Relation of QT Dispersion with Left Ventricular Anatomy in Hemodialysis Patients

Ischemic heart disease, ventricular arhythmia and congestive heart failure are major causes of mortality in hemodialysis patients (HDp). The difference between QT intervals measured from surface ECG (QT dispersion) has been found to be associated with fatal arhythmias in various cardiac diseases. In this case-control study, 35 HDp and 31 healthy controls were investigated for correctedmaximum (QTcmax) and minimum (QTcmin) QT durations, their difference; QT dispersion (QTcd) and their correlation with left ventricular dimensions. Mean time spent on dialysis was 32 (14 months. Corrected QT max (448 ± 40 vs 394 ± 22msec, p<0.0001), QTc min (389 ± 36 vs 359 ± 25msec, p<0.0001) and QTcd (59 ± 14 vs 34 ± 7msec, p<0.0001) were significantly prolonged in HDp compared with controls. ln HDp, QTcmax was correlated with interventricular septum thickness (r=0.46, p=0.007), LV posterior wall thickness (r=0.45, p=0.009) and LV mass index (r=0.48, p=0.004). QTcd was correlated with LV posterior wall thickness (r=0.37, p=0.03), interventricular septum thickness (r=0.47, p=0.005), and wall/cavity ratio (r=0.43, p=0.01), but not with LV mass index (r=0.26, p=0.13). In conclusion, QTcmax, QTcmin and QTcd was found to be increased in HDp compared to controls. Increase in QTcd which is a marker of inhomogeneity in repolarisation, was related with wall thickness directly, and was more associated with the degree of uremic cardiomyopathy.