If there is 1 QRS complex per second on an electrocardiogram (ECG), this indicates a heart rate of 60 beats per minute (bpm). Since the heart rate is calculated as the number of QRS complexes (which represent heartbeats) per minute, and there is 1 QRS per second, you simply multiply by 60 seconds in a minute:
1 QRS complex per second × 60 seconds = 60 beats per minute.
This corresponds to a normal resting heart rate range.