An 18 year old male dies suddenly during a track and field event. During a recent sports physical he was noted to have a II/VI systolic crescendo-decreshendo murmur at the right upper sternal border that became louder with Valsalva. A paradoxical split S2 heart sound was heard. Which of the following is his likely diagnosis?
A. Congenital coronary anomaly
B. Comotio cordis
C. Idiopathic hypertrophic subaortic stenosis
D. Dilated cardiomyopathy