but a newer insertable cardiac monitor called the
REVEAL LINQ most definitely is. The LINQ makes the
XT look positively clumsy. It is 87% smaller than the
XT but has 20% more data memory, improved atrial
fibrillation (AF)-detection algorithms, and a battery
that lasts 3 years (same as the XT). Insertion of the device is almost ridiculously simple—a 1 cm incision and
the device comes pre-loaded on an insertion tool that
the operator slides into place, preferably in the “best
location,” which, according to Medtronic, lies at a 45
degree tilt to the sternum over the fourth intercostal
space, 2 cm from the left lateral edge of the sternum.
In another recent study, this one presented at the
International Stroke Conference in Nashville in February of this year, investigators took a “real-world” look
into how the newer generation Medtronic ICM, the
REVEAL LINQ, performs in patients with cryptogenic
stroke. At a median of 182 days, the ICM had an AF
detection rate of 12.2%, or fully 37% higher than the
rate observed in CRYSTAL-AF at the same time point.
AF detected by implanted devices is unknown, nor is
the role of anticoagulation. This issue was addressed
in a January 2015 JACC State-of-the-art Review authored by Carol Chen-Scarabelli, PhD, from the University of Michigan, Ann Arbor, MI, and colleagues.5
Current AF guidelines either lack specific recommendations for device-detected AF or recommend
further investigation of device-detected AF to clarify
its connection with stroke risk. Chen-Scarabelli and
colleagues, however, fundamentally object to the
ambiguity in the guidelines and instead suggest that
device-detected AF offers “a unique opportunity” to
intervene early and prevent stroke or lessen its severity. They go further and suggest that clinicians have
“an inherent responsibility to act on such information
gleaned from device diagnostics, with potential legal
ramifications for those who fail to act.”
They concluded: “The reluctance of clinicians to
act on device-detected AF is bewildering, as many
would not hesitate to act on a single standard 12-lead
ECG that records 10 s of rhythm… Such failure represents a lost opportunity.”
Proven Benefit
Reveal LINQ™
“These were patients who had just been labeled
as cryptogenic stroke but didn’t have to go through
the same gauntlet of tests and things that the CRYSTAL-AF patients had to go through to exclude other
reasons for their stroke,” explained investigator John
Rogers, MD, from Scripps Clinic Torrey Pines in La
Jolla, CA.
On July 16, 2015, Medtronic announced the first
in-office implant of its miniaturized cardiac monitor as
part of its Reveal LINQ In-Office 2 (RIO 2) Study. Dr.
Rogers successfully implanted the device. Now, RIO
2 will determine if the procedure is as safe as those
performed in a more traditional setting, such as an
operating room, cardiac catheterization laboratory, or
electrophysiology laboratory.
At the same time the main CRYSTAL-AF results
were published, a second study, this one called
EMBRACE, tested a slightly less high-tech or invasive
technique for longer-term monitoring. Gladstone et
al compared a 30-day event-triggered loop recorder
to conventional 24-hour monitoring in 572 patients
without known AF who had had a cryptogenic stroke
or TIA. They found AF (30 seconds or longer) in
16.1% of the intervention group versus 3.2% of the
control group (p<0.001). AF lasting 2.5 minute or
longer was seen in 9.9% and 2.5%, respectively
(p < 0.001).
In an editorial discussing both studies, Hooman
Kamel, MD, from the Weill Cornell Medical College,
NY, suggested that while the most patients with cryptogenic stroke or TIA should undergo “at least several
weeks of rhythm monitoring,” the loop recorders like
those used in the EMBRACE trial will likely be costeffective, while “the value of more expensive implantable loop recorders is less clear.”4
One argument against prolonged cardiac monitoring is that the clinical significance of brief episodes of
32
CardioSource WorldNews
In case you thought your equipment has reached its
size limitations already in terms of being as small
as possible, interventional cardiology will continue
to benefit from the giant miniaturization boom. Or
better said, patients will continue to gain from smaller
equipment.
In transcatheter aortic valve replacement (TAVR),
miniaturization already has improved patient outcomes. In an April 2015 editorial by Blasé Carabello,
MD, from Mount Sinai Beth Israel Hospital, New
York, NY, he noted, “Progressive miniaturization,
valve designs that limit paravalvular leak (PVL), and
devices that protect patients from cerebral embolism
will almost surely facilitate the use of TAVR in lower
risk patients and facilitate enhanced outcomes with
lower complication rates.”6
Worldwide each year, we’re now seeing more left
ventricular assist devices (LVADs) implanted than
hearts transplanted. Even the devices already being
placed are a far cry from the console on wheels that
drove the pneumatic assist devices of the 1990s.
LVAD next gen units are characterized by continuous
miniaturization and enhanced pump performance,
providing increased device durability and—potentially—prolonged survival of the patients.7 Indeed, a next
generation of these devices are referred to as MVADs,
meaning mini versions of LVADs. In the case of the
HeartWare (Framingham, Massachusetts) miniature
hybrid or “HVAD” pump, it weighs 160 g compared
with the company’s preclinical MVAD pump, which
pumps you up at only 78 g.
By reducing the required thoracic space and
pump footprint, smaller F