Pacing transmural scar tissue reduces left ventricle reverse remodeling after cardiac resynchronization therapy.
BACKGROUND
In patients with ischemic heart failure undergoing cardiac resynchronization therapy (CRT) the underlying myocardial substrate at the left ventricle (LV) pacing site may affect CRT response. However, the effect of delivering the pacing stimulus remote, adjacent to or over LV transmural scar tissue (TST) identified by echocardiography is still unknown.


METHODS
First, 35 patients with healed myocardial infarction (57 ± 11 years) were prospectically studied to demonstrate the capability of echocardiographic end-diastolic wall thickness (EDWT) to identify LV-TST as defined by delayed enhancement magnetic resonance imaging (DE-MRI). Subsequently, in 136 patients (65 ± 10 years) who underwent CRT, EDWT was retrospectively evaluated at baseline. The LV catheter placement was defined over, adjacent to and remote from TST if pacing was delivered at a scarred segment, at a site 1 segment adjacent to or remote from scarred segments. CRT response was defined as LV end-systolic volume (ESV) decrease by at least 10% after 6 months.


RESULTS
A EDWT ≤ 5mm identified TST at DE-MRI with 92% sensitivity and 96% specificity. In the 76 CRT responders, less overall and posterolateral TST segments and more segments paced remote from TST areas were found. At the multivariate regression analysis, the number of TST segments and scar/pacing relationship showed a significant association with CRT response.


CONCLUSIONS
In addition to LV global scar burden, CRT response relates also to the myocardial substrate underlying pacing site as evaluated by standard echocardiography. This information may expand the role of echocardiography to guide pacing site avoiding pacing at TST areas.
Azienda Ospedaliera Universitaria, Ferrara and Fondazione Salvatore Maugeri, Brescia, Italy. donatomele@libero.it
Donato
D
Mele
Eustachio
E
Agricola
Alessandro Dal
AD
Monte
Maurizio
M
Galderisi
Antonello
A
D'Andrea
Fausto
F
Rigo
Rodolfo
R
Citro
Elisabetta
E
Chiodi
Giuseppe
G
Marchese
Patrizia Della
PD
Valentina
Alice
A
Calabrese
Roberto
R
Ferrari
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy; D002921:Cicatrix / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D016896:Treatment Outcome; D014463:Ultrasonography; D020257:Ventricular Remodeling / Q000502:physiology*