R Wave Peak Time RWPT

R Wave Peak Time (Intrinsicoid deflection)

The time from the onset of the earliest Q or R wave to the peak of the R wave in the lateral leads (aVL, V5-6).

Represents the time taken for excitation to spread from the endocardial to the epicardial surface of the left ventricle.
R-wave peak time is said to be prolonged if > 45ms.
Additionally used in Lead II in the differentiation of Ventricular Tachycardia (VT) and Supraventricular Tachycardia (SVT) with aberrancy.

Causes of Prolonged RWPT

Prolonged R-wave peak time in aVL due to left anterior fascicular block

RWPT in wide QRS complex tachycardia

R-wave peak time (RWPT) can be used in differentiating ventricular tachycardia (VT) from supraventricular tachycardia (SVT) in patients with wide QRS complex tachycardia

RWPT duration is measured in Lead II from the onset of QRS depolarization until the first change of polarity (with both positive or negative QRS deflection)

Studies in 2010 and 2013 demonstrated RWPT ≥ 50 ms in lead II to be a simple, reproducible, sensitive and specific for ventricular tachycardia.

However, more recent studies suggest RWPT of 50 ms may be optimal to differentiate between VT and SVT with RBBB and LAFB, but not with LBBB

Ventricular tachycardia.
Positive deflection wide QRS
R-wave peak time (RWPT) >50 ms

R-Wave Peak Time (RWPT) Lead II negative

Ventricular tachycardia.
Negative deflection wide QRS
R-wave peak time (RWPT) >50 ms

Supraventricular tachycardia with aberrancy.
Negative deflection wide QRS
R-wave peak time (RWPT) <50 ms

Reference

Pava LF, Perafán P, Badiel M, Arango JJ, Mont L, Morillo CA, Brugada J. R-wave peak time at DII: A new criterion for differentiatingbetween wide complex QRS tachycardias. Heart Rhythm. 2010 Jul;7(7):922-6. [PMID 20215043]
Datino T, Almendral J, Avila P, González-Torrecilla E, Atienza F, Arenal A, Fernández-Avilés F. Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect. Heart Rhythm. 2013 Sep;10(9):1393-401. [PMID 23851057]
Yu M et al. R-Wave Peak Time at Lead II in Adults With Ventricular Premature Beats, Bundle Branch Block and Left Anterior Fascicular Block. Am J Med Sci. 2018 Jan;355(1):44-47 [PMID 29289261]