Purpose Development of HLA antibodies with the use of durable left ventricular assist devices (LVAD) as a bridge to transplant (BTT) is well established. However, the effect of temporary support devices (TSD) (such as intra-aortic balloon pump (IABP) and Impella 5.5®) on HLA antibodies has not yet been reported. The aim of this study was to assess the effect of TSD as BTT on development and magnitude of HLA Class I and II antibodies compared to durable LVAD pre-transplant. Methods The prevalence and magnitude of HLA Class I and II HLA antibodies was assessed retrospectively from 32 cardiac transplant patients with TSD or durable LVAD as BTT (13 with Impella 5.5® (41%), 8 with IABP (25%), and 11 with durable LVAD (Heart Mate II, Heart Mate III, or HeartWare (34%). One Lambda LABScreen kit was used to detect anti-HLA antibodies in serum samples pre- and post-support device up to the day of heart transplantation. Results The total number of HLA antibodies detected was 22, 22, and 146 in patients with Impella 5.5®, IABP, and durable LVAD respectively (Table 1). There was no significant increase in the number and magnitude of HLA class I and II antibodies after TSD placement (Impella 5.5® and IABP). In contrast, there was a significant increase in the number and magnitude of HLA antibodies in durable LVAD recipients. Mean duration of TSD was between 7-30 days compared to 9 months-10 years for durable LVAD as BTT. Conclusion The short-term use of TSD with either (Impella 5.5® or IABP) as BTT appears to offer a reduced risk profile for developing significant HLA sensitization prior to heart transplantation compared to durable LVAD. Further long-term outcome studies should be considered to establish this potential benefit. Development of HLA antibodies with the use of durable left ventricular assist devices (LVAD) as a bridge to transplant (BTT) is well established. However, the effect of temporary support devices (TSD) (such as intra-aortic balloon pump (IABP) and Impella 5.5®) on HLA antibodies has not yet been reported. The aim of this study was to assess the effect of TSD as BTT on development and magnitude of HLA Class I and II antibodies compared to durable LVAD pre-transplant. The prevalence and magnitude of HLA Class I and II HLA antibodies was assessed retrospectively from 32 cardiac transplant patients with TSD or durable LVAD as BTT (13 with Impella 5.5® (41%), 8 with IABP (25%), and 11 with durable LVAD (Heart Mate II, Heart Mate III, or HeartWare (34%). One Lambda LABScreen kit was used to detect anti-HLA antibodies in serum samples pre- and post-support device up to the day of heart transplantation. The total number of HLA antibodies detected was 22, 22, and 146 in patients with Impella 5.5®, IABP, and durable LVAD respectively (Table 1). There was no significant increase in the number and magnitude of HLA class I and II antibodies after TSD placement (Impella 5.5® and IABP). In contrast, there was a significant increase in the number and magnitude of HLA antibodies in durable LVAD recipients. Mean duration of TSD was between 7-30 days compared to 9 months-10 years for durable LVAD as BTT. The short-term use of TSD with either (Impella 5.5® or IABP) as BTT appears to offer a reduced risk profile for developing significant HLA sensitization prior to heart transplantation compared to durable LVAD. Further long-term outcome studies should be considered to establish this potential benefit.