Remote ischemic conditioning improves coronary microcirculation in healthy subjects and patients with heart failure

Background: Remote ischemic conditioning (RIC) is a treatment modality that suppresses inflammation and improves endothelial function, which are factors involved in the pathogenesis of heart failure (HF) with reduced left ventricular ejection fraction. Coronary flow reserve (CFR) is a physiological index of coronary microcirculation and is noninvasively measured by transthoracic Doppler echocardiography (TTDE). This study aimed to investigate the effects of RIC on CFR in healthy subjects and patients with HF, through the assessment by TTDE. Methods: Ten patients with HF with left ventricular ejection fraction of less than 40%, and ten healthy volunteers were enrolled in this study. RIC treatment was performed twice a day for 1 week. Our custom-made RIC device was programmed to automatically conduct 4 cycles of 5 minutes inflation and 5 minutes deflation of a blood pressure cuff to create intermittent arm ischemia. CFR measurements and laboratory tests were examined before, and after 1 week of RIC treatment. Results: One week of RIC treatment was well tolerated in both groups. RIC treatment increased CFR from 4.0 +/- 0.9 to 4.6 +/- 1.3 (mean +/- standard deviation) in healthy subjects (P=0.02), and from 1.9 +/- 0.4 to 2.3 +/- 0.7 in patients with HF (P=0.03), respectively. Systolic blood pressure in healthy subjects, and heart rate in HF patients decreased after RIC treatment (both P<0.01). Conclusion: This study demonstrated that a 1 week course of RIC treatment improved coronary microcirculation in healthy subjects and patients with HF associated with reduced left ventricular ejection fraction.