Should the Right Coronary Artery Be Routinely Assessed During Provocative Spasm Testing?

Area of Science:

• Cardiology
• Diagnostic Imaging
• Interventional Cardiology

Background:

• Coronary artery spasm (CAS) diagnosis often relies on invasive provocation testing using acetylcholine (ACh).
• Current protocols typically assess the left coronary artery (LCA) but often omit the right coronary artery (RCA) due to procedural complexity.
• This study investigates the prevalence of inducible CAS in both LCA and RCA during multivessel testing.

Purpose of the Study:

• To compare the incidence of inducible CAS in the LCA versus the RCA.
• To determine the proportion of CAS cases missed by assessing only the LCA.
• To advocate for routine RCA assessment in CAS provocation testing.

Main Methods:

• Analysis of a multi-institutional ANOCA database including 316 patients with suspected CAS.
• Fifty patients underwent multivessel spasm provocation testing with intracoronary ACh (LCA: 25, 50, 100 μg; RCA: 25, 50 μg).
• CAS was defined as >90% epicardial coronary artery constriction on angiography.

Main Results:

• In 50 patients undergoing multivessel testing, 40% (20 patients) had inducible CAS.
• ACh induced CAS exclusively in the LCA in 45% of cases, exclusively in the RCA in 35%, and in both vessels in 20%.
• This indicates that 35% of multivessel CAS cases were confined to the RCA.

Conclusions:

• Routine assessment of the RCA during ACh provocation testing is essential for comprehensive CAS diagnosis.
• Excluding the RCA from spasm testing may lead to underdiagnosis, potentially missing up to one-third of CAS cases.
• Multivessel spasm provocation testing, including the RCA, improves diagnostic accuracy for coronary artery spasm.