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.

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.