**Core Concept**
Atrial Septal Defect (ASD) is a congenital heart defect characterized by an abnormal opening in the atrial septum, allowing blood to flow between the left and right atria. This defect can lead to various complications, including right-sided heart enlargement and failure.

**Why the Correct Answer is Right**
The correct answer states that complications of ASD do not typically include left atrial hypertrophy. This is because ASD primarily affects the right side of the heart, leading to right atrial and ventricular enlargement due to increased blood flow. The left atrium is not directly affected by the defect, and left atrial hypertrophy is not a characteristic complication of ASD. The increased blood flow through the left atrium is actually a result of the shunt, but the left atrium does not hypertrophy in response to this increased flow.

**Why Each Wrong Option is Incorrect**
**Option B:** Complications due to ASD are not of late onset. In fact, the symptoms of ASD can be present at birth or become apparent during childhood, often due to respiratory or cardiac symptoms.

**Option C:** While ASD is the most common congenital heart defect, it is not typically the most common congenital heart disease to present in adult age. Conditions like VSD (Ventricular Septal Defect) and PDA (Patent Ductus Arteriosus) are more likely to present in adulthood.

**Option D:** A wide fixed split in the second heart sound is a characteristic feature of ASD, particularly in younger patients. This occurs due to the increased flow through the pulmonary valve, resulting in a longer duration of the pulmonary component of the second heart sound.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that ASD can be asymptomatic in childhood, especially if the defect is small, and symptoms may only become apparent during adulthood. A thorough physical examination, including assessment of the heart sounds, can often reveal the presence of ASD.

**✓ Correct Answer: A. Complications include Left Atrial hypertrophy**