Risk Stratify to Avoid Postcardiotomy Shock Following CV Surgery

SAN DIEGO, CA—Postcardiotomy cardiogenic shock (PCCS) is a relatively rare complication following cardiac surgery among patients with severe LV systolic dysfunction, but new contemporary data confirm that patients with this complication bear a disproportionately high morbidity and mortality burden.

Because preoperative initiation of mechanical circulatory support (MCS) seems to attenuate the risks of morbidity and mortality as well as PCCS itself, experts speaking at the Society of Thoracic Surgeons (STS) 2023 annual meeting urged judicious preoperative risk stratification for these patients plus further prospective research regarding strategies for preoperative temporary MCS.

“We have to recognize first and foremost that this is a small group of patients, [but] why is it small?” Edward Soltesz, MD (Cleveland Clinic, OH), who presented the findings on the opening day of STS, commented to TCTMD. “I think there's a lot more patients out there being denied surgery.”

Further, Soltesz called this an opportunity for cardiac surgeons to “go beyond” the current barriers to treating these high-risk patients. “We have to appropriately risk stratify patients. We have to identify patients who may need a preoperative device and offer more patients the opportunity for surgery,” he said.

Significant Mortality, Morbidity Increases

For the study, Soltesz and colleagues looked at 44,131 patients from the STS Adult Cardiac Surgery Database with LVEF ≤ 35% who received isolated on-pump CABG with (n = 3,716) or without (n = 40,415) mitral valve surgery between 2018 and 2019. PCCS—defined as the use of an MCS device, including balloon pumps, for intraoperative hemodynamic instability or inability to wean from bypass or a cardiac death in the operating room—was experienced by 7.5% of the CABG population and 16.4% of the CABG plus mitral valve surgery group.

PCCS was linked with significant increases in both morbidity and mortality for almost all of the outcomes analyzed. Only 30-day readmission rates for both surgical groups, as well as stroke among those receiving CABG plus mitral valve surgery, failed to reach statistical significance.

30-Day Outcomes

On multivariate analysis, independent predictors of PCCS were mitral valve surgery, reoperation, STS predicted risk of mortality > 10%, preoperative cardiogenic shock, chronic lung disease, NYHA class IV, and EF < 25%.

In the overall study cohort, temporary MCS devices were used in 28.7% of CABG and 37.7% of CABG plus mitral surgery patients, with an intra-aortic balloon pump (IABP) being the most common in both groups. For the subset of patients who developed PCCS, other support like extracorporeal membrane oxygenation, temporary ventricular assist device, and catheter-based devices were more commonly used.

For patients in the CABG only cohort, those who received MCS more often had their first device deployed preoperatively (17.89%) compared with intraoperatively (9.63%) or post-operatively (1.13%). Patients undergoing both CABG and mitral surgery more often received their first device intraoperatively (21.26%) followed by pre- (13.99%) and postoperatively (2.40%). For PCCS patients, intraoperative first device placement was the most common strategy for both CABG alone (73.97%) and CABG plus mitral surgery (79.15%).

After excluding emergent and salvage cases, the researchers found that patients who received any form of MCS had higher mortality compared with those who received no support. But among those who received support, timing of first device placement mattered. The incidence of mortality was lowest for those whose device was placed preoperatively compared with intra- or postoperatively, as were the rates of stroke, prolonged ventilation, and renal failure. Also, the lowest rates of PCCS were seen in those who received preoperative MCS.

“Clearly, we can conclude from some of this work that clinicians really should be very aware that the poor outcomes associated with PCCS in this high-risk patient population mandate careful preoperative risk stratification,” Soltesz said. “Finally, the putative benefit of preoperative MCS support on PCCS morbidity and mortality warrants a prospective examination of preemptive or at least prophylactic temporary MCS strategies in patients with a high risk of PCCS like we've seen here.”

Because of the way some of the information is entered into the STS database, it was tricky to tell whether patients were truly in shock preoperatively as well as which MCS device was used first, Soltesz explained. “There is certainly more work to be done in this area by looking at specific devices, but the data is arguably a bit messy in this area,” he said.

Awaiting a Risk Model

In discussion following the presentation, audience member Stefano Schena MD, PhD (Medical College of Wisconsin, Milwaukee), asked if preoperative support should be used more often. “Based on the data, the preoperative support is clearly better,” he said. “What do you think should be the strategy here? Should we be pushing our cardiologists to put these devices in at that time of catheterization, or should we put more balloon pumps preoperatively before the operation begins in the OR?”

Before taking that leap, Soltesz said, a risk model for PCCS is needed in this patient population. Such a risk model, he told TCTMD, is in the works and will likely be ready “in 6 or so months.”

For now, he stressed “very careful entitling risk adjudication of their comorbidities and their potential for PCCS preoperatively.” Though IABP was the most common MCS device used, “that doesn’t mean there was escalation of therapy in some of those who clearly had a significant benefit from preoperative placement,” Soltesz continued. “We don't know that data yet. I think it argues for a preemptive trial.”

Francis Pagani, MD, PhD (University of Michigan, Ann Arbor), who served as discussant for the study, agreed. To TCTMD, he said in the interim between the release of a risk model for these patients, much less a randomized trial, that “preoperative ways of optimizing patients with low EF prior to operation is the key as executing an efficient operation is always important.”

Ultimately what’s needed is the ability to “understand a patient’s risk for shock and then [develop] better strategies for optimization preemptively to prevent the shock,” he added. “Because once shock develops it's hard to treat.”

Also commenting on the study, Joseph Sabik, III, MD (University Hospitals Cleveland Medical Center, OH), told TCTMD it was a “great use of the [STS] database.” More specifically, he said, “we now have millions [of] patients in this registry that have had all types of heart surgery. And so when we see a clinical problem, we can use this database to possibly identify opportunities to decrease the problem, which we can then go on and do a randomized study and see if we're correct. The opportunity is leveraging what we have and really using it.”