Effect of smoking and other traditional risk factors on the onset of coronary artery calcification: results of the Heinz Nixdorf recall study

Background: Coronary artery calcium (CAC) indicates coronary atherosclerosis and can be present in very early stages of the disease. The conversion from no CAC to any CAC reflects an important step of the disease process as cardiovascular risk is increased in persons even with mildly elevated CAC. We sought to identify risk factors that determined incident CAC>0 in men and women from an unselected general population with a special focus on the role of smoking.

Methods: All 4814 persons that were initially studied in the Heinz Nixdorf Recall Study were invited to participate in the follow-up examination after 5.1 ± 0.3 years. All traditional Framingham risk factors were quantified using standard techniques. Smokers were categorized in never, former and present smokers. The CAC scores were measured from EBCT using the Agatston method.

Results: Overall, out of 342 men and 919 women with zero CAC at baseline, 107 (31.3%) men and 210 (22.9%) women had CAC>0 at second examination. In multivariable analysis, age (OR estimate per 5 years: 1.34 (95%CI: 1.21-1.47)), LDL cholesterol (per 10 mg/dL: 1.05 (95%CI: 1.01-1.10)), systolic blood pressure (per 10 mmHg: 1.19 (95%CI: 1.11-1.28)) and current smoking (1.49 (95%CI: 1.04-2.15)) were independent predictors of CAC onset. The probability of CAC onset steadily increased with age from 23.3% (men) and 15.3% (women) at age 45-49 years to 66.7% (men) and 42.9% (women) at age 70-74 years. The difference in age-dependent conversion rates was quantified by years between reaching a given level of CAC onset probability. We found a consistent pattern with respect to smoking status: presently (formerly) smoking middle-aged men convert to positive CAC 10 (5) years earlier than never smokers, for women (middle-aged to elderly) this time span is 8 (5) years.

Conclusion: Several traditional CVD risk factors are associated with CAC onset during 5 years follow-up. CAC onset is accelerated by approximately 10 (5) years for present (former) compared to never smokers.