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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 5, September/October 2019
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AFRICA
Shortcomings of RD treatment for HT
These can be divided into two subgroups: technical challenges,
and patients who will show an inadequate response to RD.
The first shortcoming of current RD treatment is that the
completeness of RD cannot be accurately assessed. The operator,
therefore, has no indication if he has successfully denervated
the kidney. Second, since patients with polar renal arteries
and challenging renal artery anatomy (aneurysms, renal artery
stenosis and calcification) were excluded from trials, there are no
data on whether these subgroups will respond to RD. Patients
with isolated systolic hypertension will also show less response
to RD.
45
RD has not been tested in patients with secondary HT,
but it could theoretically reduce BP in patients with inoperable
paragangliomas, since RD reduces circulating catecholamine
levels.
46
Finally, although RD probably reduces BP, if correctly
performed, patients should continue to take their BP medication.
Can future studies address current uncertainties in RD?
Future studies should include an objective method to assess the
completeness of RD during the procedure. Non-adherence to
AHT and RTM phenomena confound RCTs. These challenges
can be reduced by combination AHT (reduced pill burden) and
advanced statistical tests.
AF: current management and iatrogenic side effects
Paroxysmal AF, which is a common complication of
uncontrolled HT and HTHD, originates from the muscular
sleeves inside the pulmonary veins where they enter the left
atrium.
47
Current rhythm-control treatment of paroxysmal AF
can be accomplished through drugs or pulmonary venous
isolation (PVI) techniques. Drug treatment with amiodarone
is often life-long, which associates with dangerous side effects,
including thyroid dysfunction, corneal deposits, hepatic enzyme
abnormalities and irreversible lung fibrosis.
PVI, on the other hand, is performed under general
anaesthesia with either hot or cold ablation in an attempt to
electrically isolate the pulmonary veins from the left atrium. Hot
ablation uses radiofrequency (heat) energy to induce scar tissue
around the pulmonary venous ostia. Cold ablation uses liquid
nitrogen to freeze the pulmonary venous–atrial junctions. A
high cure rate can be achieved with these techniques that require
atrial trans-septal puncture. The Fire and Ice trial confirmed
that cold ablation is non-inferior to hot ablation.
48
Despite these
technological advances, PVI is associated with rare but dangerous
side effects, including cardiac perforation, tamponade, phrenic
nerve palsy and fatal atrio-oesophageal fistula.
Can RD treat paroxysmal AF?
RD, which has an excellent safety profile, may improve outcomes
of catheter ablation in hypertensive patients with AF.
49
Canine
studies suggest that RD induced morpho-electrophysiological
changes that reduced the AF substrate.
50,51
These include changes
in the atrial effective refractory period, P-wave duration, AF
cycle length and reduced atrial fibrosis regarding substrate
modification. Meta-analyses of human studies have shown that
RD was associated with regression of both LVH and left atrial
hypertrophy.
52
Pokushalov and colleagues have also shown in an RCT
that RD, when coupled with pulmonary venous isolation as
paroxysmal AF treatment, significantly reduced incidental AF
during follow up.
53
The trial was criticised for its small sample
size and the lack of AF monitoring with an implantable
loop recorder. Another small non-randomised trial has shown
evidence that RD alone may reduce AF triggers and AF burden
in patients with both HT and paroxysmal or persistent AF.
54
Results of a larger prospective trial where RD was used as stand-
alone, upstream therapy to prevent AF in patients with HTHD
are currently awaited (NCT01990911).
55
Conclusion
AI plays a vital role in many prevalent cardiac diseases.
Restoration of AI provides the promise of upstream modification
and prevention of these disease complications. With the kidneys
at the proverbial eye of the hypertensive cyclonic storm, RD may
provide an alternative treatment for HT and many of its notorious
complications, including paroxysmal AF. Results of prospective,
randomised, sham, controlled trials are eagerly awaited.
The Hamilton Naki Clinical Scholarship supported MH. Medtronic Inc
provided study support for his PhD.
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