Cardiovascular magnetic resonance characteristics and clinical outcomes of patients with ST-elevation myocardial infarction and no standard modifiable risk factors-A DANAMI-3 substudy.

Introduction: A higher 30-day mortality has been observed in patients with first-presentation ST elevation myocardial infarction (STEMI) who have no standard modifiable cardiovascular risk factors (SMuRFs), i. e., diabetes, hypertension, hyperlipidemia, and current smoker. In this study, we evaluate the clinical outcomes and CMR imaging characteristics of patients with and without SMuRFs who presented with first-presentation STEMI. Methods: Patients from the Third DANish Study of Acute Treatment of Patients With ST-Segment Elevation Myocardial Infarction (DANAMI-3) with first-presentation STEMI were classified into those with no SMuRFs vs. those with at least one SMuRF. Results: We identified 2,046 patients; 283 (14%) SMuRFless and 1,763 (86%) had >0 SMuRF. SMuRFless patients were older (66 vs. 61 years, p < 0.001) with more males (84 vs. 74%, p < 0.001), more likely to have left anterior descending artery (LAD) as the culprit artery (50 vs. 42%, p = 0.009), and poor pre-PCI (percutaneous coronary intervention) TIMI (thrombolysis in myocardial infarction) flow ≤1 (78 vs. 64%; p < 0.001). There was no difference in all-cause mortality, non-fatal reinfarction, or hospitalization for heart failure at 30 days or at long-term follow-up. CMR imaging was performed on 726 patients. SMuRFless patients had larger acute infarct size (17 vs. 13%, p = 0.04) and a smaller myocardial salvage index (42 vs. 50%, p = 0.02). These differences were attenuated when the higher LAD predominance and/or TIMI 0-1 flow were included in the model. Conclusion: Despite no difference in 30-day mortality, SMuRFless patients had a larger infarct size and a smaller myocardial salvage index following first-presentation STEMI. This association was mediated by a larger proportion of LAD culprits and poor TIMI flow pre-PCI. Clinical trial registration: clinicaltrials.gov, unique identifier: NCT01435408 (DANAMI 3-iPOST and DANAMI 3-DEFER) and NCT01960933 (DANAMI 3-PRIMULTI).