Original Contribution

Robotic-Enhanced PCI Compared to the Traditional Manual Approach

Nathaniel R. Smilowitz, MD;  Jeffrey W. Moses, MD;  Fernando A. Sosa, BA;  Benjamin Lerman, BA; Yasir Qureshi, MD;  Kate E. Dalton, MS;  Lauren T. Privitera, MPH;  Diane Canone-Weber, MPH; Varinder Singh, MD;  Martin B. Leon, MD;  Giora Weisz, MD

Nathaniel R. Smilowitz, MD;  Jeffrey W. Moses, MD;  Fernando A. Sosa, BA;  Benjamin Lerman, BA; Yasir Qureshi, MD;  Kate E. Dalton, MS;  Lauren T. Privitera, MPH;  Diane Canone-Weber, MPH; Varinder Singh, MD;  Martin B. Leon, MD;  Giora Weisz, MD

Abstract: Remote-controlled robotic-enhanced percutaneous coronary intervention (PCI) was developed to improve procedural outcomes, reduce operator radiation exposure, and improve ergonomics. Critics questioned whether protection of the operator might result in increased radiation exposure to the patient and increase contrast media use. We studied this in a single-center comparison of robotic-enhanced versus traditional PCIs. A total of 40 patients who enrolled in the PRECISE study and had PCI with the CorPath 200 robotic system (Corindus Vascular Robotics) were compared to 80 consecutive patients who underwent conventional PCI. All patients had obstructive coronary artery disease, evidence of myocardial ischemia, and clinical indications for single-vessel PCI. Baseline demographics of the 40 robotic and 80 traditional PCIs were similar. Only 2 robotic-assisted cases required conversion to manual PCI. All patients had a final residual stenosis <30%. Robotic-enhanced PCI was associated with trends toward lower duration of fluoroscopy (10.1 ± 4.7 min vs 12.3 ± 7.6 min; P=.05), radiation dose (1389 ± 599 mGy vs 1665 ± 1026 mGy; P=.07), and contrast volume (121 ± 47 mL vs 137 ± 62 mL; P=.11). In conclusion, the initial experience with robotic-enhanced PCI was not associated with increased fluoroscopy duration, radiation, or contrast media exposure to patients, and compared favorably to the traditional approach. 

J INVASIVE CARDIOL 2014;26(7):318-321

Key words: robotic-enhanced, robotics, remote-control, percutaneous coronary intervention, radiation exposure, contrast media

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Remote-controlled robotic-enhanced percutaneous coronary intervention (PCI) was developed to enhance procedural standardization and precision, and to address the occupational hazards to the interventional cardiologist. Initial experience and the PRECISE multicenter study demonstrated that robotic-enhanced PCI is feasible and safe and results in decreased radiation exposure to the operator.1,2 Despite clear benefits to operators, critics suggest that protection of the interventionalist from radiation with a new system may result in prolonged fluoroscopy times and increased radiation exposure to the patient. We studied this hypothesis by comparing robotic-enhanced to traditional PCI.

Methods

All patients enrolled in PRECISE (Percutaneous Robotically-Enhanced Coronary Intervention Study) at a single high-volume center were compared to consecutive patients who underwent traditional PCI. All patients in the robotic and traditional PCI cohorts underwent procedures performed during the same time period by the same interventional operators. All subjects met all inclusion and exclusion criteria as published in the PRECISE trial.2 In short, adult patients were eligible if they had de novo obstructive coronary artery disease (CAD) with a stenosis of ≥50% on angiography, evidence of myocardial ischemia on non-invasive stress testing, and indications for single-vessel PCI. Single or multiple coronary artery stenoses (with 10 mm or less between diseased segments) met inclusion criteria if they were ≤24.0 mm in length, had a reference diameter of 2.5-4 mm, and could be completely covered by a single stent. Patients with left ventricular ejection fraction <30%, evidence of an acute myocardial infarction (MI) or recent PCI within 72 hours prior to the study procedure, a major recent complication from PCI within 30 days, or planned PCI or coronary artery bypass graft (CABG) within 30 days were excluded. Angiographic exclusion criteria included prior stent placement within 5.0 mm of the target lesion, ostial, tortuous, or moderately calcified target lesions, directional or rotational atherectomy prior to stent placement, and unprotected left main CAD. 

All patients underwent conventional diagnostic angiography via femoral arterial access. Traditional PCI was performed manually with the operator standing at the bedside. For robotic PCI, the guiding catheter was manually positioned at the ostium of the coronary artery after completion of the diagnostic angiogram. Remote-controlled PCI was performed with the robotic CorPath 200 System (Corindus Vascular Robotics), with the option to convert to manual PCI if necessary. The CorPath robotic system consists of a bedrail-mounted robotic drive and sterile cassette that can be loaded with commercially available 0.014˝ guidewires and rapid exchange angioplasty and stent delivery systems. The cassette manipulates the guiding catheters and angioplasty devices using motorized rollers that provide axial and rotational forces. The robotic drive is tethered to the control console via a communication cable. Operators perform PCI seated in an ergonomic and radiation-shielded interventional cockpit in the corner of the catheterization laboratory, using a joystick and touch screens to control the movements of intravascular devices. Fluoroscopy, electrocardiography, and hemodynamics are “slaved” to monitors within the interventional cockpit for enhanced viewing. During coronary interventions, an assistant operator remained in sterile attire at the foot of the bed to manually load wires, balloons, and stent-delivery systems onto the robotic sterile cassette and perform balloon inflations and deflations. All operators had training on the robotic system or a simulator prior to enrolling patients in PRECISE. Commercially available guidewires, balloons, and stents were used at the discretion of the operator in both cohorts. Anticoagulation and dual-antiplatelet therapy were administrated according to local protocol for both traditional and robotic PCI. Predilatation was mandated by protocol for robotic PCI, but not for patients undergoing traditional PCI. Postdilatation was performed at the discretion of the operator in both cohorts. 

Procedural outcomes of total fluoroscopy time, radiation dose, and delivered contrast volume were recorded. Creatine phosphokinase levels were routinely measured post procedure. Device technical success was defined as successful intracoronary advancement of the intravascular devices (guidewires, angioplasty balloons, and stent-delivery systems) by the robotic system without conversion to manual operation. Clinical procedural success was defined as a <30% residual stenosis by visual assessment at the target lesion after completion of the procedure in the absence of major adverse cardiovascular events (cardiac death, Q-wave or non-Q wave myocardial infarction, or target vessel revascularization) prior to hospital discharge. Non-Q wave myocardial infarction was defined as a peak CPK greater than twice the upper limit of normal in the absence of new pathological Q-waves, as defined in the PRECISE trial.2

Data were analyzed on an intention-to-treat basis. Statistical analyses were performed by unpaired Student’s t-test for normally distributed continuous data and by Chi-square and Fisher’s exact tests for categorical variables. Two-tailed P-values <.05 were considered statistically significant. The study was approved by the local institutional review board.

Results

All 40 patients enrolled for robotic PCI and 80 consecutive patients who underwent conventional PCI met the same study entry criteria. Baseline demographics of the two groups were similar (Table 1). Angiographic characteristics of the target coronary lesions are summarized in Table 2. All interventions in both groups achieved clinical procedural success with a final residual stenosis of <30% and TIMI-3 flow. No adverse events or elevations in CPK (greater than twice the upper limit of normal) occurred post procedure. Two robotic-assisted cases required conversion to manual PCI due to resistance during delivery of the stent to the target lesion. The conversion to manual PCI was completed successfully within seconds and was not associated with adverse outcomes. Device technical success was achieved in the remaining 38 patients (95%) who completed successful robotic PCI. Procedural characteristics of the interventions are listed in Table 3. As compared with robotic PCI, manual PCI was associated with the use of greater number of diagnostic and guide catheters (2.7 ± 1.1 vs 2.1 ± 1.0; P=.01) and less predilation (71% vs 98%; P<.001), but more postdilatation (51.3% vs 32.5%; P=.05). There was no difference in the mean number of stents used per patient (both 1.2 ± 0.4; P=.76), and stent lengths and diameters were similar. Robotic-enhanced PCI was associated with a trend toward shorter duration of fluoroscopy (10.1 ± 4.7 min vs 12.3 ± 7.6 min; P=.05), lower radiation dose (1389 ± 599 mGy vs 1665 ± 1026 mGy; P=.07), and lower contrast media volume (121 ± 47 mL vs 137 ± 62 mL; P=.11). Sensitivity analysis excluding the 2 robotic PCIs that required conversion to manual intervention demonstrated significant reductions in fluoroscopy time (9.3 ± 3.4 min vs 12.3±7.6 min; P=.01) and radiation dose (1347 ± 582 mGy vs 1665 ± 1026 mGy; P=.04), with a trend toward reduced contrast media use (119 ± 47 mL vs 137 ± 62 mL; P=.07).

Discussion

This single-center comparison of robotic-enhanced coronary intervention to traditional PCI demonstrates that robotic PCI is safe and may be favorable to patients, in addition to the previously reported benefits of improved ergonomics and reduced radiation exposure to operators.2

Remote-controlled robotic systems were initially developed to address the occupational hazards and procedural challenges of traditional coronary interventions. Chronic radiation exposure from traditional PCI is associated with posterior lens opacities and early cataracts among interventionalists, and malignancy remains a significant concern.3-5 In light of these risks, professional societies have called for reductions in radiation to improve catheterization laboratory safety.6 Orthopedic injuries from long hours of standing while wearing heavy aprons are also common, as are chronic pain complaints and missed physician workdays.7-9 Robotic PCI addresses both radiation exposure and ergonomic concerns.

Small pilot studies demonstrated the safety and technical feasibility of robotic technology for single-vessel PCI, with excellent angiographic outcomes and no major adverse events.1,10 PRECISE was a large, prospective, multicenter registry of robotic coronary interventions using the CorPath 200 system.2 This study demonstrated the efficacy of remote-controlled single-vessel PCI, with procedural success achieved in 97.6% of cases. Radiation exposure to the interventional operator was 95.2% lower than at the conventional position at the procedure table. Despite excellent outcomes and impressive benefits to interventionalists, PRECISE was a registry without a control group, and was therefore unable to rigorously evaluate the robotic system in comparison to traditional PCI. The current study provides this comparison from a large single center.

In spite of the many potential benefits of robotic technology, critics questioned whether the shielded interventional cockpit would yield fewer operator incentives to minimize fluoroscopy during interventional procedures and noted that robotic catheter manipulation could result in increased radiation exposure to the patient. On the contrary, operators in this study did not use excess radiation during robotic PCI. Instead, remote-controlled robotic-enhanced PCI was associated with trends toward reduced fluoroscopy duration, patient radiation exposure, and contrast media use when compared to traditional PCI. A per-usage sensitivity analysis also supports the safety of the robotic system to patients, with reductions noted in radiation exposure and fluoroscopy. These benefits were observed despite using a new system with no or minimal previous experience, and can be attributed to improved visualization, easy wire and catheter manipulation, and precise balloon and stent positioning, which are enhanced by the robotic system.

Robotic-enhanced PCI may confer direct benefits to patients. Traditional PCI typically requires assessment of lesion length by visual estimate, a method notorious for inaccuracies. Quantitative coronary angiography can improve the validity of lesion measurements, but is still subject to errors from foreshortening and tortuosity.11 During device deployment, unintended motion of the catheter can lead to device misplacement. These errors can contribute substantially to interoperator variability in PCI performance. Robotic PCI is an elegant solution to many of the shortcomings of traditional therapy. Robotic systems provide enhanced stability and precise incremental movements of interventional equipment. Decreased operator strain and fatigue during PCI may improve technical precision and minimize prolonged fluoroscopy. More accurate stent deployment may reduce the frequency of “geographic miss” — errors that are associated with increased rates of myocardial infarction and target vessel revascularization.12 Furthermore, by improving the accuracy of lesion length assessment, robotic PCI may improve the selection of the appropriate stent length and reduce the need for additional stents to cover the full lesion length. Simultaneous direct control over both intracoronary catheter positioning and the contrast media injector may enable reductions in fluoroscopy and total contrast delivery. Lower volumes of contrast may reduce the incidence of contrast-induced nephropathy, which is associated with increased morbidity and mortality.13,14 Minimizing radiation exposure has obvious importance to patients, as it may prevent radiation injury or iatrogenic malignancy in patients undergoing multiple staged interventions or serial fluoroscopic studies.6,15 Larger studies with longer follow-up will be necessary to identify longer-term benefits of robotic PCI.

Study limitations. This study has notable limitations. First, the study was a single-center prospective registry of robotic PCI with a cohort of traditional controls. Although not randomized, traditional PCIs were performed by the same operators and during the same time period as the robotic PCI cases, using the same local routines. Second, sample sizes were small, although nearly one-quarter of patients recruited for PRECISE were included, and the study center has the largest experience with robotic PCI to date. Third, although inclusion criteria were identical, some baseline characteristics varied between the groups. A greater proportion of right coronary artery lesions required intervention among patients who underwent robotic PCI (58% vs 28%; P=.01). Patients undergoing traditional PCI tended to have slightly higher percent diameter stenosis at the target lesion. These subtle angiographic differences were unlikely to impact clinical or procedural outcomes. Fourth, some key procedural characteristics varied between the groups. Predilation was more common with robotic PCI, while postdilation was more frequently performed in the group undergoing traditional PCI. A greater number of diagnostic and guide catheters were used in the traditional PCI group, and the robotic system may have encouraged operators to minimize catheter exchanges. The use of intravascular ultrasound was also more common in the group undergoing traditional PCI. The number of total angiographic views performed per case was not recorded. Fifth, this study evaluated early experience with the robotic system. Further reductions in radiation and contrast may be possible with additional operator experience with robotic-enhanced coronary intervention.

Conclusions

This is the first study to suggest that the robotic PCI system may protect the operator and patient simultaneously. Robotic-enhanced PCI appears to be safe and effective, and compares favorably to the traditional approach. These encouraging results may herald a new era of robotic-enhanced interventional cardiology.

References

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  13. Dangas G, Iakovou I, Nikolsky E, et al. Contrast-induced nephropathy after percutaneous coronary interventions in relation to chronic kidney disease and hemodynamic variables. Am J Cardiol. 2005;95(1):13-19.
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From the Center for Interventional Vascular Therapy, New York Presbyterian Hospital, Columbia University Medical Center, New York, New York, and Shaare Zedek Medical Center, Jerusalem, Israel. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Weisz reports personal fees from Corindus,  during the conduct of the study; non-financial support from AngioSlide, personal fees from Infraredx, Svelte, Calore, and Bloxr, outside the submitted work. Dr Moses is a consultant for Boston Scientific. The remaining authors have no disclosures. 

Funding: Although the PRECISE study was sponsored by Corindus Inc, the current subanalysis was done independently by the authors.

Manuscript submitted September 10, 2013, provisional acceptance given December 30, 2013, final version accepted April 7, 2014.

Address for correspondence: Giora Weisz, MD, Associate Professor of Medicine at Columbia University Medical Center, Chairman of Cardiology, Shaare Zedek Medical Center, 12 Beyth Street, Jerusalem 91031, Israel. Email: weiszg@szmc.org.il

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