medwireNews: Analysis of the CLARIFY registry shows a J-shaped curve between blood pressure (BP) and cardiovascular outcomes in patients with established coronary heart disease (CHD).
Patients’ risk of cardiovascular events increased when their systolic blood pressure (SBP) was 140 mmHg or more and their diastolic blood pressure (DBP) was 80 mmHg or more, but also when these fell below 120 and 70 mmHg, respectively.
“This finding warns against an extensive extrapolation of the results of the SPRINT trial (ie, that an approach of the lower the achieved blood pressure, the better, should be pursued in all individuals at high cardiovascular risk)”, writes Giuseppe Mancia (University of Milano-Bicocca, Milan, Italy) in a commentary accompanying the research in The Lancet.
The study suggests that aggressive BP reduction could “lead to clinically relevant coronary underperfusion”, he says.
Over 5 years of follow-up, the lowest risk of the primary composite outcome (cardiovascular death, myocardial infarction, stroke) among 22,672 patients with CHD and hypertension was at an SBP of about 130 mmHg and a DBP of just below 80 mmHg.
The risk of the primary outcome was not increased in patients within the SBP range of 130–139 mmHg, compared with those in the reference range of 120–129 mmHg. But those with SBPs of 140–149 mmHg or at least 150 mmHg had significant 1.51- and 2.48-fold risk increases after accounting for a range of demographical and clinical variables.
And at the other end of the range, patients with SBP below 120 mmHg had a significant 1.56-fold increased risk.
Likewise, patients with DBP above or below the reference range of 70–79 mmHg had increased risks, with the increases exceeding twofold below 60 mmHg and threefold at 90 mmHg and above.
Philippe Gabriel Steg (Hôpital Bichat, Paris, France) and study co-authors report similar results for the individual endpoints of all-cause death, cardiovascular death, myocardial infarction and hospitalisation for heart failure. Stroke differed, however, in that risk increased at high blood pressures, but not at lower pressures.
In his commentary, Mancia poses the question of whether, for select patients, the advantages of aggressive BP reduction for stroke prevention “might overcome the disadvantage of an increase of cardiac events.” This might apply to Asian patients or those with a previous stroke, he suggests.
But he notes the potential for existing cerebrovascular damage to affect autoregulation of cerebral blood flow and “extend a J-curve to stroke, an issue on which present data are not unequivocal.”
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