Characteristics, Treatment, and Mortality of Patients Hospitalized for First ST-Segment Elevation Myocardial Infarction without Standard Modifiable Risk Factors in China.

BACKGROUND

Little is known of the characteristics, treatment, and outcomes of patients with ST-segment elevation myocardial infarction (STEMI) but without standard modifiable cardiovascular risk factors (SMuRFs, including smoking, hypercholesterolemia, diabetes, and hypertension) in developing countries like China. Moreover, contributors to the excess mortality of such SMuRF-less patients remain unclear.

METHODS

This study was based on a nationally representative sample of patients presenting with STEMI and admitted to 162 hospitals in 31 provinces across mainland China between 2001 and 2015. We compared clinical characteristics, treatments, and mortality during hospitalization between patients with and without SMuRFs. We also investigated the possible causes of differences in mortality and quantified the contributors to excess mortality.

RESULTS

Among 16,541 patients (aged 65 ± 13 years; 30.0% women), 19.9% were SMuRF-less. These patients were older (69 vs. 65 years), experienced more cardiogenic shock and lower blood pressure at admission, and were less likely to be admitted to the cardiac ward compared to patients with SMuRFs. Moreover, SMuRF-less patients received treatment less often, including primary percutaneous coronary intervention (17.3% vs. 28.8%, p < 0.001), dual antiplatelet therapy (59.4% vs. 77.0%, p < 0.001), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (49.9% vs. 68.1%, p < 0.001), and statins (69.9% vs. 85.1%, p < 0.001). They had higher in-hospital mortality (18.5% vs. 10.5%, p < 0.001), with 56.1% of deaths occurring within 24 hours of admission. Although the difference in mortality decreased after adjusting for patient characteristics, it remained significant and concerning (odds ratio (OR) 1.41; 95% confidence interval (CI) 1.25-1.59). Mediation analysis found that, in patients without SMuRFs, underutilization of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and statins contributed to an excess mortality risk of 22.4% and 32.5%, respectively.

CONCLUSIONS

Attention and action are urgently needed for STEMI patients without SMuRFs, given their high incidence and excess in-hospital mortality. The use of timely and adequate evidence-based treatments should be strengthened.