Is there an association between hibernating myocardium and left ventricular mechanical dyssynchrony in patients with myocardial infarction?

OBJECTIVE: Left ventricular mechanical dyssynchrony (LVMD) is an important factor in the prognosis of patients with myocardial infarction (MI). The aim of this study is to identify the influencing factors of LVMD in MI patients by radionuclide myocardial imaging.

SUBJECTS AND METHODS: This study consisted of 91 patients who had a history of definite prior MI and underwent both technetium-99m methoxyisobutylisonitrile (99m Tc-MIBI) gated single photon emission tomography (SPET) myocardial perfusion imaging (MPI) and 18 F-FDG positron emission tomography (PET) myocardial metabolic imaging. Left ventricular (LV) functional and LVMD parameters were measured from gated SPET MPI, while myocardial viability was assessed by the integral quantitative analysis of SPET MPI and 18 F-FDG PET. Left ventricular MD was defined as >mean+2SD of phase bandwidth (PBW) in the control group.

RESULTS: Left ventricular MD was present in 37/91 (40.7%) MI patients. Hibernating myocardium (SPET/PET mismatch) and scar in patients with LVMD were significantly higher than those without LVMD (15.24±11.26% vs 4.89±5.41%, P<0.001; 11.11±9.42% vs 4.72±5.71%, P<0.001; respectively). PBW correlated with hibernating myocardium and scar (r=0.542, 0.469, P<0.001; respectively). The multivariate logistic regression analysis showed that hibernating myocardium was an independent factor of LVMD in MI patients (OR=1.110, P=0.009), and >6.5% hibernating myocardium as a threshold can be used to better discriminate LVMD. In addition, the improvement of PBW (ΔPBW) after CABG at a median follow-up time of 6 months was related with the amount of hibernating myocardium.

CONCLUSION: Myocardial infarction patients with LVMD show significantly more segments of larger amounts of hibernating myocardium and scars as compared to those without LVMD. Hibernating myocardium is independently associated with LVMD in MI patients.