Drug treatment for high blood pressure can bring on a heart attack in men, according to Swedish researchers.

In the seven year study of 1121 men who were being treated with drugs for hypertension, or high blood pressure, the more blood pressure was lowered, the more likely a patient was to have a heart attack.

The greatest risk factor was a lowered diastolic pressure, which measures the blood returning to the heart, the researchers report.

Lowering diastolic blood pressure below 95mm Hg in men suspected of having ischaemia poor blood flow to the heart or hypertrophy enlarged heart due to hypertension "may be hazardous", conclude the researchers. BMJ, 12 March 1994

l Meanwhile, further evidence has emerged that the very fact of having your blood pressure measured may be enough to send it soaring and risk your having treatment you don't need.

"White coat hypertension" where a patient's blood pressure increases in the surgery at the prospect of seeing his doctor is a well established phenomenon. However, new evidence from doctors in Oxford suggests that ambulatory monitoring, which is supposed to give a more accurate reading than the static variety, can have a similarly exaggerating effect.

Ambulatory monitoring involves a patient being connected up to a portable blood pressure monitor over the course of 24 hours while he goes about his daily life. However, it seems that the machine itself may stop a patient's blood pressure from falling as it normally would during sleep, and so lead to a falsely high reading.

Doctors from the UK's Oxford Chest Hospital studying six healthy individuals concluded that noise from the ambulatory machine and the pressure from the cuff on the subject's arm can disturb sleep. Even if a patient doesn't fully wake up, the arousal may be enough to raise blood pressure levels. "This effect should be taken into account when recordings of blood pressure at night are interpreted," they conclude.

!ABMJ, 26 March 1994.