Cardiogenic shock and perioperative low cardiac output syndrome after cardiac surgery remain associated with high morbidity and mortality. Historically, temporary mechanical circulatory support (tMCS) has often been introduced late, as a salvage strategy after exhausting treatment with inotropes and vasopressors. Surgical trauma, the inflammatory response to cardiopulmonary bypass (CPB), and reperfusion injury may act as a second hit to an already vulnerable myocardium. This is the rationale underlying the concept of protected cardiac surgery (PCS), which proposes the use of tMCS within an optimal physiologic window to mitigate this additional insult before irreversible deterioration develops.

The authors performed a review of the literature published between 2000 and 2024, analyzing 52 key studies focused on prophylactic or early tMCS, optimal timing of initiation, risk stratification, and organizational models of care, particularly Shock Teams. Current evidence suggests that continued escalation of vasoactive therapy to high doses is associated with worse outcomes and may delay mechanical support, which is less effective when introduced late as a last-resort strategy. Several of the studies reviewed also indicate that purely pharmacologic strategies, such as preoperative levosimendan, do not improve perioperative complications, morbidity, or mortality. In contrast, the authors advocate early initiation of mechanical support and cite studies supporting the use of intra-aortic balloon pump (IABP), veno-arterial extracorporeal life support (V-A ECLS), and axial-flow devices such as Impella®. A major limitation in decision-making remains the currently available risk scores and objective monitoring parameters. The usefulness of conventional risk models, including STS and EuroSCORE II, is questioned, while alternative approaches are proposed, including shock-stage classification systems such as the Society for Cardiovascular Angiography and Interventions (SCAI) classification and invasive monitoring with a pulmonary artery catheter to provide a more comprehensive assessment of the patient’s hemodynamic status.

Finally, the article emphasizes the importance of implementing multidisciplinary Shock Teams and their association with improved in-hospital survival through protocolized decision-making. Indeed, institutions with stronger organizational and institutional support appear better equipped to manage this highly time-dependent condition.

COMMENTARY:

The article encourages a shift in mindset: rather than treating shock once it has developed, the goal in cardiac surgery should be to prevent it through early and planned use of temporary mechanical circulatory support. At first glance, this seems both logical and compelling, although it also raises important concerns. In support of this proposed paradigm shift, the authors cite a series of studies that differ substantially in both methodology and the type of mechanical support used. Can we therefore conclude that delayed initiation of mechanical circulatory support is associated with worse outcomes and higher mortality? There is little doubt about the association, but randomized clinical trials confirming it are still lacking. It is important to recognize that current decision-making in perioperative cardiogenic shock is based largely on individual center experience, observational studies, and expert consensus. This inevitably limits the strength of the evidence and the conclusions that can be drawn from reviews such as the one discussed here.

The authors clearly highlight the evidence currently available regarding purely pharmacologic management. Large randomized trials such as LICORN, CHEETAH, and LEVO-CTS, which evaluated preoperative levosimendan, showed that prophylactic escalation of inotropic therapy does not reduce 30-day mortality or complications. Likewise, a study by Koponen et al. associated high vasoactive-inotropic score (VIS) values (VIS >15, and particularly VIS >24.3 combined with lactate >6.85 mmol/L) with extremely high mortality. In daily practice, escalation beyond moderate doses of inotropic agents should therefore serve as a warning signal that mechanical circulatory support needs to be considered.

Considerable emphasis is placed on the limitations of conventional risk scores, particularly EuroSCORE II and STS, in identifying vulnerable patients. These scores were evaluated in two studies in which their limited discriminatory capacity highlighted their poor ability to predict which patients would develop perioperative cardiogenic shock or require mechanical support. The authors instead propose combining the 5-stage Society for Cardiovascular Angiography and Interventions shock stage classification, ranging from stage A to stage E, with hemodynamic markers of early circulatory failure obtained through more advanced invasive monitoring of right-sided pressures, thereby potentially improving prognostic assessment.

A major practical limitation is the risk of serious complications associated with implantation of these devices, including postoperative bleeding, limb ischemia, thromboembolic events, and undesirable increases in left ventricular afterload, particularly with V-A ECLS in the absence of left ventricular unloading. A further limitation is institutional. The organizational model based on Shock Teams is presented as a cornerstone of the protected cardiac surgery (PCS) concept. As specifically reported in several of the studies cited, establishing dedicated shock teams (including cardiac surgeons, intensivists, cardiologists, and perfusionists working under standardized decision-making and cannulation algorithms) has a direct impact on in-hospital survival, increasing it significantly to 61.0% compared with 47.9% in nonstructured models. Such coordinated care may shorten the time to tMCS initiation, improve individualized device selection, and standardize explantation and weaning protocols, thereby substantially reducing the mortality associated with centers that lack this type of structured support.

REFERENCE:

Salazar L, Nersesian G, Meani P, Bari G, Mariani S, Potapov E, et al. Temporary Mechanical Circulatory Support and Shock Teams in High-Risk Cardiac Surgery: The Strategic Evolution of Protected Cardiac Surgery. Ann Thorac Surg. 2026 Jul;122(1):22-32. doi: 10.1016/j.athoracsur.2025.12.032. Epub 2026 Jan 14. PMID: 41544922.