Key result
In patients with a positive exercise ECG test, prolonged recovery QTc independently predicted critical coronary artery disease (OR 1.051), with a 404 ms cut-off yielding 90% sensitivity.
Why the study?
Exercise electrocardiography has low specificity, and parameters like QT prolongation and dispersion were not sufficiently investigated to determine if they predict critical CAD in positive tests.
Can QT interval prolongation or dispersion detected in a positive exercise ECG test predict critical coronary artery disease?
Observational (n=192)
Can QT interval prolongation or dispersion detected in a positive exercise ECG test predict critical coronary artery disease?
Odds Ratio: 1.051 (95% CI 1.031–1.071)
p-value: p=<0.001
Prolonged QTc and QT dispersion during the recovery period of a positive exercise ECG test can independently predict critical coronary artery disease, potentially enhancing the clinical accuracy of the test.
May support QTc recovery as exercise ECG adjunct; leaves open prospective validation before practice change.
Introduction Exercise electrocardiography (EET) is frequently used in coronary artery disease, but the specificity of this test is very low. In the literature, parameters such as QT prolongation and QT dispersion which show coronary artery disease and arrhythmia were not sufficiently investigated using EET. The aim of this study was to investigate whether QT interval prolongation or dispersion (QT disp) in a positive EET test could predict critical coronary artery disease (CAD). Material and methods Patients with a positive exercise test were included in the study. Data regarding QT, QTc (corrected QT interval) and QT disp values before, during and after EET were noted. Critical coronary artery occlusions (≥ 70%) was recorded from coronary angiographic images. Patients were divided into two groups (critical CAD and non-critical CAD). Results A total of 192 patients were found to be eligible for the study. There were 126 patients in the non-critical CAD group (group 1) and 66 patients in the critical CAD group (group 2). Recovery QTc, peak QT disp, and recovery QT disp were significantly increased in group 2 (p < 0.001 for each). Also, target heart rate (p = 0.012), basal systolic blood pressure (p = 0.005) and diastolic blood pressure (p < 0.001) were significantly higher in group 1. Recovery QTc (OR = 1.051) and recovery QT disp (OR = 1.117) were determined as the independent predictors for critical CAD. The ROC analysis results indicated that critical CAD could be diagnosed with 90% sensitivity when the recovery QTc cut-off value was set as 404 ms. Conclusions In patients with positive EET, prolonged QTc and QT disp values measured during the recovery period would predict critical CAD. Thus, the clinical accuracy of EET may be enhanced.
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Demirtaş et al. (2019) conducted an observational in Positive exercise ECG test with suspected coronary artery disease (n=192). Prolonged recovery QTc vs. Normal recovery QTc was evaluated on Critical coronary artery disease (≥ 70% occlusion) (OR 1.051, 95% CI 1.031-1.071, p=<0.001). In patients with a positive exercise ECG test, prolonged recovery QTc independently predicted critical coronary artery disease (OR 1.051), with a 404 ms cut-off yielding 90% sensitivity.
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