February 5, 2020 – A DCRI study stratified patients based on their exercise ECG and stress echo results and examined patient outcomes to determine whether discordant results could be used as an indicator for higher risk of adverse outcomes.
Findings from a DCRI-led study recently published in JAMA Internal Medicine suggest new prognostic implications for patients who have abnormal exercise electrocardiography (ECG) but normal stress echocardiography (Echo) results.
In clinical practice, exercise ECG is combined with stress Echo imaging for the evaluation of coronary artery disease. Although it is not uncommon for patients to have discordant results (abnormal ECGs and normal Echos), it was previously unclear whether this had any prognostic significance for these patients. An observational study led by DCRI’s Melissa Daubert, MD, sought to answer this question.
The study, which included 15,077 patients without known coronary artery disease who underwent stress exercise testing at Duke University Medical Center, stratified patients into three groups based on their test results:
- Negative ECG and negative Echo: This was the most common combination of results, with 85.5 percent of the study cohort.
- Positive ECG and negative Echo: 8.5 percent of patients fell into this group.
- Positive Echo: This group represented 6 percent of patients.
The median time each patient within the study was followed was 7.3 years. Researchers measured how many patients experienced the primary outcome of death, heart attack, hospitalization for unstable angina, or coronary revascularization. In the positive ECG-negative Echo group, 14.6 percent of patients experienced one of the primary outcomes, compared to 8.5 percent of patients with negative ECG-negative Echo.
When researchers drilled down into specific outcomes, they found that patients with positive ECG were more likely to experience death (5.9 percent versus 4.8 percent in the negative ECG group), as well as a heart attack (3.6 percent versus 2.2 percent).
The study team concluded that patients with positive ECG had a higher rate of adverse events, and that considering positive ECG may help to further risk stratify patients with normal Echo results.
“This study helped us to identify a new at-risk population,” Daubert said. “Although we often see patients with this combination of results, little was known about whether this had an effect on patient outcomes. Now, we know that patients with positive ECG and normal Echo are at higher risk for adverse events.”