Mechanisms underlying the J-curve for diastolic blood pressure: Subclinical myocardial injury and immune activation

Background: Low diastolic blood pressure (DBP) is associated with increased risk of cardiovascular events. In patients with coronary artery disease (CAD), limitations in coronary blood flow and immune activity are implicated mechanisms, but evidence is lacking. We investigated the association between DBP, biomarkers of myocardial injury, inflammation, immune activation and incident events in patients with CAD. Methods: We studied 2448 adults (mean age 65 ± 12 years, 68% male, median follow-up 4.5 years) with CAD. DBP was categorized into 10 mm Hg increments. Biomarkers of myocardial injury (high sensitivity cardiac troponin-I [hs-cTnI]) and immune activity/inflammation (soluble urokinase plasminogen activator receptor [suPAR]) were dichotomized at their median values. DBP 70–79 mm Hg was used as the referent group, and individuals were followed prospectively for adverse outcomes. Results: After adjusting for demographic and clinical covariates, individuals with DBP < 60 mm Hg had increased odds of elevated levels of hs-cTnI (OR = 1.68; 95% CI = 1.07, 2.65) and suPAR (OR = 1.71; 95% CI = 1.10, 2.65) compared to the referent group. Additionally, DBP < 60 mm Hg was associated with increased adjusted risk of cardiovascular death or MI (HR = 2.04; 95% CI = 1.32, 3.16) and all-cause mortality (HR = 2.41; 95% CI = 1.69, 3.45). Conclusion: In patients with CAD, DBP < 60 mm Hg is associated with subclinical myocardial injury, immune/inflammatory dysregulation and incident events. Aggressive BP control may be harmful in these patients, and further investigation is warranted to determine appropriate BP targets in patients with CAD.