Angiotensin converting enzyme (ACE) inhibitors are a class of drugs commonly used to treat heart attack victims. As the name suggests, they work by blocking the action of angiotensin, the chemical in the blood which causes blood vessels to narrow, t

Researchers from Scandinavia (K Swedberg et al, N Eng J Med, 1992; 327:678-84) looked at coronary patients who were given the ACE inhibitor enalapril within 24 hours of a heart attack. After interim analysis, the trial was halted when it was found that those on enalapril were at increased risk of suffering low blood pressure, hypotension, than those on placebo and "mortality was increased in patients who showed this effect" (BMJ, 27 February 1993).

Hypotension is a well documented side effect of ACE inhibitors. However, it seems that low blood pressure coming so soon after a heart attack may be particularly dangerous impeding recovery by reducing the flow of blood through the heart. Cardiologists, writing about the study in the BMJ (27 February 1993), also point out that angiotensin may help the structures of the heart to remodel themselves after an attack so administering drugs which inhibit the action of this chemical in the immediate aftermath of an attack will hinder recovery.

Another study (The SOLVD investigators, N Eng J Med 1992;327: 685-91), found that there was no reduction in mortality among those with symptomless heart conditions given enalapril supposedly as preventative measure.

The list of side effects of ACE inhibitors includes: swelling of the face; kidney failure; low white blood cells count; hyperkalemia abnormally high blood potassium levels, leading to nausea, diarrhoea, muscle weakness, and, yes, heart irregularities,