Table 2.

SCAI Classification: Summary of Stages by Clinical, Biochemical, and Hemodynamic Criteria

Stage	Description	Clinical	Biochemical	Hemodynamic	Short-Term Mortality (%)
A. “At risk”	No signs or symptoms of CS	Warm, well-perfused, normal JVP, clear lungs, and mentation	Normal lactic acid, renal function	Normotensive CI ≥2.5; CVP <10; PA saturation ≥65%	0-3.6
B. “Beginning”	Evidence of relative hypotension or tachycardia, without hypoperfusion	Warm, well-perfused, elevated JVP, rales in lungs	Minimal renal function impairment, normal lactate	sBP <90 or MAP <60 or >30 mm Hg drop from baseline HR >100 beats/min CI ≥2.2 and PA saturation ≥65%	0-33.9
C. “Classic”	Hypoperfusion requiring intervention beyond volume resuscitation to restore perfusion	Unwell, ashen, mottled extremities, cold, clammy, volume overloaded	Any of lactate ≥2; creatinine doubling or >50% drop in eGFR; increased LFTs; elevated BNP	Any of sBP <90 or MAP <60 or >30 mm Hg drop from baseline and drugs/devices used to maintain BP CI <2.2; PCWP >15; RAP/PCWP ≥0.8; PAPi <1.85; CPO ≥0.6	12.4-53.9
D. “Deteriorating”	Similar to C, but worse, fails to respond to initial interventions	Any of stage C above	Any of stage C above, and deteriorating	Any of stage C above, and requiring multiple vasopressors or addition of MCS to maintain perfusion	24.0-66.9
E. “Extremis”	Cardiac arrest with ongoing CPR and/or ECMO, supported by multiple interventions	Cardiac collapse, use of defibrillator, near pulselessness, need for mechanical ventilation	CPR pH ≤7.2, lactate = 5	No sBP without resuscitation PEA or refractory VT/VF Hypotension despite maximal support	42.0-77.4

BNP = brain natriuretic peptide; BP = blood pressure; CI = cardiac index; CPO = cardiac power output; CPR = cardiopulmonary resuscitation; CS = cardiogenic shock; CVP = central venous pressure; ECMO = extracorporeal membrane oxygenation; eGFR = estimated glomerular filtration rate; HR = heart rate; JVP = jugular venous pressure; LFT = liver function test; MAP = mean arterial pressure; MCS = mechanical circulatory support; PA = pulmonary artery; PAPi = pulmonary artery pulsatility index; PCWP = pulmonary capillary wedge pressure; PEA = pulseless electrical activity; RAP = right atrial pressure; sBP = systolic blood pressure; SCAI = Society for Cardiovascular Angiography and Interventions; VF = ventricular fibrillation; VT = ventricular tachycardia.

SCAI classification and associated in-hospital mortality from Naidu et al.²⁰