Field implementation of remote ischemic conditioning in ST-elevation myocardial infarction: the FIRST study

Background — Remote ischemic conditioning (RIC) is a non-invasive, therapeutic strategy that uses brief cycles of blood pressure cuff inflation and deflation to protect the myocardium against ischemia-reperfusion injury. We sought to compare major adverse cardiovascular events (MACE) for patients who received RIC prior to PCI for ST-segment elevation myocardial infarction (STEMI) compared to standard care.

Methods — We conducted a pre and post implementation study. In the pre-phase, STEMI patients were taken directly to the PCI lab. Post-implementation, STEMI patients received four cycles of RIC prior to PCI by paramedics or emergency department staff. The primary outcome was MACE at 90 days. Secondary outcomes included MACE at 30, 60, and 180-days. Inverse probability of treatment weighting using propensity score estimated causal effects independent of baseline covariables.

Results — 1667 (866 pre-implementation, 801 post-implementation) patients were included. In the pre-phase, 13.4% had MACE at 90-days compared to 11.8% in the post-phase (odds ratio (OR) 0.86; 95% CI: 0.62 to 1.21). There were no significant differences in MACE at 30, 60 and 180 days. Patients presenting with cardiogenic shock or cardiac arrest prior to PCI were less likely to have MACE at 90 days (42.7% pre vs. 27.8% post) if they received RIC prior to PCI (OR: 0.52; 95% CI: 0.27 to 0.98).

Conclusions — A strategy of RIC prior to PCI for STEMI did not reduce 90-day MACE. Future research should explore the impact of RIC prior to PCI for longer-term clinical outcomes and for patients presenting with cardiogenic shock or cardiac arrest.