Cardiac Medicine Certification (CMC) Practice Exam

Digoxin is a medication that is commonly used in the management of heart failure, primarily for its ability to improve cardiac contractility. It works by inhibiting the Na+/K+ ATPase pump in cardiac myocytes, which increases intracellular sodium concentration. This leads to an increase in intracellular calcium levels via the sodium-calcium exchanger, ultimately enhancing the force of myocardial contractions. This is particularly beneficial for patients with heart failure as it helps to improve symptoms and functional capacity. In addition to its positive inotropic effects, digoxin also has a secondary action of slowing down the heart rate by modulating the autonomic nervous system, making it useful for patients who may also suffer from atrial fibrillation or flutter. Other options serve different purposes in cardiac care. Warfarin is an anticoagulant used to prevent thromboembolic events, atorvastatin is a statin used for managing cholesterol levels, and furosemide is a diuretic used to manage fluid overload in heart failure, but it does not directly enhance heart contractility. Thus, the role of digoxin as a positive inotropic agent makes it the correct choice for improving contractility in heart failure management.