Defining Shock and Preshock for Mortality Risk Stratification in Cardiac Intensive Care Unit Patients

Abstract

Background: Previous studies have defined preshock as isolated hypotension or isolated hypoperfusion, whereas shock has been variably defined as hypoperfusion with or without hypotension. We aimed to evaluate the mortality risk associated with hypotension and hypoperfusion at the time of admission in a cardiac intensive care unit population. Methods: We analyzed Mayo Clinic cardiac intensive care unit patients admitted between 2007 and 2015. Hypotension was defined as systolic blood pressure <90 mm Hg or mean arterial pressure <60 mm Hg, and hypoperfusion as admission lactate >2 mmol/L, oliguria, or rising creatinine. Associations between hypotension and hypoperfusion with hospital mortality were estimated using multivariable logistic regression. Results: Among 10 004 patients with a median age of 69 years, 43.1% had acute coronary syndrome, and 46.1% had heart failure. Isolated hypotension was present in 16.7%, isolated hypoperfusion in 15.3%, and 8.7% had both hypotension and hypoperfusion. Stepwise increases in hospital mortality were observed with hypotension and hypoperfusion compared with neither hypotension nor hypoperfusion (3.3%; all P <0.001): isolated hypotension, 9.3% (adjusted odds ratio, 1.7 [95% CI, 1.4–2.2]); isolated hypoperfusion, 17.2% (adjusted odds ratio, 2.3 [95% CI, 1.9–3.0]); both hypotension and hypoperfusion, 33.8% (adjusted odds ratio, 2.8 [95% CI, 2.1–3.6]). Adjusted hospital mortality in patients with isolated hypoperfusion was higher than in patients with isolated hypotension ( P =0.02) and not significant different from patients with both hypotension and hypoperfusion ( P =0.18). Conclusions: Hypotension and hypoperfusion are both associated with increased mortality in cardiac intensive care unit patients. Hospital mortality is higher with isolated hypoperfusion or concomitant hypotension and hypoperfusion (classic shock). We contend that preshock should refer to isolated hypotension without hypoperfusion, while patients with hypoperfusion can be considered to have shock, irrespective of blood pressure.

SCAI SHOCK Stage Classification Expert Consensus Update: A Review and Incorporation of Validation Studies

“…Jentzer et al examined different definitions of shock and preshock in CICU patients and identified that hypoperfusion was associated with mortality to a greater extent than hypotension. 12 To date, no published study has directly compared the performance of different SCAI SHOCK stage classification schemes in the same population for risk stratification. Importantly, the heterogeneity in mortality in each of the different stages across various studies likely reflects the dissimilar populations and different definitions used; more objective definitions and placing the SCAI SHOCK stage in the context of etiology, phenotype, and other nonmodifiable risk modifiers will help to optimize risk assessment in the future.…”

“…4,6,8,9 Jentzer et al demonstrated that an increasing number of abnormal markers of hypotension and hypoperfusion was associated with incrementally higher mortality risk in CICU patients; an elevated lactate level or an elevated shock index (the ratio of heart rate to systolic blood pressure) was more strongly associated with mortality. 12 Biochemical phenotypes were identified in a large multicenter registry of patients with CS, highlighting the variability in observed mortality with the different phenotypes across the shock stages. 20 Finally, SCAI SHOCK stages have been used to evaluate the association between certain treatments and outcomes in patients with CS.…”

“…Patients with hypoperfusion in the absence of hypotension are at higher risk of dying than patients with hypotension and preserved perfusion. 12 Biomarkers such as lactate are commonly used to detect hypoperfusion but may be dissociated from hemodynamics in cases such as chronic HF where patients may have a normal lactate level with a depressed cardiac index. The authors suggest that a lactate level of >2 mmol/L is consistent with at least SCAI SHOCK stage C, although some patients may demonstrate other manifestations of end-organ hypoperfusion with a normal lactate level, and there are also causes of an elevated lactate level other than shock, such as mesenteric ischemia or compartment syndrome.…”

Complicating Acute Myocardial Infarction. Current Status and Unresolved Targets for Subsequent Research

“…Among 10,004 patients with acute coronary syndrome or heart failure, adjusted hospital mortality in subjects with isolated hypoperfusion was higher than in patients with isolated hypotension (17.2% vs. 9.3%, p = 0.02) and not significantly different from patients with both hypotension and hypoperfusion (33.8%, p = 0.18) [19]. Based on these observations, the experts of the Society for Cardiovascular Angiography and Interventions developed a new, clinically useful, five-stage classification of CS [20].…”

Hemodynamics for the Heart Failure Clinician: A State-of-the-Art Review

“…It should be recognized that tissue hypoperfusion can be present without hypotension if CO has significantly fallen but endogenous vasoconstrictor responses are maintaining BP. 39 In 2020, the Society for Cardiovascular Angiography & Interventions (SCAI) Clinical Expert Consensus Statement on the Classification of CS 40 leveraged an integrated diagnostic approach using both clinical assessment and invasive hemodynamics to define the CS syndrome as well as its severity across five temporal stages (Table 4). Recent data from the Cardiogenic Shock Working Group (CSWG) registry have revealed that this scheme has prognostic value in CS-particularly increases in central venous pressure, which reflect pericardial restraint and biventricular HF.…”