This ECG is from a 19 year old asymptomatic male who was known to have a loud systolic murmur similar to that depicted here. The murmur was detected 2 years prior to the recording of this ECG, was best heard in the 4th left intercostal space and was associated with a palpable thrill at that location. How would you interpret the ECG and what does it tell you about the murmur?