COMPARISON OF QTc AND QT DISPRESION IN PREDICTION OF CARDIOVASCULAR MORTALITY AND MORBIDITY AMONG THE PATIENTS WITH CHRONIC RENAL FAILURE
Abstract
Introduction: QT interval dispersion (QT-d), measured as the difference between the maximum and minimum QT interval on a standard 12 lead electrocardiograph (ECG), is a normal phenomenon. Corrected QT interval (a rate related QT interval), QTc can be calculated on QT/√R-R and normally is ≤0.44 second. Corrected QT interval dispersion can predict adverse cardiovascular outcome however QTd is a measure of regional heterogeneity in myocardial repolarization.
Aim: The objective of the present study is to assess the effects of cardiovascular morbidity and mortality by comparing the predictive values of QTc and QTd in the patients with chronic renal failure. Along with this the study also evaluates the relationship of QTc and QTd with serum sodium and potassium.
Materials and methods: Patients of chronic renal failure were included in the study. Patients of both gender and age of above 15 years with CRF on hemodialysis were selected for the study. Routine biochemistry levels, including sodium, potassium, and ionized calcium was measured pre and post hemodialysis at the time of ECG. Patients over 15 years of age with serum creatinine level >1.5 mg/dl and blood urea >40 mg/dl were included in the study.
Results: A total of 40 patients from both genders (24 males and 16 Females) were studied. 7 patients (20.5%) of CRF died of various causes in the 1-year follow-up period. 6 (15%) patients died due to cardiovascular causes whereas 1 (2.5%), the patient died due to blood transfusion reaction. There is a statistically significant difference found between the mean values of QTd and QTc between predialysis and post dialysis measurement. The t value shows the QTd value is more significant in case of prediction of Hypertension, CHF, IHD and Arrhythmias in CRF patients on haemodialysis. The QTc interval calculation may represent a simple method of monitoring patients with high risk of sudden death.
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