Which of the following is an indication of an electrical issue in the heart?

Arrhythmia indicates an electrical issue in the heart. It refers to any variation from the normal rhythm of the heart, which can arise from disruptions in the heart's electrical conduction system. This can manifest as irregular heartbeats, whether too fast, too slow, or erratically.

The heart's rhythm is orchestrated by electrical impulses that result in synchronized contractions of the heart muscles. When there is an arrhythmia, it suggests that these impulses are not functioning properly, which can lead to various complications, including decreased cardiac output, increased risk of stroke, or even sudden cardiac arrest, depending on the type of arrhythmia.

In contrast, a normal sinus rhythm and normal heart rate suggest that the heart's electrical system is functioning properly without any disturbances. Stable angina, related to inadequate blood flow usually due to coronary artery disease, does not specifically indicate an electrical problem, as it pertains more to ischemia rather than the heart's electrical conduction. Thus, arrhythmia is the clear indicator of electrical issues within the heart.