An Irregular wide QRS Complex Rhythm

Abstract

There are clearly visible sinus P-waves in the first two beats and in the last one (marked with * in Figure 1). From the third beat an irregular wide QRS complex rhythm with left bundle branch block (LBBB) morphology begins, without visible P-waves. Although the LBBB may suggest a supraventricular rhythm, the second beat is a fusion complex, revealing a ventricular origin of the wide QRS complex rhythm. On an accurate analysis indeed, the second beat has shorter PR interval and a different QRS morphology compared to the previous one (in DI lead for example it is entirely positive and slightly wider comparing to the previous one which is isodifasic and narrow).