CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 7, August 2012
412
AFRICA
Conference Reports
SA Heart Conference 2012
Treating angina pectoris with
I
f
channel blockade: evaluating treatment with a newer agent
The medical treatment of angina has
become the poor relative in coronary artery
disease (CAD) management, having been
largely overshadowed by percutaneous
coronary intervention and bypass surgery.
Nonetheless, in angina patients with minor
coronary involvement, in the very elderly,
in patients with substantial comorbidity,
and in those not wishing to have an
intervention, so-called ‘conservative’
medical therapy is appropriate.
This view was expressed by Dr Tony
Dalby, Milpark Hospital cardiologist, at
a Servier-sponsored breakfast sympo-
sium at the recent SA Heart Association
Congress. ‘While the application of
percutaneous intervention varies accord-
ing to the acumen of the interventionalist,
there remains a group of patients who
would be better treated with medical
management.
The frequency of angina seen in
patients treated in specialist practice has
been significantly reduced by coronary
intervention and coronary bypass surgery,
and possibly by the more effective
application of preventive therapies such
as statins and ACE inhibitors. However,
angina remains a relevant clinical problem.
It has been reported that in patients treated
for chronic CAD, 38% will experience
angina, 14% will have exercise-induced
ischaemia, and in 4% the two conditions
will overlap. In primary care, almost one in
three patients with coronary artery disease
had anginal events at least once a week.
1
‘The prognostic impact of angina is
also not insignificant. In a small study
of self-reported angina and treadmill-
induced ischaemia among outpatients
with stable CAD, myocardial infarction or
death from coronary heart disease (CHD)
occurred in 7% of patients with angina
alone, rising to 23% in patients with both
angina and ischaemia’, Dr Dalby noted.
2
‘The much-debated COURAGE trial
3
showed that optimal medical therapy
achieved better results in the first three
years when compared to percutaneous
revascularisation, after which no
difference in outcome was observed’, Dr
Dalby pointed out. ‘So clearly, optimal
medical therapy is an appropriate option.’
He noted that whereas the primary focus
of the I
f
channel blocker ivabradbine’s
use recently has been on heart failure and
left ventricular dysfunction, its value as
an effective anti-anginal agent has been
underplayed.
The role of heart rate increase over
70 beats/min as a significant contributor
to cardiovascular events has been well
established and is now an accepted fact.
‘When we compare ivabradine to
β
-blockers, which are currently our
standard to achieve reduction of heart
rate and ameliorate angina symptoms, it
is clear that they are distinctly different
drug types. Both drugs have heart rate
reduction and anti-remodelling effects but
ivabradine, working solely on the sinus
node, when compared to beta-blockade
in experimental animal models, preserves
ventricular relaxation and contractility,
preserves coronary vasodilatation during
exercise, thereby reducing coronary
resistance, and preserves cardiac output.
Ivabradine does not increase airways
resistance, cause hypoglycaemia or
induce fatigue and is in fact extremely
well tolerated.’
When ivabradine was compared to
the calcium channel blocker amlodipine,
it had a similar efficacy in improving
exercise tolerance, a superior effect on
the reduction of rate-pressure product (a
surrogate marker of myocardial oxygen
consumption) and similar safety.
4
The angina efficacy of ivabradine has
also been well established in everyday
clinical practice. In the multicentre
REDUCTION study of 5 000 patients,
ivabradine lowered heart rate from 70 to
less than 60 beats/min, concomitantly
reducing angina attacks from an average
of 2.5 to one per week.
5
It also reduced
nitrate use and was well tolerated by
98% of patients. ‘This is not surprising
as we know that the angina event is
preceded by an increased heart rate and
Fig. 1. Proposed algorithm for treatment of angina.
Continue
treatment
Consider
revascularisation
* Use clopidogrel if allergic to aspirin
Chronic stable angina pectoris (with/without LVD)
Aspirin 75–150 mg daily unless contraindicated*
Sublingual nitrate to alleviate acute attacks
Beta-blocker for prevention of acute attacks
Contraindication or intolerance
to beta-blocker
Add or substitute calcium
channel blocker (DHP if LVD)
and/or long-acting nitrate
Add or substitute ivabradine if
heart rate
>
60/min
Symptoms controlled
Symptoms controlled
Symptoms controlled
Yes
Yes
Yes
No
No
No
