Angina due to coronary artery spasm (variant angina): diagnosis and intervention strategies

ABSTRACT

Introduction

Since Prinzmetal first described a ‘variant’ form of angina pectoris, with predominantly resting episodes of pain and cyclic severity variations, it has gradually become apparent that this clinical presentation is caused by episodes of coronary artery spasm (CAS) involving focal or diffuse changes in large and/or small coronary arteries in the presence or absence of ‘fixed’ coronary artery stenoses. However, most clinicians have only limited understanding of this group of disorders.

Areas covered

We examine the clinical presentation of CAS, associated pathologies outside the coronary vasculature, impediments to making the diagnosis, provocative diagnostic tests, available and emerging treatments, and the current understanding of pathogenesis.

Expert opinion

CAS is often debilitating and substantially under-diagnosed and occur mainly in women. Many patients presenting with CAS crises have non-diagnostic ECGs and normal serum troponin concentrations, but CAS can be suspected on the basis of history and association with migraine, Raynaud’s phenomenon and Kounis syndrome. Definitive diagnosis requires provocative testing at coronary angiography. Treatment still centers around the use of calcium antagonists, but with greater understanding of pathogenesis, new management options are emerging.

KEYWORDS:

• Variant angina
• coronary artery spasm
• coronary slow flow phenomenon
• acetylcholine test
• pathogenesis
• diagnosis
• treatment

Article highlights

• Coronary artery spasm (CAS) occurs relatively frequently, both in the presence and absence of hemodynamically significant coronary artery stenoses

• CAS may be focal or diffuse, and may predominantly affect large or small coronary arteries: the latter causes the coronary slow flow phenomenon (CSFP).

• Symptoms of CAS are often cyclical, with most episodes of pain occurring at rest, and often being prolonged in spite of nitroglycerin administration.

• CAS is associated with increased incidence of migraine, Raynaud’s phenomenon, paroxysmal atrial fibrillation, and with the mast cell degranulation disorder Kounis syndrome.

• Definitive diagnosis of CAS requires coronary angiography, often together with intracoronary administration of acetylcholine to provoke spasm. Rates of performance of this procedure are currently far too low, leaving many patients undiagnosed.

• Prophylactic therapy for CAS centers on calcium antagonists: β-adrenoceptor antagonists and aspirin should be avoided.

• There is increasing evidence that CAS symptomatic crises are precipitated by impairment of nitric oxide/hydrogen sulfide signaling, resulting in combined vasoconstriction and platelet aggregation.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

TH Nguyen was supported in part by a grant from the Australian Heart Foundation. G-J Ong and OC Girolamo were supported in part by the University of Adelaide Postgraduate Scholarships.