Lower than normal blood pressure appears to raise the risk of death in patients with heart failure, according to a report in the American Heart Journal.

Previous studies have yielded different results regarding the effect of low blood pressure on mortality in the general population. Until now, however, no study had investigated this association in patients with heart failure.

Using data from the Digitalis Investigation Group trial database, Dr. Lana Tsao and colleagues, from Beth Israel Deaconess Medical Center in Boston, evaluated the association between blood pressure and mortality in 5,747 heart failure patients.

All of the subjects had a diagnosis of mild or moderate heart failure along with a reduced amount of blood pumped out of their heart.

Patients with a systolic blood pressure - the top number of the blood pressure reading - lower than 100 mmHg had a mortality rate of 50 percent, significantly higher than the 32-percent rate observed in a comparison group of patients who had pressures between 130 and 139 mmHg.

The association was nonlinear, meaning than mortality rates fell as blood pressure rose from greater than 100 mmHg, but mortality then increased slightly at 120 to 129 mmHg before falling again.

Low diastolic blood pressure - the lower number of a blood pressure reading - was also linked to increased mortality. But in this case, the association was linear with pressures lower than 60 mmHg conferring the greatest risk and pressures higher than 89 mmHg conferring the lowest risk.

While the findings suggest a range of blood pressures that might be suitable targets for heart failure patients, they should not lead doctors to change how they treat their heart failure patients, the authors state. For this to occur, data from more studies are needed, they add.

SOURCE: American Heart Journal, January 2006.