Association of Normal Systolic Blood Pressure Level with Cardiovascular Disease in the Absence of Risk Factors

Importance: The risk of atherosclerotic cardiovascular disease (ASCVD) at currently defined normal systolic blood pressure (SBP) levels in persons without ASCVD risk factors based on current definitions is not well defined. Objective: To examine the association of SBP levels with coronary artery calcium and ASCVD in persons without hypertension or other traditional ASCVD risk factors based on current definitions. Design, Setting, and Participants: A cohort of 1457 participants free of ASCVD from the Multi-Ethnic Study of Atherosclerosis who were without dyslipidemia (low-density lipoprotein cholesterol level ≥160 mg/dL or high-density lipoprotein cholesterol level <40 mg/dL), diabetes (fasting glucose level ≥126 mg/dL), treatment for hyperlipidemia or diabetes, or current tobacco use, and had an SBP level between 90 and 129 mm Hg. Participants receiving hypertension medication were excluded. Coronary artery calcium was classified as absent or present and adjusted hazard ratios (aHRs) were calculated for incident ASCVD. The study was conducted from March 27, 2018, to February 12, 2020. Exposures: Systolic blood pressure. Main Outcomes and Measures: Presence or absence of coronary artery calcium and incident ASCVD events. Results: Of the 1457 participants, 894 were women (61.4%); mean (SD) age was 58.1 (9.8) years and mean (SD) follow-up was 14.5 (3.9) years. There was an increase in traditional ASCVD risk factors, coronary artery calcium, and incident ASCVD events with increasing SBP levels. The aHR for ASCVD was 1.53 (95% CI, 1.17-1.99) for every 10-mm Hg increase in SBP levels. Compared with persons with SBP levels 90 to 99 mm Hg, the aHR for ASCVD risk was 3.00 (95% CI, 1.01-8.88) for SBP levels 100 to 109 mm Hg, 3.10 (95% CI, 1.03-9.28) for SBP levels 110 to 119 mm Hg, and 4.58 (95% CI, 1.47-14.27) for SBP levels 120 to 129 mm Hg. Conclusions and Relevance: Beginning at an SBP level as low as 90 mm Hg, there appears to be a stepwise increase in the presence of coronary artery calcium and the risk of incident ASCVD with increasing SBP levels. These results highlight the importance of primordial prevention for SBP level increase and other traditional ASCVD risk factors, which generally seem to have similar trajectories of graded increase in risk within values traditionally considered to be normal.