In the editorial by Alpert,1 the first aortic stenosis murmur the author heard was not aortic stenosis; it was a regurgitant murmur if it indeed was "obliterating the second heart sound." I suspect that if the diagnosis was in fact aortic stenosis, then the second heart sound (A2) was merely absent.
Robb KV. Clarification on Heart Sound. Arch Intern Med. 2004;164(1):108. doi:10.1001/archinte.164.1.108-a