Which test is commonly used in cardiology?

The electrocardiogram (ECG or EKG) is a test commonly used in cardiology because it specifically assesses the electrical activity of the heart. By measuring this activity, the ECG provides valuable information about heart rhythm, the size and position of the heart chambers, and can identify any issues such as arrhythmias, ischemia, and previous heart attacks.

In contrast, a chest X-ray is primarily used to evaluate the structures and conditions of the lungs and heart itself, but it does not specifically assess electrical activity or heart function. A complete blood count (CBC) is a broad diagnostic test that evaluates overall health and can help detect a variety of conditions, but it is not tailored for cardiac assessment. Similarly, a respiratory function test focuses on lung capacity and airflow, making it less relevant to cardiac health.

Thus, the electrocardiogram stands out as the primary and most relevant test in the field of cardiology, providing critical insights into heart health that guide diagnosis and treatment.