P1579Does remote ischaemic preconditioning improve coronary blood flow?

Abstract

Background: Remote ischemic preconditioning (RIPC) reportedly reduces the risk of myocardial injury after coronary artery bypass grafting and percutaneous coronary intervention. Limb ischemia produces nitric oxide (NO), which leads to increased blood flow. Purpose: The purpose of this study was to examine whether RIPC improves coronary blood flow. Methods: In 27 patients with unobstructed coronary arteries, the average peak velocity (APV), coronary blood flow (CBF), and hyperemic microvascular resistance (HMR) were simultaneously measured using a Doppler guide-wire during RIPC. A cuff applied to the upper left arm was inflated to a blood pressure of 200 mmHg and was maintained for 5 minutes, followed by 5 minutes of deflation. All the patients received 3 cycles of RIPC, and APV, CBF, and HMR measurements were obtained after 1 minute of deflation for each cycle. Quantitative coronary angiography was also conducted to measure vessel diameter (VD) for each cycle. Results: The mean parameter values during RIPC changed as follows (baseline, first, second, and third measurements; compared using a one-way ANOVA): for APV, 24.6, 23.5, 22.6, and 21.6 cm/s, P=0.74; for CBF, 71.6, 66.6, 63.2, and 59.8 mL/min, P=0.81; for HMR, 4.14, 4.45, 4.83, and 4.83, P=0.64; and for VD, 2.69, 2.66, 2.66, and 2.65 mm, P=0.99. Conclusions: Although a recent study showed that RIPC generates NO and transfers it to the heart, we were unable to demonstrate an increase in coronary blood flow during RIPC. These findings suggest that the cardioprotective effect of RIPC would not be provided by the improvement of coronary blood flow, suggesting that NO generated by RIPC would not activate the adenosine triphosphatesensitive potassium channels.