Predictors of high Killip class after ST segment elevation myocardial infarction in the era of primary reperfusion
Introduction
Over the last decades, mortality due to acute myocardial infarction has been reduced thanks to advances in patient care, especially rapid reperfusion and an increase of the rate of primary Percutaneous Coronary Intervention (PCI) [1], [2], [3]. However, this reduction in mortality has been accompanied by an increase in heart failure after myocardial infarction [4]. Heart failure after acute myocardial infarction is associated with a high in-hospital mortality that can be 4-fold higher than in patients without heart failure. In this regard, Killip Classification [5] continues to be useful for risk stratification. The risk of presenting heart failure after an acute myocardial infarction is the result of the interaction of baseline characteristics of the patient as well as the treatment administered [6], [7], and thus has a multifactorial origin. Patients' factors include previous cardiac and non-cardiac comorbidities and older age as predisponent conditions. Myocardial extension damage with myocyte loss or stunning and ventricular remodelling are heart-related risk factors. The incidence of heart failure after myocardial infarction is very high (approximately 25%) and is more common when left ventricular systolic dysfunction is present, but may also occur in patients with preserved left ventricular ejection fraction, in 10% of cases [7]. This endpoint may occur early, during hospital admission in two thirds of the patients, or in the long term, and is also associated with an increased risk of hospital readmissions [8].
On the other hand, the epidemiology of ST segment elevation myocardial infarction (STEMI) has changed in recent decades, due to population aging and modifications in the prevalence of cardiovascular risk factors [9].
Most studies aimed at determining the predictive impact of Killip class on acute myocardial infarction were conducted prior to the age of primary PCI [10] and in selected patients extracted from clinical trials with restrictive inclusion criteria. Primary PCI have been shown to be more effective in restoring myocardial perfusion than thrombolysis [11] so it would be expected that the risk of developing heart failure would be lower. However, although revascularization has lowered mortality risk in patients who developed heart failure, patients with heart failure received more frequently reperfusion therapy [8]. The aim of this study was to evaluate predictors of Killip class ≥ II in a current cohort of non-selected patients hospitalized for acute ST segment elevation myocardial infarction receiving current evidence-based treatment.
Section snippets
Methods
DIAMANTE (Descripción del Infarto Agudo de Miocardio: Actuaciones, Novedades, Terapias y Evolución — Description of Acute Myocardial Infarction: Management, New Therapies and Evolution) is a non-interventional prospective registry in a Cardiac Intensive Care Unit from a tertiary care hospital. The methods of the registry have been previously published [12], [13], [14]. Briefly, all patients suffering from STEMI admitted to the unit were consecutively included from January 2010 to April 2015.
Results
During the study period 1111 patients presented STEMI. Mean age was 64.0 ± 14, and 853 (76.8%) were male. According to Killip Classification, 881 (79.3%) were in class I, 105 (9.5%) in class II, 29 (2.6%) in class III, and 96 (8.6%) in class IV. Patients' baseline and demographic characteristics according to Killip class are depicted in Table 1a. Patients with Killip class ≥ II had a high-risk profile with advanced age, more women, hypertension, diabetes and comorbidities. They also presented
Discussion
We found that in patients with STEMI, Killip class is associated with in-hospital mortality and can be predicted with variables available when primary PCI is performed. Patients with Killip ≥ II were older, more often female, had more comorbidity, and more time since symptoms onset. They also presented more often an anterior location, complications, and in-hospital mortality. DIAMANTE addresses STEMI prognosis in a daily clinical practice basis. Clinical trials often have restrictive inclusion
Limitations
This study has some limitations. This is a single centre study at a tertiary care hospital, so patients with a more severe illness may have been over-represented. In-hospital outcomes may have varied in hospitals with lesser facilities. The majority of patients included underwent primary percutaneous intervention as reperfusion therapy and all patients who received fibrinolysis underwent a coronary angiography during admission, so in 10% of patients who underwent fibrinolysis we could not
Conclusions
In patients admitted for presenting STEMI, Killip class can be predicted with variables available at the time of presentation and is strongly associated with in-hospital prognosis. Close monitoring and early complete revascularization could be desirable to prevent further complications.
Conflict of interest
None declared.
Acknowledgements
No sources of funding.
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