A 13-year-old girl developed the features of congestive heart failure on day three of intracardiac repair of tetralogy of Fallot. A routine transthoracic echocardiography identified the missed supramitral ring (SMR), closely placed just above the mitral valve, the very reason for severe mitral stenosis and its implication in the present clinical deterioration. A rare association of SMR with tetralogy of Fallot may be missed narrowly because closely placed SMR can sometimes mask its hemodynamic effect when present with significant right ventricular outflow tract obstruction as in this case.

<Learning objective: This case report highlights when a case of complex congenital heart disease is referred for intervention or surgery, it is better to be verified by a pediatric cardiologist. Tetralogy of Fallot (TOF) associated with supramitral ring (SMR) is reported as an anecdotal case report. Although it is a mistake, it may be possible to miss the SMR when it is associated with TOF. The reasons are threefold: (1) The rare association of SMR with TOF. (2) The close proximity of SMR to mitral valve. (3) Right ventricular outflow obstruction in TOF reduces flow across mitral valve i.e. a low cardiac output state.>