What is the Killip classification?

The Killip classification (1967) is a four-class system that grades the severity of heart failure in acute myocardial infarction based on clinical examination findings. Class I has no heart failure signs; Class II has mild failure (S3, basal rales); Class III is frank pulmonary edema; Class IV is cardiogenic shock.

What mortality rates correspond to each Killip class?

Historical estimates: Class I ~6%, Class II ~17%, Class III ~38%, Class IV ~67%. Modern reperfusion therapy (PCI, thrombolytics) has reduced these rates substantially, but relative risk ordering remains valid.

Can the Killip class change over time?

Yes. Killip class is typically assessed at hospital admission and can worsen (e.g., Class I progressing to III) or improve with treatment. The admission class is most commonly used for risk stratification.

How is Killip class different from Forrester class?

Killip class uses bedside clinical signs only and requires no hemodynamic monitoring. Forrester class uses invasive hemodynamic measurements (pulmonary capillary wedge pressure and cardiac index). Killip is more practical in the acute setting without a Swan-Ganz catheter.

Killip Class Calculator

Select the clinical signs present on admission to determine the Killip class and estimated 30-day mortality for acute myocardial infarction.

Clinical Signs on Admission

Select the highest class whose criteria are fully met. The calculator automatically resolves the class.

Class I No Heart Failure

No clinical signs of cardiac decompensation. Clear lungs. No S3 gallop.

Class II Mild Heart Failure

S3 gallop and/or
Pulmonary rales in lower half of lung fields (<50% of fields)
Elevated jugular venous pressure may be present

Class III Acute Pulmonary Edema

Pulmonary rales in more than half of lung fields
Frank pulmonary edema with marked respiratory distress

Class IV Cardiogenic Shock

Systolic BP <90 mmHg
Signs of peripheral vasoconstriction (oliguria, cyanosis, diaphoresis)

Select a Killip class on the left to see the result.

For educational use only. Clinical decisions must be made by a qualified healthcare professional based on the full patient context.

Summary

The Killip classification is a clinical scoring system developed in 1967 to stratify the severity of heart failure in patients presenting with acute myocardial infarction (AMI). It divides patients into four classes (I through IV) based on bedside findings such as the presence of S3 gallop, pulmonary rales, pulmonary edema, and cardiogenic shock. Higher Killip classes correspond to significantly greater in-hospital and 30-day mortality, making this tool valuable for rapid risk stratification at the bedside.

How it works

Review the clinical signs observed during the patient's admission examination.
Select the highest applicable Killip class by checking the criteria that match.
The calculator automatically assigns the Killip class based on the most severe sign present.
Review the estimated 30-day mortality range associated with that class.
Use the result alongside other risk scores to guide clinical decision-making.

Use cases

Rapid bedside risk stratification for patients presenting with acute MI.
Triage decisions in emergency and coronary care unit settings.
Estimating short-term prognosis to guide intensity of monitoring and intervention.
Communicating severity to consulting teams using standardized language.
Medical education and training on heart failure classification in AMI.
Retrospective audit and quality improvement in cardiology departments.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu