Can QT interval prolongation or dispersion detected in a positive exercise ECG test predict critical coronary artery disease?

Abstract

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.

QT variability unrelated to RR variability during stress testing for identification of coronary artery disease

“…QTc interval and QT dispersion during recovery were significantly higher in the critical CAD group with respect to the non-critical CAD group. These results on increased dispersion are in accordance with our results, as they are all indicative of higher repolarization lability during recovery from exercise in CAD patients with respect to non-CAD patients, even if the markers measured in [32] are intended to measure spatial repolarization heterogeneities whereas our markers quantify temporal repolarization variability. In [32], ROC analysis based on QTc and QT dispersion revealed slightly better performance than in our study, with 90% sensitivity and 53% specificity.…”

“…These results on increased dispersion are in accordance with our results, as they are all indicative of higher repolarization lability during recovery from exercise in CAD patients with respect to non-CAD patients, even if the markers measured in [32] are intended to measure spatial repolarization heterogeneities whereas our markers quantify temporal repolarization variability. In [32], ROC analysis based on QTc and QT dispersion revealed slightly better performance than in our study, with 90% sensitivity and 53% specificity. However, the critical CAD group in that study may include patients with more severe forms of myocardial ischemia than our CAD group.…”

“…These results were confirmed in subsequent studies, which additionally revealed greater accuracy of T wave alternans when compared with conventional ST segment analysis for CAD detection [31]. Other repolarization markers, like the QT interval, HR-corrected QT interval (QTc) and spatial QT dispersion have been explored prior to, during and after stress testing in a large cohort of patients undergoing coronary angiography [32]. QTc interval and QT dispersion during recovery were significantly higher in the critical CAD group with respect to the non-critical CAD group.…”

“…Our analysis showed that when each of them was separately entered into a model together with a marker measuring normalized QTV unrelated to HRV, which was also able to separate CAD and non-CAD groups, each of them were independent predictors of CAD. Interestingly, the marker P E 25 QTVuRRV can be obtained from the first minutes of exercise, which can represent an advantage over other previously proposed markers which require evaluation either at peak exercise or during the recovery phase [32].…”

Rediscovering Clinical Utility of QT Dispersion: A Long-Forgotten Parameter

“…Aggressive recommendation toward revascularization procedures in acute Myocardial Infarction (MI) modulates spontaneous dynamicity and regresses infarction size. QT dispersion is increased in acute MI, with mean values ranging from 40±18 to 162.3±64.8 ms. QT dispersion has a trend toward regression on chronic forms of coronary artery disease [11]. There is a significant association of increased QT dispersion on acute MI and ventricular tachycardia incidence (sensitivity 68%, specificity 88%, relative risk 15.7 (p<0.001).…”