Impella 5.5 versus HeartMate 3 in Left Ventricular Unloading

The Impella 5.5 (Abiomed) is increasingly used as a bridge to durable left ventricular assist device (LVAD) implantation in advanced heart failure, yet most studies focus on survival and transition success rather than left ventricular (LV) unloading or valvular effects. This study addresses this gap by comparing Impella 5.5 and HeartMate 3 (HM3, Abbott) in terms of unloading and cardiac support at similar flow rates. We conducted a retrospective study of nine patients who received Impella 5.5 before HM3 implantation. The primary outcome was the degree of LV unloading, as assessed by changes in left ventricular end-diastolic diameter (LVEDD). There was no significant reduction in LVEDD from baseline (median 63 mm) to Impella support with medical optimization (median 66 mm; P = .9). In contrast, LVEDD decreased significantly to a median of 55 mm at discharge after HM3 implantation (P = .001). HM3 provides better LV unloading than Impella 5.5 at similar flow rates. These findings suggest that the use of an Impella 5.5, even with medical optimization, may not accurately reflect the degree of unloading achieved with a durable LVAD.