Accuracy and Reliability of Peripheral Artery Calcium Scoring Systems Using an Intravascular Ultrasound Reference Standard.

BACKGROUND: Peripheral artery calcium scoring systems are commonly used in clinical trials to categorize calcium severity but there are little data on their accuracy and reliability. The purpose of this study was to investigate the accuracy and reliability of these systems. METHODS: Angiographic, computed tomography angiography, and intravascular ultrasound (IVUS) imaging were obtained from 47 consecutive cases sourced from a prospectively collected database of patients undergoing femoropopliteal artery endovascular intervention. Two independent blinded readers graded calcium severity using the Peripheral Arterial Calcium Scoring System, Peripheral Academic Research Consortium, and Fanelli calcium scoring systems. IVUS maximum arc of calcium and calcium length were compared between severity grades for each scoring system. The diagnostic accuracy of each scoring system for identifying severe calcium was calculated using the reference standard of an IVUS maximum calcium arc ≥ 180°. Agreement testing was performed between scoring systems and between and within observers for each system. RESULTS: IVUS identified calcium in 85% (42/47) of cases, compared to 68% (32/47) of cases with angiography. There were no differences in IVUS calcium parameters between grades of calcium for any of the scoring systems. Severe calcium was detected by IVUS in 30 cases, in 23 cases by Peripheral Arterial Calcium Scoring System (sensitivity: 73%, specificity: 33%, positive predictive value [PPV]: 83%, negative predictive value [NPV]: 22%), in 12 cases by Peripheral Academic Research Consortium (sensitivity: 42%, specificity: 83%, PPV: 92%, NPV: 25%), and in 10 cases by Fanelli (sensitivity: 39%, specificity: 100%, PPV: 100%, NPV: 27%). Agreement between scoring systems was weak to moderate (range: k = 0.55-0.74). Interobserver agreement was weak (k = 0.41-0.54) and intraobserver agreement was highly variable ranging from k = 0.41 to k = 0.92. CONCLUSIONS: The poor diagnostic accuracy and weak-to-moderate reliability of calcium scoring systems raise doubts about the use of current calcium scoring systems for use in clinical trials.

Comparison of Angiographic Dissection Classification Systems in the Femoropopliteal Arteries Using IVUS Validation and Reliability Testing.

PURPOSE: Objective assessment of dissection severity is difficult. Recognition of this has led to the creation of classification systems. This study investigated the performance of the National Heart Lung and Blood Institute (NHLBI) and Kobayashi systems at differentiating severity of femoropopliteal dissection using intravascular ultrasound (IVUS) as the reference standard. Comparison between the 2 systems and the inter- and intra-observer reliability were also investigated. MATERIALS AND METHODS: Angiographic and IVUS imaging was assessed in 51 cases sourced from a RCT investigating the use of IVUS in femoropopliteal disease. A total of 2 readers independently scored the angiography images according to NHLBI and Kobayashi dissection classification systems and a consensus score was obtained for each system in each case. The NHLBI classification was condensed into 3 grades of dissection to allow comparison between systems. Dissection length, dissection arc, minimum lumen area, and lumen area stenosis were obtained from the IVUS imaging. IVUS parameters were compared between grades of severity for both systems. Agreement in grading between the systems was assessed and IVUS parameters for each level of dissection severity were compared between systems. Inter and intra-observer agreement tested for each system. RESULTS: Dissection was present on IVUS in 92.2% (47/51) of cases and angiography identified 78.7% (37/47) of these. No difference was present in any IVUS parameters between mild and severe dissections with either classification system. No difference in IVUS findings was present for the same grades of dissection between systems. The 2 systems agreed on severity grade in 47 of 51 cases. The inter-observer agreement was for NHLBI was k=0.549 and k=0.627 for Kobayashi. Intra-observer agreement for NHLBI was k=0.633 and k=0.633 and for Kobayashi was k=0.657 and k=0.297. CONCLUSION: The lack of difference in IVUS parameters between mild and severe dissection for the NHLBI and Kobayashi systems raises doubts about their ability to effectively differentiate dissection severity. Weak to moderate reliability suggests that variability in interpreting dissection may be higher than acceptable. IVUS imaging is more sensitive for detecting dissection than angiography and research is required to establish the value of adding IVUS to dissection classification systems.

Marfan syndrome resulting from a rare pathogenic FBN1 variant, ascertained through a proband with IgG4-related arteriopathy.

A 57-year-old man with a family history of aortic aneurysm was found, during assessment of unexplained fever, to have an infrarenal aortic aneurysm requiring immediate repair. Dilatation of popliteal and iliac arteries was also present. Progressive aortic root dilatation with aortic regurgitation was documented from 70 years leading to valve-sparing aortic root replacement at 77 years, at which time genetic studies identified a likely pathogenic FBN1 missense variant c.6916C > T (p.Arg2306Cys) in exon 56. The proband's lenses were normally positioned and the Marfan syndrome (MFS) systemic score was 0/20. Cascade genetic testing identified 15 other family members with the FBN1 variant, several of whom had unsuspected aortic root dilatation; none had ectopia lentis or MFS systemic score ≥ 7. Segregation analysis resulted in reclassification of the FBN1 variant as pathogenic. The combination of thoracic aortic aneurysm and dissection (TAAD) and a pathogenic FBN1 variant in multiple family members allowed a diagnosis of MFS using the revised Ghent criteria. At 82 years, the proband's presenting abdominal aortic aneurysm was diagnosed retrospectively to have resulted from IgG4-related inflammatory aortopathy.

Reconstruction of the aorto-iliac segment in occlusive disease using the AFX unibody graft.

BACKGROUND: The endovascular era has evolved the treatment of aorto-iliac occlusive disease (AIOD). Many institutions now use minimally invasive techniques including kissing iliac stents and covered endovascular reconstruction of the aortic bifurcation. These negate the high morbidity of open surgical reconstruction but do not allow for a crossover approach to treat infra-inguinal disease. The AFX stent does both by anatomically reconstructing the bifurcation in AIOD despite being marketed for aneurysmal aortic disease. This large, single-centre case series assesses the outcomes of treatment of AIOD using the AFX stent. METHODS: Patients with AIOD who presented to our institution between September 2016 and August 2018 were considered for AFX stenting if kissing iliac stents extending into the aorta or aortobifemoral bypass was required. Patient, treatment and outcome data were recorded with a primary outcome of primary patency at 12 months. RESULTS: AFX stenting was performed in 29 patients, with an average age of 69 years, 52% (15/29) patients had critical limb ischaemia. Technical success occurred in 100% of patients with clinical success in 96% (28/29). There were no cases of 30 day and 3 (10%) cases of 12 month mortality, 2 (7%) major and 7 (24%) minor complications arose. Median length of stay was 3 days. Primary patency at 12 months was 100% (n = 24). CONCLUSION: AFX stenting is a safe with satisfactory early results for the treatment of AIOD. The minimally invasive technique and preservation of cross-over approach makes AFX stenting a considered option for the treatment of AIOD.