Non-obstructive cardiovascular disease: a new challenge for invasive cardiology?

Cardiovascular disease is the leading cause of death worldwide, and coronary artery disease (CAD) is the most common type of heart disease. Up to 20–30% of patients presenting with chest discomfort demonstrate no signs of obstructive CAD. In the field of invasive cardiology more than 50% of the patients undergoing coronary angiography for non-acute chest pain have normal or near normal coronary arteries [1]. Non-obstructive CAD in acute coronary syndromes has attracted much attention because of the relatively high incidence of adverse cardiovascular events if not appropriately diagnosed and treated [2]. Especially women have severe symptoms in the absence of obstructive coronary artery disease. Unfortunately, these women are often undertreated due to a lack of correct diagnosis and are at a three times higher risk (as compared with men) to experience a cardiac event within the first year after cardiac catheterisation [3]. In general, patients suffering from chest pain without obstructive coronary artery disease are often diagnosed as non-cardiac, such as gastrointestinal or psychiatric disorders. It is important to diagnose angina in non-obstructive CAD due to concomitant epicardial spasm or microvascular dysfunction. Intracoronary acetylcholine provocation test (ACh test) is the preferred diagnostic method to document epicardial or microvascular function. However, this diagnostic procedure is rarely performed in clinical routine in the USA and Europe, because of the anticipated cardiac risk. Epicardial and microvascular spasm are consid-