Abstract 2965: QT Interval Prolongation during Severe Acute Rejection is Predictive of Sudden Cardiac Death in Heart Transplant Recipients
Background. QT interval prolongation is considered a risk factor for sudden cardiac death (SCD) in various non-transplant populations. Since acute allograft rejection is associated with a prolonged QT interval, we sought to investigate the effects of rejection-induced QT interval changes on SCD in heart transplant recipients.
Methods. Of all patients who underwent heart transplantation between 1998 and 2007, we enrolled those with severe acute cellular rejection episodes (ISHLT grade 3A or higher, accompanied with hemodynamic compromise). In this cohort, baseline ECGs were obtained within 7 days after transplantation; follow-up ECGs were recorded at the time of the rejection episode. On all ECGs, QT interval was defined as the mean duration QT interval measurements in all leads, and corrected for heart rate with Bazett formula. A significant increase of QTc during rejection (dQTc) was defined as a relative change in QTc ≥10%. Patients were followed for SCD for 1 year after the rejection episode.
Results. Of 80 patients with a severe rejection episode, 9 (11%) were excluded because of the inadequate quality of ECG recordings. Within the 1-year follow-up, 21 of 71 (30%) patients died. Of these, 14 (67%) died of SCD, and 7 (23%) died of other causes. Patients who died of SCD and survivors did not differ with regards to age (44 ± 12 years in SCD group vs. 46 ± 16 years in survivors, P = 0.61), gender (male: 83% vs. 58%, P = 0.06), incidence of infections (0.21 ± 0.43 vs. 0.20 ± 0.40, P = 0.91), malignancy (0% vs. 8%, P = 0.84), or allograft vasculopathy (29% vs. 26%, P = 0.85). No difference in Qtc prolonging drug was noted. During acute rejection, QTc interval was significantly longer in SCD group than in survivors (475 ± 57 ms vs. 437 ± 36 ms, P = 0.01), and the same was true for the incidence of dQTc > 10% (50% vs. 16%, P = 0.008). SCD-free survival as evaluated by Kaplan-Meier analysis was significantly lower in patients with dQTc > 10% (P = 0.013). On multivariate analysis, dQTc > 10% was the only independent predictor of SCD (P = 0.02). The multivariate model included left ventricular dysfunction (LVEF < 30%) and dQTc.
Conclusion. Heart transplant recipients who display a significant (> 10%) prolongation of QT interval during a severe acute rejection episode may be at increased risk for SCD.