Peculiarities of acute myocardial infarction course and distribution of the somatostatin receptor analogue 99mTc-octreotide in the heart

Aim. To study the relationship between the clinical course of myocardial infarction (MI) with changes in left ventricular (LV) geometry and myocardial accumulation of the somatostatin analogue 99mTc-octreotide according to cardiac single-photon emission computed tomography (SPECT).

Material and methods. This pilot, cohort, prospective study included 14 patients aged 37 to 72 years with primary anterior ST-segment elevation MI. Patients underwent a general clinical examination, 3-fold determination of high-sensitivity C-reactive protein (hsCRP), echocardiography on days 1-3, cardiac SPECT with 99mTc-octreotide on days 6-7 from MI onset. Statistical analysis was performed using STATISTICA 10.0, StatSoft, USA.

Results. In 10 of 14 patients, 99mTc-octreotide accumulation in LV involvement area was recorded. The accumulation analysis showed varying intensity. This made it possible to form two subgroups with high and low accumulation of 99mTc-octreotide (heart-to-cavity LV ratio more and less than 1,5, respectively).

Clinical characteristics and MI course, length of hospital stay did not differ between the subgroups. Occlusion of the infarct-related coronary artery (in 5 (62,5%) vs 0 (0%) patients, p=0,016) was more common in the group with increased versus decreased accumulation of 99mTc-octreotide, respectively.

Laboratory analysis showed a significant increase in hsCRP upon admission in patients with increased vs decreased accumulation of 99mTc-octreotide — 31,6 mg/l (10,45-42,05) vs 6,5 mg/l (3,2-11,8), p=0,043, respectively.

A significant increase in end-diastolic and end-systolic LV volumes was established. There were an increase in LV sphericity index and local contractility disruption index along with a decrease in LV ejection fraction in the subgroup with high vs reduced accumulation of 99mTc-octreotide (47,5% (45,5-51,5) vs 57,5% (54-59), p=0,020) in the damage zone, respectively. In addition, a predictive relationship between the increase in LV end-diastolic volume and the severity of 99mTc-octreotide accumulation was found (R²=0,601, F-ratio=16,562, p=0,002).

Conclusion. An increase in hsCRP and early initiation of LV remodeling after primary anterior ST-segment elevation MI is accompanied by a pronounced accumulation of 99mTc-octreotide in the damage zone, detected using cardiac SPECT, as a result of systemic and local, in our opinion, macrophage-mediated post-infarction inflammation.

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