What is an important clinical feature of hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is characterized by abnormal thickening of the myocardium, particularly affecting the left ventricle. One of the key clinical features of HCM is diastolic dysfunction. This occurs as the thickened walls of the ventricle impair the heart's ability to fill properly during diastole, leading to an increased left ventricular end-diastolic pressure. Patients often present with symptoms related to this dysfunction, such as exertional dyspnea, but the underlying mechanism is a compromised ability of the ventricle to relax and fill adequately.

While other features, such as increased left ventricular size and a mid-systolic ejection murmur, may also be present, they are not as directly indicative of the pathophysiology of HCM as diastolic dysfunction. Increased left ventricular size is typically seen in dilated cardiomyopathy rather than HCM and does not reflect the hallmark effect of myocardial thickening on diastolic filling. The presence of chest pain during rest may occur in some patients, but it is not a consistent or defining feature of HCM and is much less significant than diastolic dysfunction in the context of the disease's overall impact on cardiac function.