Significance of abnormal stress electrocardiography with normal cardiac imaging during stress testing-a meta-analysis

Diagnostic testing for coronary artery disease frequently involves functional stress testing where imaging is often coupled with electrocardiogram (ECG) analysis. While decision-making is straightforward when both functional testing and ECG are either positive or negative, interpretation is challenging and prognostic importance uncertain with positive ECG and negative imaging since imaging is considered more sensitive. Prior studies have demonstrated mixed results. We sought to perform a meta-analysis of published studies to determine the significance of this particular type of discordant stress test result.

PubMed, Cochrane, and Google Scholar were searched to identify studies reporting results of functional imaging (pharmacological exercise echocardiography or SPECT) and ECG analysis, along with the major adverse cardiovascular events (MACE) at patient follow-up. Studies were stratified based on functional imaging modality used. Primary outcome was a composite of all-cause death or myocardial infarction, and secondary outcome was the need for coronary revascularization. Random effects model was used to calculate risk ratios (RR), and heterogeneity among studies was assessed using the Higgins I² value. Nine studies with a total of 23,715 patients were included. Primary end point was more common with discordant results with exercise stress echocardiography (RR 1.33, 95% confidence intervals [1.08-1.63]) or pharmacological SPECT (RR 6.53 95% CI [2.31-18.48]).

Patients in the discordant exercise stress echocardiography and pharmacological SPECT groups were more likely to suffer the primary end point than those with a normal stress test. Discordant results should be interpreted carefully in the clinical context, given their prognostic impact based on the stress modality used.