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Implications of Abnormal Exercise ECG With Normal Stress Echo
Study Questions:
What are the clinical implications and prognostic significance of abnormal (positive) exercise electrocardiography (ECG) but normal stress echocardiography (Echo)?
Methods:
The investigators evaluated a total of 47,944 consecutive patients without known coronary artery disease who underwent exercise stress echo at Duke University Medical Center between January 1, 2000, and February 28, 2014, for inclusion in this observational cohort study. Data analysis was conducted from January 1, 2000, to December 31, 2016. Patients were categorized as having −ECG/−Echo, +ECG/−Echo, or +Echo (−ECG/+Echo and +ECG/+Echo). The primary outcome was a composite endpoint of death, myocardial infarction, hospitalization for unstable angina, and coronary revascularization. Secondary outcomes included individual adverse events and downstream testing.
Results:
After excluding submaximal tests and nondiagnostic ECG or stress imaging results, 15,077 patients (mean [standard deviation] age, 52 [13] years; 6,228 [41.3%] men) were classified by stress test results. Of these, 12,893 patients (85.5%) had −ECG/−Echo, 1,286 patients (8.5%) had +ECG/−Echo, and 898 patients (6.0%) had +Echo. Through a median follow-up of 7.3 (interquartile range, 4.4-10.0) years, the composite endpoint occurred in 794 patients with −ECG/−Echo (8.5%), 142 patients with +ECG/−Echo (14.6%), and 297 patients with +Echo (37.4%). Death occurred in 425 patients with −ECG/−Echo (4.8%), 50 patients with +ECG/−Echo (5.9%), and 70 patients with +Echo (11.2%). Myocardial infarction occurred in 195 patients with −ECG/−Echo (2.2%), 31 patients with +ECG/−Echo (3.6%), and 59 patients with +Echo (8.7%). The addition of stress ECG findings to clinical and exercise data yielded incremental prognostic value. Patients with −ECG/−Echo imaging results had the least downstream testing (2.3%), followed by +ECG/−Echo (12.8%), and +Echo (33.6%) (p < 0.001).
Conclusions:
The authors concluded that the presence of +ECG results with normal stress echo imaging may identify a population of patients who are at slightly increased risk for adverse cardiac events.
Perspective:
This observational study reports that the discordant findings of +ECG/−Echo were associated with increased downstream testing and a higher rate of short- and long-term adverse cardiac events, particularly hospitalization for unstable angina and coronary revascularization in the 30 days following testing. Furthermore, the finding of positive exercise ECG added modest incremental prognostic value to clinical factors and exercise performance and helped to further risk stratify patients with a normal stress echo. Additional studies are indicated to assess whether intensification of medical management, promotion of lifestyle modification, and increased clinical follow-up in the population with positive exercise ECG but normal stress echo may improve clinical outcomes.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Cardiac Surgery and Arrhythmias, Interventions and Imaging, Echocardiography/Ultrasound
Keywords: Angina, Unstable, Diagnostic Imaging, Echocardiography, Echocardiography, Stress, Electrocardiography, Exercise Test, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Secondary Prevention
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