1058Remote ischaemic preconditioning causes rapid increase in coronary flow reserve and reduction in microcirculatory resistance

Abstract

Background: Remote ischaemic preconditioning (RIPC) has been proposed to provide cardioprotection in the setting of primary percutaneous coronary intervention (PCI) and elective PCI, with the exact mechanism of cardioprotection unclear. Coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR), indices of microcirculatory function, have been shown to be prognostic markers in patients with coronary disease and those undergoing PCI. Purpose: We sought to investigate the effect of RIPC on coronary artery physiology. Methods: Patients referred for cardiac catheterisation were enrolled in the study. After coronary angiography, patients with a clinical indication for fractional flow reserve (FFR) measurement were randomised to RIPC (3 x 5 min inflations and deflations of a sphygmomanometer on the left arm to 200 mmHg) or sham treatment. Operators were blinded to patient treatment allocation. After advancement of a pressure/temperature sensor wire across the lesion of interest, comprehensive physiological studies using standard published techniques, including FFR, CFR, IMR, were performed before and immediately after RIPC/sham. Physiological parameters were compared before and after RIPC/Sham using paired T‐tests. Results: Twenty seven patients (13 RIPC, 14 sham), 89% male, mean age 62 years, were included in the study. Baseline characteristics and medication use were not statistically different between the RIPC and sham groups. Comparing the RIPC and sham groups, the mean FFR was similar (0.84 vs 0.82, P=0.72). RIPC was associated with an increase in CFR (2.7 vs 3.9, P=0.004) and a reduction in IMR (21.5 vs 17.8, P=0.016) (Figure) which was associated with a reduction in hyperaemic transit time (0.38 vs 0.28, P=0.007). There was no difference in resting transit time, FFR, aortic pressure or distal pressure with RIPC or with any of these measurements after sham treatment. Conclusion: RIPC is associated with a rapid improvement in microcirculatory function, exhibited by a rise in CFR and a reduction in IMR, as assessed invasively during cardiac catheterisation. These alterations in microcirculatory function may explain the mechanism behind the cardioprotective effects of RIPC during primary and elective PCI.