Lowering Blood Pressure Too Far Found Dangerous

Excessive lowering of diastolic blood pressure should be avoided in patients with coronary artery disease (CAD), according to a new study.

Researchers from the division of cardiology at St. Luke's-Roosevelt Hospital (New York, NY, USA) analyzed data from 22,576 patients in the international verapamil-trandolapril study (INVEST), to investigate whether low blood pressure could be associated with excess mortality and morbidity in CAD patients.

Lower diastolic pressure was found to lead to nearly a doubling in the total risk of all-cause mortality, nonfatal myocardial infarction, and nonfatal stroke in patients with diastolic pressure between 60-70 mm Hg, and a tripling of the risk in patients with diastolic pressure of 60 mm Hg and below. In secondary analyses, there was a J-shaped relationship with diastolic pressure for death from all causes, fatal and nonfatal myocardial infarction, and to a much lesser extent for fatal and nonfatal stroke.

The lowest unadjusted risk of adverse outcome occurred at a blood pressure of 119/84 mm Hg. Adjustment for time to primary outcome changed the ideal blood pressure to 129/74 mm Hg. There was also a J-shaped relationship between systolic blood pressure and the primary outcome, the researchers noted, but the relationship was less marked than for that between diastolic pressure and outcomes. The study was published in the June 20, 2006, edition of the Annals of Internal Medicine.

"We should remain aggressive in lowering pressure, particularly in lowering systolic pressure,” said lead author Dr. Franz H. Messerli. "As practicing physicians, however, we should remember that when diastolic pressure falls below 70 we may compromise coronary flow and increase the risk of an adverse event.”

The J-curve is a relationship theory, which states that there is a paradoxical response between extreme decreases in blood pressure and an increased morbidity and mortality.



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