Which change on an EKG might indicate congestive heart failure?

In patients with congestive heart failure, one significant finding on an electrocardiogram (EKG) is left atrial hypertrophy. This condition occurs due to the increased pressure and volume load in the left atrium as a result of poor left ventricular function and elevated left atrial pressure. The EKG changes associated with left atrial hypertrophy can include a broad, notched P wave, or an increased amplitude in P wave visible in leads I, II, and V1. These changes reflect the structural alterations in the heart due to long-standing pressure overload or volume overload typically associated with heart failure.

The other options do not directly correlate to congestive heart failure in the same way. ST elevation is generally indicative of acute myocardial infarction or other acute ischemic events. Ventricular fibrillation represents a critical, life-threatening arrhythmia that does not specifically indicate heart failure. A prolonged QT interval can be associated with various conditions, including electrolyte imbalances and certain medications but is not a direct marker of congestive heart failure. Therefore, left atrial hypertrophy is the correct change to note on an EKG as it provides information regarding the heart's structure and function in the context of heart failure.