Transcutaneous Electrical Nerve Stimulation in Patients With Angina and Non-Obstructive Coronary Arteries

Change in summary score of Seattle Angina Questionnaire

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).