Final answer:
A cardiologist is most likely to use an electrocardiogram (EKG) procedure to diagnose heart conditions.
Step-by-step explanation:
The medical specialist most likely to use an electrocardiogram (EKG) procedure is a cardiologist. Cardiologists specialize in treating heart diseases, including heart failure. They use an EKG, which measures the electrical activity of the heart, to help diagnose heart conditions. By analyzing the EKG results, a cardiologist can determine if there are any abnormalities in the heart's electrical signals, providing valuable information for diagnosis and treatment.