To the editor: In the recent paper presenting the latest insights into the therapeutic options for patients with systemic right ventricles, Winter et al1 argued that “the pragmatic use of angiotensin converting enzyme inhibitors and β blockers in these patients seems appropriate”. However, they also concluded that “the evidence base for the implementation of left ventricular failure treatment regimens in patients with a systemic right ventricle is poor” and that “most studies were underpowered, had short follow-up periods, or had a retrospective study set-up”.

There is, however, another important reason for the failure to demonstrate the efficacy of angiotensin converting enzyme inhibitors, …