Age-related increase of thromboxane B(2) and risk of cardiovascular disease in atrial fibrillation

Aging is strictly associated with an increased incidence of cardiovascular events (CVEs) in the general population. Mechanisms underlying the risk of CVEs are still unclear. Platelet activation contributes to the onset of cardiovascular complications. The incidence of atrial fibrillation (AF) increases with age, and the natural history of AF is often complicated by CVEs. We prospectively investigated the relationship between age, urinary thromboxane (Tx) B(2), which reflects platelet activation, and CVEs in 833 AF patients. Median TxB(2) level was 120 [66-200] ng/mg of urinary creatinine. At multivariable linear regression analysis, age (B: 0.097, p=0.005) and previous MI/CHD (B: 0.069, p=0.047) were associated with log-TxB(2) levels. When we divided our population into age classes (i.e. < 60, 60-69, 70-79, ≥ 80 years), we found a significant difference in TxB(2) levels across classes (p=0.005), with a significant elevation at 74.6 years. During a mean follow-up of 40.9 months, 128 CVEs occurred; the rate of CVEs significantly increased with age classes (Log-rank test, p < 0.001). TxB(2) levels were higher in patients with, compared to those without, CVEs in patients aged 70-79 (p < 0.001) and ≥ 80 (p = 0.020) years. In conclusion, TxB(2) levels enhance by increasing age, suggesting that platelet activation contributes to CVEs in elderly patients with AF.