VOLUME 8 NUMBER 1 • MARCH 2011
29
SA JOURNAL OF DIABETES & VASCULAR DISEASE
CARDIOVASCULAR FOCUS
Cardiovascular Focus
Extracts from the 11th annual South African Heart Association
Congress, August 2010
Antiplatelet agents
T
he platelet is one of the central role play-
ers in acute coronary syndromes and the
antagonism of their function is therefore one
of the big research topics in cardiology. Cur-
rently, platelets can be antagonised via the
thromboxane antagonists, the ADP receptor
blockers or the GP IIb/IIIa receptor blockers.
All these drugs have their own intricacies, and
Prof B Meier referred to some of these issues.
Questions raised in this lecture included:
how long to continue with dual anti-platelet
therapy; should aspirin be used in combination
with clopidogrel for secondary prevention; and
the possibility of drug interactions, especially
with proton pump inhibitors (PPIs) and ADP
receptor blockers.
The duration of dual anti-platelet therapy is
still a matter of opinion. In the CHARISMA trial,
it was shown that there is a benefit to using
dual anti-platelet therapy, including aspirin and
clopidogrel, for secondary prevention. Patients
on anti-platelet therapy are at increased risk
for gastrointestinal bleeding. They are however
also at risk for major adverse cardiac events
should their anti-platelet therapy be ineffec-
tive.
The TIMI 38 trial compared the effectiveness
of clopidogrel and a PPI vs prasugrel and a PPI.
It found that there was a better outcome with
the prasugrel combination than the clopidogrel
combination in patients with ST-elevation myo-
cardial infarction. The mortality was, however,
raised in patients with non-ST elevation myo-
cardial infarction. Further studies are awaited.
Prof Meier also briefly discussed some of
the problems with the newer anti-platelet
agents. It seems that there is the possibility of
an increased risk of malignancy with prasugrel
compared to placebo in patients treated with
this drug. He also referred to the side effects of
dyspnoea and bradycardia in patients treated
with the new drug ticagrelor.
In Prof Meier’s opinion, patients with mild
coronary artery disease should be treated with
aspirin only, and patients with more severe
disease should be treated with combination
therapy including aspirin and one of the newer
agents.
Acute coronary syndrome and
atrial fibrillation
The recent RELY trial has brought attention
back to atrial fibrillation and anticoagulation.
Prof Ezekowitz, an ex-South African and princi-
pal investigator of the RELY trial, was therefore
invited to the SA Heart Association congress.
It is known that the mortality of acute coro-
nary syndrome (ACS) is doubled if a patient
concomitantly has atrial fibrillation (AF). There
are, however, no studies studying anticoagula-
tion in this population group. This is reflected
by the fact that the European Society for Cardi-
ology and the American College of Cardiology/
American Heart Association guidelines also
have different recommendations.
It was stressed that anticoagulants out
perform anti-platelet drugs when it comes to
stroke prevention. There is also a lower mor-
tality in patients with ACS and AF if treated
with anticoagulation and anti-platelet com-
binations, compared to anti-platelet therapy
alone or no therapy (data is from a prospec-
tive cohort in Sweden). In all these groups, the
bleeding risk was similar and the stroke rate
was less in the anticoagulation groups.
Prof Ezekowitz concluded that there are
no good data to know how to treat these
patients. Triple therapy, including two anti-
platelet drugs (according to ACS guidelines)
and an anticoagulant is superior. Drug-eluting
stents should be avoided in order to decrease
time on triple anticoagulation. Newer agents
should be explored in this patient group.
Primary pulmonary hypertension
Prof L Rubin used this session as an overview of
primary pulmonary hypertension. This rare dis-
ease, with a prevalence of 2/1 000 000, occurs
much more frequently in women (three to four
females are affected for each male). Vascu-
lar remodelling is at the core of this disease’s
pathophysiology. The interaction of endothe-
lin with smooth muscle cells leads to alternate
handling of intracellular calcium, with subse-
quent increased vasocontraction, up-regulated
vaso-proliferation and altered cell death.
There are three pathways at the core of
this disease’s pathophysiology. Pharmaceuti-
cal agents may target all of these pathways,
which include the prostaglandin pathway, the
endothelin pathway and the nitric oxide path-
way.
Prognosis in primary pulmonary hyperten-
sion is related to the progressive decline in
right heart function. It should be noted that
pulmonary artery pressure does not correlate
with patient outcome. Echocardiography is
therefore an excellent tool to use in the prog-
nostication of patients with primary pulmonary
arterial hypertension.
Of the echo indices, TAPSE (tricuspid annu-
lar plane systolic excursion) seems to be the
best index to use. Other possible markers of
prognosis include N-terminal pro-BNP and the
six-minute-walk test.
Prof Rubin concluded his talk by saying that
disease severity is a function of right heart
function and that assessing this can help in
guiding the management of these patients.
Coronary heart disease and the
millennium woman
Prof N Wenger from the Emory School of Med-
icine in Atlanta started her lecture on national
Women’s Day by commenting on how the epi-
demiology of diseases affecting females have
changed. The average age of women in the
1900s was 48 years, in the year 2000 it is 80.
The main causes of mortality in the 1900s were
TB and childbirth; this has now shifted to heart
disease.
Coronary artery disease is the leading cause
of death worldwide for males and females.
Young adults currently have an increasing risk
of coronary artery disease due to the epidemic
of obesity, diabetes and hypertension.
Females with stable angina have a slightly
different profile to that of males. They are
older, have more hypertension, diabetes and
cardiac failure, and are less likely to have myo-
cardial infarction and coronary artery bypass
graft surgery.
Women are also less likely than their male
counterparts to have an exercise test and have
statins and anti-platelet agents prescribed by a
cardiologist. The WISE (women ischemia syn-
drome evaluation) study, however, shows that
women have twice the risk of major adverse
cardiac events as males.
To complicate matters further, 50% of
females with ischaemic-type chest pain have
no flow-limiting coronary artery disease. Intra-
vascular ultrasound performed on females
show that they have a higher atherosclerotic
burden with decreased coronary flow reserve.
Sub-endocardial ischaemia can be dem-
onstrated by magnetic resonance imaging. It
seems that women have more endothelial dys-
function, with hormones, inflammatory media-
tors and traditional risk factors all playing an
important role.
