Featured Post

Is the new professionalism and ACP's new ethics really just about following guidelines?

The Charter ( Medical Professionalism in the New Millennium.A Physician's Charter) did not deal with just the important relationship of ...

Saturday, January 13, 2018

LBBB associated non ischemic cardiomyopathy -more favorable remodeling if CRT started early

 An article by the electrophysiology group at the University of Pittsburg highlights the importance of early CRT in cases of left bundle branch induced non-ischemic cardiomyopathy with heart failure.

 First some background:

The effect of LBBB on ventricular function has been recognized at least since the 1980s and abnormal septal movement  described as  early as 1973 (4). See here for my review of the abnormal cardiac function observed in LBBB.

LBBB induced cardiomyopathy and its potential reversibility by CRT was described at least as early as 2005 in an article by Jean-Jaques Blanc(1). In 2008 Blanc co-authored a chapter on that topic in Barold and Ritter's book  "Devices for Cardiac Resynchronization" (pg 139-145)

In 2013, Vaillant et al (2) described 6 patients with so-called isolated LBBB who developed heart failure and in whom a marked improvement in cardiac function was documented following the institution of CRT.

Wang and Saba et al (3) from Pittsburg studied 123 patients with LBBB-associated idiopathic non-ischemic cardiomyopathy. About half were treated with CRT in less than 9 months after diagnosis and half received CRT after 9 months.

Improvement in left ventricular ejection fraction to greater than 35% was more likely in those who received earlier treatment. The author concluded in part " Delaying CRT may miss a critical period of halt and reverse progressive myocardial damage"

I suggest the importance of this paper is not that earlier is better than later (which seems expected) but rather that,to my knowledge, this is the first paper describing a  large number of patients with  LBBB induced cardiomyopathy   and their response to CRT.Only a handful of patients had been described previously and this article should perhaps serve to make this entity better recognized.

The patients were treated with CRT which, so far, has been virtually synonymous with bi-ventricular pacing (Bi-V). Now , however, more patients are being paced with His Bundle pacing. There is some developing evidence that His Bundle pacing is equivalent in terms of efficacy to Bi V pacing. His bundle pacing certainly seems more physiologic. His bundle pacing is capable of making the abnormal LBBB QRS complex normal or nearly so in the majority of  cases.Alberti et al  (5) from the University of Florence make the case for His Bundle pacing as an alternative to Bi-ventricular pacing in CRT and note the ongoing clinical trial (the HOPE_HF trial)  using His Bundle pacing in CRT eligible patients.Actually in 2015, Lustgarten et al(6) demonstrated an equivalent CRT response
of Bi-V pacing with His Bundle pacing in 29 patients.

All of Wang's patients were treated for 3 months with the  standard heart failure regimen but responded poorly and then with CRT. What about patients who develop "lone" LBBB and have a history of decreased exercise tolerance but ejection fractions still within the normal range? Should the patient be required to have overt HF and poor response to medication before  CRT is considered?

Again a personal note in this regard.  Two years ago  I developed LBBB and my exercise capacity decreased immediately . My echo showed a EF in the normal range ( lower limit) and mitral Doppler flow indicated impaired relaxation and stress echo showed abnormal septal movement. I had also developed an exercise induced high grade second degree heart block and on that basis was a candidate for a pacemaker. I was fortunate to have an EP cardiologist who was doing His Bundle pacing (few were at that time ) and after a series of  uncommon post procedure complications was able to enjoy a return to a level of exercise ability indistinguishable from my pre conduction problems status and I believe avoided the likelihood of a progressive LBBB induced cardiomyopathy.
Three cheers for His Bundle pacing.

1)Blanc J, Evaluation of left bundle branch block as a reversible cause of non-ischaemic dilated cardiomyopathy  with severe heart failure . A new concept of left ventricular dyssyncrhony-induced cardiomyopathy Europace. 2003  7 (6) 604-610

2)Vaillant et al. Resolution of left bundle branch block induced cardiomyopathy by cardiac resynchronization therapy.JACC 2013 vol 61 no 10  pg 1089

3)Wang,NC et al New onset left bundle branch block-associated idiopathic nonischemic cardiomyopathy and time from diagnosis to cardiac resynchronization therapy. The NEOLITH II study PACE 2018 Jan 4

4)Breithandt,G. Left bundle branch block,an old-new entity.J. Cardiovas Tranal Res2012 ,Apr 5 2 107. (authors reference the work of Curtius and of McDonald.

5)Alberti, L Hemodynamics of His bundle pacing. J of electrocardiology 50 (2017) 161-168

6)Lustgarten DL et al His-bundle pacing in cardiac resynchronization therapy patients.a crossover design comparison.Heart Rhythm 2015;12 1548-57

No comments: