Coronary Artery Calcium as a Risk Marker in Patients With Myocardial Infarction but Without Standard Modifiable Risk Factors (SMuRF-Less)

Introduction: Recent publications have reported that myocardial infarction (MI) patients (pts) without standard modifiable risk factors (SMuRF-less) are surprisingly common (14-27%) and have a notable risk of adverse outcomes. These reports raise the question of how these pts can be identified in advance and provided with effective preventive therapies (e.g., statins, aspirin). Methods: Pts presenting between 2001-2021 to Intermountain Healthcare catheterization laboratories with a diagnosis of MI were included if they also had a coronary artery calcium scan (CACS) by computed tomography within 2 years. SMuRF included a clinical diagnosis of, or treatment for, hypertension, hyperlipidemia, diabetes, and/or smoking. The co-primary endpoints for this study were the proportion of patients with an elevated (>50%ile) CACS score (MESA criteria) and the presence of an indication for statin therapy with or without aspirin (i.e., >=75%ile score or CAC>=100 AU). Major adverse cardiovascular event (MACE) outcomes at 60-days and long-term were evaluated and compared to MI pts with SMuRF. Results: We identified 429 MI pts with a concurrent CACS, of which 60 were SMuRF-less and 369 had SMuRF. The 2 groups were similar in age, sex, most risk factors, and interventions, but fewer SMuRF-less pts had a history of heart failure or a family history (Table 1). SMuRF-less pts had a high prevalence and an increased percentile of CAC (82% >=50%ile; median, 80%ile;), and 77% met criteria for preventive therapy. Pts with SMuRF, as expected, had high CAC scores and percentiles (Table 1). Outcomes were more favorable for SMuRF-less status (Table 2A) and for lower CAC scores (Table 2B). Conclusions: Despite absence of SMuRF, SMuRF-less pts presenting with an MI have a high prevalence and percentile of CAC. Wider application of CACS, to include those without SMuRF, appears promising as a method to identify an additional at-risk population for consideration of preventive therapy.