Aspirin Not Recommended for Heart Disease Anymore

November 20, 2009

_http://articles.mercola.com/sites/articles/archive/2002/01/26/aspirin-heart-par\

t-one.aspx_

(http://articles.mercola.com/sites/articles/archive/2002/01/26/aspirin-heart-par\

t-one

..aspx) January 26 2002

By Dr. John G F Cleland

Despite the vast size of these meta-analyses, the evidence in support of

aspirin preventing atherosclerotic events is still inconclusive.

The third meta-analysis from the Antithrombotic Trialists' Collaboration

contains data on over 100 000 patients at high risk of atherosclerotic

events, representing more than 250 000 patient years of follow up.1

This meta-analysis and its predecessors form the major argument for the

current widespread fashion of prescribing aspirin to such patients. 2 3 It is

an enormous body of research and the collaboration is to be congratulated

for having gathered so much data. However, quality as well as quantity

matters. And the quality is such that the results can only be inconclusive.

Summary Points:

-- The series of meta-analyses on the antiplatelet activity of aspirin

overvalues aspirin's effectiveness and safety

-- All the large long term trials of aspirin after myocardial infarction

show no effect on mortality

-- Aspirin may change the way vascular events present rather than prevent

them

-- This may lead to a " cosmetic " reduction in non-fatal events and an

increase in sudden death

-- Data on the safety and cost-benefit of aspirin are inadequate

-- Advocating the use of aspirin for preventing atherosclerotic events

diverts attention from other, more effective, drugs

Trials Do Not Show That Aspirin Saves Lives

Meta-analysis is increasingly viewed either as a way of verifying that the

outcome of an individual trial is consistent with the rest of the known

data or as a way of generating a hypothesis.

However, in the absence of a definitively positive trial, many consider

meta-analysis inadequate evidence for clinical decision making. The series of

meta-analyses from the trialists' collaboration contains serious

additional flaws.3-6

It is remarkable and probably statistically significant how seldom trials

of antiplatelet agents have shown benefit on their selected primary

outcome. The choice of the primary endpoint by the Antithrombotic Trialists'

Collaboration is arbitrary and suspect.

Antiplatelet agents seem to be substantially more effective in reducing

the incidence of non-fatal events than in reducing death. Indeed, among large

long-term trials after myocardial infarction there is no evidence that

aspirin saves lives.

An intervention can reduce non-fatal events in three ways: by genuinely

reducing them, by concealing them, or by converting non-fatal events into

fatal ones.

The failure of aspirin to reduce mortality despite a reduction in

non-fatal events in many studies suggests that aspirin may conceal, rather than

prevent, vascular events.6

Epidemiological data suggest that 25% of non-fatal myocardial infarctions

are silent. 4 5 As aspirin, even at low doses, is an analgesic and because

it may provoke dyspepsia, which may create confusion about the cause of

chest pain, it is not difficult to believe that aspirin could increase the

proportion of silent events from 25% to 30%. This could explain all the

benefits of antiplatelet agents on non-fatal myocardial in the meta-analysis.

Aspirin increased the risk of sudden death in every long-term study after

myocardial infarction that reported such events.

This increase was from 4.4% on placebo to 5.6% on aspirin in the

persantine-aspirin reinfarction (PARIS) study; from 2.0% to 2.7% in the aspirin

myocardial infarction study (AMIS); and from 2.0% to 2.4% in the

persantine-aspirin reinfarction study (PARIS-II).9

This could reflect an increased risk of sudden death among concealed, and

therefore untreated, events. Another possible mechanism by which aspirin

may convert non-fatal events into fatal ones is by increasing the risk of

hemorrhagic conversion of cerebral and myocardial infarctions.

All cause mortality and, arguably, disabling stroke are the only robust

markers of benefit with an antiplatelet agent. It is not clear that

antiplatelet agents reduce the risk of either.

Some trials that were included lost more than a quarter of their patients

to follow up.10 In similar circumstances, with other agents, it has been

suggested that all patients lost to follow up in the active treatment group

should be considered to have died and none of those in the control arm. Such

an analysis would neutralize the benefit observed in one of the few

seemingly convincingly positive studies of aspirin, the ISIS-2 trial.11

Bias In Interpretation

The Antithrombotic Trialists' Collaboration shows bias in the analysis and

interpretation of their results. We are given scant detail on how the

numbers of events credited to each trial changed between meta-analyses. 2 3

Trials were retrospectively reanalyzed, resulting in resurrection of a number

of apparently dead patients and the discovery of a number of new deaths.

Most interventions probably help some people some of the time and harm

others some of the time. A small benefit could reflect a small overall benefit

in a large population or a substantial benefit in some patients and harm

in others.

Aspirin could exert a short-term benefit followed by long term harm, in

which case the benefits and safety of aspirin could be increased by using

only a short term course of therapy.14 Aspirin may be harmful in patients with

coronary disease and heart failure. 5 6 12

The evidence for an adverse interaction between aspirin and angiotensin

converting enzyme inhibitors observed in the SOLVD (studies of left

ventricular function) and HOPE (heart outcomes prevention evaluation) trials is

also

a matter for concern. 6 12 These are important issues that have not been

adequately addressed.

Neither Safe Nor Cheap

Many believe that, even if aspirin is not effective, it is safe. Aspirin

does appear to be relatively safe for the patients included in clinical

trials, but as these studies excluded by design patients at risk of adverse

events with aspirin and tended to include younger patients with lower multiple

morbidity it is likely that aspirin is not as safe as suggested.

Low dose aspirin for cardiovascular prophylaxis may account for more than

30% of all major gastrointestinal hemorrhage in patients aged over 6, 4 6

15 and may also be associated with an increased risk of renal failure.

Finally, there is a widespread view that aspirin is cheap. However, when

evaluating the costs of treatment the amount and type of benefit and the

costs of managing adverse effects also need to be evaluated. Very few economic

appraisals of aspirin have been done.

One such analysis, recently commissioned by the chief scientist's office

in Scotland, suggested it may cost more than £80 000 to prevent one event

with aspirin for primary prevention and more than £3000 for secondary

prevention.16 These analyses have assumed that aspirin is as effective as the

meta-analyses suggest, which may not be true.

A Diversion

Perhaps the greatest potential detriment of aspirin on health care,

however, is that it diverts attention away from treatments that are of

unequivocal benefit to many groups of patients.

The reader should not accept the conclusions of the Antithrombotic

Trialists' Collaboration uncritically but rather read the original papers on

which

their conclusions are based.

Dr. Mercola's Commments:

I believe the author does an outstanding job of providing the medical

justification to stop using aspirin for heart disease prevention.

If you have been diagnosed with heart disease, or have had a heart attack

or stroke, it's important to be aware that there's a safer, more effective

and healthier option than aspirin. It's a powerful enzyme called

Nattokinase, and it's been used for circulatory problems for over 20 years.

This healthy enzyme is found in natto, a type of fermented soy, and also

in CardioEssentials, which contains the potent natto extract.

It is interesting to note that if you were just watching the news or

reading the papers, you would have never seen this article as all the media

attention was on the one that aspirin actually worked.

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