Abstract
Background: Over the past decade, there have been tremendous advances in electroanatomical mapping (EAM) technologies, including introduction of multielectrode catheters for high-resolution mapping of scar. While EAM may not be suitable for detecting mid-wall scar, it has been assumed that these are capable. We sought to examine the sensitivity of EAM for detecting cardiac MRI (CMR)-defined subendocardial scar in a swine model of myocardial infarction.
Methods: Fourteen swine underwent balloon occlusion of the mid circumflex (LCx group, 7 pigs) or mid left anterior descending artery (LAD group, 7 pigs). After 8-10 weeks, Late Gadolinium Enhancement (LGE) was performed. Within one week after CMR, EAM was performed using a multielectrode catheter (Carto®, Octaray®) by experienced electrophysiologist blinded to CMR.
Results: On CMR, both groups had similar scar size, left ventricular volumes and function. However, LAD group had significantly thinner LV walls (2.3±0.5 vs. 6.7±1.4mm), and there was good visual correspondence between the location and area of scar with low bipolar / unipolar voltage. In contrast, in LCx group, CMR scar seen was significantly larger than the area of low bipolar / unipolar voltage (Fig 1), despite large subendocardial and transmural scar. In 5 out 7 LCx group, there was no areas of low voltage, despite presence of transmural scar on CMR.
Conclusion: In preclinical model of healed MI, EAM voltage amplitude is insensitive to detect subendocardial and transmural scar on a thick wall.