Diastolic Blood Pressure, Subclinical Myocardial Damage, and Cardiac Events: Implications for Blood Pressure Control

Abstract

Background: The optimal systolic blood pressure (SBP) treatment goal is in question, with SPRINT (Systolic Blood Pressure Intervention Trial) suggesting benefit for 120 mm Hg. However, achieving an SBP this low may reduce diastolic blood pressure (DBP) to levels that could compromise myocardial perfusion.

Objectives: This study sought to examine the independent association of DBP with myocardial damage (using high-sensitivity cardiac troponin-T [hs-cTnT]) and with coronary heart disease (CHD), stroke, or death over 21 years.

Methods: The authors studied 11,565 adults from the ARIC (Atherosclerosis Risk In Communities) cohort, analyzing DBP and hs-cTnT associations as well as prospective associations between DBP and events.

Results: Mean baseline age was 57 years, 57% of patients were female, and 25% were black. Compared with persons who had DBP between 80 to 89 mm Hg at baseline (ARIC visit 2), the adjusted odds ratio of having hs-cTnT ≥14 ng/l at that visit was 2.2 and 1.5 in those with DBP <60 mm Hg and 60 to 69 mm Hg, respectively. Low DBP at baseline was also independently associated with progressive myocardial damage on the basis of estimated annual change in hs-cTnT over the 6 years between ARIC visits 2 and 4. In addition, compared with a DBP of 80 to 89 mm Hg, a DBP <60 mm Hg was associated with incident CHD and mortality, but not with stroke. The DBP and incident CHD association was strongest with baseline hs-cTnT ≥14 ng/l (p value for interaction <0.001). Associations of low DBP with prevalent hs-cTnT and incident CHD were most pronounced among patients with baseline SBP ≥120 mm Hg.

Conclusions: Particularly among adults with an SBP ≥120 mm Hg, and thus elevated pulse pressure, low DBP was associated with subclinical myocardial damage and CHD events. When titrating treatment to SBP <140 mm Hg, it may be prudent to ensure that DBP levels do not fall below 70 mm Hg, and particularly not below 60 mm Hg.

Keywords: J-curve; coronary heart disease; coronary perfusion; high-sensitivity troponin; hypertension.

Figure 1. Adjusted* Odds Ratio (95% confidence interval) for Prevalent Elevated hs-cTnT (≥14 ng/L), according to baseline Diastolic Blood Pressure (DBP) with background histogram of DBP distribution in the study sample

*Adjusted for: age (years), race-center, gender, body mass index in kg/m², smoking (current; former; never), alcohol intake (current; former; never), systolic BP (in mmHg), hypertension medication use (yes, no), diagnosed diabetes (yes, no), LDL-cholesterol (mg/dL), HDL-cholesterol (mg/dL), triglycerides (mg/dL), current use of cholesterol-lowering medication (yes or no), and estimated glomerular filtration rate in mL/min/1.73m². Restricted Cubic Spline for odds of elevated hs-cTnT with background distributional histogram of baseline Diastolic BP. Note that the "frequency" axis label identifies the number ARIC participants at each point on this background histogram. Splines are centered at 85 mmHg, have knots at 57, 68, 75 and 90 mm Hg, and are truncated at the 1^st and 99^th percentiles. The shaded area around the regression line represents the 95% confidence interval Hs-cTnT= high-sensitivity Troponin T, other abbreviations as per Table 1

Figure 1. Adjusted* Odds Ratio (95% confidence interval) for Prevalent Elevated hs-cTnT (≥14 ng/L), according to baseline Diastolic Blood Pressure (DBP) with background histogram of DBP distribution in the study sample

*Adjusted for: age (years), race-center, gender, body mass index in kg/m², smoking (current; former; never), alcohol intake (current; former; never), systolic BP (in mmHg), hypertension medication use (yes, no), diagnosed diabetes (yes, no), LDL-cholesterol (mg/dL), HDL-cholesterol (mg/dL), triglycerides (mg/dL), current use of cholesterol-lowering medication (yes or no), and estimated glomerular filtration rate in mL/min/1.73m². Restricted Cubic Spline for odds of elevated hs-cTnT with background distributional histogram of baseline Diastolic BP. Note that the "frequency" axis label identifies the number ARIC participants at each point on this background histogram. Splines are centered at 85 mmHg, have knots at 57, 68, 75 and 90 mm Hg, and are truncated at the 1^st and 99^th percentiles. The shaded area around the regression line represents the 95% confidence interval Hs-cTnT= high-sensitivity Troponin T, other abbreviations as per Table 1