Abstract
Background
Coronary bifurcation lesions are common, difficult to treat, and associated with poorer outcomes compared to non-bifurcation lesions. The Medina classification has been widely adopted as the preferred system to classify bifurcation lesions, however there have been little efforts to characterize this metric. The objective of this study was to characterize the inter-observer variability of the Medina classification and examine its contribution to treatment selection strategy.
Methods and materials
We invited 150 interventional cardiologists from the United States and Europe to complete an online survey evaluating 12 freeze frame coronary angiograms of bifurcation lesions. Each respondent was asked to characterize the bifurcation lesions using the Medina classification and other metrics including side branch vessel size and angle. Respondents were asked to designate either a provisional (1 stent) or dedicated (2 stent) treatment strategy. ‘Complex’ lesions were defined as Medina scores 1.1.1, 0.1.1, or 1.0.1.
Results
A total of 49 interventional cardiologists responded. In 7 of the 12 angiograms evaluated, there was > 75% agreement regarding lesion classification using the Medina system. There was moderate inter-observer agreement when using Medina to classify lesions as ‘Complex’ vs. ‘non-Complex’. ‘Complex’ bifurcation designation and side branch size were predictive of selection of a dedicated treatment strategy, whereas side branch angle was not.
Conclusions
The Medina classification is a useful tool in characterizing coronary bifurcation lesions. For the majority of the angiograms evaluated there was good inter-observer agreement in lesion classification using the Medina system. ‘Complex’ bifurcation designation and side branch size were predictive of selection of a dedicated treatment strategy.
1
Introduction
Coronary bifurcation lesions are common accounting for 15%–20% of percutaneous coronary interventions (PCIs) performed . Treatment of these lesions with PCI is difficult and associated with increased risk of procedure-related complications and long term cardiac events . As a result, optimal percutaneous treatment strategies for coronary bifurcation lesions (provisional 1 stent vs. dedicated 2 stent) remain a matter of debate. According to the European Bifurcation Club (EBC), a major reason is the lack of a standardized classification system for coronary bifurcation lesions . There are many classification schemes which characterize coronary bifurcation lesions , however the majority of these classification systems are cumbersome and impractical for every day clinical use. The Medina classification is an elegant straightforward system which has been widely adopted and is currently the recommended classification system by the EBC . This system classifies lesions into seven categories using a 3 component binary key based on visual assessment of lesion severity employing a ≥ 50% stenosis threshold ( Fig. 1 ) . Stenoses ≥ 50% is assigned a 1 for each of the three arterial segments of the bifurcation in the following order, proximal main vessel (PM), distal main vessel (DM), and side branch (SB) . It has been suggested that the simplicity of this system would improve inter-observer agreement with regards to the classification of bifurcation lesions, however, this has never been formally evaluated. One criticism of the Medina classification is that it does not take into account additional factors of bifurcation lesions including side branch size and side branch angle which have been demonstrated to influence procedural outcomes . With this study, we sought to characterize the inter-observer variability of the Medina classification when evaluating coronary bifurcation lesions. Furthermore, we examined how factors such as Medina classification, side branch size, and side branch angle contribute to treatment selection strategy.
2
Methods
2.1
Methods and definitions
E-mails were sent to 150 senior Interventional Cardiologists from the United States and Europe who had expressed interest in participating in an investigational device exemption (IDE) bifurcation trial to complete an online survey which included the evaluation of 12 freeze frame coronary angiograms of bifurcation lesions. De-identified freeze frame coronary angiograms were posted on the Web for evaluation by a web-based survey system (SurveyMonkey, Palo Alto, CA). Respondents were asked to characterize each bifurcation lesion using the Medina classification . They were also asked to evaluate other angiographic metrics with regards to each bifurcation lesion including side branch vessel size (small, intermediate, large) and side branch angle (narrow: < 30°, intermediate: 30°–70°, or wide > 70°). Lastly, respondents were asked to designate either a provisional (1 stent) or dedicated (2 stent) treatment strategy for each lesion. Following data acquisition, the Medina classification was then used to differentiate ‘Complex’ vs. ‘non-Complex’ bifurcation lesions which have been previously described . ‘Complex’ bifurcation lesions were defined as Medina scores 1.1.1, 0.1.1, or 1.0.1. All other scores were defined as ‘non-Complex’ bifurcation lesions.
2.2
Statistics
Kappa statistic was used to evaluate inter-observer variability when using the Medina classification to designate ‘Complex’ or ‘non-Complex’ bifurcation lesions. Univariate and multivariate logistic regression clustered on case was used to evaluate predictors for the respondents selected treatment strategies. Model calibration and discrimination were evaluated using Hosmer–Lemeshow and calculating the area under the receiver operating characteristic curve (ROC). We calculated adjusted odds ratios for ‘Complex’ bifurcation designation, side branch size, and angle using the same multivariate logistic model.
2
Methods
2.1
Methods and definitions
E-mails were sent to 150 senior Interventional Cardiologists from the United States and Europe who had expressed interest in participating in an investigational device exemption (IDE) bifurcation trial to complete an online survey which included the evaluation of 12 freeze frame coronary angiograms of bifurcation lesions. De-identified freeze frame coronary angiograms were posted on the Web for evaluation by a web-based survey system (SurveyMonkey, Palo Alto, CA). Respondents were asked to characterize each bifurcation lesion using the Medina classification . They were also asked to evaluate other angiographic metrics with regards to each bifurcation lesion including side branch vessel size (small, intermediate, large) and side branch angle (narrow: < 30°, intermediate: 30°–70°, or wide > 70°). Lastly, respondents were asked to designate either a provisional (1 stent) or dedicated (2 stent) treatment strategy for each lesion. Following data acquisition, the Medina classification was then used to differentiate ‘Complex’ vs. ‘non-Complex’ bifurcation lesions which have been previously described . ‘Complex’ bifurcation lesions were defined as Medina scores 1.1.1, 0.1.1, or 1.0.1. All other scores were defined as ‘non-Complex’ bifurcation lesions.
2.2
Statistics
Kappa statistic was used to evaluate inter-observer variability when using the Medina classification to designate ‘Complex’ or ‘non-Complex’ bifurcation lesions. Univariate and multivariate logistic regression clustered on case was used to evaluate predictors for the respondents selected treatment strategies. Model calibration and discrimination were evaluated using Hosmer–Lemeshow and calculating the area under the receiver operating characteristic curve (ROC). We calculated adjusted odds ratios for ‘Complex’ bifurcation designation, side branch size, and angle using the same multivariate logistic model.
3
Results
A total of 49 Interventional Cardiologists, 18 from Europe and 31 from the United States, responded. Demographics of the respondents are shown in Table 1 . The twelve freeze frame coronary angiograms of bifurcation lesions including a histogram demonstrating the distribution of responses using the Medina classification for each angiogram are shown in Figs. 2 and 3 . The bordered areas in each histogram delineate scores with a ‘Complex’ bifurcation designation. With regards to bifurcation lesion classification using the Medina system, there was > 75% agreement among the respondents for 7 of the 12 angiograms evaluated. There was ≥ 50% agreement regarding lesion classification using the Medina system for 11 of the 12 angiograms evaluated. When using the Medina system to classify bifurcation lesions as ‘Complex’ vs. ‘non-Complex’, evaluation of all angiograms demonstrated moderate inter-observer agreement (kappa 0.49).
| Location of Practice | United States ( N = 31) | Europe ( N = 18) |
|---|---|---|
| Type of Practice ⁎ | ||
| Full-time academic | 71% | 28% |
| Academic affiliation | 19% | 56% |
| No academic affiliation | 10% | 16% |
| Experience | ||
| < 10 years | 19% | 11% |
| 10–20 years | 36% | 39% |
| > 20 years | 45% | 50% |
| Estimated PCIs Performed Annually | ||
| < 250 | 71% | 33% |
| > 250 | 29% | 67% |
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