CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 3, April 2012
134
AFRICA
for
H pylori
at enrollment showed a higher risk for incidence
of adverse cardiovascular events during the first month of
follow up. They were 2.58 times more likely to be diagnosed
with recurrence of UA, MI or SCD, or to undergo coronary
angioplasty or CABG one month after presenting with ACS,
compared to their seronegative counterparts. Additionally, in
the logistic regression model used to predict incidence of short-
term outcomes, which also included age, gender and classic
risk factors, only
H pylori
infection proved to be a significant
determinant of these events.
Previous studies report conflicting data regarding
the relationship between
H pylori
infection and incidence
of future cardiovascular events. Some studies did not find
any association,
42,43
whereas, others revealed a significant
association.
44,45
This discrepancy may be due to differences
in the study populations. For example, some studies enrolled
healthy adult subjects, while others assessed cohorts of patients
with CAD. Furthermore, most of the previous studies measured
only
H pylori
IgG antibodies,
43,46
while in our study, we used
both IgG and IgA antibodies to detect
H pylori
infection. In
a previous study by Rupprecht
et al.
,
44
while there was no
relationship between
H pylori
IgG seropositivity and risk of
fatal cardiovascular events, IgA seropositivity was significantly
associated with fatal cardiovascular events, with a hazard ratio of
2.5, which is similar to our results.
Most importantly, in this study
H pylori
infection was only
linked to short-term adverse outcomes, such as UA, MI and
SCD, and did not show a significant long-term association with
the same outcomes during the one year of follow up. This is in
line with previous suggestions that
H pylori
infection would
probably play a role in the early events of ACS.
32
As mentioned,
H pylori
has been shown to cause platelet aggregation.
32,47
During the acute phase of ACS and plaque disruption, this could
lead to local inflammation, aggravating platelet aggregation, a
crucial event leading to acute myocardial ischaemia. However,
these effects would diminish as the plaque becomes stable
in the weeks after the ACS. This process may explain why
H
pylori
seropositivity was only associated with risk of short-
term outcomes, in spite of varying length of infection among
participants.
If a causal relationship between
H pylori
infection and early
ACS morbidity and mortality could be established with further
prospective studies, this valuable information could be used to
improve ACS patients’ survival, hypothetically by treatment of
H pylori
infection in patients presenting with ACS. A previous
randomised clinical trial on 325 patients with ACS has shown a
significant reduction in incidence of cardiac death or readmission
due to ACS as a result of antibiotic treatment for
H pylori
and
Chlamydia pneuminiae
.
18
However, further prospective studies
and randomised trials are needed in order to confirm the role of
antibiotic therapy in CAD patients.
As a prospective cohort, this study may suffer from limitations
such as unsuspected selection bias or unidentified confounding
factors. It has been suggested that
H pylori
seropositivity may
reflect the socio-economic status of patients or their early
childhood environment,
48
which may be the actual causes of
the observed relationships. However, the present study was
carried out on a fairly socially homogenous population, as
typical for a relatively small town, and the participants were
only recruited from a single hospital, which further identifies
them as having a similar socio-economic status. Therefore we
suggest it is unlikely that the observed differences were due to
socio-economic disparities reflected by
H pylori
seropositivity.
Moreover,
H pylori
seropositivity did not show any relationship
with other cardiac risk factors among our participants.
Conclusion
The results of this prospective study provide further evidence
that
H pylori
infection could affect the early prognosis in CAD
patients. Randomised clinical trials are needed to establish this
causal relationship and evaluate the role of antibiotic treatment
in these patients.
We thank the Farzan Institute for Research and Technology for technical
assistance.
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