['Remote ischemic preconditioning (RIPC) may limit myocardial infarction by improving microvascular function and maintaining myocardial blood flow. We hypothesized that a RIPC stimulus would reduce coronary microvascular resistance and improve coronary blood flow during elective percutaneous coronary intervention (PCI).', 'We prospectively recruited 54 patients with multi-vessel disease (MVD = 32) or single vessel disease awaiting elective PCI. Patients with MVD had non-target vessel (NTV) index of micro-circulatory resistance (IMR) determined, before and after target vessel (TV) PCI (cardiac RIPC). The effect of arm RIPC on serial microvascular resistance (R(p)) was assessed in patients with single vessel disease.', 'TV balloon occlusion did not alter the NTV IMR: 16.5 (12.4) baseline vs. 17.6 (11.6) post cardiac RIPC, P = 0.65 or hyperaemic transit time. Arm RIPC did not alter R( p) in patients with single vessel disease: Rp, mmHg.cm(-1).s( -1): 3.5 (1.9) baseline vs. 4.1 (3.0) post arm RIPC, P = 0.19 and coronary flow velocity remained constant.'] Does remote ischemic preconditioning stimulus reduce microvascular resistance or improve myocardial blood flow in patients undergoing elective percutaneous coronary intervention?