Treatment options for hypoplastic borderline left ventricle (LV) are critically dependent on the development of the LV itself and include different types of univentricular palliation or biventricular repair performed at birth. Since hybrid palliation allows deferring major surgery to 4–6 months, in borderline cases, the decision can be postponed until the LV has expressed its growth potential. We aimed to evaluate anatomic modifications of borderline LV after hybrid palliation. We retrospectively reviewed data from 45 consecutive patients with hypoplastic LV who underwent hybrid palliation at birth between 2011 and 2015. Sixteen patients (mean weight 3.15 Kg) exhibited borderline LV and were considered for potential LV growth. After 5 months, five patients underwent univentricular palliation (Group 1), eight biventricular repairs (Group 2) and three died before surgery. Echocardiograms of Groups 1 and 2 were reviewed, comparing LV structures at birth and after 5 months. Although, at birth, all LV measurements were far below the normal limits, after 5 months, LV mass in Group 2 was almost normal, while in Group 1, no growth was evident. However, aortic root diameter and long axis ratio were significantly higher in Group 2 already at birth. Hybrid palliation can be positively considered as a “bridge-to-decision” for borderline LV. Echocardiography plays a key role in monitoring the growth of borderline LV.