This is cardiac hypertrophy involving the left ventricle. The number of myocardial fibers does not increase, but their size can increase in response to a greater workload, leading to the marked thickening of the left ventricle. This patient with systemic hypertension had increased cardiac workload from the higher blood pressure.

Question: Why is bigger not always better?

Answer
This compensatory hypertrophy is pathologic because the process is maladaptive over time, with eventual myocyte loss, fibrosis, and ventricular dysfunction. In contrast, athletic training leads to minimal increase in heart size, but marked increase in cardiac function.