Abstract Body (Do not enter title and authors here): Background
Current US and European guidelines recommend targeting a systolic blood pressure (SBP) below 130 mmHg in patients at high cardiovascular (CV) risk, such as those with a history of acute coronary syndrome (ACS), though these recommendations are largely extrapolated from trials in the general hypertensive population.

Aims
Our aim was to evaluate the prognostic significance of SBP measured one year after an ACS event on subsequent CV outcomes.

Methods
The SPUM-ACS cohort prospectively enrolled patients with ACS between 2009 and 2017 across four Swiss tertiary care centers. We included patients who were alive at one-year post-enrollment and had available SBP measurements at that time point. The association between continuous SBP, measured one year post ACS (marking the start of the follow-up period) and the risk of the composite outcome of 3-point major adverse CV events (MACE) —including CV death, non-fatal stroke or transient ischemic stroke, and non-fatal myocardial infarction—was assessed using restricted cubic spline modeling. Outcomes were monitored up to five years after the index ACS event. Analyses were adjusted for age, sex, established CV risk factors and antihypertensive medication classes.

Results
A total of 2,731 patients (mean age 63±12 years; 82% male; mean SBP 132±19 mmHg; 55.1% ST elevation myocardial infarction) were included in the analysis. During a median follow-up of 4.0 years, 273 patients experienced a MACE. The association between SBP at 1 year and the risk of 3-point MACE demonstrated a nonlinear, J-shaped pattern (Figure 1, P_{non-linearity}=0.05) The lowest risk was observed for SBP values between ~125 and 135 mmHg (23.7% of the cohort), with a progressive increase in risk for SBP levels above 135 mmHg (40.4% of the cohort). Specifically, for SBP values above 135 mmHg, each 5 mmHg-increase was associated with a higher risk of MACE (adjusted hazard ratio: 1.09; 95% confidence interval: 1.01–1.18). In analyses stratified by age and sex, the J-shaped relationship remained consistent, with no significant interaction observed (P_{interaction for age}=0.80; P_{interaction for sex}=0.66; Figure 2).


Conclusions
In this large and well-characterized cohort of post-ACS patients, the lowest risk of CV events was observed with SBP levels between ~125 and 135 mmHg, without evidence of differences by age and sex. Our data support the recommendations of targeting SBP within a reasonable range after an ACS while avoiding both over- and undertreatment.