Despite recent advances and availability of multiple mechanical circulatory-support devices, mortality remains at 50% in patients presenting with acute myocardial infarction complicated by cardiogenic shock (AMICS).

An article in the current issue of the Journal of the American College of Cardiology¹ details a suggested care pathway that may improve the outcomes of patients with AMICS. Fundamental to our goals in cardiogenic shock are standardizing care and aligning level I, level II, and level III emergency centers like trauma care (Figure 1). Recent legislation in Georgia offers support of this approach.

Figure 1

Revascularization in 90 minutes for patients in cardiogenic shock continues to be an important inflection point, similar to door-to-balloon time in ST-segment elevation myocardial infarction. In the FITT-STEMI (Feedback Intervention and Treatment Times in ST- Elevation Myocardial Infarction) trial, there was a significant decrease in survival after 90 minutes for patients in AMICS, with 3.3% additional deaths for every 10-minute delay. The suggested care pathway (Figure 2) establishes minimum standards of care. A strong focus is on training and recognition of cardiogenic shock by emergency medical services to enable patient transfer to a shock care center.

Figure 2

The National Cardiogenic Shock Initiative (NCSI) is a treatment protocol that has shown improved survival. This initiative has set inclusion and exclusion criteria for those would benefit from percutaneous revascularization with left ventricular support. The key principle is placement of an Impella CP (Abiomed; Danvers, MA) percutaneous left ventricular assist device for left ventricular support prior to coronary revascularization. To date, NCSI has enrolled 100 patients, with a survival rate of 78%. Although this is not a randomized controlled trial, improved survival rates offer hope for cardiogenic shock patients.

Apart from blood pressure, pulmonary capillary wedge pressure cardiac output and cardiac index, two additional indices are important in the care of this group of patients:

1. Cardiac power output (CPO) in watts = (Mean arterial pressure X cardiac output) / 451
   • A CPO of <0.6 watt suggests severe left ventricular dysfunction.
2. Pulmonary artery pulsatility index (PAPI) = (systolic pulmonary artery pressure - diastolic pulmonary artery pressure) / mean RA pressure.
   • A PAPI of <1.0 suggests severe right ventricular dysfunction.

The care pathway summarizes our suggested approach to improve treatment goals:

1. Early emergency medical services recognition of cardiogenic shock
2. Bypassing level II and III centers to transfer patient directly to a level I cardiogenic shock center
3. Hypothermia with targeted temperature management in those who have sustained cardiac arrest with cardiogenic shock but have return of spontaneous circulation
4. Rapid assessment in the emergency room for mechanical complications and appropriateness of left ventricular support and revascularization based on NCSI inclusion and exclusion criteria
5. Placement of an Impella CP percutaneous left ventricular assist device to support the left ventricle prior to percutaneous coronary intervention of the culprit lesion only, with goals of achieving both in 90 minutes
6. Hemodynamic assessment with a right heart cardiac catheterization study after revascularization
7. Escalation and de-escalation of support based on the clinical course of the patient and following CPO and PAPI indices to escalate or de-escalate care

References

1. Rab T, Ratanapo S, Kern KB, et al. Cardiac Shock Care Centers. J Am Coll Cardiol 2018;72:1972-80.

Keywords: Angiography, Coronary Angiography, Myocardial Infarction, Myocardial Revascularization, Shock, Cardiogenic, Heart-Assist Devices, Survival Rate, Patient Transfer, Standard of Care, Shock, Clinical Protocols, Emergency Medical Services, Pulmonary Wedge Pressure, Shock, Cardiogenic, Blood Pressure, Ventricular Dysfunction, Right, Pulmonary Artery, Heart-Assist Devices, Heart Ventricles, Hemodynamics, Diastole, Ventricular Dysfunction, Left, Hypothermia, Induced, Heart Arrest, Cardiac Catheterization, Percutaneous Coronary Intervention

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