Cardiogenic Shock Classification System Continues to Bear Fruit

It’s been nearly five years since the Society for Cardiovascular Angiography and Interventions (SCAI) released a consensus statement outlining a five-stage classification system for cardiogenic shock (CS) that spans patients “At Risk” for developing CS (stage A) to those in “Extremis,” demonstrating frank circulatory collapse (stage E). Last year the classification system was refined to reflect data from several validation studies and now includes gradations of severity within each stage.

“The SCAI classification system is very quickly being used to fill in knowledge gaps about cardiogenic shock that will one day help us improve clinical outcomes for patients,” says David A. Baran, MD, Section Head of Advanced Heart Failure, Transplant and Mechanical Circulatory Support (MCS) at Cleveland Clinic Weston Hospital. Dr. Baran was co-chair of the writing group tasked with developing the original classification schema endorsed in 2019 and the more recent update.

Cardiogenic shock’s heterogeneity

Cardiogenic shock effects an estimated 40,000 to 50,000 people per year in the United States. It starts with reduced cardiac output leading to systemic hypoperfusion and can result in organ failure and death. CS is the top cause of death in people who have a heart attack and has an in-hospital mortality rate of more than 30%. Additional causes of CS include decompensated congestive heart failure, viral infection, and drug toxicity, among others.

“The heterogeneity of shock experienced by patients with advanced cardiovascular disease can make it very challenging to treat,” says Nicholas A. Brozzi, MD, a cardiothoracic surgeon with Cleveland Clinic’s Heart, Vascular & Thoracic Institute in Florida and Surgical Director of Mechanical Circulatory Support at Cleveland Clinic Weston Hospital. “Having a validated classification system has opened up new avenues of research into this complex clinical syndrome.”

Dr. Brozzi and Dr. Baran lead the Acute Mechanical Circulatory Support Program at Weston Hospital, which is currently involved in institutional and international clinical trials and registries to better understand the nature of CS and the value of potential therapies.

Postcardiotomy cardiogenic shock (PCCS)

Dr. Brozzi and a team of researchers at Weston Hospital recently applied the SCAI classification system to a cohort of 1,173,286 patients reported to the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database from 2015 to 2019. The goal of the study was to understand the clinical trajectory of patients experiencing postcardiotomy cardiogenic shock (PCCS), a low cardiac output syndrome developing after cardiac surgery.

“Other studies have demonstrated the prognostic value of the classification system in patients developing cardiogenic shock after AMI or as a result of an acute decompensation due to a chronic heart failure condition,” says Dr. Brozzi. “With our study, we confirmed that postcardiotomy cardiogenic shock represents a unique phenotype, and similar to shock from HF or AMI, it is a heterogeneous syndrome spanning from mild to critical.”

Dr. Brozzi presented the team’s findings earlier this year at the 59th Annual Meeting of The Society of Thoracic Surgeons (STS) held in San Diego, CA. The retrospective analysis identified 108,157 (9.3%) patients who had established or advanced CS (stage C – E) prior to their cardiac surgery. The vast majority (90.7%) were supported by one inotrope or preoperative intra-aortic balloon pump (IABP), while 2% received emergent/salvage operations or were supported by extracorporeal membrane oxygenation (ECMO) or bi-ventricular catheter-based devices before their index procedure.

Investigators determined that 5,385 patients admitted for elective cardiac surgery transitioned to worsening CS stages, resulting in a 53% increase in patients classified as stage D and E after surgery (Pre n=10,101 vs Post= 15,486). The team found that patients with a higher pre-op SCAI CS stage had a higher 30-day mortality of 10.58% (stage C), 17.63% (stage D), and 42.65% (stage E) compared to patients with a lower pre-op CS stage at 1.88% (stage A) and 2.76% (stage B).

“We also noted that a worsening progression of SCAI stage from pre- to post-op was associated with a 30-day mortality of 51% versus 3% overall in those without a change in SCAI stage,” says Dr. Brozzi.

The team concluded that SCAI stages correlated with clinical outcomes in patients developing PCCS and that transitions of stage correlated with mortality as much as preoperative staging. “This tells us that it’s important to re-profile patients on a regular basis so that we can adjust our treatment strategy to match the severity of shock,” Dr. Brozzi explains.

Cardiogenic shock registry

Another CS research initiative underway is the Multicenter Collaborative to Enhance Biological Understanding, Quality and Outcomes in Cardiogenic Shock (VANQUISH Shock) registry. It, too, relies on the SCAI classification system to help understand the clinical course, management, and outcomes of patients with CS.

The VANQUISH Shock registry is a prospective observational registry launched in 2022 that is looking at adult patients with a primary diagnosis of CS at four high-volume North American centers with multidisciplinary shock programs. It includes both acute myocardial infarction (AMI-CS) and acute heart failure (HF-CS) etiologies. The primary end point will be survival at 30 days after hospital discharge, with in-hospital adverse events and survival to 6 and 12 months as secondary outcomes.

“The VANQUISH Shock registry provides an opportunity to gather a tremendous amount of data related to the pathophysiology and management of cardiogenic shock,” says Dr. Baran, principal investigator for the Weston site. “For example, we still have a lot to learn about the revascularization, weaning and treatment escalation strategies that work best in caring for these patients.”

Multidisciplinary shock program

Weston Hospital is one of a few CS programs in Florida equipped to provide temporary mechanical circulatory support, including IABP, temporary transvalvular pumps (Impella), and ECMO. The multidisciplinary shock team consists of specialists in cardiology, cardiothoracic surgery, interventional cardiology, advanced heart failure, critical care, pulmonary medicine, emergency medicine, and nursing.

According to Dr. Brozzi, “Our shock program has become a regional hub over the last three years, in part because of the extensive care needs of patients with COVID-19 and our expertise with veno-arterial ECMO and other forms of circulatory support.”

Cleveland Clinic Florida’s SHOCK Line, established during the pandemic, continues to connect referring physicians with members of the AMCS team at Weston Hospital. Consultations to evaluate the potential application of mechanical circulatory support in patients with CS are available 24 hours a day, 7 days a week by calling 954-48-SHOCK (74625).