Adult survivors of congenital heart disease form a continuously growing population, as each successive cohort graduating from pediatric care expands the total number of patients worldwide. Consequently, there is an increasing interest and study of their late pathophysiology, the understanding of which can only truly be understood during very long-term follow-up. Indeed, we have already learned that, for some patient groups, hitherto unexpected problems may only develop decades after surgery. Consequently, many patients require careful follow-up in ACHD clinics throughout life. However, in the most frequent congenital heart disease, ventricular septal defect (VSD), most guidelines recommend that specialized follow-up in ACHD clinics may only be indicated for those patients with significant residual anatomic problems, or overt pulmonary hypertension. Indeed, the late outcome for patients undergoing 'uncomplicated' repair in childhood has been described as benign. However, recent data suggest that such characterization may be premature. Several studies have described abnormalities of right ventricular structure and function which, in turn, may be directly related to abnormal functional capacity when formally tested. Furthermore, the longer-term implications of e.g. right bundle branch block and chronotropic incompetence continue to be explored. In this review we will examine these emerging data, and discuss whether amendments to the international guidelines for these patients' may be justified.