The Relationship between P & QT Dispersions and Presence & Severity of Stable Coronary Artery Disease

Abstract

Background and objectives: The study aimed to evaluate the correlation between electrocardiographic (ECG) parameters and presence and extent of coronary artery disease (CAD) to indicate the usefulness of these parameters as predictors of severity in patients with stable CAD.

Subjects and methods: Two hundred fifty patients, without a history of any cardiovascular event were included in the study. The ECG parameters were measured manually by a cardiologist before coronary angiography. The patients were allocated into five groups: those with normal coronary arteries (Group 1), non-critical coronary lesions (Group 2), one, two and three vessel disease (Group 3, Group 4 and Group 5, respectively.

Results: Group 1 had the lowest P wave dispersion (PWD) and P wave (Pmax), QT interval (QTmax), QT dispersion (QTd), corrected QT dispersion (QTcd) and QT dispersion ratio (QTdR), while the patients in group 5 had the highest values of these parameters. Gensini score and QTmax, QTd, QTcmax, QTcd, QTdR, Pmax, and PWD were positively correlated. QTdR was the best ECG parameter to differentiate group 1 and 2 from groups with significant stenosis (groups 3, 4, and 5) (area under curve [AUC] 0.846). QTdR was the best ECG parameter to detect coronary arterial narrowing lesser than 50% and greater than 50%, respectively (AUC 0.858).

Conclusion: Presence and severity of CAD can be determined by using ECG in patients with stable CAD and normal left ventricular function.

Keywords: Coronary artery disease; Electrocardiography; P wave & QT interval.

Fig. 1. ROC Curve of electrocardiographic parameters that distinguished normal coronary from non-critical and significant stenosis groups. QTmax: maximum QT interval, QTd: QT dispersion, QTcmax: corrected QT maximum interval, QTcd: corrected QT dispersion, QTdR: QT dispersion ratio, Pmax: maximum p wave interval, PWD: P wave dispersion.

Fig. 2. ROC Curve of electrocardiographic parameters that distinguished coronary arteries with <50% narrowing from the ones with ≥50% narrowing. QTc: corrected QT, QTmax: maximum QT interval, QTcmax: corrected QT maximum interval, QTcd: corrected QT dispersion, QTdR: QT dispersion ratio, Pmax: maximum p wave interval, PWD: P wave dispersion.