The IX t h Makassed Medical Congress - American University of Beirut

T h e I X t h M a k a s e d M e d i c a l C o n g r e s s
ROLE OF ECHOCARDIOGRAPHY IN CARDIAC RESYNCHRONIZATION THERAPY
Elie Chammas MD, FESC
Cardiac resynchronization therapy (CRT) with biventricular pacing, is now recommended for
patients with heart failure (Ejection fraction < 35%), under maximal therapy with wide QRS (> 130
ms). After implantation of a CRT device, one third of the patients remain symptomatic without
any improvement. The presence of mechanical dysynchrony is one of the possible causes.
Cardiac echography is a powerful tool to detect mechanical dysynchrony by analyzing the
interventricular, the intra ventricular and the auriculo ventricular delays. With the new technologies
(Tissue synchronization imaging, 2D and 3D strain…), the echocardiography diagnosis of
mechanical dysynchrony became more accurate, Despite these techniques, the clinical data
still disappointed. One of the explanations is the complexity of cardiac mechanics which can not
be explored by one technique, another is the position of the pace maker leads.
During this presentation, all the echo techniques to detect dysynchrony will be presented with
the clinical data recently published.
SHOULD WE EXPAND CRT TO MILD HEART FAILURE?
Samer Nasr, MD
Cardiac resynchronization therapy has become an established therapy for ischemic and non
ischemic cardiomyopathies, with QRS widening. The effects of biventricular pacing were shown
to have hemodynamic and non hemodynamic positive influence on myocardial function and
increase in effectiveness of LV contraction with decrease in mitral regurgitation. Pathology studies
have also shown Changes in myocytes and surrounding fibrotic changes similar to the changes
seen with ACE inhibitions.
The initial target of cardiac resynchronization therapy was to alleviate symptoms. This is confirmed
by the design of the main trials that included improvement in NYHA class, and six minute walk test
and measurement of quality of life using the Minesota quality of life score.
With the success of the positive main initial came the AHA/ACC and ESC guidelines that we know
recommended cardiac resynchronization trials in NYHA class two, three, and ambulatory four.
The group of paucisymtomatic patients with severe left ventricular dysfunction and NYHA class
one were left to be candidates for defibrillator implantation and not for biventricular pacing.
The sole purpose of the therapy in this group of patients, was the prevention of sudden cardiac
arrhythmic death. The common thinking was to implant a defibrillator and upgrade to biventricular
pacing only if the patients worsen clinically and start showing signs and symptoms of salt and
water retention.
With growing experience it was left that many symptomatic patients with severe left ventricular
dysfunction and QRS widening worsened rapidly with time. Recent large clinical trials have
addressed this specific issue.
Not surprisingly the benefits of CRT proved to be as good as in the symptomatic patients. We
will go over the latest evidence covering the topic with emphasis on survival benefits and
pathophysiologic data available to us at this time.
78