Less risk factor at AMI onset, higher risk in prognosis---the paradoxical phenomenon from MIMIC-III database

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Natural Science Foundation of China (NSFC). Introduction Numerous epidemiologic studies have confirmed that Standard Modifiable Cardiovascular Risk Factors (SMuRFs) are independent risk factors for coronary heart disease (CHD) and are recommended by guidelines for the primary and secondary prevention of CHD. However, it is interesting to find that the increasing proportion of individuals without SMuRFs in CHD and acute myocardial infarction (AMI). Moreover, accumulating clinical trials have reported the inverse association between the number of risk factors and crude mortality in AMI. It is unknown whether this paradoxical phenomenon can be seen in critical ill patients. Purpose To analyze and validate whether the number of risk factors contradicts the mortality outcome in patients with AMI in the MIMIC-III (Medical Information Mart for Intensive Care III) database. Methods A total of 2484 AMI patients (62.8% male, mean age 71.2 [59.3;80.8] years) admitting to cardiac care unit for the first time from the MIMIC-III database were enrolled. Risk factors were defined as hypertension, diabetes,dyslipidemia, and smoking history. They were grouped according to the number of risk factors. Main outcome was mortality at 2-year following hospitalization. Kaplan-Meier curve and Cox proportional hazards models adjusting for baseline clinical characteristics and in-hospital treatment were constructed to evaluate the impact of numbers of risk factors on mortality in critical AMI patients. Results At 2-year follow-up, death was observed in 714 patients (28.7%). A total of 474(19.1%),1541(62%),469(18.9%) patients had 0,1-2,3-4 SMuRFs respectively. No risk group has a significantly higher 2-year mortality (Picture 1). Compared with no risk group, patients with 1-2 and 3-4 SMuRFs were correlated to an HR of 0.72(95%CI, 0.61-0.86) and 0.66(95%CI, 0.52-0.83) for all-cause mortality in the unadjusted model. Interestingly, after multivariate adjustment, less risk factor at AMI onset was still associated with poor prognosis. Conclusions Taking into confounders, critical AMI patients with less risk factors have higher risk in poor prognosis. Further studies on this paradoxical phenomenon are needed.