We thank Sookaromdee and Wiwanitkit [1] for their correspondence regarding our study investigating the outcomes after repair of cor triatriatum sinister [2]. Cor triatriatum sinister itself, unless it is associated with inflow obstruction, generally has a benign prognosis [3], although surgical intervention might be required mostly owing to associated defects, such as anomalous pulmonary venous connection, atrial septal defect, mitral valve anomalies, and so forth. There is no doubt that cor triatriatum itself could be repaired rather easily without concerns about recurrence; however, future development of individual pulmonary vein stenosis or the progression of preexisting pulmonary hypertension should be followed over the longer term, as Sookaromdee and Wiwanitkit [1] mentioned in their correspondence. The timing of surgical repair might depend upon symptoms usually associated with coexisting anomalies or associated inflow obstruction, but even in asymptomatic patients without inflow obstruction, cor triatriatum can be safely and effectively repaired in the era of prenatal diagnosis.