Impact of malnutrition on in-hospital outcomes in patients with acute myocardial infarction and no standard modifiable cardiovascular risk factors.

Background: Individuals who present with acute myocardial infarction (AMI) in the absence of standard modifiable cardiovascular risk factors (i.e. SMuRF-less) seem to have a significantly increased risk of mortality; however, it remains unclear whether the 'SMuRF paradox' would be influenced by patients' baseline nutritional status.

Methods: We consecutively included patients from a multi-center, prospective registry (NCT05337319) from January 2022 to October 2023. Malnutrition was defined via the Nutritional Risk Index. The primary outcome was in-hospital major adverse cardiovascular events (MACEs), which included mortality, cardiac shock, acute congestive heart failure, reinfarction, and stroke.

Results: A total of 3753 patients with first-presentation AMI were included, of which 10 % were SMuRF-less and over 21 % were malnourished. SMuRF-less malnourished had the highest MACEs (16.1 %), followed by the SMuRF-less nourished (15.5 %), ≥1 SMuRFs malnourished (12.1 %), and ≥1 SMuRFs nourished (5.2 %, p < 0.001). With ≥1 SMuRFs nourished as the reference, SMuRF-less malnourished had the highest increase in MACEs [adjusted OR (95 % CI), 3.385 (2.163-5.298), p < 0.001], followed by SMuRF-less nourished group [adjusted OR (95 % CI), 2.460 (1.214-4.985), p = 0.012], but only a nonsignificant increase in MACEs was observed in the ≥1 SMuRFs malnourished [adjusted OR (95 % CI), 1.297 (0.880-1.911), p = 0.188]. SMuRF-less was not associated with MACEs in the subgroup of malnourished patients [adjusted OR (95 % CI), 1.931 (0.892-4.178), p = 0.095], with a nonsignificant result in interaction analysis (p for interaction = 0.148).

Conclusion: Among patients with first-presentation AMI, malnutrition is prevalent, especially in those SMuRF-less. Compared with those with at least one SMuRF, SMuRF-less patients have a significantly higher risk of in-hospital MACEs irrespective of their nutritional status, while the outcome was the most favorable among ≥1 SMuRF and nourished patients.