Background: The bridging of end stage heart failure patients with continuous flow ventricular assist devices (CF-VADs) has improved the survival of these patients and has enabled longer waiting periods prior to heart transplantation (HTx). However, many patients suffer from VAD-related infections and prolonged support periods over 2 years has been suggested to affect early morbidity. We investigated the impact of prolonged waiting periods and other possible risk factors on the severity of post-operative infections after HTx. 
Methods: After Institutional Review Board approval (#16353), all HTx adult recipients from 2010 to 2016 were enrolled and retrospectively reviewed. Our primary outcome was the severity of 30-day acute post-operative infections. We categorized the severity of infections into 4 groups according to the following grading; None, Minor: infections resolving in < 14 d, Major: infections resolving in >14 d, and Severe: septic shock. Values were compared using the Wilcoxon rank-sum test. A logistic-regression model for ordinal responses was used in our multivariable analysis. Age, sex, BMI, length of CF-VAD support, active VAD-specific infections and moderate to severe primary graft dysfunction (PGD) were included as possible risk factors. A p-value of < 0.05 was considered statistically significant. 
Results: Fifty-two patients were included in our study. The median support period for recipients with CF-VADs was 964 d (interquartile range: IQR 571 - 1135). Infections occurred in 20 (38.5%) with the following severity: None 32 (61.5%), Minor 8 (15.4%), Major 8 (15.4 %), and Severe 4 (7.7%). Active VAD specific-infections and moderate to severe PGD was present in 38.5% and 25% of the recipients, respectively. The length of ICU stay was significantly longer for patients with severe infections (median 18 d, IQR 10-13) when compared to all other groups (median18d IQR (13 - 108) p < 0.01). In our multivariable analysis, active VAD-specific infections (odds ratio: OR 5.3, 95% confidence interval: CI 2.6 - 13.0, p < 0.01) and moderate to severe PGD (OR 2.5, 95%CI 1.2 - 5.6, p = 0.02) were independent risk factors for the increased severity of 30-day acute post-operative infections. The length of VAD support was not significant (p =0.92). Conclusions Active VAD-specific infections and moderate to severe PGD increases the severity of 30-day acute post-operative infections after HTx. The length of CF-VAD support does not impact early morbidity.

Factors related to the severity of early post-operative infection after heart transplantation in patients surviving prolonged mechanical support periods: experience from a single university center