Why does Russia have such high cardiovascular mortality rates? Comparisons of blood-based biomarkers with Norway implicate non-ischaemic cardiac damage.

BACKGROUND: Russia has one of the highest rates of mortality from cardiovascular disease (CVD). At age 35-69 years, they are eight times higher than in neighbouring Norway. Comparing profiles of blood-based CVD biomarkers between these two populations can help identify reasons for this substantial difference in risk. METHODS: We compared age-standardised mean levels of CVD biomarkers for men and women aged 40-69 years measured in two cross-sectional population-based studies: Know Your Heart (KYH) (Russia, 2015-2018; n=4046) and the seventh wave of the Tromsø Study (Tromsø 7) (Norway, 2015-2018; n=17 646). A laboratory calibration study was performed to account for inter-laboratory differences. RESULTS: Levels of total, low-density lipoprotein-, high-density lipoprotein-cholesterol and triglycerides were comparable in KYH and Tromsø 7 studies. N-terminal pro-b-type natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T (hs-cTnT) and high-sensitivity C-reactive protein (hsCRP) were higher in KYH compared with Tromsø 7 (NT-proBNP was higher by 54.1% (95% CI 41.5% to 67.8%) in men and by 30.8% (95% CI 22.9% to 39.2%) in women; hs-cTnT-by 42.4% (95% CI 36.1% to 49.0%) in men and by 68.1% (95% CI 62.4% to 73.9%) in women; hsCRP-by 33.3% (95% CI 26.1% to 40.8%) in men and by 35.6% (95% CI 29.0% to 42.6%) in women). Exclusion of participants with pre-existing coronary heart disease (279 men and 282 women) had no substantive effect. CONCLUSIONS: Differences in cholesterol fractions cannot explain the difference in CVD mortality rate between Russia and Norway. A non-ischemic pathway to the cardiac damage reflected by raised NT-proBNP and hs-cTnT is likely to contribute to high CVD mortality in Russia