To the Editor: Revascularization after chronic coronary total occlusion (CTO) can
relieve symptoms of angina and improve both cardiac function and clinical prognosis.[1,2]
However, percutaneous coronary intervention (PCI) for revascularization of CTO lesions
is challenging because of a high incidence of complications and long X-ray exposure
time. While the success rate for PCI in CTO has significantly increased in recent
years due to the emergence of new technologies, devices and anticoagulation strategies,[3,4]
these new devices have also led to complications such as coronary artery perforation
and cardiac tamponade, which limit their application. As routine PCI procedures for
CTO intuitively require operationally safe devices, we have developed a new device
called the real-time intravascular ultrasound (IVUS) double-lumen microcatheter (RLS
catheter). Here, we briefly describe the RLS catheter, report our experience with
this device, and provide data on its efficacy and safety in CTO revascularization.
This study was approved by the Ethics Committee of our hospital (No. 201215). All
enrolled patients provided prior written informed consent for the use of the RLS catheter
in their treatment. Statistical analysis was performed using SPSS19.0 statistical
software (SPSS Inc, Chicago, IL, USA). Normally distributed continuous variables were
expressed as mean ± standard deviation (SD), while non-normally distributed variables
were expressed as median. Categorical variables were expressed as n (%).
Patients with CTO who underwent PCI between February 2018 and May 2019 at the Department
of Cardiology in our hospital were selected for participation in this study. PCI was
performed using the RLS catheter by a cardiologist in patients with an ambiguous proximal
cap or in those where the guidewire situated in the false lumen could not easily re-enter
the true lumen. We enrolled 12 CTO patients with a median age of 54.0 years and a
median left ventricular ejection fraction of 62.0%. This cohort included nine males.
Further, nine patients suffered from unstable angina, seven (58.3%) had hypertension,
seven had diabetes, five had hyperlipidemia, five were smokers, four had a history
of myocardial infarction, and three had previously PCI.
The RLS catheter is composed of an IVUS catheter and a microcatheter.[5] The IVUS
catheter serves as a monorail lumen, and the probe at the tip of the IVUS catheter
acquires real-time cross-sectional images of the vascular wall. The microcatheter
serves as an over-the-wire (OTW) lumen such that the penetrating guidewire is advanced
through the microcatheter into the lesion through an aperture in the side [Supplementary
Figures 1A, B]. The length of the device is 1350 mm, the aperture on the side is situated
20 mm from the distal tip of the microcatheter, and the exit port is at a distance
of 240 mm from the distal tip of the IVUS catheter. The widest part of the device
is 3.6 Fr and there are three radiopaque marks on the device [Supplementary Figure
1B]. The RLS catheter can support a guidewire through the occlusion stump or upon
re-entry into the true lumen. According to our experience, when it was difficult to
find an entry point at the cap of a CTO, the RLS catheter was advanced using the guidewire
in the side branch [Supplementary Figure 1C]. Next, under the guidance of realtime
IVUS images, the CTO-dedicated guidewire was advanced through the aperture on the
side to penetrate the occluded lesion [Supplementary Figure 1D]. When the guidewire
had entered the false lumen, the RLS catheter was advanced over the guidewire into
the false lumen [Supplementary Figure 1E]. Finally, a CTO-dedicated guidewire was
selected and introduced to the true lumen under the guidance of realtime IVUS images
[Supplementary Figure 1F].
The most frequently affected vessels were the left anterior descending (9/12) and
the right coronary artery (6/12), and 3/12 of the patients had multivessel CTO lesions.
The morphology of the lesions included severely tortuous (3/12), stumpless CTO (5/12),
length of the CTO lesion >20 cm (10/12), and in-stent occlusions (1/12). We used a
6 Fr guiding catheter in 3 patients and a 7 Fr guiding catheter in the rest. Eight
cases required the use of the RLS catheter to facilitate guidewire entry into the
occlusion, while in five cases it was for guidewire re-entry into the true lumen.
The technical success rate and the procedural success rate were both calculated to
be 11/12. Technical failure was seen in one patient with an in-stent occlusion wherein
the RLS catheter was damaged during guidewire re-entry into the in-stent space. Revascularization
using the RLS catheter was successful in all the other 11 patients with a median procedure
time of 70.5 min. The median time for guidewire passage through the CTO lesion was
32.0 min, and after the RLS catheter was advanced, the median time taken for guidewire
penetration through the target lesion was 3.0 min, and the median time for guidewire
passage through the CTO lesion was 9.5 min.
Importantly, angina was relieved in all patients, and no complications such as coronary
artery perforation, pericardial tamponade, or acute myocardial infarction occurred
in any of the patients, either during or after the procedure. The median follow-up
time was 18.0 months. Only one patient reported recurrence of angina pectoris at 17
months after the procedure, and the others did not experience any main adverse cardiovascular
events.
The unique design of our RLS catheter overcomes the disadvantages associated with
exchanging the IVUS and the double-lumen microcatheter while maintaining the advantages
of both. Further, its double-lumen structure provides better support and facilitates
placement of the guidewire. As the relative positions of the guidewire and the IVUS
probe are fixed in this device, the directional accuracy of the guidewire during lesion
penetration is significantly improved. Importantly, the IVUS of the RLS catheter can
identify the entry point, distinguish between true and false lumens, define the relative
position of the guidewire and target lesion, and provide real-time guidance during
lesion entry. These characteristics of the RLS catheter improve its accuracy and thereby,
reduce both procedure time and the incidence of complications. Lastly, as the external
diameter of the RLS catheter is 3.6 Fr, it can be inserted through a routinely-used
6 Fr or 7 Fr guiding catheter.
This retrospective study provides evidence that the RLS catheter is effective and
safe for use in complex CTO revascularization procedures as it supports the guidewire
in two ways, namely, its entry into the lesion and its re-entry into the true lumen.
Both device and procedure success rates were higher than 90%. The time taken between
the guidewire entry into the lesion and its re-entry into the true lumen was only
several minutes after the RLS catheter was advanced, attesting to the efficiency of
the RLS catheter. Notably, successful CTO revascularization was achieved in four patients
using the RLS catheter after conventional ante grade and/or retrograde intervention
had failed, demonstrating that our RLS catheter could increase the success rate of
CTO revascularization. No complications occurred during the perioperative period,
and only one patient developed angina pectoris after the procedure, attesting to the
safety of the RLS catheter in the treatment of CTO lesions. As the sample size is
relatively small, the results need to be confirmed by larger multicenter studies.
In summary, these results indicate that the RLS catheter is useful in CTO revascularization
and that it can potentially be used in routine clinical practice.
Funding
This study was supported by a grant from the Key Project of Medical Science Research
in Hebei Province (No. 20130001).
Conflicts of interest
None.
Supplementary Material
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