The Killip classification is a system used in individuals with an acute myocardial infarction (heart attack), in order to risk stratify them. Individuals with a low Killip class are less likely to die within the first 30 days after their myocardial infarction than individuals with a high Killip class.[1]
The study was a case series with unblinded, unobjective outcomes, not adjusted for confounding factors, nor validated in an independent set of patients. The setting was the coronary care unit of a university hospital in the USA.
250 patients were included in the study (aged 28 to 94; mean 64, 72% male) with a myocardial infarction. Patients with a cardiac arrest prior to admission were excluded.
Patients were ranked by Killip class in the following way:
The numbers below were accurate in 1967. Nowadays, they have diminished by 30 to 50% in every class.
Within a 95% confidence interval the patient outcome was as follows:
Killip class I: | 81/250 patients; | 32% (27–38%). | Mortality rate was found to be at 6%. |
Killip class II: | 96/250 patients; | 38% (32–44%). | Mortality rate was found to be at 17%. |
Killip class III: | 26/250 patients; | 10% (6.6–14%). | Mortality rate was found to be at 38%. |
Killip class IV: | 47/250 patients; | 19% (14–24%). | Mortality rate 67% |
The Killip-Kimball classification has played a fundamental role in classic cardiology, having been used as a stratifying criteria for many other studies. Worsening Killip class has been found to be independently associated with increasing mortality in several studies.
Killip class 1 and no evidence of hypotension or bradycardia, in patients presenting with acute coronary syndrome, should be considered for immediate IV beta blockade.