Normal sinus heart rate: appropriate rate thresholds for sinus tachycardia and bradycardia.

Conventional rate limits for sinus rhythm--100/min as the tachycardia threshold and 60/min as the bradycardia threshold--were established by consensus and never formally examined. Because clinical experience indicated that both figures were too high, we investigated this formally in 500 normal individuals. Results were consistent with normal data from the Framingham Study 5,000-subject cohort and the EPICORE Center cohort of more than 18,000 normal persons. Therefore, rounded tachycardia and bradycardia thresholds of 90/min and 50/min for normal sinus rhythm should improve the sensitivity of tachycardia detection and the specificity of bradycardia detection. The appropriate rate range (rounded) for sinus rhythm is 50/min to 90/min.