NEW YORK - Simply suggesting that a treatment will ease chest pain may not only dampen the pain, but directly alter heart arteries, according to a small German study.
Among 30 patients having a procedure to evaluate their chest pain, researchers found that those who were told they were being given an infusion of a pain-relieving drug did, on average, report a decrease of pain.
But they also showed a slight but distinct narrowing of their heart vessels, said Karin Meissner and Joram Ronel of Technical University Munich, reporting their findings in the American Heart Journal.
None of the chest=pain patients actually had heart disease, and they were told about the "drug" - actually harmless saline - only after testing had shown no blockages in their heart arteries.
"The major finding was that the coronary vessels reacted so clearly to a mere psychological intervention," said Meissner and Ronel in an email to Reuters Health.
Though the meaning of the findings and whether they have implications for heart disease patients remains unclear, the reaction was in a direction opposite to the one the researchers had expected to see.
The patients were actually told that the "drug" there were receiving would widen their arteries to relieve their chest pain.
Instead, there was a small amount of blood vessel constriction in the group overall.
That constriction makes biological sense, according to Meissner and Ronel.
In a healthy person under stress, the nervous system triggers a widening in the blood vessels so that blood circulation increases to meet the body's needs.
When stress fades, the vessels can narrow again.
"When the heart works less, there is less need for blood supply, and the vessels will be less dilated than in a stressful situation. This is how we interpret our data," they said, adding that this is the process in a healthy person.
The situation may be different in a person with heart disease.
The findings build on a phenomenon seen in clinical trials on heart disease that some people receiving placebos report improvements in symptoms such as chest pain - though how much of that reaction is due to psychological or even biological effects is unclear.
To examine if there might be placebo effects on the heart arteries, Meissner and Ronel's team looked at 30 patients who underwent coronary angiography to evaluate chest pain symptoms.
The 30 patients were included in the study only after the test - in which a tube is threaded through a blood vessel into the heart, where a special dye is injected - turned up no blockages.
While still on the exam table, the patients were randomly assigned to either a "verbal suggestion" group or a control group.
In both groups, patients received an injection of saline into the tube.
Those in the verbal-suggestion group were told it was a drug that would widen their heart arteries and boost blood flow to the heart.
Patients in the control group were told nothing.
On average, the verbal-suggestion group reported a dip in their chest pain after the procedure, while showing some blood vessel narrowing.
The opposite was true in the control group:"slightly more pain, and a little more vessel dilation.
Meissner and Ronel said they suspect the pain reduction was an "indirect effect" of the verbal suggestion, but they cannot know for sure whether or to what degree the blood vessel changes may have contributed to it.