Objective To investigate the relationship between blood pressure levels and the incidence of acute myocardial infarction (AMI) in Chinese adults, and to provide evidence-based references for formulating targeted hypertension prevention strategies for populations with different blood pressure levels.

Methods This study included a total of 36 426 adults aged 18 years and older without a history of AMI event. Participants were recruited from 60 monitoring sites in 11 provinces: Hebei, Jilin, Heilongjiang, Zhejiang, Jiangsu, Jiangxi, Henan, Hunan, Sichuan, Guizhou, and Shaanxi. Baseline systolic and diastolic blood pressure measurements were collected from September to December 2010 during the Third China Chronic Disease Surveillance Survey and were used to categorize participants into groups. Follow-up assessments for AMI incidence were conducted from October 2016 to April 2017. We analyzed the association between baseline blood pressure levels and AMI risk using a multivariable Cox regression model.

Results As of April 2017, 8 929 of the original 36 426 participants were lost to follow-up, resulting in a loss-to-follow-up rate of 24.51%. After excluding 541 deaths due to other diseases and 162 cases with missing body mass index (BMI) and waist circumference data, the final analysis included 26794 participants. A total of 160 386.38 person-years were observed, with an average follow-up period of 5.99 ± 0.89 years. During this period, there were 256 cases of AMI, resulting in an AMI incidence density of 159.60 per 100 000 person-years and a cumulative incidence of 955.40 per 100 000 person-years. The proportions of participants in the four blood pressure groups were as follows: 62.92% (16 858) had normal blood pressure; 14.56% (3 901) had isolated systolic hypertension (ISH); 3.81% (1 022) had isolated diastolic hypertension; and 18.71% (5 013) had systolic-diastolic hypertension (SDH). The cumulative counts of AMI events in these groups were 101, 62, 7, and 86, with respective incidence rates of 599.12, 1 589.34, 684.93, and 1 715.54 per 100 000 person-years. The differences in AMI incidence rates among the subgroups were statistically significant (χ² = 70.576, P < 0.001). In contrast, the proportions of participants in the four groups categorized by hypertension severity were as follows: 62.92% (16 858) had normal blood pressure; 22.07% (5 913) had stage 1 (mild) hypertension; 10.07% (2 699) had stage 2 (moderate) hypertension; and 4.94% (1 324) had stage 3 (severe) hypertension. There were 101, 76, 45, and 34 observed AMI events in these groups, with respective incidence rates of 599.12, 1 285.30, 1 667.28, and 2 567.98 per 100 000 person-years (χ² = 80.247, P < 0.001). After adjusting for confounders, including gender, age, education level, marital status, residence (urban or rural), annual household income, smoking status, alcohol consumption, inadequate fruit and vegetable intake, excessive red meat consumption, physical inactivity, diabetes, and dyslipidemia, a multivariable Cox regression analysis revealed that individuals with SDH had a 61% higher risk of AMI than individuals with normal blood pressure (hazard ratio HR = 1.61, 95% confidence interval CI = 1.17–2.21). The risk increased by 60% (HR = 1.60, 95%CI = 1.17–2.20) for stage 1 hypertension, 84% (HR = 1.84, 95%CI = 1.26–2.68) for stage 2 hypertension, and 120% (HR = 2.20, 95%CI = 1.43–3.38) for stage 3 hypertension.

Conclusions For Chinese adults, SDH is an independent risk factor for AMI, and the risk of AMI increases with the severity of hypertension.