Background/Purpose: Traditionally, a coronary artery calcium (CAC) score of zero is associated with low rates (0.1-0.2% annualized risk) of major adverse cardiovascular outcomes (MACE). While systemic lupus erythematous (SLE) has previously been associated with premature coronary calcification, the predictive value of the CAC score (CACS) on long-term rates of MACE in SLE patients is unknown.

Methods: SLE patients followed at University of Michigan were prospectively identified between 2001 and 2005. SLE patients were included if they met at least 4 of the 1997 American College of Rheumatology SLE criteria, age < 55 years and had no known history of cardiovascular or cerebrovascular disease, diabetes, current smoking, or hypertension requiring more than one medication. All patients had at least one CACS measured by CT scan at time of inclusion. The primary outcome of MACE was defined as acute coronary syndrome, symptomatic heart failure, stroke, and coronary revascularization for stable coronary artery disease.

Results: Our cohort included 118 patients with SLE (mean age 37.7 +/- 9.2 years, 98% female, 84% Caucasian, 36% with hypertension, 13% with hyperlipidemia). The mean SLE activity index (SLEDAI) at time of first CAC scan was 3.8 +/- 3.6 (low to moderate disease activity). Eighty-eight patients had a baseline CACS of 0 Agatson Units (AU), 21 patients had mild CAC 1-99 AU, 3 patients had moderate CAC of 100-399 AU, and 6 patients had severe CAC >400 AU. Over an average follow-up of 16.1 +/- 6.2 years, 20 patients (17.0%) experienced a major adverse cardiovascular outcome including 10/88 (11.4%) patients with CACS of 0. A CACS of 0 compared to CACS >0 was associated with lower rates of MACE (11.4% versus 33.3%, p=0.010). After multivariable regression, CACS of zero was associated with 73% lower odds of MACE (odds ratio 0.27, 95% confidence interval 0.08-9.91, p=0.04).

Conclusion: In this single center prospective study, we observed that SLE patients experienced MACE at significant rates despite relatively low SLE disease activity at inclusion. Although a CACS of zero was associated with substantially reduced odds of MACE, a CACS of zero had a substantially lower negative predictive value in SLE patients in this study when compared to non-SLE cohorts.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictive-validity-of-coronary-artery-calcium-scoring-in-low-risk-systemic-lupus-erythematous-patients/