Diastolic Blood Pressure, Subclinical Myocardial Damage, and Cardiac Events
Key result
Compared to a DBP of 80-89 mmHg, a DBP <60 mmHg was associated with an increased risk of incident coronary heart disease (HR 1.5) and subclinical myocardial damage.
Why the study?
Achieving low systolic blood pressure targets may reduce diastolic blood pressure to levels that compromise myocardial perfusion, but its independent association with myocardial damage and clinical events remains unclear.
Does low diastolic blood pressure increase the risk of subclinical myocardial damage and incident coronary heart disease in adults without known cardiovascular disease?
Key Points
- To examine the independent association of diastolic blood pressure with subclinical myocardial damage and prospective risk of coronary heart disease, stroke, or mortality.
- Prospective cohort study analyzing 11,565 adults (mean age 57 years, 57% female, 25% black) from the Atherosclerosis Risk In Communities (ARIC) study over 21 years of follow-up.
- Evaluated baseline and 6-year changes in high-sensitivity cardiac troponin-T (hs-cTnT) across diastolic blood pressure (DBP) categories, referencing 80 to 89 mm Hg.
- Assessed incident coronary heart disease (CHD), stroke, and all-cause mortality, stratifying by baseline hs-cTnT and systolic blood pressure (SBP) levels.
- Compared with baseline DBP 80 to 89 mm Hg, adjusted odds of prevalent hs-cTnT ≥14 ng/l were 2.2 (95% CI 1.2–4.1) for DBP <60 mm Hg and 1.5 (95% CI 1.0–2.3) for DBP 60 to 69 mm Hg.
- Baseline DBP <60 mm Hg was associated with incident CHD (HR 1.5, 95% CI 1.2–1.9) and all-cause mortality (HR 1.3, 95% CI 1.1–1.6), but showed no association with stroke.
- The association between low DBP and incident CHD was strongest in individuals with baseline hs-cTnT ≥14 ng/l (HR 2.6, 95% CI 1.3–5.0; p for interaction <0.001) and baseline SBP ≥120 mm Hg.
Study Design
Type
Cohort (n=11,565)
Multicenter
Yes
Structured PICO
Does low diastolic blood pressure increase the risk of subclinical myocardial damage and incident coronary heart disease in adults without known cardiovascular disease?
P
Population
11,565 adults without known cardiovascular disease or heart failure, mean age 57 years, followed for a median of 21 years.
E
Exposure
Low diastolic blood pressure (<60 mmHg)
C
Comparator
Diastolic blood pressure 80-89 mmHg
O
Outcome
Subclinical myocardial damage (hs-cTnT ≥14 ng/L) and incident coronary heart disease, stroke, or death over a median follow-up of 21 yearshard clinical
Main Result
Hazard Ratio: 1.5 (95% CI 1.2–1.9)
Limitations
- Observational study design cannot prove causality
- Cannot distinguish if low DBP is from drug treatment or arterial stiffness
- SPRINT-eligible subsample was underpowered due to small sample size
- Longitudinal analysis may have been influenced by significant drop-out between visits 4 and 5
Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“We saw, in fact, that individuals that started off with a low diastolic blood pressure, even as low as 60 [mm Hg],... had lower risk for cardiovascular disease and MI over the course of their life. The inference from that is that the diastolic blood pressure J-curve may have little to do with diastolic blood pressure itself and more to do with other parameters like vascular stiffness or vascular calcification that are the true culprits.”
JWJ. William McEvoyPreventive cardiologist, Johns Hopkins University
“The take-home message is there is increased likelihood that if we use blood pressure drugs to push patients' systolic blood pressures down to 120, which is a strategy supported by recent clinical trials, the consequence in those starting out with low diastolic blood pressures (e.g., below 80) may be that the diastolic number falls so low that we risk doing damage.”
DBDeepak BhattInterventional cardiologist, Brigham and Women's Hospital
“If individuals have a diastolic blood pressure that is too low, there might not be enough blood flow to the heart muscle itself, and this could lead to subclinical elevations in troponin. Perhaps then, over time, it's not just subclinical elevations in troponin but [low DBP] is causing actual damage to the heart muscle. It's a way of putting it all together—there's no way of proving all that. It should be pointed out that both ARIC and CLARIFY are observational analyses. These are not randomized blood-pressure trials.”
Implication
Low diastolic blood pressure, particularly <60 mmHg, is associated with subclinical myocardial damage and increased risk of coronary heart disease, especially in patients with systolic blood pressure ≥120 mmHg.
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.
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Cite This Study
McEvoy et al. (2016) conducted a cohort in Adults without known cardiovascular disease or heart failure (n=11,565). Low diastolic blood pressure (<60 mmHg) vs. Diastolic blood pressure 80-89 mmHg was evaluated on Incident coronary heart disease (HR 1.5, 95% CI 1.2-1.9). Compared to a DBP of 80-89 mmHg, a DBP <60 mmHg was associated with an increased risk of incident coronary heart disease (HR 1.5) and subclinical myocardial damage.