The purpose is to test whether daily ischemic conditioning of the arms over 30 days could reduce the frequency and severity of angina pectoris and improve the life quality of refractory angina pectoris patients.

Refractory angina pectoris denotes "chronic stable angina that persists despite optimal medication and when revascularisation is unfeasible or where the risks are unjustified". These patients could potentially be relieved by non-conventional treatments like remote ischemic conditioning, and actually this effect has been observed in several cases in the center of the sponsor. This study is a pilot study to measure the efficacy and safety of this method in this group of patients.

Inclusion Criteria:

• Diagnosed angina pectoris that remains despite optimal medical treatment;
• No chance of further revascularization or refusal to do revascularization;
• The frequency and Canadian Cardiovascular Society (CCS) scale stays stable over the past 3 months before inclusion.

Exclusion Criteria:

• Known or highly suspected abnormality of peripheral arteries, veins, or extremities;
• Infection or fever in the past month;
• Blood pressure over 180/110 millimeters of mercury (mmHg) or below 80/50mmHg;
• Refusal to comply with the study protocol;
• Currently under sulfonylureas or prostaglandins therapy;
• Other conditions that the researchers judge as inappropriate to participate.