Patients with ACS are often treated early with clopidogrel. However, if the patient with ACS appears to be developing cardiogenic shock, its probably best to withhold the early clopidogrel. The literature indicates that patients with cardiogentic shock benefit most from emergent PCI, and many of these patients will need CABG. Generally it's best to avoid clopidogrel in patients heading for CABG.
The use of clopidogrel in patients with cardiogenic shock can be deferred to the cardiologists in the cath lab once they decide whether the patient will need CABG or not.
References
Thiele H, Allam B, Chatellier G, et al. Shock in acute myocardial infarction: the Cape Horn for trials? Eur Heart J 2010;31:1828-1835.
