Contrary to popular belief, blood pressure that is too low may be associated with worse outcomes in hypertensive patients with coronary artery disease (CAD), according to CLARIFY researchers, who presented their results at the European Society of Cardiology Congress 2016, in Rome, Italy.
“The optimal blood pressure target in patients with hypertension continues to be debated, especially in those with coronary artery disease (CAD). ESC guidelines recommend lowering blood pressure to values within the range 130–139/80–85 mmHg for patients with CAD to reduce the risk of further cardiovascular events,” said principal investigator Philippe Gabriel Steg, MD, professor, cardiology, Universite Paris-Diderot, and director, Coronary Care Unit, Hopital Bichat, Paris, France.
“Some argue ‘the lower, the better’ but there is a concern that patients with CAD may have insufficient blood flow to the heart if their blood pressure is too low,” he added.
Dr. Steg, who is also a professor at the National Heart and Lung Institute, Imperial College, London, United Kingdom, and colleagues conducted an analysis of the CLARIFY registry to determine the relationship between blood pressure achieved with treatment and cardiovascular outcomes in patients with CAD.
For their analysis, they included 22,672 subjects with stable CAD enrolled in the CLARIFY registry and treated for hypertension between November 2009 and June 2010, from 45 countries. They averaged systolic/diastolic BPs before each cardiovascular event, and estimated hazard ratios (HRs) with multivariable adjusted Cox proportional hazards models, using the 120–129 mmHg systolic BP and 70–79 mmHg diastolic BP subgroups as reference.
In these patients, they found that after a median follow-up of 5 years, a systolic BP of 140 mmHg or higher, and a diastolic BP of 80 mmHg or higher were both associated with an increased risk of cardiovascular events.
They also found that a systolic BP of less than 120 mmHg was associated with an increased risk for the primary outcome—which was the composite of cardiovascular death, myocardial infarction, or stroke—(adjusted HR: 1.56; 95% CI: 1.36-1.81), and all secondary outcomes except stroke, including primary outcome, all-cause death, and hospitalization for heart failure.
Furthermore, a diastolic BP less than 70 mmHg was associated with an increased risk of the primary outcome (adjusted HR: 1.41; 95% CI: 1.24-1.61 for diastolic BP from 60-69 mmHg; and HR: 2.01; 95% CI: 1.50-2.70 for less than 60 mmHg) and in all secondary outcomes except stroke.
“We found that systolic blood pressure less than 120 mmHg was associated with a 56% greater risk of the composite primary outcome of cardiovascular death, myocardial infarction, or stroke. Diastolic blood pressure between 60 and 69 mmHg was associated with a 41% increased risk of the primary outcome, with risk rising to 2-fold when diastolic blood pressure fell below 60 mmHg,” said Dr. Steg.
“This large study of hypertensive CAD patients from routine clinical practice found that systolic BP less than 120 mmHg and diastolic BP less than 70 mmHg are each associated with adverse cardiovascular outcomes, including mortality. The findings support the existence of a J-curve phenomenon, where the initial lowering of BP is beneficial but further lowering is harmful,” he explained.
“Our results suggest that the ESC recommendation remains valid and physicians should exercise caution when using BP-lowering treatment in patients with CAD. This should however not detract from our efforts to diagnose and treat hypertension which remains massively underdiagnosed and undertreated worldwide,” Dr. Steg concluded.
The CLARIFY registry is supported by Servier.