The Novel Use of Transcutaneous Electrical Nerve Stimulation in Patients With Angina and Non-Obstructive Coronary Arteries: a Pilot Study

In patients with angina pectoris undergoing a coronary angiography (CAG) up to 40% do not have obstructive coronary artery disease (CAD). The majority of patients with no obstructive CAD are women with a frequency of up to 70% compared to 50% in men. These patients are diagnosed as having angina and non-obstructive coronary arteries (ANOCA). There are two endotypes of ANOCA. The first endotype is microvascular angina (MVA) caused by a combination of structural microcirculatory remodelling and functional arteriolar dysregulation, also called coronary microvascular dysfunction (CMD). The second endotype is vasospastic angina (VSA) caused by epicardial coronary artery spasm that occurs when a hyper-reactive epicardial coronary segment is exposed to a vasoconstrictor stimulus. Both endotypes of ANOCA are associated with significantly greater one-year risk of myocardial infarction (MI) and all-cause mortality, have a significantly impaired quality of life and have a high health care resource utilisation.

The current treatment for ANOCA consists of three aspects. The first aspect is managing lifestyle factors such as weight management, smoking cessation and exercise. The second aspect is managing known cardiovascular risk factors such as hypertension, dyslipidaemia and diabetes mellitus. And the third aspect is antianginal medication. In both endotypes ACE inhibitors or angiotensin II receptor blockers should be considered. In MVA the antianginal medication that can be used are betablocker, calcium channel blocker, nicorandil, ranolazine, ivabradine and/or trimetazidine. In VSA calcium channel blocker, long-acting nitrate and/or nicorandil can be initiated as antianginal therapy. Despite these treatment option approximately 25% of ANOCA patients have refractory angina symptoms.

A possible treatment modality for ANOCA patients with refractory angina pectoris is spinal cord stimulation (SCS) or transcutaneous electrical nerve stimulation (TENS). Previous research (in patients with cardiac syndrome X) has shown that SCS improves time until angina and ischaemia, significantly less angina and an improvement in quality of life. These findings suggest that SCS and/or TENS could be a possible treatment modality for patients with ANOCA.

The aim of this pilot study is to investigate whether treatment with TENS during a one month period leads to a significant reduction of angina pectoris and therefore a significant improvement in quality of life in patients with proven ANOCA, encompassing both endotypes (MVA and VSA).