The goal of this clinical trial is to assess the feasibility and clinical value of acetylcholine (ACH) rechallenge after intracoronary verapamil +- nitroglycerine in a patient cohort with angina and non-obstructive coronary arteries (ANOCA).

The main questions it aims to answer are:

• to determine the efficacy of these drugs in treating ACH-induced coronary artery spasm
• to determine the efficacy of these drugs in preventing ACH-induced coronary artery spasm

The ACH rechallenge will take place during the index coronary function tests in patients with proven ACH-induced vasospastic angina. The study is considered a feasibility study, no control arm is included.

Inclusion Criteria:

• Clinically indicated coronary angiogram in the setting of angina with non-obstructive coronary artery disease (ANOCA)
• Non-obstructive coronary artery disease is defined as the absence of coronary artery stenosis ≥ 50%, or if ≥ 50% with non-ischemic resting (RFR > 0.89) and hyperemic indices (FFR > 0.80).
• ACH provoked epicardial and/or microvascular spasm
• Left ventricular ejection fraction (LVEF) > 50%
• Renal function with eGFR ≥ 40 ml/min

Exclusion Criteria:

• Obstructive coronary artery disease (both chronic and acute coronary coronary syndromes)
• Any cardiomyopathy (including takotsubo stress cardiomyopathy) or severe valvular disease
• LVEF < 50%
• Long QT syndrome (LQTS) - genetic or acquired
• Ventricular paced rhythm
• Renal failure with eGFR < 40 ml/min
• Thyroid stimulating hormone (TSH) < lower limit of normal (LLN). A subject taking thyroid replacement therapy may be enrolled with TSH level below LLN if, in the opinion of the investigator, the subject is in a clinically euthyroid state.
• Known hypersensitivity or contra-indication for either acetylcholine, verapamil, nicorandil or nitroglycerine.
• Pregnant female subjects. Female subjects of child-bearing potential should be on adequate contraceptive measures or are to be screened with a urine pregnancy test.