Abstract
BACKGROUND: Whether the region of the latest electrical activation (LEA) corresponds with the segment of the latest mechanical contraction (LMC) in ischemic cardiomyopathy (ICM) is uncertain. We aimed to investigate the relationship between the left-ventricular (LV) viable segments with LEA and with LMC after myocardial infarction (MI) and analyze the acute hemodynamic responses (dP/dt(max)) after cardiac resynchronization therapy (CRT) pacing at different LV sites. METHODS AND RESULTS: Bama suckling pigs (n = 6) were subjected to create MI models. Both gated myocardial perfusion imaging (GMPI) and electroanatomic mapping (EAM) were performed successfully before MI and 4 weeks after MI. LMC was assessed by phase analysis of GMPI, while LEA was evaluated by EAM. The dP/dt(max) was measured before CRT and when the CRT LV electrode was implanted in viable segments of LMC, viable segments of lateral wall and scar, respectively. The viable segments of LEA were consistent with the sites of LMC for five in six cases. The dP/dt(max) increased significantly compared with that before CRT when the CRT LV electrode was implanted in viable segments of LMC (1103.33 ± 195.76 vs 717.83 ± 80.74 mmHg·s(-1), P = .001), which was also significantly higher than in viable segments of lateral wall (751.17 ± 105.62 mmHg·s(-1), P = .000) and scar (679.50 ± 60.87 mmHg·s(-1), P = .001). CONCLUSIONS: Non-invasive GMPI may be a better option than invasive EAM for guiding LV electrode implantation for CRT in ICM.