The comparative study of common carotid intima-media thickness in Russian and Italian high-risk individuals

Objectives: In comparison with Europeans Russian population shows enormously high levels of cardiovascular mortality and morbidity. A recent European study (IMPROVE) has revealed the existence of a geographical gradient in subclinical atherosclerosis which parallels with the North-to South geographical gradient in cardiovascular mortality described in the WHO Europe database. This study was kept to characterize the variability of common carotid intima-media thickness (cIMT) in selected high-risk population sample recruited in Moscow (n=407) and Milan (n=435), and to investigate the hypothesis of West-to-East cIMT gradient, as well as to elucidate the role of cardiovascular risk factor in between-population cIMT variability. Methods: Asymptomatic men and women (55-79 yrs) with at least three cardiovascular risk factors were eligible. Different from the IMPROVE Study, ultrasonic scans were taken from the distal centimeter of common carotid arteries only. Quantification of cIMT was performed in Monzino Cardiology Center (Milan, Italy) by a qualified reader using Mat'h software. Results: The comparative analysis has revealed that the mean (95% CI) cIMT value was significantly higher in Moscow - 0.82 (0.81-0.85) mm than in Milan - 0.73 (0.72-0.74) mm (p<0.001). Moscow study participants have higher prevalence of arterial hypertension, blood pressure, total and HDL cholesterol and triglycerides, and take less medication. However, these differences explains only 16% between-population difference in cIMT variability. Decision tree analysis has revealed that the site of residence has a decisive impact on the observed difference in cIMT variability. The association between cIMT and the standardized mortality ratio for IHD reported in the WHO European database is non-linear (R-square 0.86, p<0.001 for logarithmic correlation). Conclusion: Cardiovascular mortality in Russia is only partially explained by a higher atherosclerotic risk profile; genetic and environmental factors should be strongly involved in between-population difference in cIMT variability, which can help explaining the striking difference in cardiovascular mortality between European and Russian populations.