Aspirin to Prevent Coronary Heart Diseases – Is Routine Use Justified?

                   Aspirin to Prevent Coronary Heart Diseases – Is Routine Use Justified?

(Dr. Guru Prasad Mohanta, Professor, Department of Pharmacy, Annamalai University,

Annamalai Nagar – 608 002, Tamil Nadu, E. mail: gpmohanta@hotmail.com)

           

Cardiovascular disease (CVD) is the leading cause of deaths and disability worldwide. The percentage of premature deaths due to CVD ranges from 4% in developed countries to as high as 42% in economically poor countries. Of the various forms of CVD, the coronary heart disease (CHD) and cerebrovascular disease (stroke) are the leading contributors for mortality due to CVD. Low dose aspirin is routinely used to prevent cardiovascular events. Aspirin acts by preventing aggregation of platelets which may cause clots. Platelets combine with the cholesterol in the arterial wall to form a clot and block the heart artery.  The blockage leads to heart attack. Aspirin prevents the clot formation due to its anti-platelet activity.

The recent study reported in the American Heart Association’s Journal “Arteriosclerosis, Thrombosis, and Vascular Biology´ following a 10 years observation “Genetic variation may modify the cardiovascular benefit of aspirin even harming some patients”.  This raises a concern of aspirin’s routine use. COMT is a key enzyme in the metabolism of catecholamines: epinephrine, norepinephrine, and dopamine. There are three variants of COMT: enzyme’s low activity methionine form (met/mets), the enzyme’s high activity valine form (val/vals) and intermediate activity (val/met) with in between high and low activities. Individuals with high activity valine form have been shown to have lower levels of catecholamines compared to individuals with methionine form. The 23 percent of the women who were 'val/vals' were naturally protected against incident cardiovascular disease but when women with the similar genetic type were allocated to aspirin, this natural protection was eliminated. Further investigation shown that val/val women who were randomly assigned to aspirin had more cardiovascular events than the val/vals who were assigned to placebo.  On the other hand, among the 28 percent of met – women there were fewer cardiovascular events when assigned to aspirin compared to placebo. The study indicates that the genetic variation has profound influence on aspirin’s activity.

USFDA, perhaps the strongest drug regulatory authority in the world, has declined the Bayer AG Company’s request for permission to make a change in the labelling that would have allowed the company to market aspirin as preventive therapy for people who have no heart problems.  The regulator warns “Benefits of aspirin outweighs the risks in cases where people have already experienced stroke or heart attacks”. 

While the studies have confirmed the usefulness of aspirin in primary prevention of cardiovascular events, its use is not free of risks. Aspirin can produce serious adverse effects. The aspirin is known to increase the incidence of gastrointestinal bleeding and haemorrhagic stroke. The present findings further increase the risk of using aspirin at least in some group of people (genetically variant). The physicians and the practicing pharmacists should refrain from routine use of aspirin for preventing CVD but restrict to those who are with moderate or high risk. Its combination with other platelet aggregation inhibitors should not be used routinely.