Objective We investigated influence of remote ischaemic conditioning (RIC) on the detrimental effect of healthcare system delay on myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI).

Methods A post-hoc analysis of a randomised controlled trial in patients with STEMI randomised to treatment with pPCI or RIC+pPCI. RIC was performed as four cycles of intermittent 5 min upper arm ischaemia and reperfusion. Healthcare system delay was defined as time from emergency medical service call to pPCI-wire. Myocardial salvage index (MSI) was assessed by single photon emission computerised tomography.

Results Data for healthcare system delay and MSI were available for 129 patients. MSI was negatively associated with healthcare system delay in patients treated with pPCI alone (−0.003 decrease in MSI/min of healthcare system delay; 95% CI −0.005 to −0.001, r²=0.11, p=0.008) but not in patients treated with RIC+pPCI (−0.0002 decrease in MSI/min of healthcare system delay; 95% CI −0.001 to 0.001, r²=0.002, p=0.74). In patients with healthcare system delay ≤120 min, RIC+pPCI did not affect median MSI compared with pPCI alone (0.75 (IQR: 0.49–0.99) and 0.70 (0.45–0.94), p=1.00). However, in patients with healthcare system delay >120 min, RIC+pPCI increased median MSI compared with pPCI alone (0.74 (0.52–0.93) vs 0.42 (0.22–0.68), p=0.02). Adjusting for potential confounders did not affect the results.

Conclusions RIC as adjunctive to pPCI attenuated the detrimental effect of healthcare system delay on myocardial salvage in patients with STEMI, suggesting that the cardioprotective effect of RIC increases with the duration of ischaemia.

Trial registration number NCT00435266; post-results.