Author + information
- Gregory Hartlage,
- Jonathan Suever,
- Michael Hoskins,
- Shahriar Iravanian,
- Robert Magrath,
- John Oshinski and
- Michael Lloyd
The site of latest mechanical delay varies widely among patients eligible for cardiac resynchronization (CRT) and is thought to be the ideal location for left ventricular (LV) lead placement. Currently, there is no validated preoperative method to determine the site of latest mechanical delay. The purpose of this study was to compare preoperative LV mechanical activation patterns by cardiovascular magnetic resonance (CMR) to intraoperatively obtained LV electrical activation by intracardiac electrograms (EGMs).
Using a previously described software algorithm, CMR dyssynchrony maps were depicted via a 17- segment AHA model. Electrical delay maps were generated intraoperatively by measuring delays at multiple sites within coronary venous branches. Electrical delays were measured as peak-to-peak differences between LV and right ventricular (RV) electrodes. Intraoperative measurements were plotted against corresponding CMR data to determine correlation. CMR and EGM maximal delays were considered concordant if in the same AHA segment, adjacent if within 1 segment, and remote if > 2 segments apart.
A total of 24 LV lead sites in 7 patients (4 classic LBBB, 3 atypical or non-LBBB) were analyzed. The mean r-value for correlation of mechanical and electrical delay was 0.94 (range: 0.83-1.00) for intrinsic conduction. Sites of greatest delay were concordant in all patients during intrinsic conduction. EGMs were also obtained during RV pacing, which replicates activation patterns during true biventricular pacing. During RV pacing, electrical delays correlated with intrinsic conduction CMR maps (correlation plot mean r = 0.94 [range: 0.85-1.00]) in LBBB patients, with all sites of greatest delay concordant or adjacent, but did not agree with CMR in non-LBBB patients (correlation plot mean r = 0.54 [range: 0.10-0.99]).
Preoperative CMR-derived dyssynchrony maps have excellent correlation with intraoperative measurements of electrical delay. In those with classic LBBB, RV pacing did not affect the predictive utility of CMR. These prospective data indicate CMR may be useful in preoperative, patient-specific planning of LV lead placement.
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Imaging: MRI VI – Clinical Applications and Advances in CMR
Abstract Category: 19. Imaging: MRI
Presentation Number: 1310-321
- 2013 American College of Cardiology Foundation