Low DBP warns of cardiac damage in hypertensive patients
medwireNews: Research shows that low diastolic blood pressure (DBP) is a marker of subclinical cardiac damage and increased coronary heart disease (CHD) risk, particularly in patients with relatively high systolic blood pressure (SBP).
“Diastolic and systolic BP are inextricably linked, and our results highlighted the importance of not ignoring the former and focusing only on the latter, instead emphasizing the need to consider both in the optimal treatment of adults with hypertension”, say John McEvoy (Johns Hopkins University School of Medicine, Baltimore, Maryland, USA) and co-researchers.
The team found that, among 11,565 participants of the ARIC cohort without known cardiovascular disease, the likelihood of having elevated high-sensitivity cardiac troponin-T (hs-cTnT; ≥14 ng/L), indicating subclinical myocardial damage, rose with decreasing DBP.
Compared with participants whose DBP was between 80 and 89 mmHg, the odds of elevated hs-cTnT were increased 1.5- and 2.2-fold in those with DBP between 60 and 69 mmHg and below 60 mmHg, respectively. These associations were independent of confounders including age, gender, SBP and use of antihypertensive medications.
Furthermore, lower DBP was associated with significantly greater increases in hs-cTnT over the subsequent 6 years of follow-up, the team reports in the Journal of the American College of Cardiology.
In line with this, patients had a significantly increased CHD risk at all DBP levels below the reference range (80–89 mmHg), with the highest relative increase of 1.5-fold seen at levels below 60 mmHg. At this level there was also a significant 1.3-fold increased mortality risk.
Deepak Bhatt (Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, USA) notes in a linked editorial that the ARIC cohort was relatively young, with an average age of 57 years, and that the potential for adverse events at low DBP might be “substantially increased” in older patients, and also in those with established CHD, who were excluded from the analysis.
In stratified analyses, the adverse effects of low DBP were greatest in patients with subclinical myocardial damage at baseline and also in those whose SBP was at least 120 mmHg, leading Bhatt to suggest that elevated pulse pressure may represent a “double whammy” that needs further research.
He concludes that “lower may not always be better with respect to BP control” and advises “careful thought before pushing BP control below current guideline targets, especially if the DBP falls below 60 mm Hg while the pulse pressure is >60 mm Hg.”
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