Differences in left anterior descending coronary artery disease in participants without standard modifiable cardiovascular risk factors: the Multi-Ethnic Study of Atherosclerosis (MESA)

Abstract

Abstract Background/Introduction The development of coronary artery disease (CAD) and myocardial infarction (MI) in the absence of standard modifiable cardiovascular risk factors (SMuRFs) has been highlighted as an unmet clinical need, accounting for between 10-27% of ST elevation MI and associated with higher 30-day mortality. One potential contributor to the early mortality is the higher observed rates of LAD territory culprit lesions in SMuRFless patients compared to those with at least one SMuRF. Purpose To characterise the differential proportion of LAD disease in an asymptomatic population with no prior cardiovascular disease (CVD) history, comparing individuals with CAD despite no SMuRFs to those with at least one SMuRF in the Multi-Ethnic Study of Atherosclerosis (MESA). Methods A MESA sub-cohort with a baseline coronary artery calcium score (CACS) >0 Agatston units (AU) was prepared. SMuRF status was assigned by self-report, treatment, or biomarkers for hypertension, hypercholesterolaemia, diabetes, and smoking. Proportion of disease in the left main, LAD, circumflex, and right coronary arteries were calculated by the vessel CACS divided by the total CACS. Standard descriptive statistics were used to characterise baseline differences. Group comparisons were completed with Wilcoxon rank sum for continuous measures and Chi-square for categorical. Results A CAC positive cohort of 3,417 participants was prepared from participants with SMuRF and CT imaging data, 14.3% of whom were considered SMuRFless. Total CACS was lower in SMuRFless participants compared to those with ≥1 SMuRF (58 AU vs. 102 AU, p<0.0001). However, proportion of calcium burden in the LAD was significantly higher in SMuRFless participants with CAD (74.2% vs. 56.8%, p<0.0001). When considering clinically significant CACS strata, proportion of LAD calcium burden was not significantly different between SMuRFless vs. ≥1 SMuRF participants with a total CACS of 1-99 AU (93.7% vs. 80.0%). However, statistically significant differences in LAD calcium proportion were observed between SMuRFless vs. ≥1 SMuRF participants with a total CACS 100-400 AU (69.5% vs. 57.8%) and CACS>400AU (45.2% vs. 40.5%). This difference remained significant during multivariate modelling, including consideration of absolute CACS. Conclusion Of patients with evidence of CAD (CACS>0) in the MESA cohort, SMuRFless status was associated with a higher proportion of LAD disease compared to participants with ≥1 SMuRF. This adds to previous observations in STEMI cohorts suggesting a heightened susceptibility to atherosclerosis development in the LAD territory against a lower traditional risk burden, and highlights the need for consideration of distinct biology and clinical significance in future studies.Fig. 1Fig. 2