RELATIONSHIP OF BLOOD PRESSURE WITH QTC INTERVAL AND C-REACTIVE PROTEIN

Abstract

Background: C-reactive protein (CRP) is a systemic inflammatory marker used extensively. QTc interval represents both ventricular depolarization and repolarization. Hypertension is one of the foremost leading causes of morbidity and mortality globally. Objectives: To explore the relationship of systolic blood pressure with QTc interval and CRP levels. Likewise to investigate the association of diastolic blood pressure with QTc interval and CRP levels. Materials and Methods : The study was carried out on 100 randomly selected subjects in the age group of 20-45 years. Both genders were included. Hypertensive subjects on treatment were also included. Three records of blood pressure in the supine position were obtained with 2 minute interval between each and average was considered. QT interval and RR interval were measured from standard 12 lead electrocardiogram (ECG). Tangent method was used for QT interval and later it was corrected for heart rate to arrive at QTc interval using Bazett’s formula. CRP levels were obtained using high sensitivity (hs-CRP) assay kits. Results: There was a positive and significant association for systolic blood pressure with both QTc and CRP. Likewise we also found a positive and significant association for diastolic blood pressure with both QTc and CRP. Discussion: The inflammatory modulatory processes are altered in hypertension, thereby increasing CRP levels. CRP increases endothelin-1 and reduces nitric oxide leading to vasoconstriction and hypertension. Further CRP causes autonomic imbalances by increasing sympathetic activity that lead to hypertension and indirectly prolonging QTc interval. QTc interval is also lengthened by left ventricular hypertrophy as a complication of hypertension. Conclusion : Hypertension with left ventricular hypertrophy can cause cardiac arrhythmias and sudden cardiac death. This may be prevented by early detection of high risk hypertensive subjects or even those prone to develop hypertension using QTc and CRP indicators. Further these markers are cheap and widely used and they provide valuable diagnostic and prognostic features especially in developing countries like India.