**Core Concept**
Diastolic dysfunction of the left ventricle refers to a condition where the left ventricle is unable to relax and fill properly during diastole, leading to impaired diastolic function and increased filling pressures. This condition can be caused by various factors such as hypertension, coronary artery disease, or cardiomyopathy.

**Why the Correct Answer is Right**
Diastolic dysfunction is characterized by a stiff left ventricle, which is unable to relax and fill during diastole. This leads to increased left ventricular end-diastolic pressure (LVEDP) and decreased left ventricular compliance. The left ventricle's inability to relax and fill properly can lead to symptoms such as dyspnea, fatigue, and palpitations. The pathophysiology involves the altered function of the left ventricle's myocardial cells, including the disruption of normal calcium handling and the altered expression of genes involved in cardiac development and function.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because diastolic dysfunction is often associated with a stiff left ventricle, which is unable to relax and fill properly. A stiff left ventricle is not able to accommodate the increased volume during diastole, leading to increased filling pressures.

**Option B:** This statement is incorrect because diastolic dysfunction is often characterized by a decrease in left ventricular compliance, which refers to the left ventricle's ability to accommodate increased volume without a significant increase in pressure. Decreased compliance is a hallmark of diastolic dysfunction.

**Option C:** This statement is incorrect because diastolic dysfunction is often associated with an increase in left ventricular end-diastolic pressure (LVEDP), not a decrease. Increased LVEDP is a consequence of the stiff left ventricle's inability to relax and fill properly.

**Option D:** This statement is incorrect because diastolic dysfunction is often associated with an increase in systolic blood pressure, not a decrease. The increased afterload and stiffness of the left ventricle can lead to increased systolic blood pressure.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that diastolic dysfunction is often characterized by a "stiff" left ventricle, which is unable to relax and fill properly. This can be remembered using the mnemonic "STIFF" - Stiffness, Thickening, Increased Filling Pressures, and Fibrosis.

**Correct Answer: B. Decreased left ventricular compliance is a hallmark of diastolic dysfunction.**