J-curve relationship between admission SBP and 2-year cardiovascular mortality in older patients admitted for acute coronary syndrome

OBJECTIVE: To investigate the relationship between admission SBP and subsequent cardiovascular and all-cause mortality in older patients hospitalized for acute coronary syndrome (ACS). METHODS: This is a retrospective observational study. Data from the CBD Bank (Cardiovascular Center Beijing Friendship Hospital Database Bank) were used to analyze the cardiovascular and all-cause mortality during hospitalization and over the follow-up period in relation to admission SBP among patients aged at least 65 years admitted for ACS from December 2012 through July 2019. Results were presented according to SBP quartiles: Q1, less than 120 mmHg; Q2, from 120 to 129 mmHg; Q3, from 130 to 143 mmHg; and Q4, at or above 144 mmHg. RESULTS: A total of 6785 patients were included in this cohort study. Mean (SD) patient age was 74.0 (6.5) years, and 47.6% were women. Mean (SD) follow-up time was 2.54 (1.82) years. A nonlinear relation was observed between SBP at admission and cardiovascular and all-cause mortality during hospitalization and over the follow-up period using restricted cubic splines. After adjustment for potential confounders, patients in Q1 had higher risk for 2-year cardiovascular death by Cox proportional hazard model compared with patients in Q2 [hazard ratio, 1.58; 95% confidence interval (CI), 1.12–2.21, P = 0.009], whereas patients in Q3 or Q4 exhibited a trend towards increased risk for 2-year cardiovascular death (hazard ratio, 1.33, 95% CI, 0.95–1.86, P = 0.094, for Q3 vs. Q2; and hazard ratio, 1.28, 95% CI, 0.91–1.82, P = 0.160, for Q4 vs. Q2). Meanwhile, when compared with patients in Q1, patients in Q2 had lower risk for 2-year cardiovascular death (hazard ratio, 0.64; 95% CI, 0.45–0.89, P = 0.009) whereas patients in Q3 or Q4 had similar risk for cardiovascular death (hazard ratio, 0.85, 95% CI, 0.63–1.14, P = 0.272, for Q3 vs. Q1; and hazard ratio, 0.82, 95% CI, 0.59–1.13, P = 0.221, for Q4 vs. Q1). However, low-admission SBP was not an independent predictor of 2-year all-cause mortality in this population. CONCLUSION: Among patients aged at least 65 years admitted for ACS, there is a J-curve relationship between supine admission SBP and risk for 2-year cardiovascular death, with a nadir at 120–129 mmHg.