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Hypertension is the strongest or one of the strongest risk factors for almost all different cardiovascular diseases acquired during life, including coronary disease, left ventricular ...hypertrophy and valvular heart diseases, cardiac arrhythmias including atrial fibrillation, cerebral stroke and renal failure. The continuous relationship between blood pressure and cardiovascular and renal events makes the distinction between high normal blood pressure and hypertension based on arbitrary cut-off values for blood pressures. Overall the prevalence of hypertension in different European countries appears to be around 30–45% of the general population, with a steep increase with ageing. The prevention of cardiovascular disease and treatment recommendations should be related to quantification of total cardiovascular risk which could be estimated from several different models. However the impact of age on risk is so strong that young adults (particularly women) are unlikely to reach high-risk levels even when they have more than one major risk factor and a clear increase in relative risk. Therefore age-adjusted models, models assessing relative risks compared to others of same age and models including thorough assessments of target organ damage and ambulatory 24h blood pressure are needed together with national models because of the large variations between countries.
Isolated systolic hypertension (ISH) in middle-aged and elderly is associated with high cardiovascular risk, but no randomised controlled trial has assessed the effect of antihypertensive treatment ...in ISH using today's definition, i.e. systolic blood pressure (SBP) ≥140 mmHg and diastolic blood pressure (DBP) <90 mmHg.
A systematic review and meta-analysis of randomised controlled trials was performed. Studies with ≥1000 patient-years of follow-up, comparing more intensive versus less intensive BP targets, or active drug versus placebo, were included if the mean baseline SBP was ≥140 mmHg and the mean baseline DBP was <90 mmHg. The primary outcome was major adverse cardiovascular events (MACE). Relative risks from each trial were pooled in random-effects meta-analyses, stratified by baseline and attained SBP level.
Twenty-four trials, including 113,105 participants (mean age 67 years; mean blood pressure 149/83 mmHg) were included in the analysis. Overall, treatment reduced the risk of MACE by 9% (relative risk 0.91, 95% confidence interval 0.88-0.93). Treatment was more effective if baseline SBP was ≥160 mmHg (RR 0.77, 95% CIs 0.70-0.86) compared to 140-159 mmHg (RR 0.92, 95% CIs 0.89-0.95; p = 0.002 for interaction), but provided equal additional benefit across all attained SBP levels (RR 0.80, 95% CIs 0.70-0.92 for <130 mmHg, RR 0.92, 95% CIs 0.89-0.96 for 130-139 mmHg, and RR 0.87, 95% CIs 0.82-0.93 for ≥140 mmHg; p = 0.070 for interaction).
These findings support antihypertensive treatment of isolated systolic hypertension, regardless of baseline SBP, to target SBP <140 mmHg and even <130 mmHg if well tolerated.
The effects of pharmacological blood pressure lowering at normal or high-normal blood pressure ranges in people with or without pre-existing cardiovascular disease remains uncertain. We analysed ...individual participant data from randomised trials to investigate the effects of blood pressure lowering treatment on the risk of major cardiovascular events by baseline levels of systolic blood pressure.
We did a meta-analysis of individual participant-level data from 48 randomised trials of pharmacological blood pressure lowering medications versus placebo or other classes of blood pressure-lowering medications, or between more versus less intensive treatment regimens, which had at least 1000 persons-years of follow-up in each group. Trials exclusively done with participants with heart failure or short-term interventions in participants with acute myocardial infarction or other acute settings were excluded. Data from 51 studies published between 1972 and 2013 were obtained by the Blood Pressure Lowering Treatment Trialists' Collaboration (Oxford University, Oxford, UK). We pooled the data to investigate the stratified effects of blood pressure-lowering treatment in participants with and without prevalent cardiovascular disease (ie, any reports of stroke, myocardial infarction, or ischaemic heart disease before randomisation), overall and across seven systolic blood pressure categories (ranging from <120 to ≥170 mm Hg). The primary outcome was a major cardiovascular event (defined as a composite of fatal and non-fatal stroke, fatal or non-fatal myocardial infarction or ischaemic heart disease, or heart failure causing death or requiring admission to hospital), analysed as per intention to treat.
Data for 344 716 participants from 48 randomised clinical trials were available for this analysis. Pre-randomisation mean systolic/diastolic blood pressures were 146/84 mm Hg in participants with previous cardiovascular disease (n=157 728) and 157/89 mm Hg in participants without previous cardiovascular disease (n=186 988). There was substantial spread in participants' blood pressure at baseline, with 31 239 (19·8%) of participants with previous cardiovascular disease and 14 928 (8·0%) of individuals without previous cardiovascular disease having a systolic blood pressure of less than 130 mm Hg. The relative effects of blood pressure-lowering treatment were proportional to the intensity of systolic blood pressure reduction. After a median 4·15 years' follow-up (Q1–Q3 2·97–4·96), 42 324 participants (12·3%) had at least one major cardiovascular event. In participants without previous cardiovascular disease at baseline, the incidence rate for developing a major cardiovascular event per 1000 person-years was 31·9 (95% CI 31·3–32·5) in the comparator group and 25·9 (25·4–26·4) in the intervention group. In participants with previous cardiovascular disease at baseline, the corresponding rates were 39·7 (95% CI 39·0–40·5) and 36·0 (95% CI 35·3–36·7), in the comparator and intervention groups, respectively. Hazard ratios (HR) associated with a reduction of systolic blood pressure by 5 mm Hg for a major cardiovascular event were 0·91, 95% CI 0·89–0·94 for partipants without previous cardiovascular disease and 0·89, 0·86–0·92, for those with previous cardiovascular disease. In stratified analyses, there was no reliable evidence of heterogeneity of treatment effects on major cardiovascular events by baseline cardiovascular disease status or systolic blood pressure categories.
In this large-scale analysis of randomised trials, a 5 mm Hg reduction of systolic blood pressure reduced the risk of major cardiovascular events by about 10%, irrespective of previous diagnoses of cardiovascular disease, and even at normal or high–normal blood pressure values. These findings suggest that a fixed degree of pharmacological blood pressure lowering is similarly effective for primary and secondary prevention of major cardiovascular disease, even at blood pressure levels currently not considered for treatment. Physicians communicating the indication for blood pressure lowering treatment to their patients should emphasise its importance on reducing cardiovascular risk rather than focusing on blood pressure reduction itself.
British Heart Foundation, UK National Institute for Health Research, and Oxford Martin School.
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