Scoring System-Based Approach for Positive Intracoronary Acetylcholine Provocation Tests

Background

Although intracoronary acetylcholine (ACh) provocation testing is a guideline-recommended invasive standard for the diagnosis of vasospastic angina (VSA), ACh tests are largely underused in clinical practice globally. Recently, the ABCD score, consisting of clinical presentation, myocardial bridge, C-reactive protein, and dyslipidemia, was developed to predict positive ACh test results.

Objectives

The authors aimed to externally validate the diagnostic ability of the score and attempted to improve the predictivity for identifying patients with VSA.

Methods

From May 2012 to September 2023, a total of 723 patients undergoing ACh provocation tests for diagnosing VSA were included. The original ABCD score was calculated according to the predefined criteria, and the modified ABCD score was internally developed to improve the diagnostic accuracy. The positive ACh provocation test (ie, VSA) was defined as a significant angiographic vasospasm accompanied by chest pain and/or ischemic electrocardiographic changes.

Results

Of the 723 patients, 383 (53.0%) had positive ACh provocation test results. The receiver-operating characteristics curve analysis indicated that the original ABCD score was significantly predictive of positive ACh tests. Using best cutoff values on receiver-operating characteristics curve analyses, we developed the modified ABCD score, which was simpler than the original score. The modified rather than original ABCD score had better diagnostic ability for positive ACh test results (area under the curve 0.65 vs 0.55; P < 0.001).

Conclusions

The original ABCD score was predictive of VSA in this external validation study with modest diagnostic accuracy, while the modified ABCD score achieved better predictivity for identifying patients with VSA.