Increased Ventricular Activation Time in Patients with the Diagnosis of Cardiac Syndrome X
Keywords: Cardiac syndrome X, electrocardiography, ventricular activation time
Introduction: Cardiac syndrome X (CSX) is defined as typical angina with detectable ischaemia on noninvasive stress tests without any evidence of coronary artery stenosis during coronary angiography. Impaired coronary microcirculation, inflammation and endothelial dysfunction are accepted aetiological factors for CSX. The ventricular activation time (VAT) has been reported to be prolonged in myocardial ischaemia due to the conduction delay in the Purkinje fibres and the myocytes. In this study, we aimed to investigate the electrocardiographic parameters including VAT in patients with CSX. Patients and Methods: This study enrolled 120 patients (mean age, 54.7 ± 8.6 years; male, 53) diagnosed with CSX and 130 healthy controls (mean age, 53.3 ± 8.9; male, 66) without ischaemia. All patients underwent electrocardiography and transthoracic echocardiography. VAT was defined as the interval from the beginning of the QRS complex until the peak of the R or R' wave. Results: There was no significant difference in terms of demographic, laboratory and echocardiographic parameters between CSX patients and controls. Comparison of electrocardiographic parameters yielded that there was no significant difference in terms of the heart rate, P-wave duration, PR interval, QT and corrected QT intervals between the groups. However, the QRS duration (95.1 ± 13.8 vs. 90.4 ± 12.7 msec; p= 0.006) and VAT (34.8 ± 5.7 vs. 29.2 ± 5.6 msec; p< 0.001) were significantly higher in patients with CSX. Conclusion: The present study demonstrated that QRS duration and VAT were prolonged significantly in patients with CSX. This prolongation may be due to the presence of impaired microvascular perfusion and ischaemia-induced conduction delay.