Study Examines SCAI's Stages of Cardiogenic Shock to Stratify Mortality Risk

September 20, 2019—The Society for Cardiovascular Angiography & Interventions (SCAI) announced the publication of a retrospective study of the application of a new shock classification scheme to analyze patients in the cardiac intensive care unit (CICU) at the Mayo Clinic in Rochester, Minnesota. The study by Jacob C. Jentzer, MD, et al is available online ahead of print in Journal of the American College of Cardiology (JACC). Dr. Jentzer is Director for CICU Research at the Mayo Clinic.

The classification scheme was recently released by the SCAI and endorsed by the American College of Cardiology, the American Heart Association, the Society of Critical Care Medicine, and the Society of Thoracic Surgeons.

According to SCAI, outcomes for patients with cardiogenic shock (CS) complicating myocardial infarction have not significantly improved over the last 30 years despite the development of various percutaneous mechanical circulatory support (MCS) technologies and the national standard of emergent angioplasty and stenting. CS continues to be associated with high rates of morbidity and mortality, posing a therapeutic challenge for clinicians.

The study analyzed 10,004 patients admitted to the CICU between 2007 and 2015. The patients were classified as SCAI CS stages A through E, based on the presence of hypotension/tachycardia, hypoperfusion, deterioration, and refractory shock.

Among the patients, 43% had acute coronary syndrome, 46% had heart failure, and 12% had cardiac arrest. Study investigators found a stepwise increase in unadjusted CICU and hospital mortality with each increase in the SCAI shock stage. These results preliminarily validate the feasibility and prognostic value of the SCAI classification system.

SCAI noted that the investigators believe the next step is prospective validation and implementation in clinical and research settings to ensure consistent outcomes reporting and to assess whether the effects of the tested intervention vary by CS stage.

Dr. Jentzer stated in the SCAI press release, “In the CICU, we see a wide spectrum of shock severity including undifferentiated and mixed shock states, so we wanted to see whether a simplified, functional definition of the SCAI shock stages classification could be applied in an unselected CICU population using data from early after CICU admission. We found a dramatic incremental increase in mortality with each successive SCAI shock stage, with an additive mortality hazard among patients who suffered a cardiac arrest, highlighting the importance of shock and cardiac arrest as major drivers of mortality in CICU patients. This confirms the validity of the SCAI CS stages construct and emphasizes its potential utility for clinical practice and future research.”

Srihari S. Naidu, MD, who served as Chair of the SCAI shock expert consensus document writing group, commented, “When we initially set out to create a new lexicon for CS, the goal was always to prove first and foremost that the increasing severity of shock predicted by the new classification would correspond to actual increasing hazard. This study is the first to validate the SCAI shock stages and add a relative risk to each successive stage, indicating in essence at what stage clinicians really have to worry about excessive mortality.”

Investigator David Baran, MD, added, “The tremendous value of the SCAI CS staging system lies in its simplicity. It can easily be used across the spectrum of care from prehospital to intensive care unit and will allow clinicians to estimate mortality risk over time. When the SCAI shock stage increases, it will be a signal to decide if transfer is warranted and potentially improve outcomes for patients. In addition, the SCAI CS classification highlights the potent risk of cardiac arrest and its effect on outcomes.” Dr. Baran is System Director for Advanced Heart Failure, Transplant, and MCS at Sentara Heart Hospital in Norfolk, Virginia.