This ECG shows signs of right ventricular enlargement, right atrial enlargement, and right axis deviation in a 20-year-old male with a known history of congenital heart disease. The ECG findings include tall peaked P waves in lead 2, predominantly positive P waves in V1, and an S1S2S3 pattern. Based on these criteria, along with the right axis deviation and clock-wise rotation, the diagnosis is tetralogy of Fallot.