The Concertina Effect of Pre-excitation

A pt is admitted due to abdominal pain, No palpitations/syncope.

Figure 1

The ECG showed short PR interval (PRI), delta wave and widened QRS (WPW pattern) . After the 5th QRS there is progressive shortening of the PRI and further widening of the QRS. 

Figure 2

This appearance is referred as "concertina effect" of preexcitation.
Concertina form of pre-excitation is a reliable predictor of a relatively long refractory period and thus a marker of low risk of sudden death.


Knight, BP. Anatomy, pathophysiology and localization of accessory pathways in the preexcitation syndrome. In: UpToDate, Downey B (Ed), UpToDate, Waltham, MA. (Accessed on August 10,2015.)

Marco P et al.2009. Adding an Electrocardiogram to the Pre-participation Examination in Competitive Athletes: A Systematic Review. Curr Probl Cardiol ;34:586-662

Surawicz B and Knilans TK. 2008. Chou’s Electrocardiography in Clinical Practice. 6th ed. PA. Saunders-Elseiver

Vivek S et al. 2013. Concertina effect: a subtle but specific marker. BMJ Case Rep (



  1. NICE case! The principal differential diagnosis is between the Concertina Effect (that you show here) — and sinus rhythm with end-diastolic ( = end-cycle) PVCs that nearly coincide with the sinus-conducted QRS complexes. The fact that there is underlying sinus arrhythmia in this example makes it more difficult to assess — but I like lead aVR which to me clearly shows varying degrees of preexcitation for the negative delta wave in this lead. Thanks for presenting!