Introduction: QT dispersion (QTd) is a measure of non-homogeneous repolarisation of the myocardium and is used as an indicator of arrhythmogenicity.
Objective: The aim of this study was to assess the relation between QT dispersion, left ventricle systolic function and frequency of ventricular arrhythmias in coronary patients.
Method: We studied 290 coronary patients, 72 with angina pectoris and 218 after myocardial infarction. Eighty-one coronary patients had frequent and complex ventricular arrhythmias (out of them 19 had ventricular tachycardia) and 209 were without arrhythmias or with infrequent ventricular premature contractions (VPC < or = 10/h). In all patients, QT dispersion, exercise test, 24-hour Holter monitoring and echocardiographic examination were performed.
Results: Patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd (71.8 +/- 25.5 vs 55.6 +/- 21.7 ms; p < 0.001), corrected QT dispersion (QTdc: 81.3 +/- 31.5 vs. 60.3 +/- 26.1 ms; p < 0.001 ), left ventricular end-diastolic diameter (LVEDd: 56.2 +/- 6.9 vs. 53.4 +/- 6.2 mm; p < 0.001) and left ventricular end-systolic diameter (LVESd: 39.5 +/- 6.2 vs. 36.0 +/- 6.3 mm; p < 0.001), and significantly lower values of left ventricular ejection fraction (LVEF: 47.7 +/- 13.9 vs. 55.9 +/- 11.6%; p < 0.001) in comparison to those without arrhythmias or with infrequent VPC. Patients with VT had significantly higher values of QTd and QTdc in comparison to other patients with frequent and complex ventricular arrhythmias (83.8 +/- 17.1 vs. 69.4 +/- 26.2 ms; p < 0.02 for QTd; 101.1 +/- 23.9: 77.6 +/- 31.4 ms; p < 0.005 for QTdc). There is a significant negative correlation of QTd and QTdc with LVEF, and a significant positive correlation of QTd and QTdc with inside dimensions of the left ventricle, in patients with frequent and complex ventricular arrhythmias.
Conclusion: The study demonstrated that patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd and QTdc, as well as a higher degree of left ventricle systolic dysfunction in comparison to those without arrhythmias or with infrequent VPC.