Modified WHO Classification for This Patient
This patient with chronic diastolic heart failure, ejection fraction 45-50%, grade 3 diastolic dysfunction, and non-ischemic cardiomyopathy falls into WHO Class II-III (depending on individual clinical status), representing significantly increased risk of maternal mortality or severe morbidity that requires expert counseling and intensive monitoring. 1
Risk Classification Rationale
The modified WHO classification specifically categorizes "mild left ventricular impairment" as WHO II-III (depending on individual factors). 1 While this patient's LVEF of 45-50% is technically preserved, the presence of grade 3 diastolic dysfunction represents significant cardiac impairment that elevates risk beyond simple LVEF considerations. 1
Key Distinguishing Features from WHO IV
This patient does not meet WHO Class IV criteria because: 1
- LVEF is not <30% (the threshold for severe systemic ventricular dysfunction)
- No documentation of NYHA Class III-IV symptoms
- No pulmonary arterial hypertension mentioned
- Not peripartum cardiomyopathy with residual impairment
Factors Determining II vs III Classification
The final placement between WHO II and III depends on: 1, 2
- Current NYHA functional class (Class II would favor WHO II; Class III would mandate WHO III)
- Presence of heart failure symptoms at baseline
- Severity of diastolic dysfunction (grade 3 is severe and concerning)
- Associated valvular disease or other comorbidities
- Response to medical therapy and clinical stability
Clinical Management Algorithm
If Classified as WHO Class II (5.7-10.5% maternal risk):
- Cardiology and obstetric follow-up every trimester 2
- Multidisciplinary team assessment at specialist center 1, 2
- Monthly monitoring may be needed if symptoms develop 2
If Classified as WHO Class III (19-27% maternal risk):
- Monthly or bimonthly cardiology and obstetric review throughout pregnancy 1, 2
- Mandatory management by expert multidisciplinary pregnancy heart team 2
- Hospital delivery at specialized center with advanced cardiac support 1
- Continuous hemodynamic monitoring during labor and delivery 1
Critical Prognostic Considerations
Cardiac events occur in 32-60% of patients with left ventricular dysfunction during pregnancy or early postpartum. 3 The CARPREG risk score may provide additional prognostic information, with LVEF <40% being a major predictor of adverse outcomes. 3, 4
High-Risk Features to Monitor:
- Development of NYHA Class III-IV symptoms (would reclassify to very high risk) 3
- Atrial fibrillation or ventricular arrhythmias 3
- Worsening mitral regurgitation secondary to diastolic dysfunction 3
- Pre-eclampsia (strongly associated with heart failure, OR 7.1) 5
Timing of Complications
Heart failure typically develops at median 31 weeks gestation, with highest incidence at end of second trimester (34%) or peripartum period (31%). 5 This patient requires intensified surveillance during these critical windows given the severe diastolic dysfunction. 5
Essential Pitfall to Avoid
Do not rely solely on preserved LVEF to underestimate risk. 1, 3 Grade 3 diastolic dysfunction represents severe cardiac impairment that significantly limits the heart's ability to accommodate the 30-50% increase in cardiac output required during normal pregnancy. 6 The modified WHO classification's strength is that it integrates all cardiovascular risk factors beyond simple LVEF measurements. 2