• Angina pectoris
• myocarditis
• coronary artery disease
• syndrome X
• coronary physiology, hypertensive heart disease

The presence of angina pectoris (AP) in patients with either normal coronary angiograms or with non-obstructive coronary artery disease (CAD) is not only a frequent clinical finding but also a clinical and therapeutic challenge. Only recently, Patel et al evaluated the diagnostic yield of coronary angiography—regarding the presence or absence of obstructive CAD—among almost 400 000 patients with suspected CAD.1 Although the majority (70%) of these patients was suffering from chest pain symptoms, only 37.6% of them demonstrated obstructive CAD by invasive coronary angiography (defined as diameter stenosis >50% of the left main coronary artery or >70% of a major epicardial vessel). This surprising finding raises the following question: how should we explain the presence of AP symptoms (typical enough to motivate coronary angiography) in patients without obstructive CAD? Moreover, we need to consider the following clinical issues: (1) non-obstructed coronary arteries are also found in a sizeable subgroup of ≥10% of patients who undergo urgent coronary angiography due to angina accompanied by troponin elevation, and these patients represent a high risk group with a worse prognosis even in the absence of obstructive CAD^w1–w3; and (2) the presence of myocardial ischaemia in the absence of obstructive CAD still predicts cardiovascular outcome and is associated with higher rates of anginal hospitalisation, repeat catheterisation, and greater treatment costs.^w4 Therefore, further evaluation of the underlying pathophysiology and potential treatment options in patients presenting with AP in the absence of obstructive CAD is a clinically highly relevant issue.

In the following review, different (sometimes overlapping) pathophysiologies causing symptoms of AP in the absence of obstructive CAD are discussed, and current diagnostic as well as therapeutic options are illustrated.