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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 1, January/February 2016
56
AFRICA
Cardio News
Leadless pacing: an advance in cardiac pacing
In March 2015, Groote Schuur Hospital
(GSH) in Cape Town made history by
becoming the first hospital in Africa, the
Middle East, Central Asia and Turkey to
implant the world’s smallest pacemaker:
the Medtronic Micra
TM
transcatheter
pacing system (TPS). Three patients in
Cape Town had this device successfully
implanted by the GSH team, led by Dr
Ashley Chin, as part of Medtronic’s
global pivotal clinical trial. After nearly
one year of follow up, all three patients’
pacemakers are functioning well with no
pacemaker-related complications.
The Micra
TM
TPS is a leadless pace-
maker that does not require the use of a
lead to connect to the heart. It is one-tenth
the size of a conventional transvenous
pacemaker and is delivered directly into
the heart through a catheter inserted in
the femoral vein. Once positioned, the
pacemaker is securely attached to the right
ventricular wall and can be repositioned
if needed. Attached to the heart via small
tines, the pacemaker delivers electrical
impulses that pace the heart through an
electrode at the end of the device.
Leadless pacemakers were designed to
avoid the need for a pacemaker pocket and
transvenous lead, with the aim of avoiding
lead complications (such as infection,
fracture and displacement), which occur
in a significant proportion of transvenous
pacemakers. Other potential benefits
include shorter procedure times, cosmetic
appeal (no pacemaker scar), shorter recover
times and fewer post-implant restrictions.
Theresultsof thislandmark,multicentre,
international study have recently been
published in the
New England Journal of
Medicine
.
1
The device was successfully
implanted in 719 of 725 patients (99.2%
implant success rate). The primary efficacy
endpoint (a pacing threshold at six months
of < 2 V @ 0.24 msec) was achieved in
96% of patients. Patients with a leadless
pacemaker had fewer complications
compared to a historical cohort of patients
with transvenous pacemakers.
The most frequent complication
included cardiac perforation or effusion
(1.6% of cases), followed by vascular
access problems (0.7% of cases). The
Micra
TM
TPS system has received FDA
approval in the United States and
obtained the CE mark in Europe, and is
globally commercially available.
The Micra
TM
TPS has some limitations.
This leadless pacemaker currently can
only pace the ventricle. This pacemaker
is not ideal for patients who require
atrial pacing (e.g. sick sinus syndrome)
or for younger, active patients with heart
block who require dual-chamber pacing.
Cardiologists will also require training
to implant the Micra
TM
TPS. The costs
are expected to be significantly more
expensive than a conventional pacemaker.
Lastly, the long-termefficacy and safety of
the device is still unknown. Nevertheless,
leadless pacing is a major breakthrough
in the field of cardiac pacing, which is
now proven to be safe and effective in the
short to medium term.
1. Reynolds D, Duray GZ, Omar R, Soejima K,
et
al
. A leadless intracardiac transcatheter pacing
system.
N Engl J Med
2016;
374
: 533–541.