This is cardiac hypertrophy involving the left ventricle. The number of myocardial fibers does not increase, but their size can increase in response to an increased workload, leading to the marked thickening of the left ventricle in this patient with systemic hypertension.

Question: Why is bigger not always better?

AnswerThis 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.