Internal Medicine

“False-Positive” Stress Tests in Patients with Coronary Microvascular Dysfunction"

Kirsten E. Fleischmann, MD, MPH, FACC, reviewing Sinha A et al. J Am Coll Cardiol 2024 Jan 16 Beltrame JF et al. J Am Coll Cardiol 2024 Jan 16

In patients with angina and no obstructive coronary disease, positive stress tests were highly predictive of CMD.

The false-positive rate of exercise stress electrocardiography testing (EST) can be substantial when EST is validated against angiography for diagnosing obstructive coronary artery disease. However, a new study calls that interpretation into question. Researchers in the U.K. evaluated 102 patients (mean age, 60) who had angina without obstructive coronary artery disease; patients underwent EST, as well as invasive assessment with acetylcholine and adenosine infusion for coronary microvascular dysfunction (CMD), which also can cause ischemia.

Thirty-two patients developed ischemia on EST, all of whom tested positive for CMD. Seventy patients had nonischemic EST results, of whom 46 (66%) received diagnoses of CMD. When the reference standard was an abnormal response to acetylcholine (indicating endothelium-dependent CMD) or an abnormal response to adenosine (indicating endothelium-independent CMD), the EST false-positive rate was 0%.

COMMENT

This study shines new light on an old problem: Positive stress tests without substantial obstructive coronary disease detected by angiography typically have been interpreted as false positives, especially in women. However, this study suggests those results might be pointing us in the direction of microvascular, rather than macrovascular, disease. Sensitivity for CMD was limited, but specificity — in the context of angina with no obstructive coronary disease by angiography — was high. Editorialists note EST might be a useful second-line test when obstructive coronary disease has been ruled out; this hypothesis awaits further testing. In the meantime, I'll make sure to consider the possibility of CMD when I get back those “false-positive” results.

CITATIONS

Sinha A et al. Rethinking false positive exercise electrocardiographic stress tests by assessing microvascular function. J Am Coll Cardiol 2024 Jan 16; 83:291. (https://doi.org/10.1016/j.jacc.2023.10.034. opens in new tab)

Beltrame JF et al. Clinical utility of the humble exercise ECG stress test. J Am Coll Cardiol 2024 Jan 16; 83:300. (https://doi.org/10.1016/j.jacc.2023.10.036. opens in new tab)