Lymphocytes telomere length and left ventricle heart functional state in emergency workers of Chernobyl accident who survived myocardial infarction

Abstract

Abstract Background The reduction of lymphocytes telomeres length (TL) reflects aging and progression of atherosclerosis. TL shortening depends on multiple risk factors including ionizing radiation and chronic stress that were typical conditions for emergency workers (EW) of Chernobyl accident. Purpose To analyse the association between lymphocytes TL and myocardial functional state in EW survived myocardial infarction (MI). Methods We examined 48 EW aged 67.1±7.7 years. Ultrasound heart examination was performed using the Diagnostic Ultrasound System DS-N3 (Mindray). Determination of relative TL was performed using flow-FISH with Telomere PNA Kit/FITC (Dako Cytomation, Denmark) by laser flow cytometry (FACSCalibur, BD, USA). Results At the first stage of descriptive analysis we found that TL negatively correlated only with left ventricle (LV) end diastolic volume (EDV) and EDV normalised by body surface area (BSA) but not with other clinical and echocardiography indices. At the second stage the hierarchical cluster analysis was used to identify relatively homogeneous patient's groups according to given LT and EDV indexed by BSA (iEDV). The first one is characterized by significantly lesser TL (10.6±1.7 units) and higher iEDV (85.8±16.2 ml/m2) comparing with second cluster (14.7±1.6 units and 68.0±10.4 ml/m2). The patients belonged to 1st cluster (n=21) were differed from 2nd cluster persons (n=27) by greater magnitude of EDV (172.6±32.5 vs 140.2±27 ml, p=0.000), end systolic volume (85.4±33.0 vs 59.7±20 ml, p=0.002), end systolic volume normalized by BSA (42.5±16.1 vs 28.9±8.2 ml/m2, p=0.000), LV myocardium mass / BSA (145.2±27.1 vs 130.4±21.3 g/m2, p=0.040) and less value of ejection fraction (52.0±10.6 vs 57.8±8.4 per cent, p=0.038). Heart failure (HF) of NYHA class I was diagnosed in 47.4% cluster 1 patients and 66.7% cluster 2 ones (p>0.05) but HF NYHA class II on the contrary in 52.6% cluster 1 and 33.3% cluster 2 patients (p>0.05). Cluster 1 patients demonstrated normal geometry or concentric remodelling LV with frequency 9.5% vs 29.6% in cluster 2 ones (p>0.05). Concentric LV hypertrophy revealed in 23.8% and 44.4% of cluster 1 and 2 patients (p>0.05) but eccentric hypertrophy in 66.7% and 25.9% correspondingly (p<0.01). Conclusion Studied EW represent a heterogeneous group in terms of scattering the extreme values of TL and LV functional indices. The use of hierarchical cluster analysis made it possible to avoid the empirical way of dividing EW into more homogeneous groups and, with mathematical precision, to determine two clusters of patients. The first cluster, in comparison with the second, was characterized by a significantly shorter TL, large LV volumes and its mass, a decrease of ejection fraction, the presence of eccentric LV hypertrophy and more severe heart failure. The TL in EW who survived myocardial infarction is associated with a more severe clinical course of coronary heart disease and a decrease in LV myocardial function. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Academy of Medical Sciences of Ukraine Scatter diagram of TL, iEDV and clusters