The 2017 American College of Cardiology/American Heart Association blood pressure (BP) guidelines lowered the hypertension threshold from a SBP/DBP level of at least 140/90 mmHg to at least 130/80 mmHg. The cardiovascular impact of isolated systolic hypertension (ISH) and isolated diastolic hypertension (IDH) under the new definition remains unclear.
We used data from the UK Biobank study, which is a prospective population-based cohort study. Participants were categorized into five groups: normal BP, normal high BP, ISH, IDH and systolic and diastolic hypertension. The primary endpoint for this study was the composite of nonfatal myocardial infarction (MI), nonfatal ischaemic stroke, nonfatal haemorrhagic stroke and cardiovascular disease (CVD) death. We also explored the results for the above-mentioned CVD outcomes separately. Baseline BP measurements were obtained twice after the participant had been at rest for at least 5 min in a seated position.
We included 385 955 participants who were not taking antihypertensive medications, were free of CVD at baseline and had available data on BP measurements. During a median follow-up of 8.1 years, 8959 CVD events were recorded, including 4729 nonfatal MIs, 2287 nonfatal ischaemic strokes, 813 nonfatal haemorrhagic strokes, and 1826 CVD deaths. According to the hypertension threshold of at least 130/80 mmHg by the American College of Cardiology/American Heart Association guidelines, both ISH (hazard ratio 1.39; 95% confidence interval 1.27, 1.15) and IDH (hazard ratio 1.28; 95% confidence interval 1.15, 1.43) were significantly associated with a higher overall CVD risk than normal BP. ISH was associated with most CVD risk, except for ischaemic stroke, while the excess CVD risk associated with IDH appeared to be driven mainly by MI and CVD death. We found heterogeneity by sex and age regarding the effects of IDH on overall CVD risk, with significant associations in younger adults (age <60 years) and women and null associations in men and older adults (age ≥60 years).
ISH was associated with the risk of most CVD events, while the association between IDH and CVD risk was mainly driven by MI incidence and CVD death. Further research is needed to identify participants with IDH who have a particular risk for developing CVD.