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.
