What is the role of the Carpreg (Cardiac Disease in Pregnancy) score in assessing cardiac risk in a pregnant woman with a history of cardiac disease?

CARPREG Score for Cardiac Risk Assessment in Pregnancy

The CARPREG score is a validated risk stratification tool that should be used to predict maternal cardiac complications in pregnant women with heart disease, with the newer CARPREG II score offering superior discrimination by incorporating 10 predictors including general, lesion-specific, and delivery-of-care variables. 1

What the CARPREG Score Measures

The original CARPREG score identifies four key predictors of maternal cardiac events 1:

• Prior cardiac events (heart failure, TIA, stroke, or arrhythmia before pregnancy) 1
• NYHA functional class >II or cyanosis at baseline 1
• Left heart obstruction (mitral valve area <2 cm², aortic valve area <1.5 cm², or peak LV outflow tract gradient >30 mmHg) 1
• Reduced systemic ventricular function (ejection fraction <40%) 1

Each predictor counts as 1 point, with scores ranging from 0 to >1, predicting cardiac event rates of approximately 5%, 27%, and 75% respectively 1.

CARPREG II: The Enhanced Version

CARPREG II represents a significant advancement and should be preferentially used over the original CARPREG score because it demonstrates higher discrimination and better calibration than the modified WHO, original CARPREG, and ZAHARA I scores 1. The 2023 AHA/ACC guidelines specifically recommend using CARPREG II for risk stratification 1.

The 10 CARPREG II Predictors

Five general predictors 2:

• Prior cardiac events or arrhythmias 2
• Poor functional class (NYHA >II) or cyanosis 2
• High-risk valve disease or left ventricular outflow tract obstruction 2
• Systemic ventricular dysfunction 2
• No prior cardiac interventions 2

Four lesion-specific predictors 2:

• Mechanical heart valves 2
• High-risk aortopathies 2
• Pulmonary hypertension 2
• Coronary artery disease 2

One delivery-of-care predictor 2:

• Late pregnancy assessment (lack of early multidisciplinary evaluation) 2

CARPREG II Risk Stratification

The score translates directly to predicted cardiac event risk 1:

• Score 0-1: 5% risk 1
• Score 2: 10% risk 1
• Score 3: 15% risk 1
• Score 4: 22% risk 1
• Score >4: 41% risk 1

Clinical Application Algorithm

Step 1: Identify absolute contraindications first 3

• Check for WHO Class IV conditions (pulmonary arterial hypertension, severe ventricular dysfunction with LVEF <30%, severe mitral/aortic stenosis, Marfan syndrome with aorta >45mm) 3, 4
• If present, pregnancy is contraindicated and termination should be discussed 1

Step 2: Calculate CARPREG II score 1

• Assign weighted points for each of the 10 predictors present 2
• Determine predicted risk percentage 1

Step 3: Establish monitoring intensity based on risk 3

• Low risk (score 0-1,5%): Limited cardiology follow-up, 1-2 visits during pregnancy 3
• Moderate risk (score 2,10%): Trimester-based follow-up 3
• High risk (score ≥3, ≥15%): Monthly or bimonthly cardiology and obstetric review by multidisciplinary team at specialist center 3

Validation and Performance

The CARPREG score demonstrates high sensitivity (87%) and negative predictive value (99%) for total cardiac events, with 100% sensitivity and negative predictive value for primary cardiac events including pulmonary edema and sustained arrhythmia 5. This means a score of 0 effectively rules out major complications 5.

Multiple validation studies confirm CARPREG's utility across diverse populations 1, 6, 5, with one study showing CARPREG score ≥1 associated with a 6.76-fold increased odds of cardiac events 6.

Critical Advantages Over Alternative Scores

CARPREG II outperforms the modified WHO classification in prospective validation studies, showing superior discrimination and calibration 1. However, the modified WHO classification remains valuable because it explicitly includes absolute contraindications to pregnancy (like pulmonary arterial hypertension) that were underrepresented in CARPREG derivation cohorts 1.

The ZAHARA score, developed specifically for congenital heart disease, has not been validated as extensively and appears less discriminant than CARPREG for maternal outcomes 7.

Essential Clinical Pitfalls

Do not rely solely on CARPREG score without considering absolute contraindications 3. The score was derived from populations that excluded or underrepresented conditions like pulmonary arterial hypertension and severe aortic dilatation, which carry 30-50% maternal mortality 4.

Major cardiac complications can occur even in women with CARPREG score of 0 7. Four women with no identified risk factors experienced major cardiac events in one cardiomyopathy cohort, emphasizing that clinical judgment must supplement risk scores 7.

The highest mortality occurs in women who do not receive early multidisciplinary care 7. Late pregnancy assessment is itself a predictor in CARPREG II, highlighting that the delivery-of-care variable directly impacts outcomes 2.

Neonatal Risk Prediction

CARPREG score ≥1 predicts not only maternal complications but also adverse neonatal outcomes, including birth weight <2,500g (OR 2.57) and preterm delivery (OR 2.4) 6, 5. Neonatal complications occur in 24-28% of pregnancies in women with heart disease 6.

Temporal Trends

While overall cardiac complication rates remain stable at approximately 16%, the frequency of pulmonary edema has decreased from 8% (1994-2001) to 4% (2001-2014), likely reflecting improved management strategies 2.