Contribution of cardiovascular comorbidity and adverse presentation to in-hospital mortality differences with first myocardial infarction in patients with and without standard modifiable risk factors

Background Patients with standard modifiable cardiovascular risk factors (SMuRFs) reportedly have lower short-term mortality after myocardial infarction (MI) than those without SMuRFs (SMuRFless). Unrecognised and untreated standard risk in first MI patients may underlie this difference. Purpose To assess the contribution of cardiovascular comorbidities and adverse presentation to differences in in-hospital mortality between first MI patients with and without SMuRFs. Methods We analysed first MI patients from nationwide MI cohorts in Switzerland (AMIS Plus) and Hungary (HUMIR) between 2014 to 2024. First MI was defined by excluding patients with a history of either prior MI, percutaneous coronary intervention, or coronary artery bypass grafting. SMuRF status was defined by a history of hypertension, hyperlipidaemia, diabetes mellitus, or smoking. The primary outcome was in-hospital mortality. Patient characteristics included SMuRFs, cardiovascular comorbidities (stroke, heart failure, chronic kidney disease [CKD], and peripheral vascular disease [PVD]) and adverse MI presentation (heart failure or cardiac arrest). Outcome analyses used sequential additive multivariable-adjusted logistic regression models (odds ratio [OR], 95% confidence intervals [CI]). Results Among a total of 12,827 first MI patients in Switzerland (mean age: 64.0 years; 25.4% female) and 25,394 first MI patients in Hungary (mean age: 64.9 years; 36.0% female), 680 (5.3%) and 1,675 (6.6%) were SMuRFless, respectively. ST-elevation MI (STEMI) prevalence was higher in SMuRFless patients in Switzerland (69.3% vs. 61.3%, p < 0.001) and Hungary (61.9% vs. 55.3%, p < 0.001). Cardiovascular comorbidities were higher in SMuRF patients in both countries (PVD: 2.6% vs.0.6%, stroke: 3.2% vs. 0.9%, CKD: 4.5% vs. 1.2%; Hungary: heart failure: 9.3% vs. 5.0%, PVD: 10.8% vs. 3.2%, stroke: 7.0% vs. 2.7%, CKD: 19.3% vs. 11.2%; all p <0.001), except heart failure in Switzerland (1.1% vs. 0.3%, p = 0.051). Cardiovascular comorbidity was higher among SMuRFless patients in Hungary compared with Switzerland. Adverse MI presentations did not differ significantly between groups in either country (p > 0.15 for all). Unadjusted in-hospital mortality rate was higher in SMuRFless patients in Switzerland (3.7% vs. 2.3%, p = 0.023; OR: 1.61, 95%CI: 1.04-2.39), but not in Hungary (4.8% vs. 5.6%, p = 0.144; OR: 0.84, 95%CI: 0.67-1.06). After full adjustment for cardiovascular comorbidities and adverse MI presentation, mortality differences in Switzerland were no longer significant (Model 3; Figure 1). Conclusion In this binational study, differences in in-hospital mortality between SMuRF and SMuRFless first MI patients appear to be explained by baseline cardiovascular comorbidities and disease presentation. Further studies should explore whether SMuRFless patients carry unrecognised standard modifiable risks rather than non-traditional risk factors.