Consequently, no recommendations regarding specific medical therapy for systolic dysfunction of the systemic right ventricle can be made. In addition to the report provided by the ERC regard- ing angiotensin-converting enzyme inhibitor, angioten- sin-receptor blocker, and aldosterone antagonist use for patients with systemic right ventricles, beta block- ers and other commonly used HF medications lack data to support recommendations in the treatment of atrial Concerns regarding rou- tine use of beta blockers for asymptomatic RV dysfunc- tion include potentially greater predisposition to brady- cardia and limited distensibility of the interatrial baffle, which creates a preload limited physiology.S4.4.1.1-8 Al- though no clear benefit has been demonstrated for HF medical therapy overall, there is speculation of benefit in more symptomatic patients or those with larger and/ or more dysfunctional right ventricles. Patients with dysfunction of the systemic right ven- tricle are at risk of developing ventricular arrhythmias. The role of ICD implantation for primary prevention of arrhythmia in patients with a low systemic ventric- ular ejection fraction is uncertain. This practice is un- supported by any research and cannot be universally recommended. Many such patients do not progress to receive therapies from their device.S4.4.1.1-2 Decisions re- garding primary prevention ICD implantation is based on the patients' full clinical presentation and in con- sultation with cardiac electrophysiologists with ACHD expertise. CLINICAL STATEMENTS AND GUIDELINES See Section 3.3 for recommendations on who should perform surgeries, cardiac catheterization, and other procedures in these patients; Section 3.4 for rec- ommendations on diagnostic evaluation; Table 29 for routine testing and follow-up intervals; and Online Data Supplement 25 for referenced studies. Recommendation-Specific Supportive Text 1. 