Dr Rachel Bastiaenen, PhD, St George's Hospital London, UK

Treatment of hypertension reduces cardiovascular risk but the most appropriate targets for systolic blood pressure (SBP) control remain unclear. The current guidelines in Europe recommend treating to a target of 150/90mmHg in patients who are ≥80 years old and to a target of 140/90mmHg in younger individuals.(1) In the latest American guidance the higher target of 150/90mmHg also applied to younger patients ≥60 years old.(2) A new American Heart Association (AHA)/American College of Cardiology (ACC) blood pressure management guideline is expected soon.

The results from the recent SPRINT trial were simultaneously presented at the AHA 2015 Scientific Sessions and published in the New England Journal of Medicine.(3) 9361 patients ≥50 years old with SBP ≥130mmHg and increased cardiovascular risk (but without diabetes) were randomized to intensive treatment (<120mmHg) or standard treatment (<140mmHg). At one year the mean SBP was 121.4mmHg for the intensive treatment group and 136.2mmHg for the standard treatment group. The primary composite outcome of myocardial infarction, other acute coronary syndromes, stroke, heart failure or death from cardiovascular causes was significantly lower in the intensive treatment group compared with the standard treatment group (1.65% per year vs 2.19% per year; HR 0.75 95%CI 0.64-0.89; P<0.001) after 3.26 years when the trial was stopped early. All-cause mortality was also lower in the intensive treatment group. This was at the expense, however, of increased rates of serious adverse events in the intensive treatment group including hypotension, syncope, electrolyte abnormalities and acute kidney injury.

This data contrasts with the ACCORD trial (including diabetics) which did not show a significant benefit with a SBP target of 120mmHg vs 140mmHg for the primary end point of composite cardiovascular events.(4) However the sample size in ACCORD was smaller and the study was underpowered, with a much lower event rate than anticipated. Secondary analysis and long-term results from ACCORD also presented at the AHA 2015 Scientific Sessions demonstrated evidence of benefit for intensive blood pressure lowering in diabetic hypertensive patients randomized to standard glycemic control.(5)

From SPRINT it appears that lowering SBP to <120mmHg is beneficial. Intensive SBP lowering had a greater impact on older patients (>75 years old) which goes against the guidelines. Even patients with baseline SBP <132mmHg appeared to benefit from intensive control. However there was significant decline in renal function in patients without chronic kidney disease at baseline (30% reduction in estimated glomerular filtration rate in 1.21% of the intensive treatment group vs 0.35% of the standard therapy group p<0.001) and the reasons for this are unclear. In addition questions remain unanswered. How generalizable are the results? How about diabetic patients, younger patients (<50 years old) and patients with baseline SBP 120-140mmHg? Should we be assessing global cardiovascular risk and tailoring individual SBP targets rather than one size fits all?

References

  1. Mancia G, Fagard R, Narkiewicz K et al. 2013 ESH/ESC guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). Eur Heart J 2013;34(28):2159-219.
  2. James PA, Oparil S, Carter BL, et al. 2014 Evidence-based guideline for the management of high blood pressure in adults: Report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA 2014;311(5):507-20.
  3. SPRINT research group. A randomized trial of intensive versus standard blood-pressure control. N Engl J Med 2015 Nov 9 (Epub ahead of print).
  4. ACCORD Study Group. Effects of intensive blood-pressure control in type 2 diabetes mellitus. N Engl J Med 2010; 362(17):1575-85.
  5. Cushman WC, Evans GW, Cutler JA. Long-term cardiovascular effects of 4.9 years of intensive blood pressure control in type 2 diabetes mellitus: The Action to Control Cardiovascular Risk in Diabetes follow-on blood-pressure study. American Heart Association 2015 Scientific Sessions; November 10, 2015; Orlando, FL.
Cardio Debate Expert Comments

Will SPRINT results change my clinical practice?

In recent years we have witnessed many "ups and downs" with regard to blood pressure (BP) targets recommended by International guidelines for the treatment of hypertension. The latest USA and European guidelines have recommended “moderation” in the BP levels achieved with treatment, thus re-dimensioning the concept that “lower is better”. SPRINT, however, has now suddenly and dramatically arrived on the scene with a newer message i.e. much lower is much better.

SPRINT is a well-designed study dealing with a specific group of hypertensive patients and the results of the trial are applicable to patients like those included in the study.  There has been criticism as to the fact that the study results may not be applicable to some categories of hypertensive patients i.e. subjects with diabetes,  low risk patients, obese subjects, the younger or  the very old, and those with severe or resistant hypertension.  In my view, there is no room for this criticism, as no study can impart information for which it has not been specifically designed. It is difficult – and possibly unwise- to extrapolate findings in SPRINT to all hypertensive individuals, as the conclusions of this important trial are likely to apply mainly to categories of patients such as those included in the trial.

In any case, I believe that a more aggressive approach, such as that suggested by SPRINT, may be adopted in lower risk patients, while a more cautious strategy should be adopted in high risk patients. It is likely that young adults (< 50 years old) with hypertension but without other major health problems would benefit from a type of therapy as suggested by SPRINT, which may prevent potential organ damage that may result from long term hypertension.  However, in patients with diabetes, severe renal failure, previous stroke, the elderly and/or patients with several co-morbidities, the risks associated with an aggressive treatment like the one proposed by the SPRINT investigators can reduce and even nullify the benefits associated with a reduced BP. It must be also remembered that aggressive treatments, like those proposed by SPRINT, require close regular patient monitoring, which can be difficult to implement in real life clinical practice.

In my view – and despite SPRINT results – a cautious approach is required in the BP management of elderly patients (> 75 years old), who make up the majority of patients in my practice and possibly in most outpatient clinics worldwide. These patients often have multiple co- morbidities and take several medications as a result. Hence the problem of drug interactions and side effects becomes a major issue in this patient group. Marked reductions in BP can contribute to impaired renal function as well as to other undesirable iatrogenic effects such as postural hypotension leading to dizziness and frequent falls with the risk of bone fractures. Implementation of aggressive BP reduction in these patients require a thorough assessment of all comorbidities and cardiovascular risk as well as a thorough assessment of patient preference.  I believe that some elderly patients would prefer to accept a slightly higher cardiovascular risk rather than feeling dizzy most of the time or having to constantly worry about serious falls. In view of the above, although I welcome the SPRINT findings, I will not, at present, change my clinical practice, which is based on current International guidelines suggesting a moderate approach towards BP reduction in the elderly.