Advantages and Limitations of Killip and Kimball Class A at Admission in Early Discharge Decision-Making in ST-Segment Elevation Acute Myocardial Infarction. ARGEN-IAM-ST Registry

pp. 255-262

Abstract

Background: Patients admitted to the coronary care unit with ST-segment elevation myocardial infarction (STEMI) without heart failure (HF) are classified as Killip and Kimball class A (KK A). They usually have a favourable prognosis and are often considered for early discharge. However, this initial assessment may be insufficient, as not all patients experience an uncomplicated clinical course. From a practical perspective, progressive HF is often used as a risk marker for mortality.

Objectives: 1. To determine the incidence of KK class A at admission in patients with STEMI and its role in overall mortality. 2. To establish the incidence of HF during the clinical course of patients classified as KK A at admission and its characterization.
To analyze the negative predictive value of the absence of HF during the clinical course on mortality.
Methods: Retrospective analysis of the ARGEN-IAM-ST registry. This prospective observational study was conducted from March 2015 to October 2024. All patients enrolled in the registry were analyzed. HF was considered a complication and defined according to the treating physician’s criteria.
Results: From March 2015 to October 2024, 7,304 patients were enrolled, with a median age of 60 years (interquartile range, IQR, 52-67); 80% were male. According to the Killip and Kimball classification, 77.6% of patients were class A, 14% class B,  1.4% class C, and 7% class D. The overall mortality rate was 7.3%. For KK A patients, hospital mortality was 2.6%, representing 28% of the overall mortality rate.
During hospitalization 5.4 % of KK A patients developed progressive HF, and 21% of these patients died. In contrast, among patients who did not develop HF, only 1.5% died (OR 17.77, 95% CI, 12.09-24.35; p<0.001). The absence of progressive HF in KK A patients had a high negative predictive value for mortality (98.5%). Independent variables related to progressive HF in KK A patients were age >70 years, female sex, diabetes, left anterior descending artery involvement, longer symptom-to-door time, and failed primary percutaneous coronary intervention.
Conclusions: Although mortality in KK A patients at admission is low, its contribution to overall mortality is elevated due to its high prevalence at presentation. The absence of HF during the clinical course identifies a group at a very low risk for mortality, supporting safe early discharge.