According to the 2020 Dutch guideline on chest pain (AP) without obstructive coronary artery disease, 70% of female and 30% of male patients undergoing a coronary angiogram (CAG), have no obstructive coronary artery disease.In the majority of patients the complaints are based on vascular dysfunction, including epicardial vascular spasms. For patients who are refractory to drug treatment, spinal cord stimulation (SCS) can be a treatment option. SCS is used for the treatment of refractory neuropathic and ischaemic pain. In recent studies the use of SCS is proven for refractory angina pectoris, but the group with refractory vasospastic angina pectoris (rVSA) predominantly seen in women with invalidating impairment of quality of life, is overlooked, as no evidence of obstruction is found at CAG. With this pilot study the investigators hypothesize that SCS is effective in reducing the number and intensity of angina attacks, reducing nitrate use, reducing inhospital treatment and ER presentations, thereby reducing medical costs, and above all, increasing quality of life.

Rationale:

Of the patients undergoing a coronary angiogram because of chest pain (AP), 67% of female and 33% of male patients have no obstructive coronary artery disease. In the majority of patients (59-89%) the complaints are based on vascular dysfunction, including epicardial vascular spasms (EVS). For patients who are refractory to drug treatment, spinal cord stimulation (SCS) can be a treatment option. SCS is used for the treatment of refractory neuropathic and ischaemic pain. In recent studies the use of SCS is proven effective for refractory angina pectoris, but the group with refractory vasospastic angina pectoris (rVSA), predominantly seen in women with invalidating impairment of quality of life, is overlooked, as no evidence of obstruction is found at CAG. With this study the investigators hypothesize that SCS is effective in reducing the number and intensity of angina attacks, reducing nitrate use, reducing inhospital treatment and ER presentations, thereby reducing medical costs, and above all, increasing quality of life.

Objective: the main objective of this study is to evaluate the clinical effects of SCS on the number and intensity of VSA attacks. Secondary objective is to objectivate the effects of SCS on coronary spasms during the provocative acetylcholine test, and assess medical costs, patient satisfaction and quality of life.

Study design: prospective study in two phases. Phase 1: evaluation of clinical effectiveness. Phase 2: evaluation of SCS on vascular spasms during acetylcholine provocation test.

Study population: 10 patients with refractory AP due to epicardial vascular spasms.

Intervention: implantation with a SCS device with one or two lead(s) in the epidural space of T1 to T4, active electrodes depending on mapping of the painfull area, under local anesthesia and sedation. Acetylcholine provocation test during coronary angiogram at 6 months.

Main study parameters/endpoints: primary endpoint is the Seattle Angina Questionnaire (SAQ) at month 1 and 3. Secundary endpoints are presentation at ER, estimated medical costs, and patient satisfaction measured on a 11 point Numeric Rating Scale and quality of life with the EQ5D at month 3, compared to baseline. Endpoints of the acetylcholine test are changes in coronary flow and coronary diameter compared to baseline.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: SCS is proven to be safe for neuropathic and ischaemic pain and is widely used in clinical practice. With the positive results of an ongoing clinical trial for refractory coronary angina, the investigators estimate the efficacy of SCS to be around 80-90% in reducing VSA attacks with 50% after 3 months and therefore very effective in otherwise refractory drug treatment regiments. Furthermore, baseline study parameters will be extracted from the routine questionnaires and during visits to the outpatient clinic.

Only in patients who specifically consent to it, an additional acetylcholine test 6 months after SCS implantation during coronary angiography (CAG) is performed. This is an additional coronary angiogram procedure under local anesthesia which potentially provokes VSA. Done by experienced personal this is a safe test with a complication risk of 0-0.7% for severe cardiac complications, comparable to coronary angiogram with functional flow reserve measurement.

A potential benefit for the participants is that SCS results in reduction of VSA attacks, reduction of nitrate use, less presentation at an ER, an improved quality of life, and acceptation as standard treatment.

Inclusion Criteria:

• VSA is objectivated with a provocative acetylcholine test
• mentally competent and able to fill in the questionnaires
• refractory VSA defined as disabling chest pain with a maximum tolerated dosage of calcium antagonists, long acting nitrates, angiotensin converting enzyme inhibitors for a minimum of three months
• absence of obstructive coronary artery disease evident in a main coronary artery (diameter stenosis<50%, Instant Flow Reserve (IFR) >0.89, or Fractional Flow reserve (FFR) >0.80)
• able to use the remote control of the SCS system

Exclusion Criteria:

• inability to visit the outpatient department for the follow-up visits
• unable to provide informed consent
• myocardial infarction in the previous three months
• procedures like percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), nor instability of the clinical signs and symptoms of refractory angina in the previous three months
• implanted pacemaker or implantable cardioverter-defibrillator (ICD) incompatible with SCS
• indication for ongoing anticoagulation therapy
• pregnant women and those who are breastfeeding

In progress

6 months after closure of database for 3 years

On request