UCLA

Background and aims

Left main (LM) coronary artery disease is associated with greater myocardial infarction-related mortality, however, coronary artery calcium (CAC) scoring does not account for disease location. We explored whether LM CAC predicts excess mortality in asymptomatic adults.

Methods

Cause-specific cardiovascular and all-cause mortality was studied in 28,147 asymptomatic patients with non-zero CAC scores in the CAC Consortium. Multivariate regression was performed to evaluate if the presence and burden of LM CAC predict mortality after adjustment for clinical risk factors and the Agatston CAC score. We further analyzed the per-unit hazard associated with LM CAC in comparison to CAC in other arteries.

Results

The study population had mean age of 58.3 ± 10 years and CAC score of 301 ± 631. LM CAC was present in 21.7% of the cases. During 312,398 patient-years of follow-up, 1,907 deaths were observed. LM CAC was associated with an increased burden of clinical risk factors and total CAC, and was independently predictive of increased hazard for all-cause (HR 1.2 [1.1, 1.3]) and cardiovascular disease death (HR 1.3 [1.1, 1.5]). The hazard for death increased proportionate to the percentage of CAC localized to the LM. On a per-100 Agatston unit basis, LM CAC was associated with a 6-9% incremental hazard for death beyond knowledge of CAC in other arteries.

Conclusions

The presence and high burden of left main CAC are independently associated with a 20-30% greater hazard for cardiovascular and total mortality in asymptomatic adults, arguing that LM CAC should be routinely noted in CAC score reports when present.