Use in adults with suspected or confirmed acute myocardial infarction to grade heart failure severity and approximate short-term mortality risk from simple bedside findings. It is not validated for chronic heart failure without acute infarction or for dyspnoea that is clearly non-cardiac.

Killip and Kimball described the classification in a 250‑patient coronary care unit cohort in the 1960s. Adults with established infarction were divided into four classes according to the severity of clinical heart failure or shock, and in‑hospital mortality increased sharply from about 6% in class I to 81% in class IV.

Subsequent large non–ST-elevation acute coronary syndrome trials and registries have confirmed that Killip class at presentation is an independent predictor of 30‑day and 6‑month mortality, even after adjustment for age, blood pressure, heart rate and ECG changes. In one contemporary cohort, 30‑day mortality rose from 2.8% in Killip class I to 8.8% in class II and 14.4% in classes III/IV, with similar gradients at 6 months.

In reperfusion-era practice, including primary PCI cohorts, absolute mortality within each Killip class is lower than in the original report but still increases with higher class. Killip class is incorporated into global acute coronary syndrome risk scores such as the GRACE model and helps inform triage, monitoring intensity and disposition.

Classification is based solely on clinical examination and can be subjective, particularly when distinguishing classes II and III or in patients with coexisting lung disease or obesity. Use the Killip class alongside ECG, cardiac biomarkers and haemodynamic data rather than as a stand‑alone decision rule.

The primary source or current guidance provides the model definition, source population and supporting evidence.

Killip Classification in Acute Myocardial Infarction