Differentiating Supraventricular Tachycardia from Sinus Tachycardia on ECG

Key Differentiating Features

The European Society of Cardiology recommends examining the rate, regularity, P wave morphology, and R-R interval variation patterns to differentiate supraventricular tachycardia (SVT) from sinus tachycardia on ECG 1
Sinus tachycardia is almost always <230 beats/min, with a gradual acceleration and deceleration over several seconds 1
SVT typically has rates of 260-300 beats/min, especially in infants, and demonstrates extreme regularity after the first 10-20 beats 1
In adults, SVT rates are typically >150 beats/min, while sinus tachycardia rarely exceeds 180 beats/min 2

The American Heart Association suggests that sinus tachycardia is typically associated with an identifiable cause, such as fever, sepsis, hypovolemia, pain, anxiety, or medications 1
SVT often occurs in patients who are otherwise healthy, and when in doubt, vagal maneuvers or adenosine administration can help differentiate, as sinus tachycardia will gradually slow while SVT will either abruptly terminate or transiently slow revealing underlying atrial activity 2
A diagnostic algorithm can be used to differentiate SVT from sinus tachycardia, starting with checking heart rate, examining R-R interval pattern, analyzing P wave morphology, and considering clinical context 1, 2

The American College of Cardiology recommends comparing with previous ECGs during normal sinus rhythm to assess P wave morphology, and considering recording a 12-lead ECG during vagal maneuvers or adenosine administration to reveal the underlying mechanism 2, 4