Percutaneous recanalization of chronically occluded coronary arteries: a consensus document: part II

New Advances in Chronic Total Occlusions

Coronary chronic total occlusions (CTOs) still represent the greatest technical challenge that interventional cardiologists face. CTOs remain seriously undertreated with percutaneous techniques, far below their prevalence. One reason for the low uptake was the suboptimal CTO percutaneous coronary intervention (PCI) success rates over a long period of time. During the last years, dedicated groups of experts in Japan, Europe and United States fostered the development and standardisation of modern CTO recanalisation techniques, along with providing focused training and proctorship worldwide. As a result, dedicated operators achieved success rates far beyond 90 %, while coping with lesions of increasing complexity. A series of studies, mainly retrospective and observational in nature, explored the prognostic impact of CTO PCI, revealing that successful lesion recanalisation is related to improved patient outcome and anginal status; further evidence from randomised trials is on the way. The following review reports on the most recent advances in the field of CTO recanalisation, in an attempt to promote a more balanced approach in patients with chronically occluded coronary arteries and encourage more operators to cope with these inherently complex lesions.

Temporal trends of fluoroscopy time and contrast utilization in coronary chronic total occlusion revascularization: insights from a multicenter United States registry

BACKGROUND

The impact of operator experience on fluoroscopy time and contrast utilization during percutaneous coronary intervention (PCI) of coronary chronic total occlusions (CTOs) has received limited study.

METHODS

We evaluated temporal trends in fluoroscopy time and contrast utilization among 1,363 consecutive CTO PCIs performed at three US institutions between January 2006 and November 2011.

RESULTS

Mean age was 65 ± 11 years, 85% of patients were men, 40% had diabetes, 37% had prior coronary artery bypass graft surgery, and 42% had prior PCI. The CTO target vessel was the right coronary artery (55%), circumflex (23%), left anterior descending artery (21%), and left main or bypass graft (1%). The retrograde approach was used in 34% of all procedures. The technical and procedural success rates were 85.5 and 84.2%, respectively. The mean procedural time, fluoroscopy time, and contrast utilization were 113 ± 61 min, 42 ± 29 min, and 294 ± 158 mL, respectively. Years since initiation of CTO PCI were independently associated with higher technical success rate (odds ratio [OR] = 1.52, 95% confidence interval [CI] = 1.52-1.70, P < 0.001), lower fluoroscopy time (OR = 0.84, 95% CI = 0.75-0.95, P = 0.005), and contrast utilization (OR = 0.84, 95% CI = 0.62-0.79, P < 0.001) during the study period.

CONCLUSIONS

Among selected US-based institutions performing CTO PCI, we observed a significant reduction in total fluoroscopy time and contrast utilization paralleled with an improved technical success rate over time.

New percutaneous approaches for chronic total occlusion of coronary arteries

Successful recanalization and percutaneous revascularization of coronary arteries with chronic total occlusion (CTO) is one of the 'last frontiers' in coronary interventions. Conquering this obstacle will enable complete percutaneous revascularization in an increasing number of patients. The introduction within the last few years of enhanced guidewires combined with increasing operator experience and creative procedural techniques, such as the retrograde approach and the re-entry subintimal tracking technique (STAR), have significantly reduced the number of CTOs that should now be considered unapproachable. In addition, novel devices have been developed over recent years that may increase the success rate, as well as the safety, of the procedure. The Safe-Cross radiofrequency combines optical coherence reflectometry that warns the operator when the wire tip moves to within 1 mm of the outer vessel wall, combined with radiofrequency energy pulses to facilitate the passage. The CROSSER catheter mechanically vibrates against the face of the CTO at 20 kHz at a stroke depth of approximately 20 microm, creating a channel through the CTO. The most novel approach is the biologic one, in which proteolytic enzymes that digest the CTO cap to facilitate mechanical passage. The success rates for otherwise refractory CTOs will continue to improve with the development and validation of new imaging modalities and active energy source catheters.

In vivo feasibility study of ultrasound potentiated collagenase therapy of chronic total occlusions

Arterial chronic total occlusions (CTOs) pose considerable challenges for percutaneous interventions, due primarily to the presence of stiff proximal fibrous caps (PFCs) which act as a barrier to the penetration of guide wires. A new approach under development for improving the success rate of guide wire crossing in CTOs is to employ collagenase to degrade the mechanical integrity of the PFCs. This has been shown to be feasible in preclinical work and in a Phase 1 clinical trial. In a recent study we demonstrated using ex vivo experimental CTO specimens that ultrasound-stimulated microbubbles (USMBs) could potentiate the effects of collagenase and result in increased mechanical degradation of the PFCs of CTOs. Here we report the results of the first in vivo study examining the feasibility of this approach, which demonstrates that the force required to puncture through the PFCs of CTOs is reduced with combined USMB+collagenase treatments relative to collagenase only treatments. This approach has the potential to further improve the efficacy of the emerging technique of collagenase facilitation of percutaneous interventions for CTO.

"Head-to-toe" kissing balloon angioplasty during PCI of right coronary artery chronic total occlusion

New techniques involving the use of retrograde channels have enabled successful revascularization of chronically occluded arteries previously not amenable to standard strategies. We describe the use of a simultaneous antegrade and retrograde approach to perform bifurcation kissing balloon angioplasty which was not possible using a standard antegrade approach. As the balloons are oriented in opposite rather than identical directions, we have named this technique "Head-to-Toe Kissing."

Distal side-branch technique: a new use for the Tornus® Catheter

Percutaneous coronary intervention (PCI) outcomes of chronic total occlusions (CTO) lesions have improved in recent years due to a better understanding of the physiopathology of the disease, more effective techniques and improvement in the design of new devices. We describe a new use of the Tornus® Catheter in the anterograde approach for CTO treatment.

The effect of percutaneous coronary intervention of chronically totally occluded coronary arteries on left ventricular global and regional systolic function

BACKGROUND

Percutaneous coronary intervention (PCI) is frequently attempted to open chronic total occlusions (CTOs) and restore epicardial coronary flow. Data suggest adverse outcomes in the case of PCI failure. We hypothesized that failure to open a CTO might adversely affect regional cardiac function and promote deleterious cardiac remodelling, and success would improve global and regional cardiac function assessed using cardiac magnetic resonance and velocity vector imaging.

METHODS

Thirty patients referred for PCI to a CTO underwent cardiac magnetic resonance examination before and after the procedure. Left ventricular function and transmural extent of infarction was assessed in these patients. Regional cardiac function using Velocity Vector Imaging version 3.0.0 (Siemens) was assessed in 20 patients.

RESULTS

Successful CTO opening (thrombolysis in myocardial infarction 3 flow) occurred in 63% of patients. Left ventricular ejection fraction significantly increased after successful PCI (50 ± 13% to 54 ± 11%; P < 0.01). Global longitudinal strain (GLS) fell significantly in the failed group (Δ = -25 ± 17%; P = 0.02) in contrast with successful PCI in which GLS did not change (Δ 20 ± 32%; P = 0.17). GLS rate followed a pattern similar to GLS (failed, Δ -30 ± 17%; P < 0.01 vs success Δ 25 ± 48%; P = 0.34). In contrast, radial and circumferential strain/strain rate were not different between groups after success/failed PCI.

CONCLUSIONS

Regional cardiac function assessment using velocity vector imaging showed a significant decline in GLS and GLS rate in patients in whom PCI failed to open a CTO, with no change in global measures of cardiac function.

The use of ultrasound-stimulated contrast agents as an adjuvant for collagenase therapy in chronic total occlusions

AIMS

To investigate the effectiveness of combining collagenase and ultrasound-stimulated microbubble (USMB) treatments in reducing the mechanical force required for crossing a guidewire through CTOs.

METHODS AND RESULTS

Experiments were conducted on ex vivo specimens of a rabbit femoral artery CTO model (n=45 total samples). Four primary groups were employed: control (n=6), collagenase only (n=15), USMB only (1 MHz frequency) (n=5), and collagenase+USMB (n=19). In one set of experiments the force required to puncture through CTO samples was measured and it was found that the puncture force was 2.31-fold lower for the combined treatment group relative to the comparable collagenase-only group (p<0.05). In a second set of experiments, the total protein and hydroxyproline content of the supernatant solution adjacent to the CTO was analysed. Significantly higher hydroxyproline levels were measured in collagenase+USMB treated CTOs (0.065 g/mL) compared to collagenase (0.030 g/mL), USMB (0.003 g/mL) and control (0.004 g/mL) (p<0.05), indicating that the combined treatment augmented collagenase degradation.

CONCLUSIONS

Ultrasound-stimulated microbubbles improved the effectiveness of collagenase in reducing the force required to cross experimental CTOs. This new approach may have the potential to reduce treatment times and improve the success rates of emerging collagenase-based treatments of CTO.

Impact of diabetes on long term follow-up of elderly patients with chronic total occlusion post percutaneous coronary intervention

Background

The prognosis of elderly patients with chronic total occlusion (CTO) and diabetes mellitus (DM) treated with percutaneous coronary intervention (PCI) is not known.

Objective

To investigate the effect of diabetes on long-term follow-up of CTO after PCI in elderly patients.

Methods

A total of 153 elderly patients (age > 65 years old) with CTO lesions which were successfully treated with PCI were enrolled. Fifty one patients with diabetes and 102 without diabetes were compared for long-term outcomes (mean follow up: 36 ± 12 months). Major adverse cardiac events (MACE) which include death, myocardial infarction or target lesion revascularization (TLR) were considered as a combined endpoint.

Results

The combined endpoint occurred in 29.4% of diabetes patients, and 11.3% of the patients without diabetes (P < 0.05). The Cox proportional hazards model identified: drug eluting stent (DES) or bare metal stent (BMS) (HR: 0.13, 95% confidence interval (95% CI): 0.03–0.62, P = 0.004), DM (HR: 6.69, 95% CI: 1.62–15.81, P = 0.01) and final minimal lumen diameter (MLD) (HR: 0.37, 95% CI: 0.13–0.90, P = 0.03 ) as independent predictors of MACE, DM with renal impairment (HR: 6.64, 95% CI: 1.32–33.36, P = 0.02), HBA1C on admission (HR: 1.79, 95% CI: 1.09–2.94, P = 0.02), as independent predictors of MACE at long term follow-up.

Conclusions

The study demonstrates that DM is a predictive factor for MACE in elderly CTO patients treated with PCI, type of stent, final minimal lumen diameter and DM with renal impairment, and HBA1C level on admission are predictors of MACE.

Effects of percutaneous revascularization of chronic total occlusions on clinical outcomes: a meta-analysis comparing successful versus failed percutaneous intervention for chronic total occlusion

BACKGROUND

Chronic total occlusions (CTOs) represent the most complex and challenging coronary lesions for percutaneous coronary intervention (PCI). PCI for a CTO is a high-risk procedure and the long-term benefits of a successful percutaneous CTO recanalization over the medical management (as a result of failed PCI) are not clear, as the studies have shown conflicting results in the past. The goal of this analysis was to clarify this issue by performing a meta-analysis of the available literature.

METHODS

Using major electronic databases, we searched for studies (randomized or observational) comparing death, major adverse cardiovascular events (MACE), myocardial infarction (MI), and target vessel revascularization (TVR) between patients who underwent PCI recanalization of CTOs versus those treated with medical management as a result of failed PCI attempts.

RESULTS

We identified 23 observational studies comparing the desired clinical parameters between patients with successful CTO recanalization and those managed conservatively as a result of attempted but failed PCI. The total number of patients observed in all of the studies was 12,970 and the mean time of follow up was 3.7 ± 2.1 years. Our results indicated that successful recanalization of a CTO results in improved all-cause mortality (relative risk [RR] of 0.54, 95% confidence interval [CI] (0.45-0.65), P-value < 0.001), lower rates of MACE (RR of 0.70, 95% CI 0.60-0.83, P-value < 0.001) and reduced needs for subsequent bypass surgery (RR of 0.25, 95% CI (0.21-0.30), P-value < 0.001). The difference in long-term mortality remained statistically significant even after the adjustment for procedure related complications and in-hospital deaths.

CONCLUSION

As compared to conservative management (as a result of failed intervention), successful PCI recanalization of a CTO appears to be associated with improved long-term clinical outcomes; however, randomized controlled trials (RCTs) are needed to further confirm these results.

Percutaneous recanalization of chronic total occlusions: wherein lies the body of proof?

Although interventional technology and skills have markedly advanced, percutaneous coronary intervention (PCI) for coronary chronic total occlusion (CTO) lesions remains challenging. Indeed, CTO PCI is technically complex, carries the potential for a relatively high likelihood of failure and acute complications, and requires specifically skilled operators and a demanding use of resources. In addition, controversy persists surrounding appropriate indications for attempting CTO revascularization. Finally, there is a wide uncertainty on the actual benefits achieved with successful CTO recanalization. A growing number of studies have reported procedural results and/or assessed functional effects and long-term clinical outcomes of CTO PCI. We therefore sought to review and critically appraise the evidence base for procedural outcomes and potential clinical benefits of CTO PCI.

Current status of percutaneous coronary intervention of chronic total occlusion

This paper describes the current status of percutaneous coronary intervention (PCI) for totally occluded coronary arteries. Chronic total occlusion is associated with 10%-20% of all PCI procedures. Results show that opening an occluded vessel, especially one supplying a considerable area of myocardium, may be beneficial for a patient's angina relief and heart function. We describe the devices used currently in re-canalization such as new wires, microcatheters (including Tonus and Cosair) and intravascular ultrasound guidance. Different techniques to improve the success rate and reduce complications are discussed in detail.

Multimodality imaging evaluation of functional and clinical benefits of percutaneous coronary intervention in patients with chronic total occlusion lesion

AIMS

To determine the effects of percutaneous coronary intervention (PCI) on cardiac perfusion, cardiac function, and quality of life in patients with chronic total occlusion (CTO) lesion in left anterior descending (LAD) coronary artery.

METHODS AND RESULTS

Patients (n=99) with CTO lesion in the LAD coronary artery who had successfully undergone PCI were divided into three groups based on the SPECT/CTCA fusion imaging: (a) no severe cardiac perfusion defects (n=9); (b) reversible cardiac perfusion defects (n=40); or (c) fixed cardiac perfusion defects (n=50). No statistical difference of perfusion abnormality was observed at 6 months and 1 year after PCI in group (a). In group (b), SPECT/CTCA fusion imaging demonstrated that cardiac perfusion abnormality was significantly decreased 6 month and 1 year after PCI. Left ventricular ejection fraction (LVEF) increased significantly at 6 months and 1 year follow up. Quality of life improved at 6 months and 1 year after PCI procedure. Moreover, patients in group (c) also benefited from PCI therapy: a decrease in cardiac perfusion abnormality, an increase in LVEF, and an improvement in quality of life. PCI of coronary arteries in addition to LAD did not significantly affect cardiac function and quality of life improvement in each group.

CONCLUSIONS

PCI exerts functional and clinical benefits in patients with CTO lesion in LAD coronary artery, particularly in patients with reversible cardiac perfusion defects. SPECT/CTCA fusion imaging may serve as a useful tool to evaluate the outcomes of patients with CTO lesion in LAD coronary artery.

Toolbox and Inventory Requirements for Chronic Total Occlusion Percutaneous Coronary Interventions

More interventional cardiologists are adopting chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in their practice. This article follows the steps of the PCI procedure to describe the toolbox and inventory requirements for successful program development. Recent innovations have allowed adoption of controlled dissection and reentry techniques as a primary revascularization strategy for CTO. Other devices have special rules in CTO PCI. Equipment and techniques to enhance guide catheter support are frequently needed during CTO PCI. Tools for complication management are important components. The necessary tools are listed at the end of the article.

Chronic total occlusions: successful recanalization of very old lesions

PURPOSE

The treatment of chronic total occlusion is thought to be the final frontier in treating coronary artery disease nonsurgically. In the past, an old occlusion was not likely to be treated successfully percutaneous. We have had success in revascularizing some very old 20 plus year old occlusions percutaneously.

METHODS

Six patients were treated who had >20-year-old occlusions. Five patients were male; mean age of patients was 72.2 years (range 63-86). Mean age of the occlusion was 24.8 years. All patients had ischemia in the corresponding territory. Four of the patients had right coronary artery occlusions; one had a left circumflex occlusion and one had left anterior descending artery occlusion.

RESULTS

Using a combination of radial and/or femoral approach, we successfully recanalized all of these old occlusions. No patients had major adverse cardiac events. Two patients developed restenosis at follow-up that was subsequently treated uneventfully. All the patients had a complete relief of angina.

CONCLUSION

In a small single center experience, even very old occlusions >20-year old can be effectively treated with dedicated systems, excellent guiding catheter support and experienced physicians.

Coronary computed tomographic angiography for prediction of procedural and intermediate outcome of bypass grafting to left anterior descending artery occlusion with failed visualization on conventional angiography

Conventional coronary angiography (CCA) has considerable limitations regarding visualization of distal vessel segments in chronic total occlusion. We assessed the ability of coronary computed tomographic angiography (CCTA) to predict the success of coronary artery bypass grafting (CABG) to the chronically occluded left anterior descending coronary artery (LAD) incompletely visualized on CCA. Thirty symptomatic patients rejected for CABG on the basis of the CCA findings underwent preoperative CCTA before intended transmyocardial laser revascularization. The LAD was explored operatively in all patients, and CABG to the LAD was attempted if the distal vessel was suitable for anastomosis. The procedural outcome of CABG and the 6-month patency of the left internal mammary artery graft at follow-up CCTA were defined as the primary and secondary end point, respectively. The primary and secondary end points were achieved in 80% and 77% of patients, respectively. We found a significant correlation between the intraoperative and computed tomographic measurement of distal LAD diameter (R = 0.428, p = 0.037). On multivariate analysis, the maximum diameter of the distal LAD by CCTA (odds ratio 8.16, p = 0.043) was the only independent correlate of procedural success of CABG. A cutoff value of 1.5 mm for the mean distal LAD diameter predicted left internal mammary artery graft patency with 100% specificity and 83% sensitivity. Successful CABG resulted in significant improvements in angina class and left ventricular function in LAD segments at 6 months of follow-up. In conclusion, CCTA predicted both the procedural and the intermediate outcome of CABG to chronic LAD occlusion with failed visualization on CCA.

Collagenase Total Occlusion-1 (CTO-1) trial: a phase I, dose-escalation, safety study

BACKGROUND

Percutaneous interventions for chronic total occlusions have low success rates, primarily because of failure of guide wire crossing. Collagen-rich matrix constitutes the main barrier to chronic total occlusion crossing. In preclinical studies, local delivery of a bacterial collagenase formulation improved guide wire crossing. The Collagenase Total Occlusion-1 (CTO-1) Trial is a phase I, dose-escalation trial to assess the safety and efficacy of collagenase therapy to facilitate guide wire crossing in coronary artery chronic occlusions.

METHODS AND RESULTS

Twenty subjects with ≥1 previous failure of chronic total occlusion guide wire crossing were enrolled at 2 sites. Subjects were treated in 4 distinct cohorts of 5 patients, with escalation of collagenase dose in each cohort from 300 to 1200 μg. Collagenase was locally delivered into the occlusions with either an over-the-wire balloon system (n=8) or a fine-cross microcatheter (n=12) for a period of 30 minutes. Subjects were brought back to the catheterization laboratory for guide wire crossing and angioplasty the next day. Guide wire crossing was successfully achieved in 15 subjects (75%). A soft-tip guide wire (Whisper, Pilot-50, Fielder XT) was either the sole or predominant guide wire used in 75% of successful crossings. Non-ST-segment-elevation myocardial infarctions occurred in 3 patients as a result of side-branch ischemia during stenting. Computed tomographic angiography at 3 months showed no late complications and patent stents in successfully treated chronic total occlusion. Anginal improvement occurred with a reduction in Canadian Cardiovascular Society class from baseline to 3 months (2.5±0.6 versus 0.9±0.9; P<0.001).

CONCLUSION

Local delivery of collagenase into coronary chronic total occlusion is feasible and safe with encouraging guide wire crossing results in previously failed cases. Larger clinical trials are required to determine efficacy.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01271335.

Computed tomography to predict surgical revascularization of a left anterior descending artery occlusion incompletely visualized by conventional angiography

PURPOSE

Previous studies demonstrated that failure to visualize distal chronic total occlusion in conventional coronary angiography (CCA) does not preclude procedural success of coronary artery bypass grafting (CABG). We assessed the utility of computed tomography angiography (CTA) in guiding CABG to the occluded left anterior descending artery (LAD) incompletely visualized by CCA.

MATERIALS AND METHODS

Twenty-four symptomatic patients rejected for revascularization of an occluded LAD on the basis of CCA underwent a preoperative CTA before intended transmyocardial laser revascularization. Off-pump CABG to the LAD was attempted in all patients depending on the intraoperative findings. The primary outcome was defined as procedural success of CABG to the LAD.

RESULTS

The success rate for CABG was 79.2%. By CCA, Rentrop 0/1 was present in 6 patients (25%), whereas Rentrop 2 was present in 18 patients (75%). By CTA, Rentrop 3 was seen in all patients. Compared with the CABG-failure group, the CABG-success group showed a larger mean distal LAD diameter (1.7 ± 0.2 mm vs. 1.3 ± 0.1 mm; P=0.001). By receiver-operating curve analysis, a cutoff value of 1.5 mm for the mean distal LAD diameter predicted CABG availability with 100% specificity and 95% sensitivity. The distal LAD short length and intramyocardial course were other significant correlates of CABG failure compared with CABG success (60% vs. 5.3%, P=0.018; 80% vs. 0%, P<0.001).

CONCLUSIONS

Noninvasive CTA is not only superior to CCA in delineating distal coronary occlusion but also very precisely predicts the procedural success of CABG. CTA represents a robust evaluation tool for coronary mapping of chronic total occlusion with doubtful distal anatomy in CCA.

[Usefulness of the Tornus® catheter in nondilatable coronary chronic total occlusion]

The treatment of coronary chronic total occlusions (CTO) remains a challenge for the interventional cardiologist. Failure of balloon angioplasty is the second more common cause of an unsuccessful procedure. We describe our experience with the use of the new Tornus® catheter (Asahi Intecc, Aichi, Japan) designed specifically for the treatment of "nondilatable" CTO. Between November 2008 and March 2010, 17 patients (age 62 years, 88% men, 82% dyslipidemia, 52% hypertension, 29% diabetes) were treated in whom balloon dilatation had failed after crossing the lesion with the guide. The use of Tornus® catheter was successful without complications in 15. All patients underwent clinical follow-up (median, 573 days) with no documented major adverse events. The use of the Tornus® catheter is safe and feasible in those patients with CTO lesions in whom balloon angioplasty has been unsuccessful.

[Treatment strategies for chronic total occlusion: current status and outlook]

The present article discusses the current status of treatment strategies for chronic total occlusion (CTO) and the prospects offered by new therapies. The indication for revascularisation recognized in the current European guidelines includes the presence of typical symptoms and evidence of ischemia of over 10% of the total myocardium, while in patients with multiple vascular diseases the aim is complete revascularisation. Although the vast majority of patients with CTO fulfil these criteria, they are currently not receiving interventional treatment as frequently as expected. The reasons often given for this include the low success rates and high recurrence rates. However, both problems have been improved by drug-eluting stents (DES) on the one hand and by wire techniques and strategies on the other, such that results almost comparable with non-occluded coronary lesions can be achieved. While more advanced approaches like retrograde recanalization should be restricted to specialized centres, marked improvements can be achieved even without these special techniques by means of consistent further training and the application of modern techniques. Despite the aggressiveness of these approaches to pass through an occluded artery, the complication rate is not higher than with non-occluded lesions when the specific complications of recanalization are avoided in a careful approach. Further technical improvements are expected with the use of modern imaging techniques such as intravascular ultrasound and high-resolution CT imaging of coronary arteries.

The feasibility and safety of applying the Magnetic Navigation System to manage chronically occluded vessels: a single centre experience

AIMS

Applying the Magnetic Navigation System (MNS) to manage chronic total occlusions (CTOs). The MNS precisely directs a magnetised guidewire in vivo through two permanent external magnets.

METHODS AND RESULTS

The first 43 consecutive MNS treated CTOs were retrospectively evaluated. Computed tomography coronary angiography (CTCA) co-integration with the MNS provided a virtual road map through the occlusion. Unsuccessful MNS cases were managed with bailout conventional guidewire techniques. Experienced CTO and MNS operators had unrestricted access to CTO devices and equipments. The MNS crossing success increased from 40% to 56% over 52 months and averaged 44.2% (19/43 patients). In 58.3% (14/24) of failed MNS cases the conventional wire approach was successful, giving an overall procedural success rate of 76.6%. Of those conventionally treated, two patients required pericardiocentesis. On average, 1.8 ± 0.9 stents (lengths 44.7 ± 21.4 mm and diameter 2.8 ± 0.4 mm) were implanted. Procedural times were lengthy (125.0 ± 35.3 min) requiring high fluoroscopy dosage (11980.2 ± 6457.9 Gy/cm2) and contrast media usage (388.8 ± 170.2 ml). Operators persevered less with magnetic wires (20.9 ± 12.4 min vs. 27.7 ± 24.4 min), and preferentially used the least stiff wire as first choice (53.5%). CTCA co-integration did not influence procedural outcome. As with conventional wires, higher magnetic wire successes occurred in low calcified lesions, those with a central stump and without bridging collaterals.

CONCLUSIONS

In unselected CTOs, the magnetic wires are safe and feasible. Current modest success rates with a high procedural bailout rate implicate the need for improved magnetic guidewire technology comparable to available sophisticated conventional CTO wires. Randomised studies are needed to clarify the value of magnetic guided recanalisation.