior emboli.

Aortic stenosis — usually bicuspid valve in young women. Severe if valve area < 1 cm² or gradient > 50 mmHg. Risks: heart failure (10%), arrhythmias (3–25%). Associated aortopathy — check the aortic root. Symptomatic disease should be corrected before pregnancy.

Regurgitant lesions — generally well tolerated; the fall in systemic vascular resistance offloads the ventricle. Risk if severe with LV dysfunction. Vasodilators if symptomatic, diuretics for overload.

Mechanical valves — high risk of both thrombosis and bleeding; every anticoagulation option carries maternal or fetal risk:

1. LMWH throughout (monitor anti-Xa; peak target 0.8–1.2 IU/ml)
2. Warfarin (if dose < 5 mg) with LMWH at 6–12 weeks
3. Warfarin throughout — lowest maternal risk Warfarin embryopathy risk is at 6–12 weeks and is dose-dependent.

Congenital Heart Disease

ASD / VSD / PDA — well tolerated if small or repaired. Risks: paradoxical embolism, arrhythmias; large left-to-right shunts can develop pulmonary hypertension. Avoid acute blood loss (shunt reversal).

Tetralogy of Fallot — most surgically repaired; residual pulmonary regurgitation common. Risks: RV failure, arrhythmias. LMWH if unrepaired.

Coarctation — risks of hypertension, aortic dissection, cerebral aneurysm; associated bicuspid aortic valve. Beta-blockers preferred for BP control; MRI pre-pregnancy to assess aneurysms.

Marfan syndrome — 80% have cardiac involvement. Aortic root dilatation carries dissection risk, highest in the third trimester and postpartum. Aorta > 4.5 cm is high risk, > 4 cm increased risk. Monthly echo, beta-blockers throughout, caesarean if the aortic root is dilated or dilating.

Eisenmenger syndrome / pulmonary hypertension — pregnancy contraindicated, maternal mortality 25–50%. Fixed pulmonary vascular resistance; deaths usually peripartum or early postpartum.

Cardiac Drugs in Pregnancy

| Class | Safe options | Notes / contraindications | |---|---|---| | Beta-blockers | Labetalol, metoprolol, bisoprolol, propranolol | Monitor for fetal bradycardia and IUGR | | Diuretics | Furosemide, bumetanide | Avoid thiazides (neonatal thrombocytopenia) | | Vasodilators | Hydralazine, GTN, isosorbide | ACE inhibitors and ARBs contraindicated (fetal renal agenesis) | | Antiarrhythmics | Adenosine, beta-blockers, verapamil, flecainide, digoxin | Avoid amiodarone (fetal thyroid, neurological effects) | | Anticoagulants | LMWH (enoxaparin, dalteparin, tinzaparin) | Warfarin: embryopathy 6–12 weeks, ICH risk throughout | | Antiplatelets | Low-dose aspirin | Clopidogrel: limited data, stop before delivery | | Statins | None | Contraindicated — stop pre-conception |

Intrapartum Management

• Timing: aim for term vaginal delivery in most; induction at 38–40 weeks often preferred for planning; earlier if maternal deterioration
• Mode: vaginal delivery preferred for most conditions, with a shortened (assisted) second stage for severe lesions. Caesarean indicated for aortic pathology (> 4.5 cm), unstable patients, anticoagulation issues. Avoid Valsalva — passive descent and assisted delivery
• Anaesthesia: early epidural avoids pain-induced tachycardia and hypertension; regional preferred for caesarean; avoid rapid changes in preload or afterload
• Monitoring: continuous ECG and pulse oximetry, strict fluid balance; arterial line and possible central access in high risk
• Third stage: avoid ergometrine (vasoconstriction, hypertension). Use syntocinon cautiously — slow infusion, not bolus (hypotension)
• Postpartum: watch for decompensation at 24–72 hours from autotransfusion and fluid shifts

References

• Gelson et al. Cardiac disease in pregnancy. Part 1: Congenital heart disease. TOG 2007;9(1):15–20
• Gelson et al. Cardiac disease in pregnancy. Part 2: Acquired heart disease. TOG 2007;9(2):83–87
• Wuntakal et al. Myocardial infarction and pregnancy. TOG 2013;15(4):247–255
• Kulkarni. Peripartum cardiomyopathy. TOG 2021
• Timmons et al. Valvular heart disease in pregnancy. TOG 2023
• Freeman et al. Acute coronary syndromes in pregnancy: a literature review. TOG 2023;25(2):101–109

Source: The Obstetrician & Gynaecologist (TOG), RCOG journal — see references below

Clinically reviewed by NHS obstetricians and gynaecologists

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