Birthplace in area with high coronary heart disease mortality predicts the severity of coronary atherosclerosis among middle-aged Finnish men who had migrated to capital area: The Helsinki Sudden Death Study

Background. Reasons why eastern-born male Finns have higher coronary heart disease (CHD) mortality than do western-born men are still unsettled. Recently, eastern birthplace was found to be an independent predictor of pre-hospital sudden cardiac death (SCD) in the new low-mortality area of residence. Aim. To investigate the association of birthplace with high CHD mortality attributes to more severe coronary atherosclerosis among men migrated to the low-mortality capital area. Method. Coronary atherosclerosis was measured in 373 western-born and 314 eastern-born out-of-hospital male deaths aged 33-70 years in Helsinki (The Helsinki Sudden Death Study), covering 24.6% of male deaths within this age-group. CHD risk factors were obtained from an interview of a next of kin. Results. In multivariate analysis there was a strong birthplace-by-age interaction with atherosclerosis (P - 0.0005). Eastern-born men <54 years had larger areas of fatty streaks (P = 0.0195), fibrotic plaque (P = 0.0133), calcification (P = 0.0009), total plaque area (P = 0.0011), and greater stenosis (P = 0.0004) in the left coronary compared to western-born men, independent of CHD risk factors. Amongst older men (>= 54 years) such an association no longer appeared. Conclusion. Higher CHD mortality among eastern-born men may be due to more severe coronary atherosclerosis independently of CHD risk factors, reflecting Finns' two-phase settlement history.