[CRT-FORUM] 30E Indications and selection criteria for patients. Dr. Perez Riera

[CRT-INFO]

Dear Dr. Dr Llanes from Cuba: Your question is very smart, polemic and
interesting. Dr. Turtito and El-Sherif from the Methodist Hospital, in New
York City; USA, approached this topic two years ago. They wrote:
“available evidence supports the hypothesis that CRT results in favorable
structural as well as electrical remodeling. This can lead to amelioration
of the arrhythmogenic substrate associated with depressed LV systolic
function and HF. Additionally, a direct electrophysiological effect due to
favorable remodeling of repolarization with reduction of the dispersion of
repolarization cannot be ruled out. On the other hand, in a small subgroup
of patients, CRT could increase the dispersion of repolarization and induce
malignant ventricular tachyarrhythmias. Clinical trials have consistently
shown improved outcome with CRT-defibrillators (CRT-D) and more trials have
demonstrated the benefits of the defibrillator in the population with
depressed LV function. However, some physicians argue that implanting the
less expensive and less complicated CRT-pacemaker (CRT-P) may be appropriate
in certain groups of patients. Before this position is accepted, it is
imperative that criteria for the selection of this group of patients with
presumably low risk for sudden arrhythmic death as well as the proarrhythmic
effect of CRT be clearly defined”.
Recently, Freedman et al (2) compares the performance of integrated versus
dedicated leads with respect to anodal stimulation incidence, sensing, and
inappropriate ventricular tachyarrhythmia detection in patients implanted
with CRT-D. From a universe of 292 patients were randomly assigned to
receive dedicated or integrated bipolar RV leads at the time of CRT-D
implantation. Patients were followed for 6 months. Patients with dedicated
bipolar RV leads exhibited markedly higher rates of anodal stimulation than
did patients with integrated leads. The incidence of anodal stimulation was
64% at implant for dedicated bipolar RV leads compared to 1% for integrated
bipolar RV leads. The likelihood of anodal stimulation in patients with
dedicated leads fell progressively during the 6-month follow-up (51.5%), but
always exceeded the incidence of anodal stimulation in patients with
integrated leads (5%). Clinically detectable undersensing and oversensing
were very unusual and did not differ significantly between lead designs.
There were no inappropriate VT detections for either lead type. The authors
conclude that integrated bipolar RV defibrillator leads had a significantly
lower incidence of RV anodal stimulation when compared to dedicated bipolar
RV defibrillation leads, with no clinically detectable oversensing or
undersensing, and with no inappropriate VT detections for either lead type.
References
1) Turitto G, El-Sherif N. Cardiac resynchronization therapy: a review
of proarrhythmic and antiarrhythmic mechanismsPacing Clin Electrophysiol.
2007 Jan; 30: 115-122.
2) Freedman RA, Petrakian A, Boyce K, Haffajee C, Val-Mejias JE, Oza AL
Performance of dedicated versus integrated bipolar defibrillator leads with
CRT-defibrillators: results from a Prospective Multicenter Study. Pacing
Clin Electrophysiol. 2009 Feb; 32:157-165.

Andrés Ricardo Pérez Riera.MD
Chief of electrovectorcardiographic sector. ABC’s Medical School, ABC
Foundation, Santo André, São Paulo, Brazil Riera at uol.com.br
> I'm interested in everything related to the current conditions and 
> criteria,
> selection guidelines, and so on, of patients with ectopic foci of 
> aberrant
> cardiac activation, regarding CRT.
> Thank you,
>
> Dr Llanes (Cuba)
>


-- 
Dr. Sergio Dubner
President of Scientific Committee

Dr. Edgardo Schapachnik
President of Steering Committee