Elsevier

American Heart Journal

Volume 158, Issue 4, October 2009, Pages 554-561
American Heart Journal

Clinical Investigation
Imaging and Diagnostic Testing
Cardiovascular events with absent or minimal coronary calcification: The Multi-Ethnic Study of Atherosclerosis (MESA)

https://doi.org/10.1016/j.ahj.2009.08.007Get rights and content

Background

Elevated coronary artery calcium (CAC) is a marker for increase risk of coronary heart disease (CHD). Although most CHD events occur among individuals with advanced CAC, CHD can also occur in individuals with little or no calcified plaque. In this study, we sought to evaluate the characteristics associated with incident CHD events in the setting of minimal (score ≤10) or absent CAC (score of zero).

Methods

Asymptomatic participants in the MESA (N = 6,809) were followed for occurrence of all CHD events (including myocardial infarction, angina, resuscitated cardiac arrest, or CHD death) and hard CHD events (myocardial infarction or CHD death). Time to incident CHD was modeled using age-and gender-adjusted Cox regression.

Results

The final study population consisted of 3,923 MESA asymptomatic participants (mean age 58 ± 9 years, 39% males) who had CAC scores of 0 to 10. Overall, no detectable CAC was seen in 3415 individuals, whereas 508 had CAC scores of 1 to 10. During follow-up (median 4.1 years), there were 16 incident hard events and 28 all CHD events in individuals with absent or minimal CAC. In age-, gender-, race-, and CHD risk factor-adjusted analysis, minimal CAC (1-10) was associated with an estimated 3-fold greater risk of a hard CHD event (HR 3.23, 95% CI 1.17-8.95) or of all CHD event (HR 3.66, 95% CI 1.71-7.85) compared to those with CAC = 0. Former smoking (HR 3.57, 95% CI 1.08-11.77), current smoking (HR 4.93, 95% CI 1.20-20.30), and diabetes (HR 3.09, 95% CI 1.07-8.93) were significant risk factors for events in those with CAC = 0.

Conclusion

Asymptomatic persons with absent or minimal CAC are at very low risk of future cardiovascular events. Individuals with minimal CAC (1-10) were significantly increased to 3-fold increased risk for incident CHD events relative to those with CAC scores of zero.

Section snippets

Recruitment and baseline examination

The MESA cohort6 is a longitudinal, population-based study of 6,814 men and women, free of clinical cardiovascular disease, aged 45 to 84 years at baseline, and recruited from 6 field centers: Baltimore, MD; Chicago, IL; Forsyth County, NC; Los Angeles, CA; New York, NY; and St. Paul, MN. Specific racial/ethnic groups enrolled included white, black, Hispanic, and Chinese. Approximately 50% of the participants enrolled were female. Details of the MESA recruitment strategy are contained elsewhere.

Study cohort

In the MESA population of 6,814 at baseline, 5 participants were discovered to have had a cardiovascular event before enrollment and as a result were excluded from the analysis. In addition, 2,890 individuals with CAC >10 were also excluded from the study population. The final study population consisted of 3,923 asymptomatic individuals free of known cardiovascular disease at baseline (mean age 58 ± 589 years, 39% males). Overall, 3415 individuals had no detectable CAC, whereas 508 had CAC

Discussion

This large, population based multiethnic study demonstrated a remarkably low rate of cardiovascular events among those individuals with calcium scores of zero. This is concordant with prior study results.5 Conventional cardiovascular risk factors, particularly smoking and diabetes mellitus, are associated with a higher relative risk of CHD with no CAC, although absolute event rates remain low. Individuals with low CAC scores (1-10) had a 3-fold increased risk of CHD compared to those with no

Acknowledgements

This research was supported by R01 HL071739 and contracts N01-HC-95159 through N01-HC-95165 and N01-HC-95169 from the National Heart, Lung, and Blood Institute. The authors thank the other investigators, the staff, and the participants of the MESA study for their valuable contributions. A full list of participating MESA investigators and institutions can be found at http://www.mesa-nhlbi.org.

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