Abstract
Background/purpose
Coronary stent deployment outcomes can be negatively impacted by inaccurate lesion measurement and inappropriate stent length selection (SLS). We compared visual estimate of these parameters to those provided by the CorPath 200® Robotic PCI System.
Methods
Sixty consecutive patients who underwent coronary stent placement utilizing the CorPath System were evaluated. The treating physician assessed orthogonal images and provided visual estimates of lesion length and SLS. The robotic system was then used for the same measures. SLS was considered to be accurate when visual estimate and robotic measures were in agreement. Visual estimate SLSs were considered to be “short” or “long” if they were below or above the robotic-selected stents, respectively.
Results
Only 35% (21/60) of visually estimated lesions resulted in accurate SLS, whereas 33% (20/60) and 32% (19/60) of the visually estimated SLSs were long and short, respectively. In 5 cases (8.3%), 1 less stent was placed based on the robotic lesion measurement being shorter than the visual estimate.
Conclusions
Visual estimate assessment of lesion length and SLS is highly variable with 65% of the cases being inaccurately measured when compared to objective measures obtained from the robotic system. The 32% of the cases where lesions were visually estimated to be short represents cases that often require the use of extra stents after the full lesion is not covered by 1 stent [longitudinal geographic miss (LGM)]. Further, these data showed that the use of the robotic system prevented the use of extra stents in 8.3% of the cases. Measurement of lesions with robotic PCI may reduce measurement errors, need for extra stents, and LGM.
Highlights
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Manual measurement of coronary lesions is variable and subject to error.
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Objective measurement of lesions by robotic PCI may reduce measurement errors.
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Measurement by robotic PCI prevented the use of extra stents.
1
Introduction
Despite advances in percutaneous coronary intervention (PCI) technology, restenosis leading to target lesion revascularization still occurs in 3%–9% of the cases . The ultimate success of PCI procedures is multi-factorial and dependent on both non-modifiable patient-related factors and modifiable procedure-related factors. The importance of modifiable procedural factors was highlighted in the 1419 patient STLLR trial. The results of this study showed that longitudinal geographic miss (LGM), which was defined as a stent failing to fully cover the entire injured or stenotic arterial segment, resulted in a 2.5-fold increase in the number of patients requiring target vessel revascularization .
A potential cause of LGM is the traditional visual estimate of lesion length. Numerous studies have shown that there is a high degree of inter-rater and intra-rater variability associated with visual assessment of stenosis severity when compared to objective measurement techniques . A recent survey study of 40 interventional cardiologists comparing visual estimate to qualitative coronary angiography (QCA) showed that visually estimated lesion length was accurate in only 30% of the cases, which lead to both the selection of overly long and overly short stents in 23% and 24% of the cases, respectively .
Based on these data, it is possible that the employment of objective lesion measurement techniques could improve PCI outcomes. Robotic PCI (R-PCI) has been shown to be effective and safe for treating coronary lesions . These early studies of R-PCI did not employ the objective lesion measurement features built into the system, although a subsequently conducted case series has demonstrated the utility of using this feature . This study represents a single center case series comparing visual estimate to R-PCI lesion measurement.
2
Methods
2.1
Procedure
This study was conducted as a single center case series. Sixty (60) consecutive patients who underwent coronary stent placement utilizing the CorPath System between April 22, 2014 and August 1, 2014 were evaluated. The Robotic PCI System was used in stable interventional patients with coronary anatomy deemed appropriate by the interventional cardiologist. This series of patients equates to approximately 6% of the hospital’s annual interventional volume. Prior to using any of the measurement capabilities of the CorPath System, the treating physician reviewed orthogonal lesion images from the diagnostic angiography and provided visual estimates of lesion length and stent length selection (SLS). The robotic system was then used to assess the same measures.
2.2
Robotic system
The CorPath 200 Robotic PCI System (Corindus Vascular Robotics, Waltham, MA) has been described in detail elsewhere . Briefly, the system consists of two major components: an interventional cockpit and a bedside unit. The interventional cockpit comprises radiation-shielded, workstation where the interventional cardiologist sits at the cockpit and performs PCI by manipulating joysticks or touch-screen controls. Monitors inside the cockpit provide fluoroscopy, ECG, and hemodynamic data. The bedside unit consists of an articulated arm mounted to the procedure table to support a robotic drive housing a single-use sterile cassette. The guide catheter is connected to the cassette, through which the guide wire and interventional devices (balloons and stents) are introduced. The interventional cardiologist can manipulate the linear and rotational motions of the guide wire and interventional devices to facilitate the lesion treatment. The physician controls the measurement feature by advancing the balloon or guide wire markers to the distal and proximal edges of the lesion of interest. The distal edge is marked as “0” on the touch screen display. When the marker is at the proximal edge a measurement of the distance traveled by the marker is displayed to provide a lesion length.
2.3
Study endpoints and definitions
The study evaluated SLS based on both visual estimate and robotic measurement of lesions. Stent length selection was considered to be accurate when the visual estimate and robotic measurement were in agreement and the visual estimate SLS would adequately cover the robotically measured lesion. Visual estimate SLSs were considered to be “short” or “long” if they were below or above the robotic-selected stents, respectively and a more appropriately sized stent could be used to cover the lesion. The data were further analyzed to describe cases with definite stent savings. Definite stent savings was defined as those cases where the lesion measurement provided by the R-PCI system resulted in the use of fewer stents than that determined through visual estimation.
2.4
Statistical analysis
Continuous variables are expressed as mean ± SD. Categorical variables are presented as absolute numbers and percentages. A paired T-test was used to compare visual estimate to robotic measurement of the lesions. A P value of less than 0.05 was considered to indicate a significant difference.
2
Methods
2.1
Procedure
This study was conducted as a single center case series. Sixty (60) consecutive patients who underwent coronary stent placement utilizing the CorPath System between April 22, 2014 and August 1, 2014 were evaluated. The Robotic PCI System was used in stable interventional patients with coronary anatomy deemed appropriate by the interventional cardiologist. This series of patients equates to approximately 6% of the hospital’s annual interventional volume. Prior to using any of the measurement capabilities of the CorPath System, the treating physician reviewed orthogonal lesion images from the diagnostic angiography and provided visual estimates of lesion length and stent length selection (SLS). The robotic system was then used to assess the same measures.
2.2
Robotic system
The CorPath 200 Robotic PCI System (Corindus Vascular Robotics, Waltham, MA) has been described in detail elsewhere . Briefly, the system consists of two major components: an interventional cockpit and a bedside unit. The interventional cockpit comprises radiation-shielded, workstation where the interventional cardiologist sits at the cockpit and performs PCI by manipulating joysticks or touch-screen controls. Monitors inside the cockpit provide fluoroscopy, ECG, and hemodynamic data. The bedside unit consists of an articulated arm mounted to the procedure table to support a robotic drive housing a single-use sterile cassette. The guide catheter is connected to the cassette, through which the guide wire and interventional devices (balloons and stents) are introduced. The interventional cardiologist can manipulate the linear and rotational motions of the guide wire and interventional devices to facilitate the lesion treatment. The physician controls the measurement feature by advancing the balloon or guide wire markers to the distal and proximal edges of the lesion of interest. The distal edge is marked as “0” on the touch screen display. When the marker is at the proximal edge a measurement of the distance traveled by the marker is displayed to provide a lesion length.
2.3
Study endpoints and definitions
The study evaluated SLS based on both visual estimate and robotic measurement of lesions. Stent length selection was considered to be accurate when the visual estimate and robotic measurement were in agreement and the visual estimate SLS would adequately cover the robotically measured lesion. Visual estimate SLSs were considered to be “short” or “long” if they were below or above the robotic-selected stents, respectively and a more appropriately sized stent could be used to cover the lesion. The data were further analyzed to describe cases with definite stent savings. Definite stent savings was defined as those cases where the lesion measurement provided by the R-PCI system resulted in the use of fewer stents than that determined through visual estimation.
2.4
Statistical analysis
Continuous variables are expressed as mean ± SD. Categorical variables are presented as absolute numbers and percentages. A paired T-test was used to compare visual estimate to robotic measurement of the lesions. A P value of less than 0.05 was considered to indicate a significant difference.
3
Results
Sixty patients were included in this evaluation. Baseline demographic and lesion characteristics are detailed in Tables 1 and 2 . The majority (68%) of the patients were male and there were similar number of patients presenting with stable (53%) and unstable (47%) angina. Majority (55%) of the treated lesions were complex lesions that were graded as ACC/AHA class B2 (20%) or C (35%). The radial artery was the most common access site (88%). Table 3 shows the lesion measurement characteristics by visual estimation and the robotic PCI System. When comparing measurement of each lesion, only 35% of the visually estimated lesions matched the robotic measurement. Of the 65% of the lesions that were not accurate, 32% were short and 33% were long. Table 4 displays the direct comparison of the lesion lengths measured visually versus those measured by the robot. Lesions that fall into the accurate category tended to be shorter, yet covered by the visual estimate SLSs, whereas longer lesions were more likely to be under or over-estimated by visual estimation. Further analysis of the cases, showed that there were 5 cases where the visual estimate would have led to the use of two stents, but the robotic lesion measurement, which was shorter resulted in the use of a single stent. (See Table 5 .)
