Comparative assessment of renal function by cystatin C level in patients with hypertension and extrasystole

Abstract

Although the tight connection of the cardiovascular system and the kidneys is well known, using of cystatin C (Cys-C) opens new horizons in studying early renal failure stages. The study aimed to compare the functional status of the kidneys in patients with hypertension and extrasystole to the level of Cys-C. 156 patients with stage II hypertension (EH II) were examined. 124 of them had frequent symptomatic extrasystoles (74 - of supraventricular origin and 50 - ventricular), 32 patients had no arrhythmias, and were referred to the comparison group. The control group consisted of 30 healthy people with normal blood pressure (BP). All patients underwent a complete clinical examination, blood pressure measurement, daily blood pressure monitoring, daily electrocardiogram monitoring, echocardiography, and determination of renal function (creatinine, blood electrolytes, serum cystatin C) followed by calculation of glomerular filtration rate (GFR). The level of Cys-C in patients with hypertension was significantly higher (p<0.001) compared with healthy individuals. Among patients with arrhythmias, the highest level of Cys-C was noted in patients with ventricular arrhythmias. The correlation analysis showed that the level of Cys-C was higher in the presence of frequent extrasystoles (namely of ventricular origin), smoking, high blood pressure, increased systolic and pulse blood pressure, the presence of concentric left ventricular hypertrophy, dyslipidemia, increased creatinine level and decreased GFR. All three EH II patient groups had significantly lower GFR (calculated by creatinine level) (p<0.001). The lowest creatinine-based GFR was revealed in patients with ventricular extrasystole. All patients with EH II had significantly lower Cys-C based GFR than the control group (p<0.001). Mean Cys-C-based GFR values in patients with extrasystole were significantly lower than in patients without extrasystole (p<0.03). The analysis of GFR levels depending on the extrasystole origin was provided. The lowest level of GFR was recorded in patients with ventricular extrasystole. It was significantly different from the patients with supraventricular extrasystole (p=0.02). Our findings confirm the opinion of other researchers that Cys-C is an early marker of renal dysfunction in patients with hypertension, which is more sensitive than creatinine. Another finding is that ventricular extrasystole is more hemodynamically and metabolically unfavorable compared to supraventricular based on clinical and prognostic evaluation