Anaemia associated with MI is an independent predictor of cardiac events and increased mortality, and can be exacerbated by the use of antiplatelet and anticoagulant agents. Until now, there has been no conclusive information on the benefit of blood transfusions for these patients, the only randomised data coming from two small, underpowered trials, which have provided conflicting results.1,2 This has led to inconsistency in clinical practice guideline recommendations.
Enrolling 668 patients from 35 hospitals in France and Spain, the REALITY trial is the largest randomised study comparing a restrictive (Hb ≤8 g/dL) with a more liberal (Hb ≤10 g/dL) blood transfusion strategy in adults with MI and anaemia (defined as Hb >7 g/dL to ≤10 g/dL at any time during admission). Elevated troponin levels were required for trial entry, while patients with MI following percutaneous coronary intervention (PCI), coronary artery bypass graft, cardiogenic shock or life-threatening bleeding were excluded.
The trial’s primary clinical endpoint was a composite of major adverse cardiac events (MACE) at 30 days, including all-cause death, MI, stroke and emergency PCI prompted by myocardial ischaemia. A second primary endpoint was cost effectiveness, defined as the incremental cost-effectiveness ratio at 30 days.
The restrictive transfusion strategy was noninferior to the liberal strategy in preventing 30-day MACE, with rates of 11.0% (36 patients) in the restrictive group and 14.0% (45 patients) in the liberal strategy group (difference –3.0%; 95% confidence interval –8.4 to 2.4). The restrictive strategy reduced the relative risk of 30-day MACE compared with the liberal strategy (relative risk 0.79). In addition, the restrictive strategy had an 84% probability of being cost-saving while improving clinical outcomes, i.e. ‘dominant’ from a medico-economic standpoint. In addition, patients treated with the restrictive, rather than the liberal, strategy were less likely to develop an infection (restrictive 0.0% vs. liberal 1.5%; p=0.03) or acute lung injury (restrictive 0.3% vs. liberal 2.2%; p=0.03).
According to the Principal Investigator, Professor Philippe Gabriel Steg (Hospital Bichat, Paris, France), “The REALITY trial supports the use of a restrictive strategy for blood transfusion in MI patients with anaemia. The restrictive strategy saves blood, is safe, and is at least as effective in preventing 30-day cardiac events compared to a liberal strategy, while saving money.”