Association between low diastolic blood pressure and subclinical myocardial injury

Coronary arteries perfuse cardiac myocytes during diastole. We hypothesized that marked lowering of diastolic blood pressure (DBP) is associated with increased risk of subclinical myocardial injury (SC-MI).

This analysis included 6107 participants without history of cardiovascular disease (CVD) from the third National Health and Nutrition Examination Survey. SC-MI was determined by a validated electrocardiogram-based scoring system. Logistic regression was used to examine the cross-sectional association between DBP (< 70, 70-80 mmHg (reference group), and > 80 mmHg; and per each 10 mmHg decrease, separately) with SC-MI across levels of systolic blood pressure (SBP) (< 120, 120-139, or > 140 mmHg).

In a multivariable model, DBP < 70 mmHg was associated with a higher risk of SC-MI [OR (95% CI) 1.40 (1.02, 1.94)] in participants with SBP > 140 mmHg. This association was consistent in subgroups stratified by age, race, diabetes, hypertension, obesity and smoking, but was stronger in women than in men [OR (95% CI) 1.58 (1.06, 2.37) vs. 1.10 (0.62, 1.94), respectively; interaction p value = 0.006]. Also, among participants with SBP > 140 mmHg, every 10 mmHg decrease in DBP was associated with a 12% increased odds of SC-MI [OR (95% CI) 1.12 (1.01, 1.23)]. No significant associations between DBP and SC-MI were observed in those with SBP < 120 mmHg or 120-139 mmHg, or between DBP > 80 mmHg and SC-MI in any of SBP levels.

Low DBP < 70 mmHg in those with SBP > 140 mmHg carries higher risk of SC-MI, especially in women. Further research is needed to understand the therapeutic implications of these findings.