How it's calculated
Killip class is assigned purely from clinical examination findings — no calculation is involved, just a 4-tier classification based on signs of heart failure at presentation with myocardial infarction.
Killip classes
| Class | Findings |
|---|---|
| I | No signs of heart failure |
| II | Rales/crackles, elevated jugular venous pressure, or S3 gallop |
| III | Frank pulmonary oedema |
| IV | Cardiogenic shock |
Clinical use
- Killip class is assigned at presentation with acute MI and correlates with in-hospital and short-term mortality risk, historically used to guide triage and intensity of monitoring.
- The original 1967 mortality figures (approximately 6%, 17%, 38%, and 81% for classes I-IV) substantially predate reperfusion therapy, dual antiplatelet therapy, and modern intensive care — actual mortality today is considerably lower at every class.
- A higher Killip class at presentation still identifies patients needing closer haemodynamic monitoring and a lower threshold for escalation, even though absolute mortality has fallen since the original description.
- Class IV (cardiogenic shock) mandates urgent escalation — mechanical circulatory support and emergency revascularisation are typically considered without delay.
Frequently asked questions
What is the Killip classification used for?
It classifies the severity of heart failure at presentation with acute myocardial infarction into four clinical grades, historically used to estimate mortality risk and guide the intensity of monitoring and treatment.
Are the original Killip mortality percentages still accurate today?
No — the original 1967 mortality figures predate reperfusion therapy, modern antiplatelet regimens, and contemporary intensive care, so actual mortality today is considerably lower at every class than the historical figures suggest.
What is Killip Class IV?
It represents cardiogenic shock — the most severe class, associated with the highest mortality risk, and typically prompting urgent escalation including consideration of mechanical circulatory support and emergency revascularisation.
Does Killip class require any blood tests?
No — unlike many other risk scores, Killip classification is based entirely on clinical examination findings (looking and listening for signs of heart failure), making it usable immediately at the bedside without waiting for labs.
References
- Killip T, Kimball JT. Treatment of myocardial infarction in a coronary care unit. Am J Cardiol. 1967;20:457-464.
- Amsterdam EA, et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes. Circulation. 2014;130:e344-e426.
- El-Menyar A, et al. Killip classification in patients with acute coronary syndrome. Angiology. 2012;63:161-166.