Cardiology

Killip Classification for Heart Failure in Acute MI

Assessment of heart failure severity in acute myocardial infarction

Primary source: Killip T, Kimball JT. Am J Cardiol 1967; 20(4): 457-464

Aleksandr A. Aulov, MD, internal medicine Last clinical review: April 28, 2026

Online calculation

Killip Class

About this score

The Killip classification (Killip T, Kimball JT, Am J Cardiol, 1967) is a standard scale for assessing acute heart failure in myocardial infarction, based on clinical signs without instrumental data.

Class I: no signs of HF. In-hospital mortality ~6%. Class II: mild-to-moderate HF — rales in the lower lung fields in < 50% of the fields, S3, jugular venous distension. Mortality ~17%. Class III: pulmonary edema — rales in > 50% of the fields. Mortality ~38%. Class IV: cardiogenic shock — hypotension (SBP < 90), signs of hypoperfusion (oliguria, confusion, cold extremities). Mortality 60-80%.

The scale is used at admission and for serial reassessment in the ICU. ESC guidelines recommend the Killip classification as the standard tool for assessing acute HF in the setting of MI. Class III-IV indicates a need for intensive care and consideration of mechanical circulatory support.

When to use

At admission of a patient with MI — a mandatory part of the medical record.
Serial monitoring during the first 48-72 hours in the ICU.
Predicting in-hospital mortality and guiding the intensity of therapy.
Incorporation into risk stratification scores (TIMI, GRACE).

Clinical example

Case

A 71-year-old man with anterior STEMI, presenting 90 minutes after symptom onset. Heart rate 110/min, BP 95/60. Auscultation reveals fine crackles in the lower two-thirds of both lungs. SpO2 88% on room air. Alert and oriented.

Calculation

Rales in > 50% of the lung fields with preserved perfusion = Class III.

Interpretation and management

Killip III (pulmonary edema, in-hospital mortality ~38%). Management: oxygen therapy with escalation to CPAP/NIV if worsening, diuretics (furosemide 40-80 mg IV), nitrates if hemodynamically stable, emergency PCI (door-to-balloon < 90 min). Continuous reassessment of Killip class in the ICU.

Limitations and cautions

Does not incorporate echocardiographic findings or biomarkers — a complete picture requires LVEF, BNP/NT-proBNP, and troponin.
Auscultatory assessment is subjective; patients with COPD may have baseline rales.
Not applicable in mechanically ventilated patients.
Developed in the pre-reperfusion era; contemporary mortality is lower owing to PCI and optimal medical therapy.

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Frequently asked questions

What counts as "rales over 50% of the lung fields"?

Fine or medium crackles extending bilaterally from the level of the inferior scapular angles upward. Rales confined to the lower fields only correspond to class II.

How does Killip relate to GRACE?

Killip class is a component of the GRACE score for risk stratification in acute coronary syndrome. A higher Killip class predicts higher mortality on the GRACE scale.

Can it be used in NSTEMI?

Yes, the scale is validated for all types of MI. Acute HF is less common in NSTEMI, and most patients remain in class I.

How often should the class be reassessed?

At admission, with any significant change in hemodynamics, and at least every 6 hours during the first 24 hours.

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Aleksandr A. Aulov Physician, internal medicine, Sechenov School — independent medical education platform. Calculators are compiled from the original publications and current clinical guidelines. Interpretation thresholds follow the source study unless stated otherwise.

This calculator is intended for healthcare professionals. Do not use it for self-diagnosis or self-treatment. Management decisions are made by the treating clinician based on the full clinical picture of the individual patient.