A patient presents with a grade IV/VI systolic crescendo-decrescendo murmur. What is the most likely pathology?

A grade IV/VI systolic crescendo-decrescendo murmur is most commonly associated with aortic stenosis. This type of murmur typically occurs due to the turbulent blood flow across a narrowed aortic valve during systole. The crescendo-decrescendo pattern signifies that the intensity of the sound rises to a peak (crescendo) as the blood flows through the narrowed opening and then decreases (decrescendo) as the flow exits the valve.

In aortic stenosis, the murmur begins after the first heart sound (S1) and is maximized towards the middle of systole, distinguishing it from other murmurs associated with different conditions. The grade IV indicates that it is a loud murmur that can be heard with a stethoscope, further supporting the diagnosis.

This murmur is often accompanied by clinical symptoms such as exertional dyspnea, chest pain, or syncope, especially in cases of significant stenosis. These clinical features, combined with the characteristic murmur pattern, help to establish a diagnosis of aortic stenosis as the most likely pathology in this scenario.