Role of inflammation and cholesterol efflux in myocardial infarction patients without standard modifiable risk factors

Abstract Background A substantial proportion of ST-segment elevation myocardial infarction (STEMI) patients has no standard modifiable cardiovascular risk factors (SMuRF) at admission. Knowledge on pathogenesis and risk markers of mortality in these patients remain limited. Aims We described the characteristics and prognosis of SMuRF-less patients admitted for a first STEMI in the light of recent prognostic biomarkers. Methods Baseline characteristics including interleukin (IL)-1β, hs-CRP and serum cholesterol efflux capacity were compared between patients with and without SMuRF. Determinants of 1-year all-cause mortality were assessed using univariable and multivariable Cox regression analyses. Results Among the 1604 patients included, 178 (11.1%) were SMuRF-less. SMuRF-less patients were older (66.9 ± 15.3 vs 61.9 ± 13.9, p<0.001), less often men (66.9 vs 75.9%, p<0.001) and had lower body mass index (24.2 ± 3.9 vs 26.0 ± 4.4, p<0.001) compared to patients with ≥1 SMuRFs. SMuRF-less patients presented higher rates of altered LVEF<45% and killip≥2 at admission (31.8% vs 22.8%, p=0.014 and 19 vs 12.9%, respectively, p=0.027) without differences in proportions of late STEMI presenters (symptoms-to-balloon time >360 min) did not differ between groups. SMuRF-less patients had lower rates of revascularization (82 vs 92.3%, p<0.001) and received less guidelines recommended medications (statins, β-blockers or angiotensin-converting enzyme (ACE) inhibitors) at discharge; p<0.001 for all. Compared to patients with SMuRF, SMuRF-less patients had lower serum cholesterol efflux capacity (0.79 ± 0.16 vs 0.83 ± 0.16, respectively, p<0.001), were more often in the highest tertile of IL-1β (28.7% vs 18.9%, respectively, p=0.002) with a trend towards more patients within the highest hs-CRP level tertile (24.7% vs 19.1%, respectively, p=0.077). Crude rates of mortality were more than doubled in the SMuRF-less group (18.5% vs 7.7%, respectively, p<0.001). After multivariable adjustment SMuRF-less status was associated with a higher rate of mortality at one year aHR 1.87 [1.05-2.38], p=0.029) as well as inflammation biomarkers IL-1β (HR 1.81 [1.23-2.66], p=0.003) and high tertiles of hs-CRP (HR 1.87 [1.31-2.66], p<0.001) whereas having a high serum cholesterol efflux capacity was associated with a lower mortality (HR 0.27 [0.09-0.87], p=0.0208). Conclusion In STEMI patients, SMuRF-less patients have higher levels of inflammatory biomarkers and more frequent defective serum cholesterol efflux capacity, are undertreated, and have higher rate of mortality than patients with standard modifiable cardiovascular risk factors. Optimized management of such patients is needed.