Inverse association of alanine aminotransferase within normal range with prognosis in patients with coronary artery disease

Background: Data regarding the association between alanine aminotransferase (ALT) and prognosis of patients with coronary artery disease (CAD) are limited. The aim of this study was to assess the association of ALT with the prognosis of patients with CAD. Methods: The study included 9523 patients with angiography-proven CAD who underwent percutaneous coronary intervention. Baseline ALT activity measurements were available for analysis in all patients. The primary outcome was 3-year cardiac mortality. Results: Patients were divided into three groups: a group with ALT within the 1st tertile (ALT 2.0 U/L to ≤17.0 U/L; n = 3276 patients), a group with ALT within the 2nd tertile (ALT >17.0 U/L to ≤26.0 U/L; n = 3075 patients) and a group with ALT within 3rd tertile (>26 U/L to ≤50.0 U/L; n = 3172 patients). Cardiac death (primary outcome) occurred in 441 patients: 201 (7.1%), 126 (4.7%) and 114 (4.0%) of these occurring in patients in the 1st, 2nd and 3rd ALT tertiles, respectively (with percentages representing Kaplan–Meier estimates of 3-year cardiac mortality); adjusted hazard ratio = 1.43, 95% confidence interval 1.11 to 1.85, P = 0.006 calculated for 1 unit decrement in the logarithmic scale of ALT. The multivariable model for cardiac mortality with baseline variables without ALT had a C-statistic of 0.827 [0.801–0.853], P < 0.001, which increased to 0.832 [0.806–0.857], P < 0.001 after incorporation of ALT (P = 0.020). Conclusions: In patients with CAD, ALT was inversely and independently associated with the risk of 3-year cardiac mortality. Low ALT may reflect cardiovascular risk that is poorly mediated by traditional cardiovascular risk factors.