Mortality After ST-Segment–Elevated Myocardial Infarction Among Patients With and Without Standard Modifiable Cardiovascular Risk Factors in China

BACKGROUND: Patients without standard modifiable cardiovascular risk factors (SMuRF) have an associated increased mortality with ST-segment–elevation myocardial infarction. This study aims to provide insight into the clinical features, treatments, and outcomes of SMuRF-less patients. METHODS: This nationwide, multicenter cohort study utilized data from the Chinese Cardiovascular Association Database–Chest Pain Center, a national registry derived from electronic medical records of accredited chest pain centers across China. We included adults aged ≥18 years with ST-segment–elevation myocardial infarction admitted between January 1, 2017, and December 31, 2021. The index date was the date of hospital admission. SMuRF included hypertension, diabetes, hyperlipidemia, or smoking, ascertained from medical records at admission. SMuRF-less status was defined as the absence of all 4 risk factors. Outcomes included all-cause mortality at 0 to 30 days and 31 to 365 days. Multivariable Cox regression and landmark analysis were used to assess associations between SMuRF status and mortality. RESULTS: Of 379 811 ST-segment–elevation myocardial infarction patients, 87 830 (23.1%) were SMuRF-less. The 30-day all-cause mortality was higher in SMuRF-less patients than in those with SMuRF (10.7% versus 6.7%). After multivariable adjustment, SMuRF-less status remained independently associated with increased 30-day mortality (adjusted hazard ratio, 1.22 [95% CI, 1.19–1.25]). In the 31- to 365-day follow-up period, the mortality rate was numerically higher in the SMuRF-less group (3.8% versus 3.2%), but there was no significance after covariate adjustment (adjusted hazard ratio, 1.00 [95% CI, 0.95–1.04]). The elevated 30-day mortality associated with SMuRF-less status was consistent across most subgroups but significantly more pronounced in men than in women ( P for interaction <0.001). CONCLUSIONS: In this nationwide analysis, nearly one-quarter of ST-segment–elevation myocardial infarction cases were SMuRF-less. Compared with patients with SMuRF, the mortality excess in SMuRF-less patients was confined to the first 30 days, and mortality did not differ subsequently.