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Clinical research
EuroIntervention 2009;5:90-95
A multicentre evaluation of the safety of intracoronary
optical coherence tomography
Peter Barlis1, MBBS, MPH, FRACP, FESC; Nieves Gonzalo1, MD; Carlo Di Mario2, MD, PhD, FESC;
Francesco Prati3, MD, FESC; Lutz Buellesfeld4, MD; Johannes Rieber5, MD; Miles C. Dalby6, MRCP;
Giuseppe Ferrante2, MD; Maria Cera3, MD; Eberhard Grube4, MD, FESC; Patrick W. Serruys1, MD,
PhD, FESC; Evelyn Regar1*, MD, PhD
1. Thoraxcenter, Erasmus Medical Centre, Rotterdam, The Netherlands; 2. Royal Brompton Hospital, London, United Kingdom;
3. San Giovanni Hospital, Rome, Italy; 4. Helios Heart Centre, Siegburg, Germany; 5. Medizinische Klinik Innenstadt, Ludwigs-
Maximilians University, Munich, Germany; 6. Harefield Hospital, Middlesex, United Kingdom
The authors have no conflict of interest to declare.
Abstract
Aims: Optical coherence tomography (OCT) is increasingly being applied to the coronary arteries. However,
the risks associated with the imaging procedure are not yet well defined. The purpose of the present
multicentre registry was to assess the acute complications associated with the clinical use of intra-coronary
OCT in a large number of patients.
Methods and results: Consecutive patients from six centres who had OCT examination were retrospectively
included. All adverse events and complications, even if transient, were noted. Risks were categorised into:
1) self-limiting 2) major complications including major adverse cardiac events (MACE) and 3) mechanical
device failure. A total of 468 patients underwent OCT examination for evaluation of: plaque (40.0%),
percutaneous coronary intervention (28.2%) or follow-up stent tissue coverage (31.8%). OCT was performed
using a non-occlusive flush technique in 45.3% with a mean contrast volume of 36.6±9.4ml. Transient chest
pain and QRS widening/ST-depression/elevation were observed in 47.6% and 45.5% respectively. Major
complications included five (1.1%) cases of ventricular fibrillation due to balloon occlusion and/or deep
guide catheter intubation, 3 (0.6%) cases of air embolism and one case of vessel dissection (0.2%). There
were no cases of coronary spasm or MACE during or within the 24 hour period following OCT examination.
Conclusions: OCT is a specialised technique with a relatively steep learning curve. Major complications are
uncommon and can be minimised with careful procedural planning and having an awareness of the
potential contributory risks, especially deep guide catheter intubation during contrast flushing. Upcoming
developments will make OCT more practical and less procedurally demanding, also potentially conserving
contrast volume considerably.
KEYWORDS
Imaging, optical
coherence tomography,
safety, coronary
arteries
* Corresponding author: Department of Cardiology, Thoraxcenter, Room Ba 585, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD
Rotterdam, The Netherlands
E-mail: e.regar@erasmusmc.nl
© Europa Edition. All rights reserved.
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Introduction
Optical coherence tomography (OCT) is an intracoronary imaging
technique using near infrared light with a much higher spatial
resolution than intravascular ultrasound (IVUS). The 15 micron
resolution permits detailed characterisation of the vessel wall giving
new insights into the in vivo characterisation of atherosclerotic
plaque and tissue responses following stent implantation. Unlike
IVUS however, the technique requires flushing of the coronary
artery to allow light transmission with the first generation OCT
system also mandating proximal vessel balloon occlusion. Whilst
the imaging resolution benefits of OCT are clear, the need for a flush
system increases the complexity of the technique, and the risks
associated with this have not been evaluated. The purpose of the
present multicentre registry was, for the first time, to assess the
acute complications associated with the clinical use of intracoronary
OCT in a large number of patients.
Methods
Study population and OCT procedure
We conducted a multicentre registry to evaluate the safety of OCT.
Data from patients undergoing OCT examination in six centres were
reviewed. Consecutive patients who had OCT examination performed
before January 31, 2008 were retrospectively included. Weight
adjusted heparin was administered as standard prior to OCT imaging.
All OCT examinations were carried out using a dedicated optical wire
(ImageWire, LightLab Imaging Inc., Westford, MA, USA) connected to
either the M2 or M3 OCT console (LightLab Imaging Inc., Westford,
MA, USA). All participating centres completed the demographic,
clinical and procedural case information using a uniform data sheet
that was centrally analysed. The indications to perform OCT were
categorised into evaluation of: A), lesion/plaque; B), percutaneous
coronary intervention PCI) (stent apposition); or C), stent tissue
coverage at follow-up. The number of vessels imaged, together with
the OCT flushing strategy (with or without proximal vessel balloon
occlusion, see below) were recorded. OCT exclusion criteria applied
by operators/centres included impaired left ventricular ejection
fraction (<30%), renal impairment (serum creatinine >1.5 mg/dL),
single remaining or tortuous vessel. When the non-occlusive
technique was used, the additional contrast load required to permit
imaging in a blood-free environment was documented.
Flush strategy
Infra-red light is unable to penetrate blood, thus imaging must be
accompanied by transient clearance of the field of view from blood.
In clinical intracoronary OCT, two methods have been established:
1), using a proximal occlusion balloon with flushing of crystalloid
solution through the end hole of the balloon catheter using a power
injector or 2), a non-occlusive approach with contrast flush injection
via the guiding catheter.1
Balloon occlusion method
A low-pressure, short over-the-wire balloon (Helios, Goodman Inc,
Nagoya, Japan) with large inner lumen is advanced over a
conventional guidewire distal to the region of interest. The
guidewire is then replaced with the dedicated OCT imaging wire
and the balloon catheter is positioned in the proximal part of the
vessel. Inflation of the balloon is performed using a dedicated
indeflator to 0.5-0.7 atm during which coronary blood flow is
replaced by continuous infusion of Ringer’s lactate or physiological
saline at a rate of 0.5-1.2 ml/sec using a power injector (e.g. Mark-
V ProVis, Medrad, Inc. Indianola, PA, USA).1-3 A motorised pullback of
the image wire is then commenced at a rate of 1.0 mm/sec to acquire
images.
Non-occlusive technique
As the handling of the OCT image wire is limited by the fact that it
contains an optical fibre and is not comparable to a standard
guidewire with respect to steerability, pushability and torqueability,
its safe passage distal to the region of interest can be facilitated by
use of an over-the-wire catheter (e.g., the single lumen Transit,
Cordis, Johnson & Johnson, Miami, FL, USA or the double lumen
0.023” TwinPass, Vascular Solutions Inc, Minneapolis, Minnesota,
USA). The automated pullback (at 3.0 mm/sec) is then commenced
during simultaneous flushing of viscous iso-osmolar contrast (e.g.
Iodixanol 320, Visipaque™, GE Health Care, Cork, Ireland) through
the guiding catheter. This can be achieved either manually or by
use of an automated power injector (e.g. Mark-V ProVis, Medrad,
Inc. Indianola, PA, USA).1-3
OCT risks
Any complication judged by the operators to have occurred during
or within the immediate 24-hour period following OCT examination
was included, even if transient and with no clinical sequelae.
Risks were categorised into:
1) Self-limiting events
2) Major complications (arrhythmia, embolisation, coronary
dissection or spasm) including major adverse cardiac events
(defined as MI, emergency revascularisation – including percutaneous
or surgical – and death).
3) Mechanical device failure
Furthermore, all risks were classified based on their eventual
outcome as: A), Immediate correction with no specific action
required; B), transient, but requiring specific treatment with
resolution before the patient left the catheterisation laboratory; or C),
required treatment/surveillance following discharge from
the catheterisation laboratory (including lengthening patient’s
hospitalisation).
Study centres
The six participating centres were located in the Netherlands (one
centre), United Kingdom (two centres), Italy (one centre), Germany
(two centres). The number of OCT studies contributed by each
centre was: Thoraxcenter (Rotterdam, the Netherlands n= 162,
34.6%); Royal Brompton Hospital (London, United Kingdom, n=91
19.4%); St. Giovanni Hospital (Italy, n=85, 18.2%); Helios Heart
Centre (Siegburg, Germany, n=64, 13.7%). Medizinische Poliklinik,
University of Munich (Munich, Germany, n=36, 7.7%) and
Harefield Hospital (Middlesex, United Kingdom, n=30, 6.4%).
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