Effect of QT Interval Prolongation on Cardiac Arrest following Liver Transplantation and Derivation of a Risk Index.

Abstract

Liver transplantation(LT) has a four-fold higher risk of periprocedural cardiac arrest and ventricular arrhythmias(CA/VA) compared with other noncardiac surgeries. Prolongation of the corrected QT interval(QTc) is common in patients with liver cirrhosis. Whether it is associated with an increased risk of CA/VA following LT is unclear. Rates of 30-day CA/VA post-LT was assessed in consecutive adults undergoing LT between 2010-2017. Pre-transplant QTc was measured by a cardiologist blinded to clinical outcomes. Among 408 patients included, CA/VA occurred in 26(6.4%) patients. QTc was significantly longer in CA/VA patients(475±34 vs 450±34 milliseconds, p<0.001). Optimal QTc cut-off for prediction of CA/VA was ≥480ms. After adjustment, QTc≥480ms remained the strongest predictor for the occurrence of CA/VA(Odds ratio[OR] 5.2 95%CI 2.2-12.6). A point-based cardiac arrest risk index(CARI) was derived with the bootstrap method for yielding optimism-corrected coefficients(2-points:QTc ≥480, 1-point:MELD≥30, 1-point:age≥65 and 1-point:male). CARI score≥3 demonstrated moderate discrimination(c-statistic 0.79, optimism-corrected c-statistic 0.77) with appropriate calibration. Conclusion: QTc≥480ms was associated with a five-fold increase in the risk of CA/VA. The CARI score may identify patients at higher risk of these events. Whether heightened perioperative cardiac surveillance, avoidance of QT prolonging medications or beta-blockers could mitigate the risk of CA/VA in this population merits further study.