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Maximal Exercise-Corrected QT as a Predictor of Coronary Artery Disease: Comparison of Simpler Heart Rate Corrections
Aydın Akyuz1, Seref Alpsoy, Dursun Cayan Akkoyun
1Department of Cardiology, Namık Kemal University Medical School, Tekirdag, Turkey.
Insights
Patients with coronary artery disease (CAD) exhibit longer corrected QT (QTc) intervals during maximal exercise. However, exercise QTc prolongation offers insufficient evidence for routine use in diagnosing CAD presence or severity.
Area of Science:
- Cardiology
- Clinical Electrophysiology
- Diagnostic Imaging
Background:
- The link between QT prolongation and myocardial ischemia is established.
- ST depression has limited diagnostic value for coronary artery disease (CAD).
- Accurate diagnosis of CAD is crucial for timely intervention.
Purpose of the Study:
- To evaluate the diagnostic utility of maximal exercise-corrected QT (QTc) prolongation for CAD.
- To assess the correlation between exercise QTc and CAD severity using different heart rate correction formulas (Bazett, Framingham, Fridericia, Hodges).
Main Methods:
- 234 subjects with suspected CAD underwent exercise testing and coronary angiography.
- CAD severity was assessed using Gensini scoring.
- QTc intervals at maximal exercise were compared between CAD patients (n=122) and controls (non-CAD).
Main Results:
- CAD patients showed significantly higher raw QT values compared to controls.
- Framingham QTc (≥350 ms) and Fridericia QTc (≥340 ms) were useful for CAD diagnosis.
- Exercise QTc did not add diagnostic value beyond ST depression; weak positive correlations were found with Gensini scoring.
Conclusions:
- Patients with CAD have longer QTc intervals at peak exercise heart rates.
- Current evidence does not support routine integration of peak exercise QTc into exercise test interpretation.
- Further research may explore refined QTc measurement techniques for improved diagnostic accuracy.
Background And Objectives:
The relationship between QT prolongation and myocardial ischemia is widely known. Due to the limited value of ST depression, we aimed to evaluate, by using four simpler heart rate corrections (Bazett, Framingham, Fridericia and Hodges), the value of maximal exercise-QTc prolongation in the diagnosis of coronary artery disease (CAD) presence and severity.
Subjects And Methods:
We enrolled 234 subjects (mean age 57.3±9 years, 143 men) who had undergone exercise testing and coronary angiography due to a suspicion of CAD in the study. Evaluating CAD severity with Gensini scoring, the CAD group (n=122) and controls with non-CAD were compared in terms of corrected QT duration at maximal exercise.
Results:
Age, gender, hypertension, dyslipidemia, smoking, exercise duration, resting, and peak heart rate were similar between the two groups (all p>0.05). The CAD group had higher raw QT values than the controls {268 (169-438) vs. 240 (168-348), p<0.001}. Although Framingham QTc of ≥350 ms and Fridericia QTc of ≥340 ms were seen to be useful for the diagnosis of CAD, there was no additive diagnostic value of exercise QTc in addition to ST depression. Maximal exercise-QTc Bazett (r=0.163, p=0.01), Framingham (r=0.239, p=0.001), and Fridericia (r=0.206, p=0.001) equations were weakly positively correlated with Gensini scoring.
Conclusion:
The patients with CAD have longer QTc intervals at peak heart rates during exercise. This finding provides insufficient evidence to support routine incorporation of QTc at peak heart rates into exercise test interpretation.
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