Trends in conventional cardiovascular risk factors and myocardial infarction subtypes among young Chinese men with a first acute myocardial infarction

Abstract Background There is limited data on the characteristics of conventional risk factors (RFs) in young Chinese men hospitalized with a first acute myocardial infarction (AMI). Hypothesis We analyzed the trends in and prevalence of cardiovascular RFs and subtypes of MI during the first AMI in young Chinese men. Methods A total of 2739 men aged 18–44 years hospitalized for a first AMI were identified from 2007 to 2017. The overall prevalence of RFs and their respective temporal trends and subtypes of AMI were evaluated. Results The most prevalent conditions were smoking, followed by hypertension and then obesity. Patients aged <35 years had a much higher prevalence of hypercholesterolemia and obesity. Compared with a similar reference population in the United States, young Chinese men had a higher prevalence of smoking and dyslipidemia, but a lower prevalence of obesity, hypertension, and diabetes. The prevalence of hypertension increased from 2007 through 2017 (p trend <.001), whereas smoking decreased gradually. AMI frequently presented as ST‐segment elevation MI (STEMI) (77.5%). Cluster of conventional RFs (3 RFs, odds ratio [OR]: 1.69, 95% confidence interval [CI]: 1.11–2.57; ≥4 RFs, OR: 2.50, 95% CI: 1.55–4.03] and multivessel disease (OR = 1.32, 95% CI: 1.08–1.60) increased the risk of non‐STEMI (NSTEMI). Conclusions Conventional RFs were highly prevalent in young Chinese men who were hospitalized for first AMI events, and the temporal trends varied different between China and US populations. Multivessel disease and cluster of conventional RFs are closely related to NSTEMI. Optimized preventive strategies among young adults are warranted.


| INTRODUCTION
The primary and secondary prevention of coronary heart disease (CHD) in young adults has garnered tremendous attention given the rapid increase in the incidence of acute coronary events and hospitalization rates, especially in young men. Evidence from observational epidemiological studies showed the incidence of acute coronary events increased by 37.4% in the year 2009 compared to 2007 in young adults aged 35-39 years, making it the largest increase for this age group. 1 Hospitalization rates for acute myocardial infarction (AMI) per 100 000 population experienced the most significant increase in young men (<55 years), by 45.8% from 2007 to 2012 in Beijing; 2 the proportion of young adults hospitalized for CHD was nearly 90% in men from 2013 to 2014 in Beijing. 3 This trend parallels an increase in cardiovascular risk factors (RFs) including smoking, hypertension, diabetes, obesity, and dyslipidemia in the general Chinese population as well as an increase in hospitalizations for AMI. 2,[4][5][6] The Prospective Urban Rural Epidemiology (PURE) study showed that approximately 70% of cardiovascular disease (CVD) cases were attributed to modifiable RFs. 7 Though several studies have evaluated the prevalence of these RFs during a first or any episode of AMI and have found a high prevalence of at least 1 RF (approximately 90%), [8][9][10] most patients were classified as being at low or intermediate risk by traditional CHD risk prediction scores. 11,12 Unfortunately, this does not aid in the development of appropriate primary preventive strategies to decrease the risk of CHD. The prevalence of conventional RFs, other clinical characteristics, and their trends need to be clarified, which can be used in formulating preventive strategies.
Few studies have evaluated recent long-term trends and prevalence of modifiable RFs during a first AMI in young adults in China.
In a retrospective analysis of patients with coronary artery disease aged ≤45 years conducted from 2010 to 2014, 6  Hospitalizations for AMI were determined according to the fourth universal definition of MI. 13 AMI cases were first identified by excluding cases with secondary diagnoses of prior MI, prior percutaneous coronary intervention, prior coronary artery bypass grafting, post-AMI syndrome, chronic ischemic heart disease, heart transplant recipient, and coronary arterial disease of bypass grafts or in transplanted hearts. Cases with a history of heart failure (HF), arteritis, congenital heart disease, and cancer were excluded. Those without coronary angiography and those with missing values for laboratory reports were excluded. Yandrapalli' et al. 10

| Statistical analysis
Categorical variables were expressed as total numbers (proportions), differences in RF prevalence across age groups were compared using χ 2 tests for categorical variables and trends in the prevalence of RFs were analyzed using linear-by-linear association.

| Trends of conventional RFs and AMI subtypes
The trends in the prevalence of conventional RFs are shown in Figure 1A. No differences were seen in mean DBP and FPG over the three periods (Table S1). Healthcare providers should also focus more attention on the control of metabolic factors and encourage smoking cessation.

| LIMITATIONS
There are some limitations that deserve consideration. This was a single-center study and the data were collected from Beijing Anzhen hospital, which is well known for the management of CHD.