Mortality Risk and Treatment Disparities in the Chinese SMuRF-less STEMI Patients: A Nationwide Cohort Study

Aims In ST-segment elevation myocardial infarction (STEMI) patients, standard modifiable cardiovascular risk factors (SMuRFs) are strongly associated with increased risk of morbidity and mortality. However, clinical studies have shown that SMuRF-less patients have worse clinical outcomes. Limited research exists in China, and the clinical characteristics and prognosis of SMuRF-less patients remain unclear. This study aims to provide insight into the clinical features, treatments, and outcomes of SMuRF-less patients in China. Methods We retrospectively analysed adult patients with STEMI using data from the China Chest Pain Center database. We examined the impact of SMuRF-less on short-term (0 to 30 days) and long-term (31 to 365 days) mortality. Cox-proportional hazard models and Kaplan-Meier analysis for short-term and long-term mortality. Results Of the 379,811 patients, 87,830 (23.1%) were SMuRF-less. Patients in the SMuRF-less group were older (65 years vs. 63 years), a higher proportion of female (29.4% vs. 23.3%) and less like to receiving reperfusion therapy (81.1% vs. 85.6%). On short-term SMuRFs patients had significantly lower all-cause mortality (5.1% vs 8.7%, hazard ratios (HR) 0.82 [95% Confidence interval (CI) 0.80–0.84], P < 0.001). However, on long-term there was no significant difference in mortality between the groups (3.4% vs 3.8%, HR: 1.00, 95% CI: 0.96-1.05; P = 0.841). Conclusions SMuRF-less patients exhibited higher mortality, particularly within the first 30 days after STEMI onset, with a more pronounced effect observed in male patients. Treatment disparities and delayed care were key contributors to this difference. Graphical abstract Comparison of clinical characteristics and outcomes between STEMI patients with SMuRF-less and SMuRFs. SMuRF-less was defined as having no traditional risk factors (hypertension, hyperlipidemia, diabetes, or smoking history), while SMuRFs had ≥1 risk factor. Among STEMI patients, SMuRF-less patients, who accounted for 23% of the cohort, had a higher proportion of females, longer delays to first medical contact (FMC), lower rates of guideline-directed medical therapy (GDMT) and reperfusion, and higher short-term mortality compared to SMuRFs (77%). Kaplan-Meier analysis shows lower 30-day mortality in SMuRF-less patients (HR:0.82, 95% CI: 0.80–0.84, P < 0.001), with no significant difference in long-term mortality (HR: 1.00, 95% CI: 0.96–1.05, P = 0.841). Abbreviations: STEMI, ST elevation myocardial infarction; SMuRFs, standard modifiable cardiovascular risk factors; FMC, first medical contact; GDMT, guideline-directed medical therapy; HR, hazard ratio; CI, confidence interval.