What does the QT interval assess on an ECG strip?

The QT interval on an ECG strip represents the time from the beginning of the QRS complex to the end of the T-wave. It reflects the total time taken for ventricular depolarization and repolarization. An extended QT interval can indicate issues with the heart's electrical activity, potentially leading to life-threatening arrhythmias. Therefore, understanding this interval is crucial for evaluating cardiac health and diagnosing various conditions.

The other choices do not accurately describe the QT interval. The P wave relates to atrial depolarization and does not encompass the full process of ventricular activity, while the R-R interval measures the time between heartbeats, not accounting for the repolarization of the ventricles. Lastly, mentioning only the R-R interval ignores the crucial aspects of depolarization and repolarization that the QT interval assesses.