OBJECTIVE

To study regional sympathetic activity of the left ventricle using single-photon emission tomography (SPECT) with I¹²³-labeled metaiodobenzylguanidine (I¹²³-MIBG) compared to perfusion changes according to 99mTc SPECT data in acute and long-term period of myocardial infarction.

MATERIAL AND METHODS

The study included 52 people with new anterior or inferior MI and no other conditions potentially leading to regional disturbances in sympathetic activity of the heart. All patients underwent SPECT with I¹²³-labeled metaiodobenzylguanidine and Technetium [99mTc] within a week and 8 months after MI.

RESULTS

Regional disturbances of sympathetic activity of the left ventricle corresponded to perfusion disturbance zone, but they were larger. In most patients, perfusion disturbance zone decreased after 8 months from 23% (13; 32) to 19% (5; 30) (p<0.001) compared to acute period. The area of impaired sympathetic activity decreased from 34% (24; 40) to 27% (22; 36) (p<0.05). Changes in sympathetic innervation and myocardial perfusion over time were unidirectional in more than 70% of patients. In addition, there was a correlation between zones of myocardial perfusion and innervation disorders with LV ejection fraction, as well as myocardial innervation with cardiac chamber dimensions.

CONCLUSION

Regional sympathetic disorders in MI are largely determined by perfusion changes and correlate with LV ejection fraction and remodeling in long-term period. Severe disorders of sympathetic innervation with smaller zone of perfusion changes in long-term period can indicate viable myocardium in peri-infarction zone.