Symmetrical Ambulatory Arterial Stiffness Index: relationship with serum cystatin C levels

Increased central arterial stiffening is the consequence of many disease states such as diabetes, atherosclerosis, and chronic renal disease. Symmetrical Ambulatory Arterial Stiffness Index (Sym-AASI) may provide a simple clinical approach to evaluate arterial stiffness. This study has tried to evaluate the relationship of Sym-AASI with cystatin C levels.

The sample subjects were 53 males and 34 females (mean age = 59.3 ± 13.5 years). Kidney function was evaluated by measuring serum cystatin C and estimated glomerular filtration rate (eGFR). The ambulatory BP was measured noninvasively for 24 h.

Patients in the highest quartile showed an older age (p < 0.001) and worse eGFR (p < 0.001). Pulse pressure (PP) increased as cystatin C was higher. Mean Sym-AASI showed an increase from the first to the last cystatin C quartile. Correlation test showed a significant relationship of Sym-AASI with age (r = 0.573), serum creatinine (r = 0.237), eGFR (-0.323), cystatin C (r = 0.427), systolic blood pressure (r = 0.525), and PP (r = 0.647). Multivariate regression analysis showed that age, cystatin C, nocturnal systolic blood pressure reduction, and nocturnal diastolic blood pressure fall were independently related to Sym-AASI. There was not any independent association between eGFR and Sym-AASI or between cystatin C and PP.

Increased Sym-AASI seems to be independently associated with serum cystatin C levels. Sym-AASI seems to be better than PP to detect changes in the arterial wall. This could be a simple and easy method to evaluate arterial stiffness in hypertensive patients without needing more complex devices.