I have written before about a sub group of Cardiac resynchronization patients (CRT) who have a hyper response with marked improvement in indices of cardiac function, e.g. ejection fraction and end diastolic volume.
Such responses have been reported with Biventricular pacing (Bi-V) and His Bundle Pacing ( HBP). There are two forms or types of HBP: 1) pure HBP also known as selective and 2) Para Hisian pacing also known as non selective HBP.
The QRS is normalized with selective HBP while in nonselective although the widened QRS duration is significant reduced it may not be restored to the pre bundle branch block configuration. There is both activation of the His Bundle fibers and adjacent ventricular septal muscle giving a fused or fusion ventricular activation pattern and an EKG with a delta wave resembling pre-excitation pattern.
According to Lida et al writing in the December 2016 Journal of Arrhythmia (1) "there seems to be no significant clinical difference between selective HBP and non selective HBP because both do not alter physiological impulse conduction and possibly maintain rapid and synchronous LV ( left ventricular) activation "
A similar case report was published by Ajijola et al from UCLA in 2015 (2)
His Bundle pacing seems to gaining momentum both as an alternative to right ventricular pacing and as a method of cardiac resynchronization.
1)Lida, Y et al Successful resynchronization by permanent His-bundle pacing in patient with pacing -induced cardiomyopathy' J Arrhythmia , 2016 Dec. 32(6), 499-501
2)Ajijola,O et al Hyper-response to cardiac resynchronization with permanent His bundle pacing:Is parahisian pacing sufficient? Heart Rhythm Society, open access article http://dx'doi.org/19.10.hrcr.2015.05.006
Addendum: 5/26/2017 Several papers presented at the May 2017 meeting of the Heart Rhythm Society indicated that His Bundle pacing is ready for prime time. See Dr. John Mandrola's article on Medscape entitled " His Bundle pacing hits the mainstream at HRS 2017".
On a personal note-It is now almost two years since I was implanted with a Pacemaker with Bundle of His pacing before the practice became more mainstream. I had developed a left bundle branch block and an exercise induced second degree heart block. The LBBB had markedly decreased my exercise tolerance . My LBBB was "fixed" and after getting over a few complications of the procedure my exercise tolerance was back to my pre LBBB level with an EKG pattern that appears to be Parahisian.