Radiation and non-radiation factors and their impact on the natural history of coronary heart disease in Chornobyl accident clean-up workers.

The objective of the study was to evaluate the impact of a range of risk factors and ionizing radiation on the severity of clinical presentation of coronary heart disease (CHD) in Chornobyl accident clean-up workers (ACW). Materials and methods. A total of 376 ACW and 123 Kiev city residents with no exposure to radiation participated in the study. Study scope included the case history recording, clinical check-up, electrocardiography (ECG), daily ECG-monitoring, daily arterial blood pressure monitoring, exercise ECG, Doppler ultrasound (Doppler echocardiography), and serum lipid profile assay. The severity of CHD was scored as a sum of functional class (FC) of angina pectoris and stage of heart failure (HF) to estimate the combined impact of several risk factors. Participation in the clean-up work, age, gender, body mass excess, hypercholesterolemia, CHD, diabetes mellitus (DM), survived myocardial infarction (MI) and acute cerebral stroke, heart rhythm abnormalities, and a complete bundle branch block were accounted as risk factors. Both separate and combined impact of those factors was assayed. The combined effect was scored as a sum where value zero corresponded to no sign and value one corresponded to its presence, whereas values from 1 to 4 explained the expression of a sign according to severity or stage of a disease according to contemporary classifications. Results and conclusions. Despite the fact that clinical characterization, functional state of cardiovascular system, and comorbidities in ACW were almost similar to that in control group the onset of CHD in ACW was significantly earlier (55.9 vs. 59.8 years old). According to Spearman's rank-order correlation data there was a reliable link of FC grades and HF severity values sum to the sum of indices scoring the age group of patients, their gender, presence of arterial hypertension, MI in a history, DM type 2, heart rhythm abnormalities, and a complete bundle branch block. Cluster of risk factors impacting the CHD natural history was of higher correlation vs. separate factor. No significant link was found between participation in the accident clean-up work and external radiation dose and respectively the angina pectoris FC and HF.