WHO Risk Class IV Cardiac Lesion in Pregnancy
The correct answer is (b) Pulmonary artery hypertension—this is explicitly classified as WHO Risk Class IV where pregnancy is contraindicated and carries extremely high maternal mortality risk.
Direct Classification from Guidelines
Pulmonary arterial hypertension (PAH) of any cause is definitively classified as modified WHO Risk Class IV, meaning pregnancy is contraindicated. 1 This classification applies regardless of the underlying etiology of the pulmonary hypertension. 1
The European Society of Cardiology guidelines explicitly state that WHO Class IV represents "extremely high risk of maternal mortality or severe morbidity; pregnancy contraindicated. If pregnancy occurs termination should be discussed." 1
Why Pulmonary Hypertension is WHO Class IV
Maternal mortality in PAH during pregnancy ranges from 30-50%, making it the highest risk cardiac condition in pregnancy. 2 This catastrophic risk occurs because:
- Life-threatening rises in pulmonary vascular resistance develop particularly rapidly in the peripartum and postpartum periods due to pulmonary thrombosis or fibrinoid necrosis 2
- Right ventricular overload increases with systemic vasodilation, worsening right-to-left shunting and cyanosis 2
- The condition can prove fatal even in patients who previously had minimal disability 2
Recent data confirms maternal cardiac event rates of 40-100% during pregnancy in women with PAH. 3
Classification of the Other Options
Repaired VSD (Option a): WHO Class I
Successfully repaired ventricular septal defects are classified as WHO Risk Class I, representing no detectable increased risk of maternal mortality and no/mild increase in morbidity. 1
Supraventricular Arrhythmias (Option c): WHO Class II
Most arrhythmias, including supraventricular arrhythmias, are classified as WHO Risk Class II (if otherwise well and uncomplicated), representing only small increased risk of maternal mortality or moderate increase in morbidity. 1
Hypertrophic Cardiomyopathy (Option d): WHO Class II-III
Hypertrophic cardiomyopathy is classified as WHO Risk Class II-III (depending on individual circumstances), not Class IV. 1 This represents significantly increased risk requiring expert counseling, but pregnancy is not absolutely contraindicated as it is in Class IV conditions. 1
Critical Clinical Pitfall
The most dangerous error is failing to recognize that PAH represents an absolute contraindication to pregnancy, regardless of how mild the patient's symptoms may appear. 1, 3 Even women with oxygen saturation >85% at rest and PAH should be advised against pregnancy. 1 Women who become pregnant despite counseling require immediate referral to specialized centers with multidisciplinary teams experienced in managing this life-threatening condition. 3, 4, 5