Introduction: Clinical trials have shown increased survival at lower blood pressures, but low diastolic blood pressure (DBP) is associated with increased cardiovascular (CV) events and mortality. The suggested mechanism in patients with coronary artery disease (CAD) is limitation in coronary blood flow; however, evidence is lacking. We investigated the association between DBP, biomarkers of myocardial injury, and incident events in patients with CAD.
Methods: We assessed 2448 individuals (aged 65±12 years, 68% male, median follow-up 4.5 years) with stable CAD undergoing cardiac catheterization. Those with acute coronary syndromes or heart failure with reduced ejection fraction were excluded. DBP was categorized into 10 mm Hg increments. Biomarkers of myocardial damage (high sensitivity cardiac troponin-I [hs-cTnI] and soluble urokinase plasminogen activating receptor [suPAR]) were dichotomized at their median values. DBP 80-89 mmHg was used as the referent group and individuals were followed for MACE (CV death or non-fatal myocardial infarction) and all-cause mortality.
Results: After adjusting for relevant demographic and clinical covariates, individuals with DBP < 60 mm Hg had increased odds of elevated hs-cTnI (OR = 1.75; 95% CI = 1.05, 2.90) and suPAR (OR = 1.73; 95% CI = 1.09, 2.76) compared to the referent group. Additionally, DBP < 60 mm Hg was associated with increased risk of MACE (HR = 2.01; 95% CI = 1.24, 3.25) and all-cause mortality (HR = 2.18; 95% CI = 1.50, 3.19). Adding hs-cTnI and suPAR into the Cox proportional hazards model attenuated the association between DBP < 60 mmHg and MACE (HR =1.63, 95% CI 0.91, 2.91), but not all-cause mortality (HR = 1.67, 95% CI = 1.06, 2.63).
Conclusion: In patients with CAD, low DBP is associated with biomarkers of myocardial injury and incident events. Aggressive blood pressure control may be harmful in these patients, and further investigation is warranted to determine appropriate blood pressure targets in patients with CAD.