Patients receiving music, imagery and touch therapy experienced less distress before their procedures, and those who received both MIT therapy and 'high-dose' prayer may have been slightly less likely to die in the following six months, researchers found.

The study of more than 700 heart patients, one of the most ambitious attempts to test the medicinal power of prayer, showed that those who had people praying for them from a distance, and without their knowledge, were no less likely to suffer a major complication, end up back in the hospital or die.

While skeptics of prayer welcomed the results, other researchers questioned the findings, and proponents of prayer maintained God's influence lies beyond the reach of scientific validation.

But the idea that praying for someone else -- even when they are unaware of it -- can affect a person's health has been much more controversial. Several studies have purported to show that such prayer is beneficial, but they have been criticized as deeply flawed.

The debate prompted a spate of new studies aimed at avoiding those shortcomings, including the new study, which is the first to test prayer at multiple centers.

For the Mantra II study, Mitchell Krucoff, a cardiologist at Duke University Medical Center in Durham, NC, and his colleagues designed a complicated experiment involving 748 patients who underwent treatment at nine hospitals around the country for heart problems between 1999 and 2002.

The researchers enlisted 12 congregations of various Christian denominations, Jews, Muslims and Buddhists around the world to pray for some of the patients, giving them names, ages and descriptions of the illness. The researchers then divided the patients into four groups.

The first quarter had people praying for them. The second quarter received a nontraditional treatment known as music, imagery and touch therapy, which involved breathing techniques, soothing music, touch and other ways to relieve stress, such as imagining calming images. The third group received both prayer and MIT, while the fourth received nothing.

In the final year of the study, the researchers took the additional step of asking more religious congregations to pray for the prayers of the initial group to work. Neither the patients nor their doctors knew whether someone was praying for them. The prayers varied depending on the religion, lasting between six and 30 days.

The researchers then followed all the patients for six months to see which patients suffered serious complications, such as heart attacks, were rehospitalized, or died from heart problems. Overall, there was no difference among the four groups, the researchers report in the Saturday issue of The Lancet medical journal.

The researchers did find evidence, however, suggesting those receiving the MIT therapy experienced less distress before their procedures, and those who received both MIT therapy and the "high-dose" prayer may have been slightly less likely to die in the following six months. Those findings provide avenues for future research, Krucoff said.

The researchers acknowledged that it was impossible to make any firm conclusions because of the difficulty of studying something like prayer.