Sequential spasm provocation tests might overcome a limitation of the standard spasm provocation tests

Standard spasm provocation tests have limitations in detecting coronary artery spasm in some patients. Prior research has shown that acetylcholine (ACh) and ergonovine (ER) tests are commonly used diagnostic tools for identifying vasospastic angina. However, these tests may fail to provoke spasm in certain cases, leaving a diagnostic gap. No prior work had resolved how to improve detection rates when initial tests are negative. This uncertainty drove the need to evaluate alternative testing sequences. Researchers have proposed that modifying the order of spasm provocation agents may increase sensitivity. It was already known that focal and diffuse spasm patterns differ by agent. Yet, the clinical usefulness of a sequential approach remained unclear. This gap motivated the current investigation into a three-step spasm provocation protocol.

The aim of this study was to assess whether a sequential spasm provocation test could improve diagnostic yield compared to standard single-agent tests. The specific problem addressed was the inability of isolated ACh or ER tests to provoke spasm in some patients. The motivation stemmed from clinical observations of missed diagnoses using conventional methods. Researchers sought to determine if administering ACh after ER could detect additional cases. The study focused on patients who tested negative with standard protocols. The goal was to evaluate the added diagnostic value of a three-step approach. No prior research had directly compared this sequential method to standard tests. The researchers proposed that a modified sequence might overcome current diagnostic limitations.

The study involved 461 patients who underwent standard spasm provocation tests with acetylcholine and ergonovine. In 240 of these patients, an additional ACh test was performed after the ER test. The ACh test was administered incrementally in the right and left coronary arteries. Ergonovine was delivered in fixed doses over a 2-4 minute period. ACh was given in increasing concentrations depending on the coronary artery tested. If no spasm was provoked, a second ACh test was performed after ER administration. Spasm was defined as transient luminal narrowing exceeding 99%. The study compared spasm detection rates across three test sequences. No prior studies had evaluated this specific combination of sequential tests.

A positive spasm was observed in 221 patients (47.9%) using the standard tests. Of these, 181 were ACh-positive and 119 were ER-positive. In 240 patients with negative initial tests, 48 developed spasm after the sequential ACh test following ER. The spasm detection rate increased by 10.4% with the added test. Focal spasm was more common in the ER-positive group. Diffuse spasm was more frequent in the ACh-positive group and after the sequential test. The distribution of cardiac disorders was similar among positive groups. No major complications were observed during the tests. The added ACh test after ER identified additional cases not detected by standard protocols. These findings suggest that the sequential approach may enhance diagnostic sensitivity.

The authors propose that sequential spasm provocation tests may overcome limitations of standard single-agent tests. The added ACh test after ER identified spasm in 10.4% of initially negative cases. The spasm patterns differed by test sequence, with focal spasm more common in ER-positive patients. Diffuse spasm was more frequently observed in ACh-positive cases and after the sequential test. No major complications were reported during the procedure. The study suggests that a three-step approach may improve diagnostic yield in vasospastic angina. The authors did not claim this method is essential for all patients. They emphasized the need for further research to confirm these findings in larger populations.