It is more likely to make a correct diagnosis of unfrequent disease when you remember this disease. 

A middle aged woman, apex of the heart:

There is a typical auscultatory finding of a widespread cardiological condition. If you do not know what I mean, I will explain later. The most dramatic event happened nearly five years after this recording has been made when this patient returned with complaints of fever and night sweats during last four months. 

Apex of the heart, supine position:

Apex of the heart, left decubitus position:

Apex of the heart, standing position:

The late systolic murmur has changed: now it is louder and longer.

What is the diagnosis?
At both cases, there was late systolic murmur, which is very typical sign of mitral valve prolapse.
This murmur has changed at the time of fever. Mitral valve prolapse rises the risk of infective endocarditis:

There are prolapse and vegetations of both mitral valve’s leaflets. This is infective endocarditis.

Despite the fact that mitral valve prolapse is not an indication for infective endocarditis’ prophylaxis now, it significantly increases the risk of this dangerous condition. Sometimes the diagnosis is simple like in this case. But even in this case, the diagnosis was not made during some months.