Using Restricted Cubic Splines to Study the Trajectory of Systolic Blood Pressure in the Prognosis of Acute Myocardial Infarction

Shuai Zheng; Fengzhi Zhao; Rui Yang; Wentao Wu; Hui Liu; Wen Ma; Fengshuo Xu; Didi Han; Jun Lyu

doi:10.3389/fcvm.2021.740580

Using Restricted Cubic Splines to Study the Trajectory of Systolic Blood Pressure in the Prognosis of Acute Myocardial Infarction

Front Cardiovasc Med. 2021 Sep 10:8:740580. doi: 10.3389/fcvm.2021.740580. eCollection 2021.

Authors

Shuai Zheng^{1

2}, Fengzhi Zhao³, Rui Yang⁴, Wentao Wu⁴, Hui Liu⁵, Wen Ma⁴, Fengshuo Xu⁴, Didi Han⁴, Jun Lyu¹

Affiliations

¹ Department of Clinical Research, The First Affiliated Hospital of Jinan University, Guangzhou, China.
² School of Public Health, Shaanxi University of Chinese Medicine, Xianyang, China.
³ Intensive Care Unit, The First Affiliated Hospital of Jinan University, Guangzhou, China.
⁴ School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China.
⁵ School of Public Health, Lanzhou University, Lanzhou, China.

Abstract

Background: Acute myocardial infarction (AMI) is still the most serious manifestation of coronary artery disease. Systolic blood pressure (SBP) is the best predictor of blood pressure in AMI. Thus, its influence on AMI is necessary to be explored. Methods: A total of 4,277 patients with AMI were extracted from the Medical Information Mart for Intensive Care database. Chi-square test or Student's t-test was used to judge differences between groups, and Cox regression was used to identify factors that affect AMI prognosis. SBP was classified as low (<90 mmHg), normal (90-140 mmHg), or high (>140 mmHg), and a non-linear test was performed. Meaningful variables were incorporated into models for sensitivity analysis. Patient age was classified as low and high for subgroup analysis, and the cutoff value of the trajectory was identified. P < 0.05 indicates statistical significance. Results: The effect of SBP on the prognosis of patients with AMI is non-linear. The risks in models 1-3 with low SBP are 6.717, 4.910, and 3.080 times those of the models with normal SBP, respectively. The risks in models 1-3 with high SBP are 1.483, 1.637, and 2.937 times those of the models with normal SBP, respectively. The cutoff point (95% confidence interval) of the trajectory is 114.489 mmHg (111.275-117.702 mmHg, all P < 0.001). Conclusions: SBP has a non-linear effect on AMI prognosis. Low and high SBP show risks, and the risk of low SBP is obviously greater than that of high SBP.

Keywords: AMI; MIMIC; SBP; non-linear; prognosis.