Evaluation of Dexamethasone in Cardiac Surgery Using a Novel Trial Design

High-dose corticosteroids attenuate the inflammatory response to surgery with CPB and are commonly used in some countries,but uncommonly in the US, Canada and Australia. Steroids can reliably attenuate activation of the complement pathways associated with cardiac surgery, but clinical trials have had mixed results. The current evidence is dominated by the results of two recent large randomized trials: DECS (n=4,494)6 and SIRS (n=7,507).

Both DECS and SIRS assigned patients undergoing cardiac surgery with CPB to receive either a high intraoperative dose of steroids (dexamethasone 1 mg/kg, or methylprednisolone 500 mg, respectively) or placebo. The point estimates of both trials suggested a possible reduction in serious complications and mortality. Planned subgroup analyses in the DECS trial steroids reduced the incidence of respiratory failure (3.0 % vs. 4.3%, P=0.02), infection (9.5% vs. 14.8%, P=0.009), and shortened hospital stay (median 8 [7-13] vs. 9 [7-13] days, P=0.009).6 Severe renal failure (need for RRT) was reduced, 0.4% vs. 1.0%, P=0.04.8 But SIRS found methylprednisolone was associated with a higher incidence of myocardial injury (as measured by elevation of CK-MB enzyme). Nether trial identified a higher risk of myocardial infarction (MI). The methylprednisolone-induced elevation of CK-MB may therefore be a class effect.

Another compelling finding in pre-planned subgroup analysis of patient age groups is that when limiting analysis to those aged less than 75 years in the DECS trial, dexamethasone reduced the risk of the primary composite endpoint, RR 0.74 (95% CI: 0.58-0.95), P=0.017; as well as respiratory failure RR 0.62 (95% CI: 0.42-0.91), P=0.014; and possibly mortality RR 0.53 (95% CI: 0.26-1.10), P=0.08.6 This age-interaction effect is supported by the demonstration of increased C-reactive protein concentrations in younger patients enrolled in the DECS trial.

Therefore, it is highly plausible that prophylactic steroids can suppress deregulated inflammation and thus improve outcomes in cardiac surgery, but only when used in a less elderly (i.e. <75 years) patient population.

In retrospect, the primary endpoints of both DECS and SIRS trials can be challenged, in that they used composites heavily weighted by thrombotic events (MI, stroke) and not specific to inflammation (respiratory failure, kidney injury, sepsis, prolonged ICU and hospital stay, mortality). We thus plan to re-evaluate dexamethasone in cardiac surgery, using a patient-centred, clinically important endpoint focused on enhanced recovery and earlier hospital discharge: "days alive and at home up to 30 days after surgery".