SCAI Shock Classification Helps Predict Survival in AMICS

Ivan Hanson, MD, discusses his recently published paper “SCAI Shock Classification in Acute Myocardial Infarction: Insights from the National Cardiogenic Shock Initiative.” In this paper, Hanson and colleagues retrospectively applied the SCAI shock staging system to patients with AMI and cardiogenic shock (AMICS) enrolled in the National Cardiogenic Shock Initiative (NCSI) Study and assessed survival rates. Dr. Hanson is an interventional cardiologist and associate program director of the fellowship program at Beaumont Hospital in Royal Oak, Michigan.

Dr. Hanson describes the SCAI staging system, which classifies patients into 1 of 5 stages (A through E) based on the severity of cardiogenic shock as “very helpful and intuitive…the only issue is that it hasn’t been validated.” As a result of this study, Hanson concluded that the SCAI shock staging system is not only reproducible but predicts survival when applied at presentation and at 24 hours.

Hanson and his colleagues looked at 300 patients in Stages C, D, and E. Surprisingly, they found that the index clinical characteristics among Stage C, D, and E patients were similar and thus, the clinical characteristics were not very useful for determining a patient’s outcome. “But invasive hemodynamics and measurement of lactate, and pH, and physical examination at the time of the event—all of the features that go into the SCAI criteria—will further refine the clinical presentation and allow us to predict outcome,” Hanson explains.

“What we found is that survival in all 3 stages was actually higher than expected. When you use the SCAI shock criteria at baseline to assess prognosis, what we’re finding is, in Stage C you’ve got an 80% survival. Stage D and E really have the same survival when you look at baseline. When you move out to 24 hours, though, the staging system has much more discriminating ability. So that, by the time you’re at 24 hours, if you are in Stage E, the survival rate is only 17%. Whereas, if you’re in Stage E at baseline and you improve to Stage C at 24 hours, your survival is 77%. So really we think that applying the SCAI shock criteria at both baseline and 24 hours will give us the best ability to predict outcome in these patients.”

Dr. Hanson emphasizes, “with that staging system, we now have a way to approach cardiogenic shock and how to diagnose it and how to inform patients and their families of prognosis.” He believes that the system can help inform the difficult clinical decision of whether to escalate care or withdraw support in patients with AMI cardiogenic shock. For example, even if a patient presents in Stage E with florid shock with profound acidosis and active CPR, if the patient improves to Stage C at 24 hours there’s nearly an 80% chance of survival, which means clinicians should consider escalating care.