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Table 1: Modified World Health Organization risk scale. |
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Class |
Pathology |
Maternal event rate (%) |
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I No increased risk of mortality Low morbidity |
• Small or mild uncomplicated injury including pulmonary stenosis, patent ductus arteriosus, or mitral valve prolapse Repaired simple lesions: atrial or ventricular septal defects, ductus arteriosus, and anomalous pulmonary vein return Isolated ventricular or supraventricular extrasystoles |
2.5-5 |
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II Slight increase in mortality risk A moderate increase in morbidity risk |
• Unrepaired atrial or ventricular septal defect Repaired Tetralogy of Fallot Arrhythmias |
5.7-10.5 |
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II–III Intermediate increase in mortality risk |
• Mild deterioration of the LVEF (> 45%) Hypertrophic cardiomyopathy Native valve disease not considered class I or IV Marfan syndrome without aortic dilatation Bicuspid aortic valve with dilated aorta < 45 mm Repaired coarctation of the aorta |
10-19 |
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III Significant increase in maternal mortality or serious morbidity |
• LVEF deterioration (30-45%) Previous peripartum cardiomyopathy Mechanical prosthesis Systemic right ventricle Fontan circulation Cyanotic heart disease (unrepaired) Other complex congenital disease Moderate aortic dilatation: 40-45 mm in Marfan, 45-50 in the bicuspid valve, < 50 in Fallot |
19-27 |
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IV High risk or contraindicated pregnancy |
• Pulmonary hypertension of any cause Severe LV dysfunction (LVFE < 30% or FC III-IV) Previous peripartum cardiomyopathy with impaired residual LVEF Severe obstruction of the left cavities (aortic valve area < 1 cm2 or peak gradient > 50 mmHg or mitral valve area < 1.5 cm2) Marfan syndrome with aortic dilatation > 45 mm. Bicuspid aortic valve with aortic dilatation > 50 mm Severe coarctation of the aorta severa Ehler Danlos and severe re-coarctation |
40-100 |
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LVEF = left ventricle ejection fraction. |
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