Shock Classification Stratifies Mortality Risk
Is the new Society for Cardiovascular Angiography and Intervention (SCAI) 5-stage cardiogenic shock (CS) classification a good predictor of mortality in a cardiac intensive care unit (CICU) population?
The study authors retrospectively analyzed single-center CICU patients admitted between 2007 and 2015. Utilizing CICU admission data based on the presence of hypotension or tachycardia, hypoperfusion, deterioration, and refractory shock, the study authors classified subjects in SCAI CS stages A-E. They stratified hospital mortality in each SCAI shock by cardiac arrest (CA). The study authors utilized logistic regression to determine the association between the SCAI shock stages and hospital mortality before and after adjusting for age, gender, Charlson Comorbidity Index (CCI), APACHE (Acute Physiology and Chronic Health Evaluation)-IV predicted hospital mortality, admission diagnosis of CA, and the use of vasoactive medications, intra-aortic balloon pump, coronary angiography, percutaneous coronary intervention, and mechanical ventilation.
The study authors reported that among the 10,004 unique patients, 43.1% had acute coronary syndrome, 46.1% had heart failure, and 12.1% had CA. The proportion of patients in SCAI CS stages A-E was 46.0%, 30.0%, 15.7%, 7.3%, and 1.0%. There was a stepwise increase in unadjusted CICU and hospital mortality with each higher SCAI shock stage in the overall population, with hospital mortality rising from 3.0% in SCAI shock stage A, 7.1% in stage B, 12.4% in stage C, 40.4% in stage D, to 67.0% in SCAI shock stage E (p < 0.001). After multivariable adjustment, each higher SCAI shock stage was associated with increased hospital mortality (adjusted odds ratio [aOR], 1.53-6.80; all p < 0.001) compared with SCAI shock stage A, as was CA (aOR, 3.99; 95% confidence interval, 3.27-4.86; p < 0.001). These results were consistent in the subset of patients with acute coronary syndrome or heart failure.
These authors concluded that when assessed at the time of CICU admission, the SCAI CS classification, including presence or absence of CA, provided robust hospital mortality risk stratification. This classification system could be implemented as a clinical and research tool to identify, communicate, and predict the risk of death in patients with, and at risk for, CS.
Although this is a retrospective study, these findings suggest that the SCAI CS classification scheme is an important predictor of mortality in patients with CS. Unless prospective studies suggest otherwise, this scheme should be a valuable tool in the management of patients with CS.
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Coronary Angiography, Critical Care, Heart Arrest, Heart Failure, Heart-Assist Devices, Hospital Mortality, Hypotension, Intensive Care Units, Intra-Aortic Balloon Pumping, Percutaneous Coronary Intervention, Respiration, Artificial, Shock, Shock, Cardiogenic, Tachycardia, Ventricular
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