importance of LV-RV interaction in patients who have undergone TOF repair. 8 Geva et al showed that lower LVEF and older age at repair were the strongest independent factors associated with impaired clinical status in long-term survivors of rTOF. 13 Recently, Diller et al showed that LV longitudinal dysfunction, such as impairment in longitudinal global strain and decreased mitral annular plane systolic excursion, were associated with an increased risk of sudden cardiac death and/or life threatening ventricular arrhythmias in patients with rTOF. 12 Therefore, the assessment of LV function in patients with TOF is crucial because it is the strongest determinant of a poor clinical outcome in these patients. Despite the importance of LV dysfunction, the mechanisms and time course of the development of LV dysfunction remain poorly understood. 14 Its mechanisms and time course in patients with rTOF are important because it has the potential to become T etralogy of Fallot (TOF) is the most prevalent form of cyanotic congenital heart disease. 1 Significant advances in the early management of TOF have dramatically improved the survival of TOF patients, 2 with current 30-year survival rates reaching 89%. 3 However, late ventricular dysfunction related to residual hemodynamic and electrophysiological abnormalities remains a problem, contributing to increasing morbidity and mortality rates beginning in the third decade of life. 2,4-6 Previous investigators assessing ventricular function in patients with repaired TOF (rTOF) have primarily focused on right ventricular (RV) mechanics and their interaction with pulmonary regurgitation (PR). 7-9 Moreover, the importance of left ventricular (LV) dysfunction as a risk factor for long-term adverse outcomes is increasingly acknowledged. (rTOF) is an important risk factor for adverse outcomes. The aim of this study was to assess the details and time course of such LV dysfunction using layer-specific strain analysis by echocardiography.